Channel quality reporting in a mobile communication system

(56) References cited:

US-A1- 2006 223 449 US-A1- 2008 253 336 US-A1-2009 175 232 • LTE; Evolved Universal Terrestrial Rádió Access (E-UTRA); Physical layer procedures (3GPP TS 36.213 version 8.7.0 Release 8) TECHNICAL SPECIFICATION, EUROPEAN TELECOMMUNICATIONS STANDARDS INSTITUTE (ETSI), 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS ; FRANCÉ, no. V8.7.0, 1 June 2009 (2009-06-01), XP014044750 • ITRI: Carrier Identification in PDCCH 3GPP DRAFT;

R1-092683_CARRIER_INDICATION_IN_PDCCH, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCÉ, no. Los Angeles, USA; 20090624, 24 June 2009 (2009-06-24), XP050351161 [retrieved on 2009-06-24] • FRANK Η P FITZEK ED - HUNG-YU WEI ET AL: The Médium is the Message COMMUNICATIONS, 2006. ICC Ό6. IEEE INTERNATIONAL CONFERENCE ON, IEEE, Pl, 1 June 2006 (2006-06-01), pages 5016-5021, XP031025708 ISBN: 978-1-4244-0354-7 • KAMRAN ETEMAD, HUJUN YIN, SASSAN AHMADI: Updated Proposal fór Generalized Multi-carrier Support in IEEE 802.16m Systems IEEE 802.16 BROADBAND WIRELESS ACCESS WORKING GROUP <HTTP://IEEE802.ORG/16>IEEE 802.16 BROADBAND WIRELESS ACCESS WORKING GROUP <HTTP://IEEE802.ORG/16>, vol. IEEE C80216m-08/401r2, 5 May 2009 (2009-05-05), XP002569509

Note: Within nine months ofthe publication ofthe mention ofthe grant ofthe European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall nőt be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).

Printed by Jouve, 75001 PARIS (FR)

ΕΡ 2 462 759 Β1

Description

FIELD OF THE INVENTION [0001] The invention relates methods fór triggering and reporting on a downlink channel quality (channel quality feedback) experienced by a terminál (e.g. a mobile terminál or a user equipment) by means of channel quality information fór at least one of plural component carriers of a communication system available fór downlink transmission to the terminál. Furthermore, the invention alsó relates to an implementation of these methods in hardware and software.

TECHNICAL BACKGROUND

Long Term Evolution (LTE) [0002] Third-generation mobile systems (3G) based on WCDMA radio-access technology are being deployed on a broad scale all around the world. A first step in enhancing or evolving this technology entails introducing High-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, alsó referred to as High Speed Uplink Packet Access (HSUPA), giving a radio-access technology that is highly competitive.

[0003] In order to be prepared fór further increasing user demands and to be competitive against new rádió access technologies 3GPP introduced a new mobile communication system which is called Long Term Evolution (LTE). LTE is designed to meet the carrier needs fór high speed data and média transport as well as high capacity voice support to the next decade. The ability to provide high bit rates is a key measure fór LTE.

[0004] The work item (Wl) specification on Long-Term Evolution (LTE) called Evolved UMTS Terrestrial Rádió Access (ÚTRA) and UMTS Terrestrial Rádió Access Network (UTRAN) is to be finalized as Release 8 (LTE). The LTE system represents efficient packet-based rádió access and rádió access networks that provide full IP-based functionalities with low latency and low cost. The detailed system requirements are given in. In LTE, sealahle multiple transmission bandwidths are specified such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in order to achieve flexible system deployment using a given spectrum. In the downlink, Orthogonal Frequency Division Multiplexing (OFDM) based rádió access was adopted because of its inherent immunity to multipath interference (MPI) due to a low Symbol rate, the use of a cyclic prefix (CP), and its affinity to different transmission bandwidth arrangements. Single-carrier frequency division multiple access (SC-FDMA) based rádió access was adopted in the uplink, since provisioning ofwide area coverage was prioritized over improvement in the peak data rate considering the restricted transmission power ofthe user equipment (UE). Many key packet rádió access techniques are employed including multiple-input multiple-output (ΜΙΜΟ) channel transmission techniques, and a highly efficient control signaling structure is achieved in LTE (Release 8).

LTE architecture [0005] The overall architecture is shown in Fig. 1 and a more detailed representation ofthe E-UTRAN architecture is given in Fig. 2. The E-UTRAN consists of eNodeB, providing the E-UTRA user pláne (PDCP/RLC/MAC/PHY) and control pláne (RRC) protocol terminations towards the user equipment (UE). The eNodeB (eNB) hosts the Physical (PHY), Médium Access Control (MAC), Rádió Link Control (RLC), and Packet Data Control Protocol (PDCP) layers that include the functionality of user-plane header-compression and encryption. It alsó offers Rádió Resource Control (RRC) functionality corresponding to the control pláne. It performs many functions including rádió resource management, admission control, scheduling, enforcement of negotiated uplink Quality of Service (QoS), cell information broadeast, ciphering/deciphering of user and control pláne data, and compression/decompression ofdownlink/uplink user pláne packet headers. The eNodeBs are interconnected with each other by means ofthe X2 interface.

[0006] The eNodeBs are alsó connected by means of the S1 interface to the EPC (Evolved Packet Core), more specifically to the MME (Mobility Management Entity) by means ofthe S1-MME and to the Serving Gateway (SGW) by means ofthe S1-U. The S1 interface supports a many-to-many relation between MMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user data packets, while alsó acting as the mobility anchorforthe user pláne during intereNodeB handovers and as the anchorfor mobility between LTE and other 3GPP technologies (terminating S4 interface and relaying the traffic between 2G/3G systems and PDN GW). Fór idle state user equipments, the SGW terminates the downlink data path and triggers paging when downlink data arrives fór the user equipment. It manages and Stores user equipment contexts, e.g. parameters ofthe IP bearer service, network internál routing information. It alsó performs replication ofthe user traffic in case of lawful interception.

[0007] The MME is the key control-node fór the LTE access-network. It is responsible fór idle mode user equipment tracking and paging procedure including retransmissions. It is involved in the bearer activation/deactivation process and is alsó responsible fór choosing the SGW fór a user equipment at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation. It is responsible fór authenticating the user (by interacting with the HSS).

ΕΡ 2 462 759 Β1

The Non-Access Stratum (NAS) signaling terminates at the MME and it is alsó responsible fór generation and allocation of temporary identities to user equipments. It checks the authorization of the user equipment to camp on the service provider’s Public Land Mobile Network (PLMN) and enforces user equipment roaming restrictions. The MME is the termination point in the network fór ciphering/integrity protection fór NAS signaling and handles the security key management. Lawful interception of signaling is alsó supported by the MME. The MME alsó provides the control pláne function fór mobility between LTE and 2G/3G access networks with the S3 interface terminating at the MME from the SGSN. The MME alsó terminates the S6a interface towards the home HSS fór roaming user equipments.

Channel Quality Report in LTE (Release 8) [0008] Channel quality information is used in a multi-user communication system to determine the quality of channel resource(s) fór one or more users. This information may be used to aid in a multi-user scheduler algorithm ofthe eNodeB (or other radio-access elements such as a relay node) to assign channel resources to different users, or to adapt link parameters (e.g. modulation scheme, coding rate, or transmit power) so as to exploit the assigned channel resource to its fullest potential.

[0009] Assuming a multi-carrier communication system, e.g. employing OFDM, as fór example discussed in the Long Term Evolution work item of 3GPP, the smallest unit of resources that can be assigned/allocated by the scheduler is one resource block. A physical resource block is defined as consecutive OFDM symbols in the time domain and /yRB consecutive subcarriers in the frequency domain as exemplified in Fig. 3. In 3GPP LTE (Release 8), a physical resource block thus consists of resource elements, corresponding to one siót in the time domain and 180 kHz in the frequency domain (fór further details on the downlink resource grid, see 3GPP TS 36.211, Evolved Universal Terrestrial Rádió Access (E-UTRA); Physical Channels and Modulation (Release 8), version 8.7.0, section 6.2, available at http://www.3gpp.org). In the ideál case, channel quality information fór all resource blocks fór all users should be always available to the scheduler so as to take an optimum scheduling decision. However, due to constrained capacity of the feedback channel it is nőt possible/feasible to ensure this type of up-to-dateness of channel quality information. Therefore, reduction and/or compression techniques are required so as to transmit - fór example - channel quality information only fór a subsetof resource blocks fór a given user. In 3GPP LTE, the smallest unit fór which channel quality is reported is called a sub-band, which consists of multiple (n) frequency-adjacent resource blocks (i.e. n- subcarriers).

Channel Quality Feedback Elements [0010] In 3GPP LTE, there exist three basic elements which mayormay nőt be given as feed back fór the channel quality:

Modulation and Coding Scheme Indicator (MCSI), which is alsó referred to as Channel Quality Indicator (CQI) in the 3GPP LTE specifications,

Precoding Mátrix Indicator (PMI) and

Ránk Indicator (Rl) [0011] The MCSI suggests a modulation and coding scheme that should be employed fór downlink transmission to a reporting user equipment, while the PMI points to a precoding matrix/vector that is to be employed fór multi-antenna transmission (ΜΙΜΟ) using an assumed transmission mátrix ránk or a transmission mátrix ránk that is given by the Rl. Details on channel quality reporting and transmission mechanisms are can be found in 3GPP TS 36.212, Evolved Universal Terrestrial Rádió Access (E-UTRA); Multiplexing and channel coding (Release 8), version 8.7.0, sections 5.2 and 3GPP TS 36.213, Evolved Universal Terrestrial Rádió Access (E-UTRA); Physical layer procedures (Release 8), version 8.7.0, section 7.2 (all documents available at http://www.3gpp.org).

[0012] All of these elements are summarized as under the term channel quality feedback herein. Hence, a channel quality feedback can contain any combination of or multiple MCSI, PMI, Rl values. Channel quality feedback reports may further contain or consist of metrics such as a channel covariance mátrix or elements, channel coefficients, or other suitable metrics as apparent to those skilled in the art.

Triggering and Transmission of Channel Quality Feedback [0013] In 3GPP LTE (Release 8) there are different possibilities defined, how to trigger the user equipments to send

ΕΡ 2 462 759 Β1 channel quality feedback on the downlink channel quality. Besides periodic CQI reports (see section 7.2.2 in 3GPP TS 36.213, version 8.7.0), there is alsó the possibility to use L1/L2 control signaling to a user equipment to request the transmission ofthe so-called aperiodic CQI report (see section 7.2.1 in 3GPP TS 36.213, version 8.7.0). This L1/L2 control signaling can alsó be used in the random access procedure (see section 6 in 3GPP TS 36.213, version 8.7.0). In both these cases, a special CQI request field/bit/flag is included in the control message from the eNodeB/relay node. [0014] The L1/L2 control signaling that conveys information about an Uplink assignment is sometimes called UL-DCI (Uplink Dedicated Control Information). Fig. 4 shows an example ofthe DCI formát 0 for FDD operation as defined in 3GPP TS 36.212, section 5.3.3.1.1 which serves to convey uplink DCI (please note that the CRC field of DCI formát 0 is nőt shown in Fig. 4 forsimplicity. The CQI request flag contains information whether the receiver should transmit CQI within the allocated uplink resources or nőt. Whenever such a trigger is received, the user subsequently transmits the feedback generally togetherwith uplink data on the assigned Physical Uplink Shared CHannel (PUSCH) resources (the detailed procedure is described in section 7.2 et seq. in 3GPP TS 36.213, version 8.7.0).

Further Advancements for LTE - LTE-Advanced (LTE-A) [0015] The frequency spectrum for IMT-Advanced was decided at the World Radiocommunication Conference 2007 (WRC-07) in November 2008. Although the overall frequency spectrum for IMT-Advanced was decided, the actual available frequency bandwidth is different according to each region or country. Following the decision on the available frequency spectrum outline, however, standardization of a rádió interface started in the 3rd Generation Partnership Project (3GPP). At the 3GPP TSG RAN #39 meeting, the Study Item description on Further Advancements for E-UTRA (LTE-Advanced) was approved which is alsó referred to as Release 10. The study item covers technology components to be considered for the evolution of E-UTRA, e.g. to fulfill the requirements on IMT-Advanced. Two major technology components which are currently under consideration for LTE-A are described in the following.

[0016] In order to extend the overall system bandwidth, LTE-A (Release 10) uses carrier aggregation, where two or more component carriers are aggregated in order to support wider transmission bandwidths e.g. up to 100 MHz and for spectrum aggregation. It is commonly assumed that a single component carrier does nőt exceed a bandwidth of 20 MHz. [0017] A terminál may simultaneously récéivé and/or transmit on one or multiple component carriers depending on its capabilities:

An LTE-Advanced (Release 10) compatible mobile terminál with reception and/or transmission capabilities for carrier aggregation can simultaneously récéivé and/or transmit on multiple component carriers. There is one Transport Block (in absence of spatial multiplexing) and one HARQ entity per component carrier.

An LTE (Release 8) compatible mobile terminál can récéivé and transmiton a single component carrier only, provided that the structure ofthe component carrier follows the Release 8 specifications.

[0018] It is alsó envisioned to configuré all component carriers LTE (Release 8)-compatible, at least when the aggregated numbers of component carriers in the uplink and the downlink are same. Consideration of non-backward-compatible configurations of LTE-A component carriers is nőt precluded.

[0019] The 3GPP contribution R1-092683 by ITRI, Carrier Identification in PDCCH, Sophia-Antipolis Cedex, 24 June 2009, XP050351161, discusses possibilities to provide a carrier indication in the PDCCH for the case in which the PDCCH for a given component carrier is nőt transmitted on the same component carrier. In particular, a 3-bit carrier indicator field (CIF) may be added to the PDCCH. It discusses additional options for carrier indication including carrier specific RNTIs, special CRC masking and a new DCI formát indication.

Channel Quality Feedback in LTE-A (Release 10) [0020] As there is only one component carrier defined in LTE (Release 8), there is no ambiguity at the user equipment on which portion ofthe system bandwidth CQI reporting is to be done. The CQI request flag (togetherwith the current transmission mode) is unambiguously indicating to the user equipment how to provide CQI feedback to the eNodeB. [0021] With the introduction of carrier aggregation in LTE-A (Release 10) and assuming that the LTE (Release 8) CQI reporting procedures should be reused, there are different possibilities how a CQI request can be interpreted by the user equipment. As shown in Fig. 5, it may be generally assumed that UL-DCI (containing the CQI request) for uplink transmission that is transmitted from a eNodeB or relay node to a user equipment is placed within a single downlink component carrier. A simple rule to handle the CQI request at the user equipment would be that whenever a UL-DCI requests a CQI transmission by the user equipment, same applies to the downlink component carrier where the corresponding UL-DCI is transmitted. I.e. the user equipment would only send aperiodic CQI feedback in a given UL transmission for those downlink component carriers that comprised a UL-DCI requesting a CQI report at the same time.

ΕΡ 2 462 759 Β1 [0022] An alternative handling of UL-DCI comprising a CQI request is shown in Fig. 6. Whenever a UL-DCI requests a CQI transmission by the user equipment, the user equipment applies said request to all downlink component carriers available fór downlink transmission to the user equipment.

[0023] When downlink transmission can occur on multiple component carriers, an efficient scheduling and link adaptation depends on the availability of accurate and up-to-date CQI. However, in order to make efficient use ofthe control signaling and CQI transmission resources, it should be possible to control fór how many and which component carriers a CQI is to be requested (from the network side) and transmitted (from the terminál side).

[0024] According to the first solution discussed above with respect to Fig. 5, in order to request CQI fór multiple component carriers the number of component carriers fór which CQI is requested is identical to the number of required transmitted UL-DCI messages. In other words, to request CQI fór five component carriers it is required to transmit five times more UL-DCI messages than fór the case of requesting CQI fór just a single component carrier. This solution is therefore nőt very efficient from a downlink control overhead point of view. According to the second solution above illustrated in Fig. 6, a single uplink DCI message requests CQI fór all component carriers. Therefore the downlink control overhead is very small. However, the resulting uplink transmission always requires a large amount of resources to accommodate the transmission of CQI fór all component carriers, even though the network knows that it currently requires CQI only fór a single selected component carrier. Therefore this is nőt efficient fór the usage of uplink resources, and does nőt offer any flexibility fór the number of requested component carrier CQI.

SUMMARY OF THE INVENTION [0025] One object ofthe invention is to suggest a mechanism fór triggering channel quality feedback from a mobile terminál where the downlink control signaling overhead fór the selection of component carrier(s) to be reported on is minimized.

[0026] The object is solved by the subject matter of the independent claims. Advantageous embodiments of the invention are subject to the dependent claims.

[0027] In particular, the status ofthe CQI request flag is nőt decisive forthe interpretation ofthe remaining fields within the dedicated control information. In this exemplary alternative embodiment ofthe invention a combination ofat least one bit ofthe second control information field and the CQI request flag is unconditionally interpreted as the CQI control information indicative of one or more of the component carriers available fór downlink transmission to the terminál on which the terminál is to report channel quality information.

[0028] Generally, the invention can be used in 3GPP-based communication systems, in particular in a 3GPP LTE-(Release 10) system. Fór example, in one implementation, the dedicated control information ofthe predetermined formát is Dedicated Control Information of DCI formát 0 defined in 3GPP LTE (Release 8).

BRIEF DESCRIPTION OF THE FIGURES [0029] In the following the invention is described in more detail in reference to the attached figures and drawings. Simiíar or corresponding details in the figures are marked with the same reference numerals.

Fig. 1 shows an exemplary architecture of a 3GPP LTE system,

Fig. 2 shows an exemplary overview ofthe overall E-UTRAN architecture of LTE,

Fig. 3 shows an exemplary downlink resource grid as defined fór 3GPP LTE (Release 8),

Fig. 4 shows the formát DCI formát 0 of dedicated control information (DCI) according to 3GPP LTE (Release 8) fór FDD operation,

Figs. 5 &amp; 6 show exemplary Solutions fór triggering aperiodic CQI reporting from a user equipment in a 3GPP LTE-A (Release 10) system,

Fig. 7 shows the formát DCI formát 0 of dedicated control information (DCI) according to 3GPP LTE (Release 8) fór FDD operation, when frequency hopping is activated,

Figs. 8 to 12 show different interpretations ofthe content of dedicated control information (DCI) according to DCI formát 0 of 3GPP LTE (Release 8) fór FDD operation, when reusing the formát in 3GPP LTE-A (Release 10) system,

EP 2 462 759 Β1

Figs. 13 to 17 show different formats of dedicated control information (DCI) according to different embodiments of the invention, when considering the interpretationsof Figs. 8 to 12 as individual formats ofthe dedicated control information,

Fig. 18 shows flow chart ofan exemplary operation of a node in the access network and a terminál according to an embodiment of the invention

Fig. 19 shows an exemplary formát fór dedicated control information according to an embodiment of the invention,

Fig. 20 shows the maximum size of allocatable physical resource blocks depending on the overall system bandwidth, when using and nőt using hopping in the uplink, in a 3GPP LTE (Release 8) system, and

Fig. 21 shows the signaling messages of a contention free random access procedure in a 3GPP LTE (Release

8) system

Figs. 22 &amp;23 show two exemplary formats fór dedicated control information according to further embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION [0030] The following paragraphs will describe various embodiments ofthe invention. Fór exemplary purposes only, most ofthe embodiments are outlined in relation to an orthogonal single-carrier uplink rádió access scheme according to 3GPP LTE (Release 8) and LTE-A(Release 10) mobile communication systems discussed in the Technical Background section above. It should be noted that the invention may be advantageously used fór example in connection with a mobile communication system such as 3GPP LTE (Release 8) and LTE-A (Release 10) communication systems previously described, bút the invention is nőt limited to its use in this particular exemplary communication network.

[0031] The explanations given in the Technical Background section above are intended to better understand the mostly 3GPP LTE (Release 8) and LTE-A (Release 10) specific exemplary embodiments described herein and should nőt be understood as limiting the invention to the described specific implementations of processes and functions in the mobile communication network. Nevertheless, the improvements to the random access procedure proposed herein may be readily applied in the architectures/systems described in the Technical Background section and may in somé embodiments ofthe invention alsó make use of standard and improved procedures of theses architectures/systems.

[0032] As indicated in the Summary of Invention section, one aspect of this invention is to suggest a new interpretation of a predetermined formát fór dedicated control information comprísing a CQI request flag. The CQI request flag is a flag (e.g. 1 bit) that is used to request a terminál receiving the dedicated control information to provide channel quality feedback. The interpretation ofthe content ofthe dedicated control information may or may nőt depend on the status of the CQI request flag, depending on the implementation. In one exemplary implementation, the predetermined formát of the dedicated control information is the DCI formát 0 as defined fór 3GPP LTE (Release 8) that is interpreted in a different manner depending on the status of at least the CQI request flag comprised therein. Fig. 4 exemplarily shows the DCI formát 0 as defined fór 3GPP LTE (Release 8) fór the FDD operation.

[0033] As indicated above, in somé exemplary embodiment ofthe invention that will be outlined in the following in more detail, the status ofthe CQI requestflag comprised in the dedicated control information according the predetermined dedicated control information formát is determining how the remaining content ofthe dedicated control information is interpreted by the terminál. The terminál may be fór example a mobile terminál, a user equipment or a relay node. To pút this differently, in these examples, the CQI request flag could alsó be considered a formát identification: In case the CQI requestflag is nőt set, the content ofthe dedicated control information is interpreted as defined forthe predetermined formát. In case the CQI requestflag is set, the dedicated control information is nőt interpreted as defined forthe predetermined formát, i.e. has a different formát than the predetermined formát.

[0034] In case the CQI request flag is set, at least one further bit of the dedicated control information fór uplink transmission is interpreted by a terminál receiving the dedicated control information as information indicative ofthe one or more component carriers available fór downlink transmission to the terminál and the terminál is providing channel quality feedback on the channel quality experienced on the indicated component carrier or component carriers. This at least one further bit that can be considered as CQI control information could correspond to a part or parts of one or more control information fields comprised in the dedicated control information according to the definition ofthe predetermined formát, or

ΕΡ 2 462 759 Β1 one or more control information fields comprised in the dedicated control information according to the definition of the predetermined formát, or a mixture between a part or parts of and entire control information fields comprised in the dedicated control information according to the definition ofthe predetermined formát.

[0035] In one example, the control information field or fields (part or parts of which are) interpreted as CQI control information include a hopping flag, a resource assignmentfield, a DMRS field, an uplink carrier indicatorfield and padding bits. When implementing the invention in an LTE-A (Release 10) system, the numberof padding bits within the dedicated control information may depend on the system’s bandwidth. In typical scenarios, one can expect that there are 0,1 or 2 padding bits (depending on the system bandwidth).

[0036] In another alternative exemplary implementation, the combination ofthe CQI requestflag and the at leastone further bit of the dedicated control information is used to indicate the one or more component carriers available for downlink transmission to the terminál on which the terminál is to report channel quality feedback. Hence, in this example, the interpretation of the dedicated control information may nőt depend on the status ofthe CQI request flag. Instead, a combination ofthe CQI requestflag and at least a part of at least one further control information field indicates the one or more component carriers available for downlink transmission to the terminál and the terminál is providing channel quality feedback on the channel quality experienced on the indicated component carrier or component carriers [0037] According to another, alternative aspect ofthe invention, the indication ofthe component carrier or component carriers the terminál is requested to provide channel quality feedback on is indicated by the time and/or frequency resources on which the dedicated control information is received at the terminál and/or the transport formát of the dedicated control information. For example, it can be assumed that the one or more control channel elements onto which the dedicated control information for a terminál is mapped is/are themselves mapped to the physical resources of one or more component carriers for downlink transmission according to different patterns. Each pattern could thereby indicate a combination of component carriers (at least one) available for downlink transmission to the terminál on which the terminál is to provide channel quality feedback.

[0038] Generally, it should be noted that available in formulations like component carriers available for downlink transmission or available component carriers should refer to the fact that there may be more component carriers configured or existing in the system than at a given point of time used for downlink transmission to the terminál. Available in this context refers to the component carriers actually used for downlink transmission to the terminál.

[0039] Available component carriers may therefore be one of:

all component carriers that the base station (e.g. eNodeB or relay node) can use for conveying data on the downlink to the terminál (e.g. user equipment), all component carriers that a terminál assumes for reception of data (e.g. this may be configured individually per terminál by the network/eNodeB/relay node using higher-layer signaling such as RRC signaling), all component carriers where a terminál detects reception of data, all component carriers that a terminál is configured to consider for channel quality feedback reporting (which may be a superset or subset of the component carriers in the preceding buliét point, and which can be configured using higher-layer signaling such as RRC signaling) all component carriers that are within the reception capability of the receiver (this is mostly related to hardware restrictions or capabilities ofthe terminál, such as rádió frequency circuitry complexity and power consumption) [0040] Typically, terminals that are most suitable for a high data rate in the downlink are those that are close to the transmitter (cell-centre) and that do nőt move fást, i.e. where the channel characteristics ofthe downlink barely fluctuate over a certain time. The reason is that for cell-centre terminals, the available transmission power can be very efficiently used for high code rates (close to rate r = 1) or high-order modulation schemes (such as 64-QAM), and for slowly moving terminals, the channel characteristics is nearly constant over time. This means that one can alsó assume that channel quality feedback of such slow-moving terminál that has been reported has a very long validity, allowing a very accurate and efficient link adaptation.

[0041] Accordingly, in order to exploit the capability of those slow-moving, cell-centre terminals, it is advantageous to configuré same to use component carrier aggregation, i.e. to use multiple component carriers at least for downlink transmissions. Generally it can be assumed that higher layer configuration or semi-static configuration is available to the network, so that a node in the access network is able to configuré a terminál to operate in a single or multiple

ΕΡ 2 462 759 Β1 component carrier transmission/reception mode. The terminál is thus awareofwhetherornot multiple component carriers are available in the downlink so that it can judge whether a dedicated control information fór an uplink transmission where the CQI request flag is set must be interpreted as a request to provide channel quality feedback fór a single downlink component carrier (only one component carrier is available) or as a request fór channel quality feedback on one or more of the multiple downlink component carriers identified within the dedicated control information (multiple component carriers are available). Accordingly, depending on the number of downlink component carriers configured fór a terminál, the terminál interprets the dedicated control information differently.

[0042] Simiiarly, the access network node (typically a base station, eNodeB or relay node) is alsó aware ofthe number of downlink component carriers that have been configured fór the terminál and may therefore control the channel quality feedback reporting behavior ofthe terminál accordingly (e.g. by setting the CQI request flag, orby signaling the dedicated control information according to special pattern on time and/or frequency resources, as will be explained further down below). Hence, the access network node can request channel quality feedback from the terminals so as to properly schedule downlink transmissions to the respectíve terminals.

[0043] Fig. 18 shows a flow chart of an exemplary operation of a node in the access network and a terminál according to an embodiment of the invention. The node of the access network (or access network node) is fór exampie a base station in the access network of a mobile communication system. In a 3GPP-based communication system, such as LTE-A, a base station is alsó referred to as an eNodeB or relay node. Furthermore, the terminál may be fór exampie a mobile terminál such as a user equipment in a 3GPP-based communication system. Please note that the terminál may alsó be a relay node as far as communication between an eNodeB and a relay node are concerned.

[0044] The terminál and the node may fór exampie communicate with eaeh other via an air interface. The system bandwidth available fór communication may be considered to be divided intő a plurality of component carriers. Fór exampie, the system bandwidth could be fór exampie divided intő 2, 3, 4 or 5 component carriers.

[0045] The operation ofthe node ofthe access network is shown on the left hand side of Fig. 18. The node first selects 1801 one or more component carriers available fór downlink transmission to the terminál on which it desires to récéivé channel quality feedback.

[0046] Based on the selection of component carrier(s) the node further transmits 1802 dedicated control information to the terminál that include an indication ofthe selected component carrier(s) on which the terminál is to provide channel quality feedback. As will be outlined in more detail below, there exist numerous possibílities how the selected component carrier(s) can be indicated to the terminál. The dedicated control information alsó compríses a resource allocation on the uplink fór the terminál, on which the terminál is to send the channel quality feedback. Therefore the dedicated control information may alsó be referred to as an uplink grant.

[0047] It is assumed fór exemplary purposes in Fig. 18 that the dedicated control information has a predetermined formát and compríses a CQI request flag being set in order to trigger aperiodic channel quality feedback from the terminál and CQI control information (CQI control info) that is indicating which component carrier(s) have been selected, respectivelyon which component carrier(s) the terminál is to report. As will be outlined in more detail below, there exist numerous possibílities how the selected component carrier(s) can be indicated to the term inai by means ofthe CQI control information comprised in the dedicated control information.

[0048] The terminál receives 1803 transmission of the dedicated control information from the node of the access network on downlink. The dedicated control information may be transmitted via a control channel to the terminál. In this exampie, the terminál checks whether the CQI request flag is set in the dedicated control information. If the CQI) request flag is nőt set, the terminál would interpret the contents ofthe dedicated control information using the standard definition ofthe dedicated control channel information formát used.

[0049] Ifthe CQI report flag isset, i.e. is requesting channel quality feedback from the terminál, the terminál will interpret the content of the dedicated control information differently than in the case where the CQI request flag is nőt set. More specifically, if the CQI report flag is set, the terminál will interpret at Ieast a part/one bit of at Ieast one further field comprising control information (second control information field) within the dedicated control information as the CQI control information and will determine 1804 the CQI control information indicating the access network node selection of the component carrier(s) to provide channel quality feedback fór. Next, the terminál generates 1805 a channel quality feedback message identifying the channel quality experienced by the terminál on the selected component carrier(s) indicated within the dedicated control information received from the access network node. This could fór exampie involve that the terminál is performing somé channel quality measurement on the selected component carrier(s). In a more detailed exemplary implementation, the terminál determines a SINR or channel covariance measurement, based on e.g. the reception of so-called reference symbols, fór the selected component carrier(s) and may optionally further convert the measurement results intő Channel quality feedback, such as fór exampie an MCSI or Channel Quality Indicator (CQI) as in an LTE or LTE-A specifications, a PMI or Rl. Channel quality feedback may alsó be provided in form of directly measured or measurement-derived metrics such as a channel covariance mátrix or elements, channel coefficients, or other suitable metrics.

[0050] The terminál transmits 1806 a message containing the channel quality feedback fór the selected component

ΕΡ 2 462 759 Β1 carrier(s) to the node in the access network, which receives the message and extracts the channel quality feedback information. The terminál sends the channel quality feedback on the selected component carrier(s) indicated in the dedicated control information on the uplink resources that are alsó indicated in the dedicated control information. Optionally, the terminál may multiplex the channel quality feedback and further control or user data in this transmission. The node receives 1807 channel quality feedback for the selected component carrier(s). The node may store the obtained channel quality feedback and may make the channel quality feedback available to a scheduler (which could be located in the node) so that the downlink channel quality experienced by the terminál on the selected component carrier(s) can be considered in the scheduling ofthe terminál, i.e. in the process of deciding on the allocation of physical downlink or uplink resources to the terminál.

[0051] Although Fig. 18 shows only the triggering and transmission of channel quality feedback from a single terminál, it should be noted thatthe access network node may of course serve multiple terminals. Accordingly, the access network node may request multiple terminals to provide (aperiodic) channel quality feedback on the downlink component carries available to the respective terminals. Furthermore, the access network node may schedule nőt only one terminál, bút may schedule multiple terminals in a resource assignment process taking intő account the channel quality experienced by the different terminals on the different component carriers ofthe system in its scheduling decision.

[0052] In a more detailed exemplary embodiment of the invention, it may be assumed that the procedure shown in Fig. 18 is implemented in a 3GPP LTE-A (ReleaselO) communication system. In this exemplary embodiment, the node ofthe access network may be an eNodeB or a relay node. The terminál is a user equipment (UE). The eNodeB selects the component carrier(s) on which the user equipment is to report channel quality feedback and indicates its selection to the user equipment by means of L1/L2 control signaling on the PDCCH.

[0053] More specifically, the L1/L2 control signaling is comprising dedicated control information (DCI) that comprises a trigger of aperiodic channel quality feedback by the user equipment, e.g. by means of the CQI report flag, and an indication of the component carrier(s) for which channel quality feedback, e.g. by means of a so-called CQI report, is requested. This indication ofthe component carrier(s) is the CQI control information that may alsó be referred to as a CQI carrier indicator field (CQI-CI) ofthe uplink dedicated control information.

[0054] In one further more detailed exemplary implementation the employed dedicated control information has one of a plurality of predetermined formats, e.g. the DCI formát 0 as defined for LTE (Release 8) and an exemplary structure of which is shown in Fig. 4 and Fig. 7 in case of operating the LTE-A (Release 10) communication system in FDD mode. In this case the CQI-CI may be for example composed of part(s) of one or more control information fields that already exist in the DCI formát 0 of Release 8.

[0055] As shown in Fig. 4 and Fig. 7, the UL-DCI for FDD consists of:

a formát flag (Flag Formát 0/1 A) for distinguishing DCI Formát 0 and DCI formát 1 A, which are defined to have the same number of bits/size, a hopping flag (Hopping Flag) indicating whether or nőt the user equipment should employ uplink resource hopping, a resource block assignment field assigning uplink resources on the PUSCH to the user equipment (when triggering aperiodic channel quality feedback, the channel quality feedback and optionally further user data is multiplexed and transmitted on these assigned resources via that PUSCH), a modulation and coding scheme field (MCS&amp;RV) that is indicating the modulation scheme, coding rate and the redundancy version for the transmission on the assigned resources on the PUSCH, a new data indicator (NDI) to indicate whether the user equipment has to send new data or a retransmission, a DMRS field (Cyclic Shift DMRS) for configuring the cyclic shift applied to the reference Symbol sequence, a CQI request flag for triggering an aperiodic channel quality feedback report from the user equipment, and if required one or more padding bit(s) to align the size ofthe dedicated control information to a predetermined number of bits.

[0056] If the hopping flag is set, the first 1 or 2 bits of the resource block assignment field are used to indicate the hopping sequence or hopping configuration to the user equipment. This means that the resource block assignment field has 1 or 2 bits less, and may therefore only indicate a smaller resource block allocation size.

[0057] Another possibility according to another embodiment ofthe invention is to reuse the definition of DCI formát 0 as defined for LTE (Release 8) and to extend same for the use in LTE-A (Release 10), i.e. to define a new DCI formát

ΕΡ 2 462 759 Β1

Ο fór the use in LTE-A (Reiease 10) based on DCI formát 0 as defined fór LTE (Reiease 8). Such an exemplary DCI formát 0 fór LTE-A (Reiease 10) according to one embodiment of the invention is shown in Fig. 19. In LTE (Reiease 8) there is only one component carrier defined, so that there is no question fór which component carrier an uplinkor down link resource assignment is pertaining to.

[0058] When using multiple component carriers, the association between the resource assignment and the component carrier(s) fór which it should be valid is nőt self-evident. When reusing the DCI formát 0 as defined fór LTE (Reiease 8) in a multiple-component carrier system like LTE-A (Reiease 10), the user equipment may fór example assume that the resource allocation in the dedicated control information is pertaining to the downlink component carrier on which the dedicated control information is received (fór downlink resource assignment), respectively, an uplink component carrier associated (linked) to the downlink component carrier on which the dedicated control information is received (fór uplink resource assignments). Aiternativeiy, in this embodiment and as shown in Fig. 19, the DCI formát 0 as defined fór LTE (Reiease 8) can be extended by an uplink carrier indicator field (UCI) fór indicating to the user equipment fór which component carrier or component carriers the dedicated control information is valid. It should be noted that the uplink carrier indicator field (UCI) can be placed alsó on other locations within the exemplary DCI formát 0 fór LTE-A (Reiease 10). Assuming that only one component carrier can be indicated by the uplink carrier indicator field (UCI) and the system may be configured with up to five component carriers, the uplink carrier indicator field (UCI) should have a size of 1,2 or 3 bits, depending on the number of available or existing component carriers. Ifthe uplink carrier indicator field (UCI) should be able to indicate arbitrary combinations of the valid or existing component carriers fór which the dedicated control information is valid, the number of bits required fór the uplink carrier indicator field is upper-bounded by rlog₂NoCl, where NoC is the number of different combinations of component carriers being possible.

[0059] It should be alsó noted that the invention may alsó be implemented in a LTE-A (Reiease 10) communication system operating in TDD mode. In this case the dedicated control information fór the uplink (UL-DCI) according to DCI formát 0 as defined fór LTE (Reiease 8) or LTE-A (Reiease 10) - according to the exemplary embodiment in the paragraphs above - further comprises an uplink index field (UL index) or a Downlink Assignment Index (DAI) field (see 3GPP TS 36.212, version 8.7.0, section 5.3.3.1.1 and 3GPP TS 36.213, version 8.7.0, sections 5.1.1.1,7.3 and 8).

[0060] In the following several exemplary embodiments ofthe invention are described with respect to Figs. 8 to 17 that are intended to exemplify how the CQI control information may be comprised intő the dedicated control channel information. Please note that fór exemplary purposes, the different examples are based on a reuse of DCI formát 0 defined fór dedicated control information in LTE (Reiease 8) that has been discussed previously. Nevertheless, the exemplary embodiments may equally make use - fór example - ofthe formát fór dedicated control information as shown in Fig. 19 orof other dedicated control information form ats. In all embodiments, it may be assumed that the userequipment has already been configured to use component carrier aggregation, i.e. there are plural component carriers available fór downlink transmission to a particular user equipment.

[0061] In one embodiment of the invention, the dedicated control information comprises a CQI request flag and at least a hopping flag. The hopping flag (typically 1 bit) is included to determine whether a user equipment should employ uplink resource hopping fór transmission. The main merít of employing hopping is to obtain frequency diversity, i.e. to exploit different channel and/or interference characteristics to be more robust against instantaneous and limited Signal to Interference-plus-Noise Ratio (SINR) fluctuations in time or frequency. Such fluctuations can fór example occur ifthe user equipment is moving at a high speed, orwhen it is in a rádió channel scenario where the impulse response results in a very frequency-selective transmission characteristic, or when it is close to a rádió cell boundary where generally the interference experienced from other user equipments in the same or adjacent cell can be relatively high compared to the received signal power from the target user equipment.

[0062] In generál, a down link transmission using multiple component carriers atthe same time is interesting to increase the instantaneous data rate fór a user equipment. Traditionally, the user equipments which are most suitable fór a high data rate are those that are close to the transmitter (cell-centre) and that do nőt move fást, i.e. where the channel characteristics barely fluctuate over a certain time. The reason is that fór cell-centre user equipments, the available transmission power can be very efficiently used fór high code rates (close to rate r= 1) or high-order modulation schemes (such as 64-QAM), and fór siowly moving user equipments, the channel is nearly constant over time, such that a CQI that is reported has a very long validity, allowing a very accurate and efficient link adaptation. It should be understood that even though the terms cell-centre and cell boundary are originating from the geographical position ofthe terminál with respect to the position ofthe rádió network element (such as an eNodeB orrelay node), the term cell centre/ cell boundary alsó refers to a terminál that faces generally/on average good/bad rádió conditions, respectively. This is nőt only a function ofthe geographical distance bút alsó of e.g. the existence of obstacles that block a line-of-sight connection between the two ends of the rádió communication. Therefore, even a terminál that has a very small Euclidean distance to an eNodeB or relay node could be considered to be in a cell boundary environment, ifthe transmission path(s) are blocked by obstacles such as walls, buildings, vegetation, metál shields, and the like.

[0063] Consequently, slow moving cell-centre user equipments are traditionally nőt associated with conditions where uplink hopping is required. Therefore the Hopping flag (and consequently the Hopping configuration bits - see Fig. 4

ΕΡ 2 462 759 Β1 and Fig. 7) are rarely activated/employed, if ever, when CQI for multiple component carriers is requested. Generally, higher layer or semi-static configuration can be used to configuré a user equipment to operate in a single or multiple component carrier transmission/reception mode. Therefore a user equipment can know whether a CQI request flag being set in an uplink dedicated control information (UL-DCI) should be used for single or multiple component carrier channel quality feedback request. Accordingly, in case there are multiple component carriers available for a user equipment for downlink transmission the user equipment can interpret the hopping flag as CQI control information that is indicating the component carrier(s) on which the user equipment is to report.

[0064] A further reason why hopping should nőt be applied for a slow-moving, cell-centre user equipment, or why nőt being able to employ hopping does nőt jeopardize the system operation significantly, is that for downlink as well as for uplink these user equipments can convey large packets per allocated transmission due to their generally advantageous rádió channel conditions. Generally, this means that the user equipment should be able to transmit over a large portion ofthe available spectrum, i.e. the number of allocated resource blocks should be large. However, as can be seen in Fig. 20, the maximum resource allocation size in case hopping is activated (Hopping Flag = 1 - see alsó Fig. 7) is employed is radically smaller than without hopping. Additionally, the number of bits taken from the Resource Block Allocation field depends on the system bandwidth in terms of available resource blocks in the cell (or component carrier). Fig. 20 shows on the y-Axis, the effect on the maximum allocatable number of resource blocks and on the x-Axis the bandwidth of the system. lt can be seen that only a limited fraction ofthe available resources can be allocated to a single user equipment in the uplink when employing hopping, which will have a negative effect on the system and cell throughput. Therefore, it is preferable that cell-centre slow-moving user equipments do nőt use hopping.

[0065] In a typical implementation of the LTE-A (Release 10) communication system, it can be assumed that the dedicated control channel information according to the formats (such as DCI formát 0) exemplified in Fig. 4 and Fig. 19 will have at leastone padding bittó match the size ofthe dedicated control information to that of DCI formát 1 A - generally to match the size of a first DCI formát to the size of a second DCI formát. Accordingly, if the payload for DCI formát 0 is smaller than the payload for DCI formát 1A (including any padding bits appended to DCI formát 1 A), zeros are appended to DCI formát 0 until the payload size equals that of DCI formát 1 A. Even though the value of these padding bits is fixed, they are nőt defined for any particular purpose other than to adjust the payload size. Consequently, in one embodiment ofthe invention, the padding bit(s) within the dedicated control information are used to signal the CQI control information to indicate the component carrier(s) on which the user equipment should report. In this embodiment ofthe invention, the dedicated control information transmitted to the user equipment comprises the CQI request flag and at least one padding bit.

[0066] Fig. 9 shows an exemplary interpretation ofthe content of dedicated control information (DCI) according to DCI formát 0 of 3GPP LTE (Release 8) for FDD operation (see Fig. 4), when reusing the formát in 3GPP LTE-A (Release 10) system, to exemplify this embodiment ofthe invention. Of course this example could be likewise realized using a DCI formát 0 as of Fig. 19 or on DCI formát 0 for TDD operation, since it can be assumed that the fields available for FDD operation are alsó available for TDD operation. The user equipment that is receiving the dedicated control information according to Fig. 9 is checking whether or nőt the CQI request bit is set (=1) to trigger aperiodic channel quality feedback from the user equipment. Assuming that this is the case, the user equipment will interpret the padding bit(s) of the dedicated control information as the CQI control information, i.e. an indication ofthe downlink component carrier(s) to be reported and will send channel quality feedback for the indicated component carrier(s).

[0067] The interpretation ofthe padding bits as CQI control information as exemplified above may alsó be viewed as a new DCI formát 0 for cases where the CQI request bit is set (=1). Fig. 14 exemplary shows this new dedicated control channel formát. Hence, similarto the case of using the hopping flag for signaling the CQI control information as described with respect to Fig. 8 and Fig. 13 above, the CQI request flag may alsó be viewed as a formát indicator that is indicating whether the dedicated control information has a first formát (CQI request flag is nőt set (=0)) - that is the dedicated control information is interpreted by the user equipment according to the default definition ofthe DCI formát - or has a second formát (CQI request flag is set (=1)) - that is a formát where the portion of the dedicated control information that is carrying padding bit(s) according to the default definition ofthe DCI formát is carrying the CQI control information as exemplified in Fig. 14.

[0068] According to a further embodiment of the invention, the bits used to determine a cyclic shift applied to the transmission of demodulation reference symbols (DMRS) at the terminál (Cyclic Shift DMRS bits) are used to indicate on which and how many of the available component carrier(s) a user equipment is to report channel quality feedback. Accordingly, in this exemplary embodiment ofthe invention the uplink dedicated control information provided to the user equipment comprises a CQI request flag and at least somé Cyclic Shift DMRS bits. In one exemplary implementation, there are Cyclic Shift DMRS bits foreseen in the predetermined formát ofthe dedicated control information.

[0069] The cyclic shift for the DMRS is typically employed in a 3GPP-based communication system to enable transmission from two different terminals using the same or at least partly overlapping time-frequency resources in the uplink. By means of a cyclic shift of the DMRS between the two transmitting terminals, it is possible for the eNodeB to distinguish/decompose the two interfering signals received from the terminals again and to decode both successfully. This is

EP 2 462 759 Β1 sometimes referred to as employing a multi-user ΜΙΜΟ uplink scheme (UL MU-MIMO).

[0070] A fundamental requirement of a multi-user ΜΙΜΟ uplink scheme is that the rádió channels on which the two terminals send their uplink data should be statistically independent as possible, otherwise the decomposition and decoding will be suboptimal and may result in a lót of decoding errors. Looking at the case of slow-moving cell-centre terminals, it is however highly likely that the rádió channels are highly correlated, particularly if looking at line-of-sight scenarios. Therefore it is unlikely that two such terminals will be assigned to transmit on the same frequency resource. Consequently, the Cyclic Shift DMRS field in the uplink dedicated control information is commonly nőt used fór such terminals and can be re-used fór indicating the component carrier(s) fór which a user equipment should send channel quality feedback.

[0071] Even ifthe Cyclic Shift DMRS bits are reused as fór example in DCI formát 0 exemplified in Fig. 4 and Fig. 19, employing a multi-user ΜΙΜΟ uplink transmission from two (or more) terminals is still possible. The only constraint fór such a scenario would be then that the two (or more) terminals which share part or all uplink time/frequency resources at the same time should nőt récéivé a CQI trigger at the same time. If this is ensured by the access network node (e.g. the eNodeB or relay node), the terminál receiving a trigger fór reporting channel quality feedback would employ a predefined cyclic shift of which both sides - the network (eNodeB) and the reporting terminál - are aware (e.g. by specification or control signaling). The eNodeB or relay node can therefore determine another orthogonal cyclic shift(s) fór the other terminal(s) and signal same using the Cyclic Shift DMRS field fór the other terminal(s) nőt receiving the CQI trigger (if the CQI request flag is nőt set, the cyclic shift signaled in the Cyclic Shift DMRS field is applied by the terminál as usual). Therefore effectively the eNodeB or relay node can ensure that the DMRS transmitted by these terminals are mutually orthogonal, even ifone ofthe terminals is triggered to send channel quality feedback. This method can further be extended such that multiple terminals can be triggered to send channel quality feedback, under the condition that the mentioned predefined cyclic shift fór each such terminál is different, resulting in mutually orthogonal employed DMRS sequences.

[0072] Fig. 11 shows an exemplary interpretation ofthe content of dedicated control information (DCI) according to DCI formát 0 of 3GPP LTE (Release 8) fór FDD operation (see Fig. 4), when reusing the formát in 3GPP LTE-A (Release 10) system, to exemplify this embodiment ofthe invention. Ofcourse this example could be Iikewise realized using a DCI formát 0 as of Fig. 19 or on DCI formát 0 fór TDD operation. An eNodeB or relay node that is requiring a user equipment to send channel quality feedback on one or more component carriers available fór downlink transmission to this user equipment can signal dedicated control information fór an uplink transmission to the user equipment in which the CQI request flag is set. The eNodeB or relay node includes an indicator of the component carrier(s) to be reported intő the Cyclic Shift DMRS field which would be commonly used to signal the cyclic shift to be applied by the user equipment fór the uplink transmission. The user equipment that receives the dedicated control information recognizes the CQI request flag being set and interprets the content of the Cyclic Shift DMRS field within the dedicated control information as CQI control information indicating the component carrier(s) fór which the user equipment is to provide channel quality feedback.

[0073] In case the user equipment recognizes the CQI request flag set, the user equipment may apply a cyclic shift to the DMRS that has been previously configured by higher-layer control signaling or a default cyclic shift fór the uplink transmission, and transmit the channel quality feedback fór the indicated component carrier(s) and optionally further uplink data.

[0074] In one further embodiment ofthe invention, nőt all ofthe bits ofthe Cyclic Shift DMRS field are used fór indicating the CQI control information. Fór example, assuming that there are 3 bits foreseen fór the Cyclic Shift DMRS field, 2 bits thereof could be used to indicate to the user equipment fór which component carrier(s) available fór down link transmission to the user equipment, the user equipment should report, while the remaining 1 bit could be used to signal the application or non-application of a cyclic shift to the DMRS sequence fór the uplink transmission. Hence, in case this 1 bit is set, the user equipment applies a configured or predetermined cyclic shift to the uplink transmission, while it does nőt do so, if this 1 bit is nőt set.

[0075] Again, the interpretation of the Cyclic Shift DMRS bits of the dedicated control information as CQI control information as exemplified above may alsó be viewed as a new DCI formát 0 fór cases where the CQI request bit is set (=1). Fig. 16 exemplary shows this new dedicated control channel formát. Again, the CQI request flag can be viewed as a formát indicator that is indicating whether the dedicated control information has a first formát (CQI request flag is nőt set (=0)) - that is the dedicated control information is interpreted by the user equipment according to the default definition of the DCI formát - or has a second formát (CQI request flag is set (=1)) - that is a formát where (a portion of) the Cyclic Shift DMRS bits in the dedicated control information is carrying the CQI control information as exemplified in Fig. 16.

[0076] In the examples that have been discussed in the preceding paragraphs, there has been a further, second control information field (in addition to the CQI request flag) that has been used to indicate the component carrier(s) fór which a terminál (e.g. user equipment) is to report channel quality feedback. lt should be noted that it is alsó possible to interpret more than one further second field as indicative ofthe component carrier(s) fór which channel quality feed back

ΕΡ 2 462 759 Β1 is to be provided by the terminál.

[0077] For example, in a further embodiment ofthe invention, the hopping configuration bits that areforeseen to signal the hopping configuration in a conventional dedicated control information formát as exemplified in Fig. 7 are used to signal the CQI control information to the userequipment in an LTE-A (Release 10) communication system. As explained before, hopping may be generally undesirable for slow-moving cell-centre user equipments, so that the 1-2 bits that indicate the hopping configuration would rarely if ever be used. However, the interpretation of the Resource Block Assignment (RBA) field in case hopping is activated (see Fig. 7) can be re-used forthe case that channel quality feedback for oneor more of multiple component carriers is requested, such that the 1-2 bits originally used as Hopping Configuration Bits are used as CQI control information (CQI-CI). The advantage of this solution is that the use of hopping in the uplink would still be possible, as the Hopping Flag retains its original function and meaning. The hopping configuration may be for example configured in advance by higher layer signaling (e.g. RRC signaling). The potential drawback of this solution is that the maximum allocatable uplink resource size is quite strictly limited (see Fig. 20), which may nőt be in the interest for the operator. Therefore, in a variant of this embodiment it may be a good trade-off to steal only one bit from the Resource Block Assignment field for CQI control information, so that the CQI control information space is extended by 1 bit bút the limitation on the maximum allocatable uplink resource size is less severe than shown in Fig. 20. [0078] In another exemplary embodiment, a combination ofthe Hopping Flag and (one bit of) the Hopping Configuration Bits are used as CQI control information. As exemplified in Fig. 10, in case the CQI request flag is set (=1) in the dedicated control information, the userequipment is interpreting a combination ofthe hopping flag and hopping configuration bit(s) that span intő the resource block Assignment field as the CQI control information. In this example, as the Hopping Flag is alsó used for the CQI control information signaling, it is nőt possible to utilize hopping forthe uplink transmission by the user equipment any longer. However, this solution may be advantageous as for example only one bit ofthe Hopping Configuration Bits could be used in combination with the Hopping Flag for indicating the CQI control information, so that this solution imposes fewer restrictions to the maximum allocatable uplink resource size. As further illustrated in Fig. 15, this exemplary solution may be again considered a new dedicated control information formát for cases where the CQI request flag is set.

[0079] Another exemplary implementation and embodiment ofthe invention is the use of a combination ofthe Hopping flag and (at least a part of) the Cyclic Shift DMRS bits for the signaling of the component carrier(s) for which the user equipment is to provide channel quality feedback. This is exemplified in Fig. 12, where - in case the CQI request flag is set (=1) - the user equipment will combine the bit of the Hopping flag and (at least a part of) the Cyclic Shift DMRS bits and will interpret this combination as CQI control information indicating the component carrier(s) for which it should report. This way, there is up to a totál number of 4 bits that is available to signal different combinations of one or more component carriers for which the user equipment is to provide channel quality feedback. Again this exemplary implementation may be considered a definition of a new formát for the dedicated control information in case the CQI request flag is set. Fig. 17 is illustrating the new dedicated control information formát that is corresponding to the interpretation of a combination of the Hopping flag and (at least a part of) the Cyclic Shift DMRS bits as the CQI control information as discussed above.

[0080] In one further embodiment ofthe invention, a combination ofthe Hopping flag, the padding bit(s) and (at least a part of) the Cyclic Shift DMRS bits is used for signaling the combination of one or more component carriers for which channel quality feedback is to be reported. If the CQI request flag is set in the dedicated control information, the user equipment will combine the bits of all three fields in a predetermined fashion and will interpret the resulting combined bit combination as the CQI control information that indicates the component carrier(s) forwhich channel quality feedback is to be reported. This exemplary embodiment would allow to use up to 5 bits (or even more, depending on the number of the padding bits) for signaling combinations of component carrier(s) for which channel quality feedback is to be reported, so that any arbitrary combination of component carriers can be indicated, assuming that there is a maximum aggregation of five component carriers for downlink transmission.

[0081] In another exemplary embodiment ofthe invention, there are uplink carrier indicator bits foreseen in the formát of the dedicated control information in order to indicate the component carrier(s) for which the uplink dedicated control information is valid, specifically on which uplink component carrier(s) the subsequent UL transmission is to occur. An exemplary dedicated control information formát comprising an uplink carrier indicator is illustrated in Fig. 19.

[0082] For multiple component carrier downlink/uplink transmission, one possibility to identify the component carrier on downlink/uplink to which the downlink/uplink dedicated control information is pertaining to is that the component carrier where the dedicated control information is transmitted determines forwhich component carrier in downlink/uplink the resource assignment is valid. For uplink dedicated control information (UL-DCI), this is known as the paired DL-UL component carrier relation. However, there may be case a UL-DCI is transmitted on a downlink component carrier bút the corresponding assignment should be valid for another bút nőt the corresponding paired uplink component carrier. The paired uplink component carrier may alsó be referred to as a linked uplink component carrier as it is linked to the downlink component carrier on which the UL-DCI is received according to a given relation. It may be possible that different downlink component carriers are linked to the same uplink component carrier, which may be for example

ΕΡ 2 462 759 Β1 advantageous when there is an asymmetric configuration of uplink and downlink component carriers, e.g. there are more downlink component carriers than uplink component carriers available.

[0083] One solution to identify the uplink component carrier to which the dedicated control information pertains is to include an uplink carrier indicatorfield (UCI) to the dedicated control information to determine the target uplink component carrier(s). In case channel quality feedback fór one or multiple component carriers is requested, in one embodiment of the invention, the uplink carrier indicator is fully or partly used fór signaling the CQI control information. This will restrict the UL-DCI to be valid fór the paired uplink component carrier(s) only. Alternatively, the pairing may be alternatively configured by control signaling or be predetermined fór cases where the CQI request flag is set in the dedicated control information.

[0084] Depending on how the CQI control information is included in the dedicated control information, respectively, which control information field or fields thereof are used, different numbers of bits are available fór indicating on which component carrier(s) the user equipment is to report channel quality feedback. In the examples given above, the number of bits containing the CQI control information can rangé from 1 to 4 or even more bits. Therefore, the flexibility how the CQI control information (CQI-CI field) indicates fór which downlink component carriers the user equipment should provide channel quality feedback can be quite different, depending alsó on the actual number of downlink component carriers that are available. it can be generally assumed that the i^th CQI control information value denotes an i^th combination of component carrier(s) fór which channel quality feedback is requested. In the following paragraphs, different examples are discussed how to use the different possible numbers of bits available fór CQI control information.

[0085] In one exemplary embodiment, the carrier indicatorfield (UCI) ofthe dedicated control information determines the target uplink component carrier(s) of the uplink resource assignment (UL-DCI) and is further indicating CQI control information, ifthe CQI request flag is set. As outlined above, the carrier indicatorfield (UCI) may fór example consist of 3 bits which allows the signaling of 8 different bit combinations (values) - which are required fór distinguishing the component carriers ofa communication system using a maximum offive uplink component carriers.

[0086] As the carrier indicator field (UCI) still needs to indicate the uplink component carrier fór which the uplink resource assignment is valid, in this exemplary embodiment, the bit combinations of the carrier indicator field (UCI) are used to implicitly or explicitly indicate the uplink component carrier to which the resource assignment pertains as well as to indicate the downlink component carrier(s) fór which channel quality feedback is requested and to be provided. [0087] The following tables show different examples how the carrier indicatorfield (UCI) within an UL-DCI could be interpreted, ifthe CQI request flag is set. The column UCI value indicates the different bit combinations (alsó referred to as values or code-points) that can be signaled in the carrier indicatorfield, while the other columns define the different meanings fór the given bit combinations.

[0088] The column Uplink Component Carrier Index indicates fór which component carrier in the uplink (UL) the ULDCI is valid (i.e. on which uplink component carrier the UL-DCI is assigning resources). Unless stated otherwise, the examples below assume that there are up to five component carriers in the uplink identified by a respective index #/, where /=[1.....5], The linked UL CoCa is the uplink component carrier that is (commonly) linked (paired) to the downlink component carrier on which the UL-DCI is received. semi-statically configured UL CoCa means that the UL-DCI pertains to a component carrier that has been semi-statically configured, e.g. using RRC signaling. The semi-static configuration may be under certain circumstances be identical to the linked UL CoCa, however it may generally be determined based on other criteria. The semi-statically configured UL CoCa could therefore indicate the linked UL CoCa, i.e. includes a reference to the corresponding downlink component carrier, the semi-statically configured UL CoCa can alsó be an uplink component carrier where it is irrelevant whether or to which downlink component carrier it is linked.

[0089] As can be told from the name, the column Downlink Component Carrier(s) to be Reported indicates fór which downlink (DL) component carrier or carriers channel quality information is requested and to be provided in the uplink. CoCa carrying UL-DCI means that the terminál is to report fór the downlink component carrier on which the UL_DCI (with the CQI flag being set) has been received. All available DL CoCas means all available downlink component carriers as has been defined previousiy herein while semi-statically configured DL CoCa(s) means that the terminál should reportforone or more ofthe downlink component carriers according to a semi-static configuration, e.g. configured by means of RRC signaling between the terminál and the access network (e.g. eNodeB).

Table 1

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> #1</td><td> CoCa carrying UL-DCI</td>

<td> 001</td><td> #2</td><td> CoCa carrying UL-DCI</td>

<td> 010</td><td> #3</td><td> CoCa carrying UL-DCI</td>

<td> 011</td><td> #4</td><td> CoCa carrying UL-DCI</td>

ΕΡ 2 462 759 Β1 (continued)

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 100</td><td> #5</td><td> CoCa carrying UL-DCI</td>

<td> 101</td><td> linked UL CoCa</td><td> CoCa carrying UL-DCI</td>

<td> 110</td><td> linked UL CoCa</td><td> all available DL CoCas</td>

<td> 111</td><td> linked UL CoCa</td><td> semi-statically configured DL CoCa(s)</td>

[0090] As mentioned previously, in the physical layer of a 3GPP-based system such as 3GPP LTE or LTE-A, the dedicated control information is part of the L1/L2 control signaling that is transmitted via the PDCCH to the user equipments. The eNodeB that is signalling the L1/L2 control information in a 3GPP-based system may send several DCI messages to a single user equipment, wherein each DCI may be transmitted on different downlink component carriers. [0091] At Ieast in those cases where an UL-DCI does nőt contain a carrier indicator field (UCI) even though there are multiple uplink component carriers available, it can be assumed that a downlink component carrier is linked to a single uplink component carrier, where that link may be established by means of e.g. semi-static configuration. Consequently, the user equipment can assume that UL-DCI transmitted on a downlink component carrier is valid fór the single linked uplink component carrier, just in the same way it would be valid in case no carrier indicator field was present. Where applicable, it is assumed in the following embodiments and examples that this component carrier linkage is established even though a carrier indicator field (UCI) may be present in the UL-DCI.

[0092] The values representable by the carrier indicator field may be divided in different subsets associated with respective common properties. In a first subset of values or code-points 000 to 100 is used fór signalling the uplink component carrier to which the resource assignment ofthe UL-DCI pertains and it is so to say common to these values that channel quality feedback is to be provided by the terminál fór the downlink component carrier on which the UL-DCI is received. Moreover, a second subset may be formed by the values signalling that channel quality feedback is to be provided fór all downlink component carriers. In the example of this second subset thus only contains the code-point 110, however as mentioned before, only shows one possible implementation, and there may be others where more than a single code-point indicates that channel quality feedback is to be provided fór all downlink component carriers. [0093] Further, it should be noted that the UCI value 101 is redundant in the example shown in assuming that there are up to five uplink carriers available. In case there are up to five uplink component carriers available, the UCI value 101 is nőt required in this form, as the linked UL CoCa can only refer to one of uplink component carriers #1 to #5, so that effectively alsó one of UCI values 000 to 100 could be used forthe same purpose.

[0094] Nevertheless, if there are more than five uplink component carriers available, the code-points 000 to 100 ofthe component carrier indicator field could be used to indicate a defined uplink component carriers index, while one code-point could identifies the linked uplink component carrier. Fór example, if there are six component carriers in the uplink, the implementation of would allow to individually indicating each of the uplink component carriers - UCI values 000 to 100 could be used to indicate uplink component carriers #1 to #5 respectively, while e.g. UCI value 101 could indicate uplink component carrier index #6 provided that the UL-DCI is transmitted on a DL component carrier that is linked to uplink component carrier #6.

[0095] Another exemplary implementation relates to a scenario where there are six, seven or eight uplink component carriers available. In this case, one or more ofthe UCI values 101 , 110 and 111 , depending on the exact number of uplink component carriers, could be used to indicate the respective component carrier(s) in a similar fashion as fór UCI values 000 to 100. In an further alternative implementation, UCI values 110 and 111 could be used as discussed above with respect to (or at Ieast one of them could be reserved forfuture use), while the UCI value 101 is used to implicitly identify one of uplink component carriers #6 to#8 by transmitting the UL-DCI (PDCCH) on the respective linked downlink component carrier of these uplink component carriers #6 to #8.

[0096] The embodiments, implementations and examples that have been described with respect to are particularly beneficial in case that the network wants to have a very flexible control over the uplink transmissions from the user equipments in a cell, and where there are actually many uplink allocations (i.e. transmissions) in the same subframe. In that case, the eNodeB needs to send many PDCCHs carrying UL-DCI, where nőt all PDCCHs may be transmitted in the desired linked component carrier. Therefore the eNodeB needs to be flexible in balancing the load between the user equipments and the uplink component carriers by being able to explicitly assign many user equipments with channel quality feedback transmission to the uplink component carriers.

[0097] In a further exemplary implementation - and again assuming fór exemplary purposes up to five component carriers in the uplink - and as shown in Table 2, the UCI value 101 could alsó be used to indicate that the uplink assignment is valid fór a component carrier that has been defined and configured semi-statically, e.g. by RRC signalling. In an exemplary embodiment, this uplink component carrier is a default or fallback component carrier that is used to

EP 2 462 759 Β1 convey control information such as HARQ feedback messages in the absence of an implicit or explicit uplink component carrier indication. This may further preferably be the one out of multiple uplink component carriers with the smallest pathloss, or that is configured to occupy the largest bandwidth.

Table 2

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> #1</td><td> CoCa carrying UL-DCI</td>

<td> 001</td><td> #2</td><td> CoCa carrying UL-DCI</td>

<td> 010</td><td> #3</td><td> CoCa carrying UL-DCI</td>

<td> 011</td><td> #4</td><td> CoCa carrying UL-DCI</td>

<td> 100</td><td> #5</td><td> CoCa carrying UL-DCI</td>

<td> 101</td><td> semi-statically configured UL CoCa</td><td> all available DL CoCas</td>

<td> 110</td><td> linked UL CoCa</td><td> all available DL CoCas</td>

<td> 111</td><td> linked UL CoCa</td><td> semi-statically configured DL CoCa(s)</td>

[0098] Furthermore, the UCI value 111 in and Table 2 indicates channel quality feedback fór one or more downlink component carriers according to a semi-static configuration. Such a semi-static configuration can preferably encompass the downlink component carriers with a path-loss below a certain threshold, or simply the component carriers that are facing the smallest path-loss(es). Alternatively, the UCI value 111 can further be modified to request channel quality feedback fór semi-statically configured downlink component carriers and assigns uplink resources on a semi-statically configured uplink component carrier. It should be understood that both these semi-static configurations can be done independently from each other. Alternatively, the value 111 could alsó be reserved forfuture use. Similarly, forexample if there are six uplink component carriers, six of the UCI values could be used to indicate the respective six uplink component carriers, while the two remaining UCI values may be reserved forfuture use.

[0099] It may be further beneficial to be able to indicate with the component indicator field (UCI) that channel quality feedbackfor all downlink component carriers (all available DL CoCas) should be transmitted in a single uplink component carrier without any higher layer data. In the context of LTE Release 8 and Release 10, higher layer data would be fór example any data belonging to a MAC PDU which is transmitted on UL-SCH (see 3GPP TS 36.321, Médium Access Control (MAC) protocol specification, version 8.5.0. section 5.4 and its subsections, available at http://www.3gpp.org). In that respect, without any higher layer data would mean that no MAC PDU data is transmitted (multiplexed) with the channel quality feedback, or equivalently that there is no associated UL-SCH available in the assigned uplink resource. It may be further noted that a MAC PDU is usually associated with a transport block on the physical layer. On the other hand, it may still be desired that lower layer control channels or signals such as HARQ feedback (ACK/NACK) still multiplexed with the channel quality feedback, i.e. in this case the UL-DCI would allow fór sending the channel quality feedback, bút no higher layer data except fór control signaling, e.g. HARQ feedback. In another embodiment, at least one entry of the component indicator field indicates that neither higher layer nor lower layer channels or signals are transmitted by the user equipment together with the channel quality feedback, with the exception of signals that are required to successfully récéivé the uplink transmission such as reference symbols.

[0100] Hence, in another exemplary implementation, the code-points could be defined as in or Table 2, bút the codepoint 101 or 111 indicates the UL-DCI to be valid forthe linked UL CoCa and requests sending only channel quality feedback (e.g. CQI) on the allocated resources (i.e. particularly no higher layer data, even though other control signals such as HARQ feedback (ACK/NACK) may still be included in the transmission on the allocated resources together with the channel quality feedback).

[0101] The examples that have been described with respect to Table 2 provide basically the same advanfageous as the exemplary implementations that have been described in connection with.

[0102] However, since it is possible to address and request fór semi-statically configured uplink and downlink component carriers respectively, the exemplary implementations that have been outlined with respect to Table 2 are alsó applicable in case there is a preferred uplink or downlink component carrier available in a system. Fór example, one or more special uplink component carrier(s) could be defined where all control messages fór uplink are conveyed, unless explicitly requested otherwise. This special uplink component carrier may be chosen because it has generally favourabie transmission characteristics fór a user equipment. According to another embodiment of the invention, the network (eNodeB) can request the channel quality feedback to be transmitted on that special uplink component carrier. Likewise, one or more special downlink component carrier(s) could be identified, where e.g. channel conditions are generally

ΕΡ 2 462 759 Β1 favourable, where the major partof down link control and/or data transmission happens. In this case, the network (eNodeB) may request channel quality feedback fór those special downlink component carriers in order to allow an optimum scheduling or link adaptation decision. In these cases, the special component carrier(s) should constitute the semistatically configured uplink and downlink component carrier(s), respectively, as outlined previously.

[0103] In addition, it should be noted that the possibility to explicitly request a channel quality feedback message without higher layer data or channels is an efficient way to savé uplink resources fór channel quality feedback, or to establish more control over the quality of the channel quality feedback transmission, since then the assigned forward error correction coding needs to be optimised just fór the channel quality feedback, without need to care of implications to the error correction coding performance fór the higher layer data or channels. It should be alsó noted that in this context, unless explicitly stated otherwise, it is possible to transmit the channel quality feedback together with higher layer or other lower layer data or channels on the assigned uplink resources.

[0104] As can be seen from various figures, e.g. Fig. 4 or Fig. 19, the dedicated control information formát may have a varying size depending on the length of the Resource Block Assignment (RBA) field - this is because the size of the RBA field may depend on the respective component carrier’s bandwidth. Fór example, in 3GPP LTE (Release 8) the DCI Formát 0 fór a single antenna transmission on a component carrier with 20 MHz bandwidth has a size of 30 bits. The DCI size fór a transmission to use spatial multiplexing in a 5 MHz component carrier and PMI of 4 bits could be alsó 30 bits. Hence, alsó in cases where the uplink component carriers have different bandwidth, it should be known to the terminál fór which component carrier the dedicated control information is valid, e.g. by means of a carrier indicator field as discussed previously herein.

[0105] As can be anticipated, the interpretation ofthe carrier indicator field (UCI) in cases where the CQI request flag is nőt set can be assumed to be defined as shown in Table 1 fór UCI values 000 to 100. However, there may be cases that UCI values would be interpreted in a different fashion in case the CQI request flag is set, as shown e.g. in Table 3. Since the interpretation ofthe carrier indicator field therefore possibly depends on whether CQI request flag in the DCI is set or nőt, it is advantageous ifthe CQI request field is located at a fixed (i.e. known, independent ofthe formát or bandwidth of the component carrier on or fór which it is transmitted) position within the DCI. Fór example, Fig. 22 shows an exemplary formát fór dedicated control information according to an embodimentofthe invention that is similar to that shown in Fig. 19 regarding the contained information. However, in contrast to Fig. 19, the carrier indicator field (CIF) - that is the UCI field of Fig. 19 - is located at the beginning of the DCI information in this exemplary formát. Generally, it should be noted that the fixed position is nőt necessarily the beginning ofthe DCI, bút a position that irrespective of the usage or size of other fields. In a specific example, such a position is before the first variable length field of the DCI or in a block which has identical fields independent of the DCI formát (e.g. before the RBA field). In another specific example, such a position is close to the end such that the same criterion can be met if checking the contents ofthe DCI information from end to beginning, as it were. In this context, in a further embodiment ofthe invention, alsó the CQI request flag may be located at a fixed position as shown in Fig. 23, illustrating a further exemplary formát fór dedicated control information according to an embodiment ofthe invention.

[0106] In the examples discussed above with respect to and Table 2, the carrier indicatorfield (UCI) has been interpreted so as to still (explicitly) indicate the uplink component carrier (index) on which the UL-DCI grants resources, while the downlink component carrier(s) to be reported fór have been either identified as the component carrier carrying the ULDCI, all component carriers, or according to semi-static configuration. In the example shown in Table 3 below, the uplink component carrier (index) is interpreted such that there is more flexibility in indicating the downlink component carrier(s) to be reported fór, trading off the flexibility in the Identification ofthe uplinkcomponent carrier to which the UL-DCI pertains.

Table 3

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> linked UL CoCa</td><td> #1</td>

<td> 001</td><td> linked UL CoCa</td><td> #2</td>

<td> 010</td><td> linked UL CoCa</td><td> #3</td>

<td> 011</td><td> linked UL CoCa</td><td> #4</td>

<td> 100</td><td> linked UL CoCa</td><td> #5</td>

<td> 101</td><td> linked UL CoCa</td><td> CoCa carrying UL-DCI</td>

<td> 110</td><td> linked UL CoCa</td><td> all available DL CoCas</td>

<td> 111</td><td> linked UL CoCa</td><td> all available DL CoCas (no UL higher layer data) higher layer</td>

ΕΡ 2 462 759 Β1 [0107] In Table 3 the carrier indicator field is essentially no longer explicitly indicating the uplink component carrier, bút the terminál assumes that the UL-DCI refers to the linked uplink component carrier ofthe downlink component carrier on which the UL-DCI is received, ifthe CQI request flag is set in the UL-DCI. Using values 000 to 100 the individual downlink component carriers can be indicated (assuming again no more than five downlink component carriers in the system). The value 101 may be thus redundant again as explained above for and may be used otherwise (reserved, different meaning as explained above, or applicable for cases where there are more than five downlink component carriers). The code-point 110 triggers the transmission of channel quality feedback for all available downlink component carriers, where the assigned uplink resources on the linked uplink component carrier can be used by the terminál for transmitting channel quality feedback and uplink higher layer data (such as MAC PDU(s)) simultaneously. The codepoint 111 triggers the transmission of channel quality feedback for all available downlink component carriers, where the uplink grant on the linked uplink component carrier is to be used for signalling channel quality feedback only (no UL higher layer data).

[0108] Please note that in the example of Table 3, one could alsó view this solution as the CQI request flag indicating that the UL-DCI is pertaining to the linked uplink component carrier (the respective column in Table 3 yields the same meaning for all code-points in this example) so that the carrier indicator field essentially (only) defines the downlink component carriers for which channel quality feedback is to be provided.

[0109] The embodiments, implementations and examples that have been described with respect to Table 3 are particularly beneficial in case that the network wants to have a maximum control over the kind of channel quality feedback, i.e. just for a single downlink component carrier, for all available downlink component carriers including higher layer data, or for all available downlink component carriers without higher layer data. This is for example beneficial in scenarios where there are many user equipments in a cell where there is a lót of downlink traffic bút nőt so much uplink traffic, as can be expected for example in case that the main application is HTTP internet browsing or transferring files through the network to the user equipment.

[0110] In a further example, it is assumed that there are only four uplink and downlink component carriers available to the terminál. Accordingly, again using a carrier indicator field (UCI) of three bits, this ailows for signaling two subsets of values as shown in Table 4.

Table 4

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> #1</td><td> #1</td>

<td> 001</td><td> #2</td><td> #2</td>

<td> 010</td><td> #3</td><td> #3</td>

<td> 011</td><td> #4</td><td> #4</td>

<td> 100</td><td> #1</td><td> all available DL CoCas</td>

<td> 101</td><td> #2</td><td> all available DL CoCas</td>

<td> 110</td><td> #3</td><td> all available DL CoCas</td>

<td> 111</td><td> #4</td><td> all available DL CoCas</td>

[0111] In the example of Table 4 again two subsets of code-points are provided. The first subset is indicating a single uplink component carrier to which the UL-DCI pertains, and further a single downlink component carrier for which channel quality feedback is to be provided. Please note that the same index numbers being used for the uplink and downlink component carriers forthe respective code-points ofthe first subset is only exemplarily - forthe example shown in Table 4 it is only important that each component carrier in uplink and downlink is indicated once by the respective four codepoints ofthe first subset. More specifically, it should be understood that downlink component carrier#n is nőt necessarily linked to an uplink component carrier #n, i.e. having the same index, bút the index numbers are just for exemplary purposes herein to distinguish the component carriers in uplink and downlink, respectively. The remaining code-points 100 to 111 can be considered to form a second subset of code-points, which have in common that they indicate that the terminál is to provide channel quality feedback for all available downlink component carriers (i.e. available for down link transmission to the terminál at the time of receiving the dedicated control information).

[0112] In another example, it is assumed that there are only three uplink component carriers available for uplink transmission to the user equipment. In this case, the carrier indicator field (UCI) code-points could have a meaning as exemplified in Table 5 below.

ΕΡ 2 462 759 Β1

Table 5

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> #1</td><td> #1</td>

<td> 001</td><td> #2</td><td> #2</td>

<td> 010</td><td> #3</td><td> #3</td>

<td> 011</td><td> #1</td><td> all available DL CoCas</td>

<td> 100</td><td> #2</td><td> all available DL CoCas</td>

<td> 101</td><td> #3</td><td> all available DL CoCas</td>

<td> 110</td><td> linked UL CoCa</td><td> all available DL CoCas</td>

<td> 111</td><td> linked UL CoCa</td><td> all available DL CoCas (no UL higher layer data)</td>

[0113] This example is - in part - similar to Table 4, as the first subset of values (000, 001, 010) indicates a single uplink component carrier to which the UL-DCI pertains, and further a single downlink component carrier for which channel quality feedback is to be provided, while the second subset of values (011 , 100, 101) indicates that the terminál is to provide channel quality feedback for all available downlink component carriers. The code-point 110 triggers the transmission of channel quality feedback for all available downlink component carriers, while the uplink assignment on the linked uplink component carrier can be used by the terminál forsignalling channel quality feedback and uplink higher layer data simultaneously. The code-point 111 triggers the transmission of channel quality feedback for all available downlink component carriers, while the uplink assignment on the linked uplink component carrier is to be used for signalling channel quality feedback oniy (no UL higher layer data). Again it should be noted that in one exemplary embodiment, HARQ feedback, e.g. ACK/NACK, may be signalled together with the channel quality information, even in cases where no (other) uplink higher layer or lower layer data or channels should be transmitted.

[0114] In another further example, it is assumed that there are oniy two uplink component carriers and two downlink component carriers available to the user equipment. As can be seen from Table 6, the values representable by the 3 bit ofthe carrier indicatorfield are split up intő four subsets. Again, identical numbering for uplink and downlink component carriers should nőt be read as restricting that carriers of the same index in uplink and downlink are required to be linked to each other. The first subset is formed by values 000 and 001, and triggers channel quality feedback for the first downlink component carrier, while the UL-DCI pertains to either the first or second uplink component carrier, respectively. The second subset of values is formed by values 010 and 011, and triggers channel quality feedback for the second downlink component carrier, while the UL-DCI pertains to either the first or second uplink component carrier, respectively. [0115] The third subset is formed by values 100 and 101, and triggers channel quality feedback for all available component carriers in the downlink (e.g. the first and second downlink component carrier), while the UL-DCI pertains to either the first or second uplink component carrier, respectively. The fourth subset is formed by values 110 and 111, and triggers channel quality feedback for all available component carriers in the downlink (e.g. the first and second downlinkcomponent carrier), while the UL-DCI pertains to either the first or second uplink component carrier, respectively and oniy the channel quality feedback for both downlink component carriers should be sent on the allocated uplink resources. It should be obvious that this example can be applied to any case where there are two uplink component carriers and an arbitrary number,of downlink component carriers.

[0116] It can be observed that in the example of Table 6 , the last bit ofthe code-points determínes the uplink component carrier to which the UL-DCI refers to, which may beneficially exploited in an implementation.

Table 6

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> #1</td><td> #1</td>

<td> 001</td><td> #2</td><td> #1</td>

<td> 010</td><td> #1</td><td> #2</td>

<td> 011</td><td> #2</td><td> #2</td>

<td> 100</td><td> #1</td><td> all available DL CoCas (usually #1 + #2)</td>

<td> 101</td><td> #2</td><td> all available DL CoCas (usually #1 + #2)</td>

ΕΡ 2 462 759 Β1 (continued)

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 110</td><td> #1</td><td> all available DL CoCas (no UL higher layer data)</td>

<td> 111</td><td> 111 #2</td><td> all available DL CoCas (no UL higher layer data)</td>

[0117] In another example, it is assumed that there are only two uplink component carriers available to the user equipment, bút the number of available downlink component carriers is arbitrary (i.e. one or more). In this case, the carrier indicator field (UCI) code-points could have a meaning as exemplified in Table 7 below.

Table 7

<td> UCI Value (binary)</td><td> Uplink Component Carrier Index</td><td> Downlink Component Carrier(s) to be Reported</td>

<td> 000</td><td> #1</td><td> CoCa carrying UL-DCI</td>

<td> 001</td><td> #2</td><td> CoCa carrying UL-DCI</td>

<td> 010</td><td> #1</td><td> all available DL CoCas linked to uplink CoCa #1</td>

<td> 011</td><td> #2</td><td> all available DL CoCas linked to uplink CoCa #2</td>

<td> 100</td><td> #1</td><td> all available DL CoCas</td>

<td> 101</td><td> #2</td><td> all available DL CoCas</td>

<td> 110</td><td> #1</td><td> all available DL CoCas (no UL higher layer data)</td>

<td> 111</td><td> #2</td><td> all available DL CoCas (no UL higher layer data)</td>

[0118] In this example, it is further envisioned that UCI values 010 and 011 request channel quality feedback reports fór all available downlink component carriers that are linked to uplink component carriers #1 and #2 respectively. As outlined before, it is assumed that a single downlink component carrier is linked to just a single uplink component carrier; however a single uplink component carrier may be linked to several downlink component carriers, particularly in asymmetric downlink-to-uplink component carrier scenarios where each downlink component carrier is required to be linked to an uplink component carrier. Reporting channel quality feedback fór the linked downlink component carriers may help the network to decide, if and which component carriers should be disabled fór a given user equipment. Fór example, in case that all downlink component carriers that link to the same uplink component carrier can be disabled (e.g. because they report low quality CQI), it wouid subsequently alsó be possible to disable that linked uplink component carrier since no related control signals (such as HARQ feedback) are required to be transmitted thereon.

[0119] Furthermore, it should be noted that in the example discussed above, it has been assumed that the carrier indicator field (UCI) is comprised in each UL-DCI. However, in another embodiment of the invention, the eNode B may decide fór each UL-DCI transmitted to a user equipment, whether the UL-DCI is including a carrier indicator field (UCI) - see Fig. 19, Fig. 22, or Fig. 23 - or nőt - see Fig. 4 or Fig. 7. In this embodiment, if a UL-DCI does nőt contain an carrier indicator field (UCI), the terminál assumes that the UL-DCI relates to the linked uplink component carrier and that CQI control information are included in the UL-DCI (if the CQI request flag is set) as described with respect to Fig. 8 to Fig. 17 herein. If the carrier indicator field (UCI) is included in the UL-DCI, the terminál will interpretthe carrier indicator field (UCI) as discussed with respect to to Table 6 herein.

[0120] In the following sections there further exemplary implementations fór implementing the signalling of CQI control information depending on the number of bits available fór the CQI control information are provided. Please note that these examples may alsó be employed when using (a part of) the carrier indicator field fór signaling the CQI control information.

CQI-CI field: 1 bit [0121] In case of only 1 bit is available fór the CQI control information (see fór example Fig. 8 or Fig. 9), according to one exemplary embodiment ofthe invention, this bit is used to switch between two possible States: Requesting channel quality feedback fór a first combination of component carrier(s), or fór a second combination of component carrier(s). The two combinations of component carrier(s) to be reported may be fór example predefined (e.g. determined by the user equipment based on a predetermined rule or procedure) or could be configured by higher-layer control signaling (e.g. RRC signaling). In one exemplary implementation, the first combination oorresponds to only the single downlink

ΕΡ 2 462 759 Β1 component carrier where the UL-DCI carrying the set CQI request flag is transmitted, and the second combination corresponds to all available downlink component carriers.

[0122] This exemplary implementation is summarized in the Table 8 below:

Table 8

<td> CQI-CI Value</td><td> Requested channel quality feedback</td>

<td> 0</td><td> channel quality feedback fór component carrier #n</td>

<td> 1</td><td> channel quality feedback fór all available component carriers</td>

[0123] In one exemplary implementation, component carrier #n would be identified with the component carrier number that carries the UL-DCI carrying the set CQI request flag.

CQI-CI field: 2 bits [0124] In cases where there are 2 bits available to signal the CQI control information (e.g. when using a combination of Hopping flag and one Hopping Configuration bit), this could be seen as an extension to the one-bit case discussed above, where an additional third and fourth combination of downlink component carrier(s) can be indicated. Assuming that the downlink component carrier where the requesting UL-DCI is transmitted can be identified by index #n, in one exemplary embodiment of the invention, the third combination of component carrier(s) corresponds to the downlink component carrier with index #n+m, and the fourth combination of component carrier(s) corresponds to the downlink component carrier with index #n+k.

[0125] This exemplary implementation is summarized in the Table 9 below:

Table 9

<td> jth combination of component carrier(s)</td><td> CQI-CI Value (binary)</td><td> Requested channel quality feedback</td>

<td> 1</td><td> 00</td><td> channel quality feedback fór component carrier #n</td>

<td> 3</td><td> 01</td><td> channel quality feedback fór component carrier #n+m</td>

<td> 4</td><td> 10</td><td> channel quality feedback fór component carrier #n+k</td>

<td> 2</td><td> 11</td><td> channel quality feedback fór all available component carriers</td>

[0126] The integer numbers k and m can be generally any integer number. Advantageously, k should nőt be equal to m, and k and m are both non-zero, fór improved efficiency. It may be further preferable to set k=+1 and m=-1, which can be beneficially employed to probe the channel quality fór component carriers adjacent to component carrier #n. [0127] In another alternative and exemplary embodiment ofthe invention, the third combination of component carrier(s) corresponds to downlink component carrier #n and #n+m, while the fourth combination of component carrier(s) corresponds to #n and #n+k (see Table 10).

Table 10

<td> i^th combination of component carrier(s)</td><td> CQI-CI Value (binary)</td><td> Requested channel quality feedback</td>

<td> 1</td><td> 00</td><td> channel quality feedback fór component carrier #n</td>

<td> 3</td><td> 01</td><td> channel quality feedback fór component carriers #n and #n+m</td>

<td> 4</td><td> 10</td><td> channel quality feedback fór component carriers #n and #n+k</td>

<td> 2</td><td> 11</td><td> channel quality feedback fór all available component carriers</td>

ΕΡ 2 462 759 Β1 [0128] Again, k and m can be generally any integer number. Advantageously, k should nőt be equal to m, and k and m are both non-zero, for improved efficiency.

[0129] In a further alternative and exemplary embodiment ofthe invention, the third combination of component carrier(s) corresponds to down link component carrier#nto#n+m, while the fourth combination of component carrier(s) corresponds to #n to #n+k. The number m may be for example a positive integer and the number k may be a negative integer (see Table 11).

Table 11

<td> jth combination of component carrier(s)</td><td> CQI-CI Value (binary)</td><td> Requested channel quality feedback</td>

<td> 1</td><td> 00</td><td> channel quality feedback for component carrier #n</td>

<td> 3</td><td> 01</td><td> channel quality feedback for component carriers #n to #n+m</td>

<td> 4</td><td> 10</td><td> channel quality feedback for component carrier #n to #n+k</td>

<td> 2</td><td> 11</td><td> channel quality feedback for all available component carriers</td>

[0130] In a further extension to this embodiment, in case that #n+k or #n+m overflows or underflows the available component carrier indices, a cyclic wrap-around is employed as for example given by the modulo function to generate only numbers within the available index rangé.

[0131] In all the embodiments discussed above where there are 2 bits available for signaling the combination of component carrier(s) channel quality feedback for which is to be reported, it may further be beneficial to set k=-m to achieve a kind of symmetric behavior.

CQI-CI field: 3 bits [0132] In cases where there are 3 bits available to signal the CQI control information (e.g. when using the cyclic shift DMRS field), this could be seen as an extension to the two-bit case discussed above, where an additional fifth to eighth combination of downlink component carrier(s) can be indicated. The exemplary embodiments for the two-bit case can be extended to the three-bit case mutatis mutandis, e.g. to request channel quality feedback for component carrier(s) #n, #n+m1, #n+m2, #n+m3, #n+k1, #n+k2, #n+k3, orfor all available component carriers, respectively. The same holds to extend requesting channel quality feedback for multiple component carriers or ranges of component carriers mutatis mutandis. This exemplary implementation is summarized in the Table 12 below:

Table 12

<td> i^th combination of component carrier(s)</td><td> CQI-CI Value (binary)</td><td> Requested channel quality feedback</td>

<td> 1</td><td> 000</td><td> channel quality feedback for component carrier #n</td>

<td> 3</td><td> 001</td><td> channel quality feedback for component carrier #n+m1</td>

<td> 4</td><td> 010</td><td> channel quality feedback for component carrier #n+m2</td>

<td> 5</td><td> 011</td><td> channel quality feedback for component carrier #n+m3</td>

<td> 6</td><td> 100</td><td> channel quality feedback for component carrier #n+k1</td>

<td> 7</td><td> 101</td><td> channel quality feedback for component carrier #n+k2</td>

<td> 8</td><td> 110</td><td> channel quality feedback for component carrier #n+k3</td>

<td> 2</td><td> 111</td><td> channel quality feedback for all available component carriers</td>

[0133] Another exemplary implementation would be to extend the implementation exemplified above with respect to Table 10 to the 3-bit case:

ΕΡ 2 462 759 Β1

Table 13

<td> jth combination of component carrier(s)</td><td> CQI-CI Value (binary)</td><td> Requested channel quality feedback</td>

<td> 1</td><td> 000</td><td> channel quality feedback fór component carrier #n</td>

<td> 3</td><td> 001</td><td> channel quality feedback fór component carriers #n to #n+m1</td>

<td> 4</td><td> 010</td><td> channel quality feedback fór component carriers #n to #n+m2</td>

<td> 5</td><td> 011</td><td> channel quality feedback fór component carriers #n to #n+m3</td>

<td> 6</td><td> 100</td><td> channel quality feedback fór component carriers #n to #n+k1</td>

<td> 7</td><td> 101</td><td> channel quality feedback fór component carriers #n to #n+k2</td>

<td> 8</td><td> 110</td><td> channel quality feedback fór component carriers #n to #n+k3</td>

<td> 2</td><td> 111</td><td> channel quality feedback fór all available component carriers</td>

CQI-CI field: 4 bits when 5 downlink component carriers are available [0134] In case there are 4 bits available, it is possible to address 16 combinations of component carriers. Assuming that there are 5 downlink component carriers configured (numbered 0 to 4) and usable by a user equipment, there is a totál number of 32 possible combinations of available component carriers. Hence, using 4 bits, nőt all 32 possible combinations of component carriers can be signaled. It can be assumed that it is more interesting to represent the cases of requesting channel quality feedback fór few component carriers than fór many component carriers, because then it is more applicable to user equipments that are operating in the grey zone between cell-centre and cell-edge, where it would be interesting to probe the channel quality fór one or two component carriers to check where the rádió conditions are generally favorable. Therefore, according to one embodiment ofthe invention, one ofthe following two correspondences of CQI-CI value and combinations of component carrier(s) is suggested:

Table 14

<td> CQI-CI Value (decimai)</td><td> Correspondence 1: Requested channel quality feedbackfor component carrier index # (0-4)</td><td> Correspondence 2: Requested channel quality feedbackfor component carrier index # (0-4)</td>

<td> 0</td><td> 0</td><td> 0</td>

<td> 1</td><td> 1</td><td> 1</td>

<td> 2</td><td> 2</td><td> 2</td>

<td> 3</td><td> 3</td><td> 3</td>

<td> 4</td><td> 4</td><td> 4</td>

<td> 5</td><td> 0,1</td><td> 0,1,2</td>

<td> 6</td><td> 0,2</td><td> 0,1,3</td>

<td> 7</td><td> 0,3</td><td> 0,1,4</td>

<td> 8</td><td> 0,4</td><td> 0,2,3</td>

<td> 9</td><td> 1,2</td><td> 0,2,4</td>

<td> 10</td><td> 1,3</td><td> 0,3,4</td>

ΕΡ 2 462 759 Β1 (continued)

<td> CQI-CI Value (decimai)</td><td> Correspondence 1: Requested channel quality feedbackfor component carrier index # (0-4)</td><td> Correspondence 2: Requested channel quality feedbackfor component carrier index # (0-4)</td>

<td> 11</td><td> 1,4</td><td> 1,2,3</td>

<td> 12</td><td> 2,3</td><td> 1,2,4</td>

<td> 13</td><td> 2,4</td><td> 1,3,4</td>

<td> 14</td><td> 3,4</td><td> 2,3,4</td>

<td> 15</td><td> 0,1,2,3,4</td><td> 0,1,2,3,4</td>

Inclusion of Component Carrier containing the UL-DCI/CQI request [0135] in the examples on how to establish a correspondence between the logical value signaled in the CQI control information in Table 8 to Table 14, it has been assumed that the Índication ofthe component carrier(s) on which the user equipment is to provide channel quality feedback is indicated by the bits of the dedicated control information interpreted as CQI control information. Forthe examples in Table 9 to Table 11, the index #n ofthe component carrier on which the dedicated control information (UL-DCI) is received is considered in the determination ofthe combination of combination carrier(s) on which is to be reported in that it is the reference index fór determining the component carrier(s) to report fór the first, third and fourth combination.

[0136] In one further embodiment of the invention, the component carrier on which the dedicated control information (UL-DCI) including a request fór channel quality feedback (CQI request flag is set) is always to be reported fór. In one exemplary variant of this embodiment, the network configures whether to include the channel quality experienced by the user equipment on the component carrier on which a dedicated control information (UL-DCI) including a request fór channel quality feedback (CQI request flag is set) is received, to the channel quality feedback in addition to that of another or other component carriers. Fór example, the eNodeB or relay node may use control signaling (such as RRC signaling) to configure the user equipment to include or nőt include by default a measure of the channel quality of the downlink component carrier on which the a dedicated control information (UL-DCI) including a request fór channel quality feedback (CQI request flag is set) is received to the channel quality feedback. In such a way, there is one component carrier less fór which CQI control information is required.

[0137] With this strategy, the correspondences of Table 10 and Table 11 fór scenarios where there are 2 bits available fór the CQI control information can be considered as an alternative embodiment alsó makíng use of the component carrier on which the dedicated control information is received. If the component carrier on which a dedicated control information (UL-DCI) including a request fór channel quality feedback (CQI request flag is set) is received, and is further configured to be always included as a requested component carrier, then component carrier #n can be identified with any of the other available component carriers. Fór scenarios, where there are more than 2 bits available fór signaling the CQI control information, this exemplary implementation can be particulariy advantageous. Fór example, employing this implementation in a scenario where 4 bits are available fór the CQI control information (CQI-CI) and where there are 5 component carriers available, the default inclusion ofthe component carrier on which the UL-DCI triggering channel quality feedback is received to the channel quality feedback effectively reduces the number of component carriers that have to be addressed by the CQI control information from five to four. Hence, the 4 bits of CQI control information (CQICI) can now address the full rangé of combinations of four component carriers in the finest possible granularity. Fór example, in one implementation a CQI-CI value of 0 could indicate that channel quality feedback fór only the component carrier conveying the corresponding UL-DCI is requested, while a CQI-CI value of 15 could indicate a CQI request fór all available (i.e. five) component carriers.

[0138] In most of the embodiments discussed in further detail so far, the CQI request bit has been a trigger fór determining how to interpret other control information field(s) contained in the dedicated control information. In an alternative embodiment ofthe invention, the CQI control information alsó includes the CQI request flag so that the CQI request flag essentially loses its original meaning of triggering a channel quality feedback report from the userequipment. Fór example in one exemplary implementation ofthis embodiment, the CQI request flag can be combined with the e.g. Hopping flag and the combination ofthe two flags is the CQI control information. Essentially, the combination ofthe CQI request flag and the Hopping flag would result intő two bits that can be used to configure the channel quality feedback from the user equipment. An exemplary interpretation ofthe two flags could look like as Table 15.

ΕΡ 2 462 759 Β1

Table 15

<td colspan="2"> CQI control information (CQI-CI)</td><td rowspan="2"> Interpretation</td>

<td> CQI request bit</td><td> Hopping Flag</td>

<td> 0</td><td> 0</td><td> No CQI request</td>

<td> 0</td><td> 1</td><td> channel quality feedback request for all component carriers</td>

<td> 1</td><td> 0</td><td> channel quality feedback for the component carrier carrying this UL-DCI</td>

<td></td><td> 1</td><td> channel quality feedback for a single configured component carrier</td>

[0139] When interpreting certain fields of the dedicated control information in a different fashion as defined original formát, somé functionality may be lost. For example, when using the Hopping Flag for signaling the CQI control information, this effectively means that the dedicated control information cannot be longer used for activating/deactivating hopping in the uplink. Similar, considering the example, where the Hopping Configuration Bits are used for the CQI control information, hopping may be still activated/deactivated by means ofthe Hopping flag; however, there is no longer the possibility to configure the hopping configuration in the dedicated control information. A similar observation can alsó be made for using the Cyclic Shift DMRS field for signaling the CQI control information.

[0140] In all these examples where certain information can no longer be signed in the dedicated control information, according to one further embodiment, the lost functionality may be maintained by using dynamic to higher layer/semistatic signaling.

[0141] For example, as already indicated previously, the hopping configuration could be for example signaled by RRC signaling. Similarly, a default cyclic shift to be applied to the uplink transmission could alsó be configured by RRC signaling orsemi-static configuration, so that the user equipment would use this default cyclic shift for uplink transmission, if the Cyclic Shift DMRS field is reused for signaling the CQI control information.

[0142] Furthermore, in most ofthe examples above, the component carrier(s) on which the terminál is to provide channel quality feedback has been (at least to somé extent) explicitly indicated by the CQI control information. In a further exemplary embodiment ofthe invention, the component carrier(s) on which the terminál is to provide channel quality feedback may alsó be signaled implicitly or by combining explicit and implicit signaling. For example, Table 10 and Table 11 above show an example, where implicit (downlink component carrier used forthe UL-DCI defines the index #n) and explicit (the two bits ofthe UL-DCI containing the CQI control information indicates one ofthe fouroptions shown in the tables) signaling. Similarly, in the example where the component carrier on which the dedicated control information (UL-DCI) including a request for channel quality feedback (CQI request flag is set) is always to be reported on can be alsó considered using a combination of implicit and explicit signaling for indicating forwhich component carrier(s) the terminál is to provide channel quality feedback.

[0143] In generál, it can be assumed that the UL-DCI, orthe corresponding PDCCH, is transmitted to a receiver using one of multiple time/frequency resource combinations. For example, in LTE (Release 8), there is a choice bythe eNodeB on what resources and with which parameters any dedicated control information (DCI) is transmitted. This encompasses such parameters as the modulation scheme, coding rate, aggregation level, and the mapping onto time/frequency resources corresponding to a common or user equipment-specific search space. Details of these characteristics can be found e.g. in St. Sesia, I. Toufik, M. Backer, LTE The UMTS Long Term Evolution, Wiley and Sons Ltd., 2009 (ISBN: 978-0-470-69716-0), sections 9.3.2.2, 9.3.2.3, 9.3.3.2, 9.3.4.

[0144] Consequently, it is further possible to link the requested component carrier CQI nőt only to the CQI-CI as mentioned above, bút alsó to the formát or location of the corresponding UL-DCI. For example, a UL-DCI which is transmitted with a modulation and coding scheme (MCS) offering a high spectral efficiency (e.g. above a certain threshold) is most applicable for cell-centre user equipments. Therefore, in one further embodiment of the invention a CQI trigger (in form of a CQI request flag being set) in UL-DCI employing a highly-efficient MCS (e.g. above a certain threshold value) for the transmission of UL-DCI transmission triggers a channel quality feedback for all available component carriers. Conversely, a CQI trigger using a poorly-efficient modulation and coding scheme (e.g. below or equal to the certain threshold value) for the transmission ofthe UL-DCI triggers channel quality feedback from the terminál for a single component carrier. This single component carrier is for example the component carrier conveying that UL-DCI message or a pre-configured set of component carriers. Alternatively, the desired channel qualityfeedback content could alsó be signaled by means of the code rate or modulation scheme of the modulation and coding scheme instead of modulation and coding scheme.

[0145] Please note that in this exemplary embodiment, no further control information fields in the UL-DCI need to be interpreted in fashion different of theirdefault meaning. It is however alsó possible to use this alternatíve implementation of indicating the desired content ofthe channel quality feedback by a certain modulation and coding scheme in combination

EP 2 462 759 Β1 with the other Solutions that are discussed herein, so that more conditions can generate more flexibility. Fór example, a code rate criterion as mentioned above can be combined with the Hopping flag to form the CQI control information, resulting in a totál of four combinations that can be used aiong the lines ofthe examples outlined above.

[0146] Furthermore, it is to be noted that nőt only the modulation and coding scheme or the code rate or modulation scheme thereof, bút alsó transmission parameters like the PDCCH transmit power, mapping pattern to physical resource elements, transmission on certain resource blocks or transmission on certain component carriers, or combinations of these with the other methods applied to the UL-DCI message can be employed to deliver information to expand the flexibility ofthe requested channel quality feedback (i.e. the indication of different (combinations of) available component carriers fór which channel quality feedback should be provided). Furthermore, different RNTIs fór masking the CRC sequence (see e.g. Sesia et al., section 9.3.2.3 CRC attachment) fór a UL-DCI can be employed, such that e.g. the choice of a first RNTI indicates that channel quality feedback is triggered fór one component carrier (e.g. the one on which the UL-DCI is received by the user equipment) and the choice on a second RNTI indiactes channel quality feed back is triggered fór all component carriers.

[0147] The concepts outlined above are alsó applicable fór random access of terminals the access network. Fig. 21 is illustrating the contention-free random access procedure of LTE (see alsó 3GPP TS 36.213, version 8.7.0, section 6.2). The eNodeB provides 2101 the user equipment with the preamble to use fór random access so that there is no risk of collisions, i.e. multiple user equipment transmitting the same preamble. Accordingly, the user equipment is sending 2102 the preamble which was signaled by eNodeB in the uplink on a PRACH resource. After eNodeB has detected a RACH preamble, itsends 2103 a Random Access Response (RAR) on the PDSCH (Physical Downlink Shared Channel) addressed on the PDCCH with the (Random Access) RA-RNTI identifying the time-frequency siót in which the preamble was detected (Please note that the Random Access Response is sometimes alsó referred to as the Random Access Response Grant). The Random Access Response itself conveys the detected RACH preamble, a timing alignment command (TA command) fór synchronization of subsequent uplink transmissions, an initial uplink resource assignment (grant) forthe transmission of thefirst scheduled transmission by the user equipment and an assignment ofa Temporary Cell Rádió Network Temporary Identifier (T-CRNTI). This T-CRNTI is used by eNodeB in order to address the mobile(s) whose RACH preamble were detected until RACH procedure is finished, since the reál identity ofthe mobile is at this point nőt yet known by eNodeB.

[0148] Although the Random Access Response alsó contains initial uplink resource assignment fór the first uplink transmission by a user equipment, same is nőt identical to the UL-DCI formats discussed previously herein, such as fór example the formats shown in Fig. 4 or Fig. 19. The initial uplink resource assignment however alsó contains inter alia a CQI request flag and the Hopping flag, as well as a 10-bit Fixed size resource block assignment. Hence, alsó during random access the user equipment can be requested by the eNodeB or relay node to provide channel quality feedback within the allocated resources fór the initial transmission (i.e. setting the COI request flag in the Random Access Response). When reusing the random access procedure as outlined with respect to Fig. 21 above in a communication system using component carrier aggregation, e.g. in LTE-A (Release 10), again the Hopping flag and/or (one or more bits of) the Fixed size resource block assignment could be used fór indicating to the user equipment, on which ofthe available downlink component carriers the user equipment should provide channel quality feedback in the initial uplink transmission. Fór example, an implementation as discussed with respect to Fig. 8 and Fig. 10 can be directly applied to the interpretation ofthe contents ofthe Random Access Response message by the user equipment.

[0149] Another embodiment ofthe invention relates to the implementation ofthe above described various embodiments using hardware and software, lt is recognized that the various embodiments of the invention may be implemented or performed using computing devices (processors). A computing device or processor may fór example be generál purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, etc. The various embodiments of the invention may alsó be performed or embodied by a combination of these devices.

[0150] Further, the various embodiments ofthe invention may alsó be implemented by means of software modules, which are executed by a processor or directly in hardware. Alsó a combination of software modules and a hardware implementation may be possible. The software modules may be stored on any kind of computer readable storage média, fór example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc.

[0151] lt should be further noted that the individual features of the different embodiments of the invention may individually or in arbitrary combination be subject matter to another invention.

[0152] lt would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments. The present embodiments are, therefore, to be considered in all respects to be illustrative and nőt restrictive.

ΕΡ 2 462 759 Β1