Radio resource assignment in control channel in wireless communication systems

TECHNICAL FIELD [0001] The present invention relates generally to wireless communication, and in particular to control of shared channel signaling in wireless communication systems, for example cellular networks, and to respective units and methods.

BACKGROUND ART [0002] For programming downlink data transmission in the Lon g Term Evolution standard (LTE) of UMTS terrestrial radio access (UTRĄ) and UTRĄ networks (UTRAN), in addition to separate and common coding of control channel signaling, methods have been proposed time division (TDM) and frequency division (FDM) multiplexing, including their hybrids. In the case of TDM and FDM transmission of control channel signaling, control information regarding downlink and uplink allocations may be transmitted in the first few symbols of the downlink frame, or may be spread over the entire length of the frame. The frame duration is about 0.5 ms, although other durations are also possible.

[0003] Publication by Harri Holm, Antti Toskala entitled 'WCDMA for UMTS', 2000, Wiley and Sons, ISBN: 0 471 72051 8, pages 95-97, section 6.4.5 describes the dedicated downlink channel that is transmitted in dedicated downlink physical channel (downlink DPCH). Downlink DPCH uses time multiplexing for the transmission of physical control information and user data. Dates physical dedicated data transmission channel Dedicated Physical Data Channel (DPDCH) and Dedicated Physical Control Channel (DPCCH) are used for dedicated downlink channels. Downlink DPCH can use either open loop or closed loop diversity to increase performance. In the open loop, diversity of information is encoded to send it from two antennas.

[0004] PCT Application Publication No. WO 2005/050852 describes a method and system for providing channel allocation information used to support uplink (UL) and downlink (DL) channels. The system includes at least one Node-B and at least one wireless transmission / reception unit (WTRU). The WTRU receives a message from the Node B through a common control channel, which is used to transmit channel assignment information for both UL and DL transmissions. The message shall indicate whether the message is intended for the allocation of radio resources to the UL channel or to the DL channel. The WTRU determines whether the message is intended for the WTRU, and if so, the WTRU determines whether the message relates to the allocation of radio resources to the UL channel or DL ​​channel and takes appropriate action.

[0005] Patent application publication No. US 2003/0112778 describes a method and apparatus for effective multi-cast for packet data systems. Single MACJD is used for broadcasting to a group of subscribers. By using channel quality information for a group of subscribers, the base station determines the subscriber's identity with the worst channel operating conditions. The time course and transmission format for group transmission are then adapted to

That the subscriber with the worst operating conditions of the channel is able to restore transmission, and therefore it is likely that other subscribers will also be able to restore transmission. Therefore, only one MACJD must be used to perform a single broadcast instead of sending multiple transmissions to multiple subscribers.

[0006] The various forms, features and advantages of the disclosure will become fully apparent to those of ordinary skill in the art after careful consideration of the further detailed description and attached drawing figures described below. The drawing figures may have been simplified for clarity and they do not necessarily have to be drawn to scale.

SUMMARY OF THE INVENTION [0007] The present invention provides a method implemented in a wireless communication network infrastructure unit according to the features of claim 1. 1, and also a wireless communication network infrastructure unit according to the features specified in 5. Further embodiments of the invention are in accordance with the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS [0008] Fig. 1 illustrates a wireless communication system.

[0009] Fig. 2 illustrates a radio frame including a composite control channel having a plurality of control channel elements.

[0010] Fig. 3 illustrates a composite control channel having various types of control channel elements.

[0011] Fig. 4 illustrates a flow diagram of a process.

[0012] Fig. 5 illustrates a different flowchart of the process.

DETAILED DESCRIPTION [0013] Fig. 1 illustrates a wireless communication system 100 comprising a plurality of base units serving a plurality of cells forming a network distributed in a geographical region. The base unit may also be referred to as an access point, access terminal, node B, or similar term known in the art. One or more base units 101 and 102 support multiple remote units 103 and 110 within a served area or cell or within a sector thereof. Remote units may also be referred to as subscriber units, mobile units, users, terminals, subscriber stations, user equipment (UE), user terminals or by other terminology known in the art. Network base units communicate with remote units to perform functions such as scheduling terminals to receive or transmit data using available network resources. The wireless network also includes a management function including data routing, access control, subscriber billing, terminal authentication, etc., which can be controlled by other network entities, which in principle is known to those having ordinary skill in the art.

[0014] Base units 101 and 102 send downlink communication signals 104 and 105 to supported remote units in at least part of the same resources (time and / or frequency). Remote units 103 and 110 communicate with one or more base units 101 and 102 via uplink communication signals 106 and 113. One or more base units may include one or more transmitters and one or more receivers that

-3 support remote units. The number of transmitters in the base unit may be associated, for example, with the number of transmit antennas 109 in the base unit. When multiple antennas are used to support each sector to provide various advanced communication modes, for example, adaptive beamforming, transmission diversity, SDMA multi-access, multi-stream transmission, etc., many base units can be used. These base units within the sector can be highly integrated and can share various hardware and software components. For example, all base units assigned to cell service together may constitute what is traditionally known as a base station. Remote units may also contain one or more transmitters and one or more receivers. The number of transmitters can be associated, for example, with the number of transmit antennas at the remote unit.

[0015] In one embodiment, the communication system uses OFDMA or the next generation FDMA architecture based on a single carrier for uplink transmission, such as interleaved FDMA (IFDMA), localized FDMA (LFDMA), OFDM extended with DFT (DFT-SOFDM) ) with IFDMA or LFDMA. In other embodiments, the architecture may also include the use of scattering techniques such as direct-scattering CDMA (DS-CDMA), multi-carrier CDMA (MCCDMA), Direct-scattering multi-carrier CDMA (MC-DSCDMA), orthogonal frequency division and code division multiplexing (OFCDM) with one-dimensional or two-dimensional diffusion or simpler time and frequency division multiplexing / multi-access techniques.

In general, the wireless network infrastructure planning unit located, for example, in each base unit 101 and 102 in Fig. 1, allocates or allocates radio resources to remote units in the network. Each base unit contains a planner for planning and allocating resources to remote units in their respective supported areas or cells or sectors. In multi-access schemes such as those based on OFDM methods and the long-term evolution of UTRA / UTRAN study items (UTRA / UTRAN Study Item) in 3GPP (also known as evolving UTRA / UTRAN (EUTRA / EUTRAN)), planning can be done in terms of time and frequency using a frequency selective pianist (FS). In some embodiments, each remote unit may provide a frequency band channel quality indicator (CQI) or other metric to the planner to enable scheduling.

[0017] In OFDM systems or OFDM based systems such as DFT-SOFDM and IFDMA, resource allocation is a frequency and time allocation that maps information for a specific base unit to subcarrier resources from the set of available subcarriers determined by the planner. This allocation may depend, for example, on the channel quality index of a selectively selected frequency or some other metric reported by the UE to the planner. The channel coding efficiency and modulation scheme that may be different for different parts of the subcarrier's resources are also determined by the planner and may also depend on the reported CQI or other metric. In code-partitioned multiplexing networks, resource allocation is a code allocation that maps information for a specific base unit to subcarrier resources from the set of available subcarriers determined by the planner.

[0018] Fig. 2 illustrates a frame 200 that is part of a radio frame. A radio frame generally contains a plurality of frames that can form a combined frame continuum. In Fig. 2, each frame includes a part with the control channel 210 assembled containing at least two control channel elements.

-4Fig. 2 illustrates a composite control channel comprising a plurality of control channel elements 212, 214, 216 and 218. Each control channel element includes a code word that provides a physical mapping of the logical control channel to a sequence of symbols, e.g., QAM symbols. The control channel elements are not essentially the same type. In Fig. 2, for example, control channel elements 212 and 218 have different sizes. Control channel elements may also be for uplink or downlink assignments and have different associated data block information. Control channel elements may also be associated with various specification releases. In some embodiments, the composite control channel includes reference symbols, e.g., pilot symbols, which are different from the control channel elements. Reference symbols are usually read by all remote units.

[0019] Each frame corresponds to a transmission time interval (TTI). An example TTI is 1 ms. In one embodiment, a single TTI is 1 ms or 2 ms long, the TTI is divided into two subframes, each 0.5 ms long. This construction, however, implies the need to address multiple blocks of the resource, i.e. more than the number of resource blocks in one 0.5 ms subframe, unless the resource block (RB) definition is extended to automatically define RB as extending over the entire length of the TTI, regardless of the duration of the TTI. However, this can lead to inefficiency in the form of excessive capacity per RB. In the event that RB is defined to extend over a portion of the length of the TTI, it would be possible to address each of the resource blocks independently in multiple subframes forming the TTI. For this reason, mechanisms are required to signal resource allocations for frames or TTI transmission time intervals consisting of linked subframes. In addition, mechanisms are required to allow resource allocation based on the needs of a single UE, with less resource allocated for a UE served by smaller packets, while more resources allocated to a larger packet managed UE. In the case of UMTS (Universal Mobile Telecommunications System), the TTI is defined as the period of time during which the transmission or transport block is transmitted. The transmission block or transport block is composed of a block of jointly coded data, protected by one CRC. In the present case, the alternative definition of TTI could be the transmission period controlled by one instance of control channel signaling.

[0020] In one embodiment, each control channel element includes only radio resource assignment information, e.g., a code word, addressed only to a single wireless communication unit, e.g., one of the remote units 110, 103 in Fig. 1. Information the radio resource assignment includes, among others, information specific to the remote unit and the time-frequency radio resource assignment. In other embodiments, the radio resource assignment information may further include modulation, code efficiency, block size information, antenna mode indicator, and other information.

[0021] In one embodiment, the wireless communication network infrastructure entity, e.g., the planner, may address more than one control channel element for the same wireless communication entity, e.g., one of the remote units 110 or 103 in Fig. 1. In particular, the control channel may include a first version of the codeword containing the resource allocation in the first control channel element of the composite control channel and a second version of the codeword containing the resource allocation in the second control channel element of the composite control channel in which both the first and second versions of the codeword are addressed to the same

-5 mobile unit. In one embodiment, the first and second versions of the codeword are the same and in another embodiment, the first and second versions of the codeword are different. Whether code words addressed to the same unit are different or the same affects how the addressed units connect control channel elements, as will be discussed below. Thus, the wireless communication network infrastructure entity transmits a composite control channel comprising at least two control channel elements, each element having a corresponding first and second codeword version addressed to the same entity. In some cases, a wireless network infrastructure entity may, typically based on the entity's channel operating conditions, send a composite control channel including one control channel element addressed to the entity.

[0022] In the examples, where the composite control channel comprises a composite control channel comprising at least two different types of control channel radio resource allocation elements, the remote unit typically determines the number of types of evil control channel elements composite control channel after receiving the composite control channel. In one example, the composite control channel includes type indicator information for each type of control channel element constituting the composite control channel. The remote unit may thus determine the number of types of control channel elements based on the type indicator information. In Fig. 3, the radio frame 300 includes a composite control channel 310 comprising a first type of control channel element 312 and a second type of control channel element 316. The first type of control channel element is identified by the first pointer, e.g., a sequence of bits, 314 attached to the last control channel element of the first type. The second type of control channel element is identified by a second indicator 318 attached to the last control channel element of the second type. In another example, indicators 314 and 318 are not present and the type of control channel element is determined after the control element has been successfully decoded. For example, the type bit may indicate an uplink or downlink control element in the decoded data block. The control element can be addressed to a single UE by color coded CRC or by other means. According to another embodiment of the disclosure, the remote unit determines the number of control channel elements constituting at least one or at least two control channel elements of the composite control channel. FIG. 3 is only one illustrative embodiment of the physical arrangement of control channel elements in a subframe. In an alternative embodiment, the system can be seen as a logical system where the control channel elements comprise a plurality of subcarriers arranged throughout the frame.

[0023] In one example, determining the number of types of control channel elements constituting the composite control channel includes determining the number of uplink control channel elements and determining the number of downlink control channel elements. The number of uplink control channel elements can be determined based on the first bit sequence and the number of downlink control channel elements based on the second bit sequence located within the frame. In one example, the number of uplink and downlink control channel elements is determined based on where the first and second bit of the sequence are located within the frame. Alternatively, the use of different bit sequences may be used to indicate different numbers of control channel elements. For example, the first bit sequence may indicate a first number of uplink elements and the second bit sequence may indicate a second number of uplink elements.

[0024] In some embodiments, the composite control channel includes a first portion of the composite control channel in a first frequency band at a first center frequency and a second composite control channel in a second frequency band at a second center frequency. This control channel structure can be implemented to accommodate remote users having limited frequency response. Generally, the composite control channel may be divided into many parts of the composite control channel at respective center frequencies. For example, terminals may have their receiver bands limited to 10 MHz, while the carrier bandwidth is 20 MHz. To accommodate such terminals with limited minimum bandwidth, it may be necessary to convert the composite control channel to both 20 MHz carrier subband, 10 MHz lower band and 10 MHz upper band. 10 MHz terminals wait for the upper or lower subband and receive the corresponding composite channel.

[0025] In the process 400 of Fig. 4, at 410 a wireless communication unit, e.g., a remote unit, the terminal receives a composite control channel comprising at least two control channel elements. In one embodiment, each control channel element includes only radio resource allocation information exclusively addressed to a single wireless communication unit.

[0026] In Fig. 4, in 420 two or more control channel elements are connected before decoding at 430. However, in general, the remote unit may attempt to decode a single control channel element without first joining the elements or it may attempt to decode a single control channel element after decoding. or trying to decode connected items. Whether a connection is necessary or not generally depends on whether the remote unit successfully decodes individual control channel elements. Linking may be required, for example, in cases where a cyclic redundancy check (CRC) or other control information check fails after decoding a single control channel element or where decoding is not successful. Control information typically refers to information specific to a remote unit that can be contained in a decoded control channel element or masked in a coded control channel element or masked or entered into CRC in the case of CRC color coding.

[0027] In some implementations, each of the plurality of control channel elements has an associated root index that can be used as a basis for joining control channel elements. For example, if the composite control channel contains 12 control channel elements, 4 of these elements may have the same associated main index and may be used as the basis for decoding and combining and decoding control channel elements. In embodiments where the control channel is divided into parts at respective center frequencies, as discussed above, the remote unit only connects control channel elements from the same control channel part. In other words, control channel elements from different control channel parts are not combined.

[0028] In some embodiments, the remote unit combines at least two control channel elements of the composite control channel, each control channel element being of a type that only contains radio resource assignment information exclusively addressed to a single wireless communication unit. Combination may be required, for example, in cases where a cyclic redundancy check (CRC) or other control information check fails after decoding a single control channel element, or in cases where

-Ί decoding is not successful. However, generally the remote unit may attempt to decode the control channel element without first connecting.

[0029] In one embodiment, at least two control channel elements are combined by summing soft information obtained from information about the first and second code words, the information about the first code word being in the first control channel element and information about the second code word is in the second control channel element. In this combination, the combined control channel elements are temporarily aligned and superimposed (known as Chase joining). The imposition can involve the combination of max-ratio combining or the sum of log-likelihood-ratios (LLRs) or the like. It is assumed here that the information about the first and second codeword is addressed to the same remote unit. If this is not the case, then either decoding or checking the control information after decoding will fail. If unsuccessful, the remote unit may create a different combination of control channel elements, for example, by connecting another set of control channel elements or by connecting to an additional element.

[0030] In another embodiment, at least two control channel elements are combined by rearranging and summing the soft information obtained from different information about the first and second code words, the information about the first code word being in the first control channel element, and the information about the second code word is in the second control channel element. For example, the first code word and the second code word may include subsets of the information set and parity bits generated from the lower efficiency channel coder. The subsets may be non-overlapping or partially overlapping. The soft information corresponding to the overlapping bit positions of the codeword is usually aggregated in the remote unit, while the non-overlapping bit positions are usually moved to the correct positions for decoding.

[0031] In one embodiment, the remote unit combines at least two control channel elements in accordance with predefined combinations of control channel elements. For example, at least one of the predefined combinations comprises a combination of at least two logically continuous control channel elements. Logically continuous control channel elements may or may not be physically continuous. For example, if a set of frequency-spaced subcarriers (comb) is used for one control channel element, another control channel element may or may not occupy physically subcarriers adjacent to the first control channel element. Or, if the logical and physical arrangements of subcarriers are identical, that is, there is a one to one mapping of logical and physical subcarriers, then logical attachment implies physical adhesion and vice versa. In other embodiments, at least two nonadjacent control channel elements are combined, wherein nonadjacent control elements can be physical or logical.

[0032] In some implementations, the order in which the remote unit attempts to combine control channel elements according to predefined combinations is based on one or more hypotheses and assumptions. For example, control channel elements may be combined based on determining the number of control channel elements constituting the composite control channel. Such determination also includes determining the number of control channel elements constituting the determined one

- control channel element type in embodiments where the composite control channel includes more than one element type as discussed above. The number of control channel elements may be determined, for example, based on the existence of information about the number of control channel elements contained in the composite control channel. For example, the number of control channel elements may be determined based on the sequence of bits attached to the composite control channel. In one implementation, different bit sequences indicate different numbers of control channel elements. In another implementation, the location of the bit sequence within the frame indicates the number of control channel elements.

In the latter implementation, the same bit sequence can be used to indicate different numbers of control channel elements depending on where the bit sequence is located within the frame. The number of control channel elements can also be determined based on data or messages shared between the wireless communication devices and the network infrastructure unit. This may occur in a message sent to all remote units via a broadcast channel sent from time to time or a broadcast message sent in each TTI. The number of control channel elements or subsets of control channel elements that the remote unit should decode can also be sent by a message dedicated to that remote unit.

[0033] In one embodiment, the control channels may be one or two control channel elements with the size of the control element indicating the type of control element. Convolutional encoding can be used for controls. And the decoder can decode the first control element, check the CRC and then stop decoding if the control element is intended for the user. If not, decoding can start from the point just before placing the last bit in the first control element, to the end of the trellis consisting of both controls. CRC is being checked again. In this way, control channel decoding can be achieved with less effort than if the combined control elements were decoded from the beginning of the lattice. Note that the code efficiency for one and two controls must be the same in this embodiment.

[0034] In some embodiments, a portion of the composite control channel is allocated to allocate radio resources in each frame. In these embodiments, the unallocated portion of the control channel may be used to transfer data. Thus, the wireless communication network infrastructure entity, e.g., the planner, may allocate a portion of the control channel for allocating radio resources in each frame by embedding the bit sequence within the corresponding frame. In one embodiment, the location of the bit sequence within the frame indicates the size of the control channel, e.g., how many control channel elements are allocated for allocating radio resources to one or more remote units. In this implementation, control channel elements may be addressed only to a single remote unit or to more than one remote unit. More generally, the network infrastructure entity may dynamically change a portion of the control channel for allocating radio resources in each frame by changing the bit sequence or the position of the bit sequence embedded in each frame before transmitting the frames. In addition, as indicated earlier, the network infrastructure entity may also dynamically allocate different types of control channel elements and their different number within the frame.

[0035] In another embodiment, the bit sequence embedded within the subframe is used to recognize whether the control channel element is for a remote unit. In this case, the bit sequence embedded within the subframe may be a data-dependent bit sequence, such as CRC processed with wireless communications device identity information, a code word masked with wireless communications device identity information or the like. In this embodiment, the first subframe, which may be the last subframe of the TTI, includes control information including the modulation type, resources, or antenna mode indicator. Each control channel may be one or more control channel elements, and the size of the control channel may be different in the first and second subframes. The second subframe may occur in the same or different parts of the control channel as the control information from the first subframe. If another part of the subframe is used, the complexity of blind decoding can be reduced by knowing the control channel elements in the second subframe based on the position of the control channel elements of remote units from the first subframe.

[0036] In the process block 500 of Fig. 5, at 510 the wireless communication infrastructure unit allocates a portion of the control channel for allocating radio resources in each frame by embedding the bit sequence within the corresponding frame. The allocation of control channel parts includes the allocation of all or less of all available control channel parts than all of its available parts, wherein the unallocated part can be used for other purposes, for example, to transfer data. At 520, the wireless communication network infrastructure entity dynamically changes a portion of the control channel for allocating radio resources in each frame, the multiple frames being a radio frame. According to this form of disclosure, potentially, a different portion of each control channel in each frame constituting the radio frame may be allocated for allocating radio resources. A portion of the control channel for allocating radio resources in each frame can be changed dynamically by changing the position of the bit sequence embedded in each frame or by using different bit sequences as discussed above. At 530, the wireless communication network infrastructure entity transmits at least two frames, e.g., forming a radio frame, each frame comprising a control channel, part of which is allocated for radio resource allocation.

[0037] For example, in Fig. 2, a portion of the control channel used for radio resource allocation is indicated based on where the bit sequence 220, designated as termination tag or signature, is embedded within the corresponding frame. Depending on where the bit sequence is located, part of the control channel, e.g., number of elements, used for radio resource allocation may be smaller than the entire control channel of the frame. Generally, different frames constituting a radio frame may allocate different portions of respective control channels for radio resource allocation. In one embodiment, the wireless communication device includes a receiver capable of receiving a frame corresponding to a transmission time interval, the frame comprising a control channel and a bit sequence embedded within the frame. The controller in communication with the receiver is configured to determine the portion of the control channel used for radio resource allocation based on where the corresponding bit sequence is embedded within the received frame, wherein the portion of the control channel used for radio resource allocation may be smaller than the entire control channel.

[0038] In a wireless communication device, for example, one of the remote units 101 or 103 in Fig. 1, the device receives a plurality of at least two frames, each frame having a control channel having at least two control channel elements and each the frame contains a bit sequence embedded within the frame. In one embodiment, the wireless communication device determines the control channel portion used for radio resource allocation in each frame based on where the corresponding bit sequence is embedded within the frame. Generally, the portion of the control channel used for radio resource allocation may be smaller than the entire control channel, and each frame may use different parts of the control channel for radio resource allocation based on where corresponding bit sequences are embedded within the frame.

[0039] In some cases, all of the control channel elements of the composite control channel communicate control channel information. In this particular embodiment, the lack of information about the number of control channel elements, e.g., the bit sequence embedded within the frame, indicates the use of the entire composite control channel for radio resource allocation. For example, in the absence of information about the number of control channel elements, the remote unit may assume that the default number of control channel elements is used for allocating radio resources.

[0040] Although the present disclosure and its best practices have been described in a way that describes ownership and allows those of ordinary skill in the art to make and use the same, it will be understood and understood that equivalents for the exemplary embodiments disclosed herein exist and that modifications and variants can be made to them without departing from the scope of the invention, which is not limited by example embodiments, but by the appended claims.