Method and apparatus for transmitting cell shaping indication in wireless communication system

The present invention relates to wireless communication, and more particularly to methods and devices for transmitting cell shaping instructions in wireless communication systems.

UMTS (universal mobile telecommunications system) operates on WCMDA (wide band code division multiple access) based on European system, GSM (registered trademark) (global system for mobile communications) and GPRS (general packet radio services). 3rd generation Asynchronous mobile communication system. LTE (long-term evolution) of UMTS is under discussion by 3GPP (3rd generation partnership project) that standardizes UMTS.

3GPP LTE is a technology that enables high-speed packet communication. Many methods have been proposed to reduce user and operator costs, improve service quality, expand coverage and increase system capacity, which are LTE goals. 3GPP LTE requires higher level requirements such as cost savings per bit, improved service usefulness, flexible use of frequency bands, simple construction, open interfaces and proper power consumption of terminals.

Figure 1 shows the structure of the LTE system. Communication networks are widely installed to provide a variety of communication services such as IMS and Internet Protocol (VoIP) via packet data.

Referring to FIG. 1, the LTE system structure includes one or more terminals (UE) 10, E-UTRAN (evolved-UMTS terrestrial radio access network) and EPC (evolved packet core). The terminal 10 is a communication device operated by a user. The terminal 10 may be fixed or mobile, in other terms such as MS (mobile station), UT (user terminal), SS (subscriber station), wireless device (wireless device), etc. Sometimes called.

E-UTRAN can include one or more eNB (evolved node-B) 20 and can have multiple terminals in one cell. The eNB 20 provides the terminal with a control plane and end points for the user plane. eNB20 generally means a fixed station that communicates with a terminal 10, and may be referred to by other terms such as BS (base station), BTS (base transceiver system), and access point (access point). .. One eNB 20 can be arranged for each cell. One or more cells can exist within the coverage of eNB20. A cell is configured to have one of bandwidths such as 1.25, 2.5, 5, 10 and 20MHz and is a downlink (DL; downlink) or uplink (UL; uplink) transmission service to multiple terminals. Can be provided. At this time, cells that are different from each other can be set to provide different bandwidths from each other.

Hereinafter, DL means communication from the eNB 20 to the terminal 10, and UL means communication from the terminal 10 to the eNB 20. In DL, the transmitter is part of the eNB 20 and the receiver is part of the terminal 10. In UL, the transmitter is part of terminal 10 and the receiver is part of eNB 20.

The EPC can include an MME (mobility management entity) responsible for the function of the control plane and an S-GW (system architecture evolution (SAE) gateway) responsible for the function of the user plane. The MME / S-GW30 is located at the end of the network and is connected to the external network. The MME has information on the access information of the terminal and the capability of the terminal, and such information can be mainly used for the mobility management of the terminal. S-GW is a gateway that has E-UTRAN as a terminal point. The MME / S-GW30 provides the terminal 10 with session termination points and mobility management functions. EPC can further include PDN (packet data network) -GW (gateway). PDN-GW is a gateway having PDN as a terminal point.

MME includes NAS (non-access stratum) signaling to eNB20, NAS signaling security, AS (access stratum) security control, inter CN (core network) node signaling for mobility between 3GPP access networks, and idle mode terminal arrival. Possibility (including control and execution of paging retransmission), tracking area list management (for terminals in idle and activated modes), P-GW and S-GW selection, MME for handover with MME change Bearer management features including selection, SGSN (serving GPRS support node) selection, roaming, authentication, and dedicated bearer configuration for handover to 2G or 3G 3GPP access networks, PWS (public warning) system: Provides various functions such as earthquake / tsunami warning system (ETWS) and commercial mobile warning system (CMAS)) message transmission support. S-GW hosts are based on each user packet filtering (eg, through deep packet inspection), legal blocking, terminal IP (internet protocol) addressing, transport level packing marking on DL, UL / It provides various functions of DL service level billing, gating and grade enforcement, and DL grade enforcement based on APN-AMBR. For clarity, the MME / S-GW30 is simply referred to as the "gateway", which can include both the MME and the S-GW.

Interfaces for sending user traffic or sending control traffic can be used. The terminal 10 and the eNB 20 can be connected by the Uu interface. The eNB20 can be interconnected via an X2 interface. The adjacent eNB 20 can have a mesh network structure with an X2 interface. The eNB20 can be connected to the EPC via the S1 interface. The eNB20 can be connected to the MME via the S1-MME interface and can be connected to the S-GW via the S1-U interface. The S1 interface supports many-to-many-relation between the eNB 20 and the MME / S-GW30.

Figure 2 shows the structure of a typical E-UTRAN and EPC. Referring to FIG. 2, the eNB 20 selects for the gateway 30, routes to the gateway 30 during RRC (radio resource control) activation, schedules and sends paging messages, and schedules BCH (broadcast channel) information. And transmission, dynamic allocation of resources from UL and DL to terminal 10, eNB measurement configuration and provisioning, wireless bearer control, RAC (radio admission control) and connection mobility control function in LTE active state Can be carried out. As mentioned above, the gateway 30 can perform paging start, LTE idle state management, user plane encryption, SAE bearer control and NAS signaling encryption and integrity protection functions at the EPC.

FIG. 3 is a block diagram of the user plane protocol stack and the control plane protocol stack of the LTE system. FIG. 3- (a) is a block diagram of the user plane protocol stack of the LTE system, and FIG. 3- (b) is a block diagram of the control plane protocol stack of the LTE system.

The layers of the wireless interface protocol between the terminal and E-UTRAN are L1 (first layer) and L2 (second layer) based on the lower three layers of the OSI (open system interconnection) model widely known in communication systems. Layer) and L3 (third layer). The wireless interface protocol between the terminal and the E-UTRAN can be horizontally divided into a physical layer, a data link layer and a network layer, and vertically, It can be divided into a control plane, which is a protocol stack for transmitting control signals, and a user plane, which is a protocol stack for transmitting data information. The layer of wireless interface protocol can exist in pairs with the terminal in E-UTRAN, which can be responsible for the data transmission of the Uu interface.

The physical layer (PHY) belongs to L1. The physical layer provides an information transfer service to a higher layer via a physical channel. The physical hierarchy is connected to the MAC (media access control) hierarchy, which is a higher hierarchy, via a transport channel. Physical channels are mapped to transport channels. Data can be transmitted between the MAC hierarchy and the physical hierarchy via the transport channel. Data can be transmitted between different physical layers, that is, between the physical layers of the transmitter and the physical layers of the receiver, using wireless resources via physical channels. The physical hierarchy can be modulated using the OFDM (orthogonal frequency division multiplexing) method, utilizing time and frequency as radio resources.

The physical hierarchy uses several physical control channels. PDCCH (physical downlink control channel) reports to the terminal for resource allocation of PCH (paging channel) and DL-SCH (downlink shared channel), and HARQ (hybrid automatic repeat request) information related to DL-SCH. .. The PDCCH can transmit the uplink grant to report to the terminal for the resource allocation of the uplink transmission. PCFICH (physical control format indicator channel) informs the terminal of the number of OFDM symbols used for PDCCH and is transmitted for every subframe. PHICH (physical hybrid ARQ indicator channel) is HARQ for UL-SCH transmission. Transmits ACK (acknowledgment) / NACK (non-acknowledgment) signals. PUCCH (physical uplink control channel) transmits UL control information such as HARQ ACK / NACK, scheduling request and CQI for downlink transmission. PUSCH (physical uplink shared channel) transmits UL-SCH (uplink shared channel).

FIG. 4 shows an example of a physical channel structure.

A physical channel is composed of a plurality of subframes in the time domain and a plurality of subcarriers in the frequency domain. One subframe is composed of a plurality of symbols in the time domain. One subframe is composed of a plurality of resource blocks (RBs). One resource block is composed of a plurality of symbols and a plurality of subcarriers. In addition, each subframe can utilize a specific subcarrier of a specific symbol of the corresponding subframe for PDCCH. For example, the first symbol of a subframe can be used for PDCCH. PDCCH can transmit dynamically allocated resources such as PRB (physical resource block) and MCS (modulation and coding schemes). The TTI (transmission time interval), which is the unit time for data transmission, is the same as the length of one subframe. The length of one subframe is 1ms.

Transport channels are classified into common transport channels and dedicated transport channels, depending on whether the channels are shared. The DL transport channel that sends data from the network to the terminal is the BCH (broadcast channel) that sends system information, the PCH (paging channel) that sends paging messages, and the DL that sends user traffic or control signals. -Includes SCH etc. DL-SCH supports dynamic link adaptation and dynamic / semi-static resource allocation with changes in HARQ, modulation, coding and transmit power. DL-SCH also allows the use of broadcast and beam formation throughout the cell. System information transmits one or more system information blocks. All system information blocks can be transmitted in the same cycle. MBMS (multimedia broadcast / multicast service) traffic or control signals are transmitted via MCH (multicast channel).

UL transport channels that send data from terminals to the network include RACHs (random access channels) that send initial control messages, UL-SCHs that send user traffic or control signals, and so on. UL-SCH can support dynamic link adaptation with HARQ and transmit power and potential modulation and coding changes. UL-SCH also allows the use of beam formation. RACH is commonly used for initial access to cells.

The MAC hierarchy belonging to L2 provides services to the RLC (radio link control) hierarchy, which is a higher hierarchy, via a logical channel. The MAC hierarchy provides the ability to map from multiple logical channels to multiple transport channels. The MAC hierarchy also provides a logical channel multiplexing function by mapping from multiple logical channels to a single transport channel. The MAC sub-tier provides data transfer services on the logical channel.

The logical channel is divided into a control channel for information transmission on the control plane and a traffic channel for information transmission on the user plane according to the type of information transmitted. That is, a set of logical channel types is defined for different data transfer services provided by the MAC hierarchy. The logical channel is located above the transport channel and is mapped to the transport channel.

The control channel is used only for information transmission on the control plane. The control channels provided by the MAC hierarchy include BCCH (broadcast control channel), PCCH (paging control channel), CCCH (common control channel), MCCH (multicast control channel) and DCCH (dedicated control channel). BCCH is a downlink channel for broadcasting system control information. PCCH is a downlink channel used to transmit paging information and to page terminals whose cell-by-cell location is unknown to the network. CCCH is used by terminals when there is no RRC connection with the network. MCCH is a one-to-many downlink channel used to send MBMS control information from the network to the terminal. DCCH is a one-to-one bidirectional channel used by a terminal to transmit dedicated control information between the terminal and the network in the RRC connection state.

Traffic channels are used only for communicating information on the user plane. The traffic channels provided by the MAC hierarchy include DTCH (dedicated traffic channel) and MTCH (multicast traffic channel). DTCH is a one-to-one channel used for transmitting user information of one terminal, and both uplink and downlink can exist. MTCH is a one-to-many downlink channel for transmitting traffic data from a network to a terminal.

Uplink connections between logical and transport channels are DCCH that can be mapped to UL-SCH, DTCH that can be mapped to UL-SCH, and CCCH that can be mapped to UL-SCH. including. The downlink connection between the logical channel and the transport channel can be mapped to BCH or DL-SCH BCCH, PCH can be mapped to PCCH, DL-SCH can be mapped to DCCH. Includes DTCH, which can be mapped to DL-SCH, MCCH, which can be mapped to MCH, and MTCH, which can be mapped to MCH.

The RLC hierarchy belongs to L2. Features of the RLC hierarchy include resizing data by splitting / concatenating data received from the upper hierarchy in the radio section so that the lower hierarchy is suitable for transmitting data. In order to guarantee the various QoS required by the radio bearer (RB), the RLC hierarchy has transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). ) Provides three operation modes. AM RLC provides a retransmission function via ARQ (automatic repeat request) for reliable data transmission. On the other hand, the function of the RLC hierarchy can be realized by the functional block inside the MAC hierarchy, and at this time, the RLC hierarchy may not exist.

The PDCP (packet data convergence protocol) hierarchy belongs to L2. The PDCP layer has a header compression function that reduces unnecessary control information so that data transmitted by introducing IP packets such as IPv4 or IPv6 on a wireless interface with a relatively small bandwidth is transmitted efficiently. provide. Header compression increases transmission efficiency in the radio section by transmitting only the information needed in the header of the data. In addition, the PDCP hierarchy provides security features. Security features include encryption to prevent third party inspection and integrity protection to prevent third party data manipulation.

The RRC (radio resource control) hierarchy belongs to L3. The RRC hierarchy located at the bottom of L3 is defined only in the control plane. The RRC hierarchy plays the role of controlling the radio resources between the terminal and the network. To that end, terminals and networks exchange RRC messages through the RRC hierarchy. The RRC hierarchy is responsible for controlling logical, transport, and physical channels in relation to RB configuration, re-configuration, and release. RB is the logical path provided by L1 and L2 for data transmission between the terminal and the network. That is, RB means the service provided by L2 for data transmission between the terminal and E-UTRAN. Setting RB means defining the characteristics of the radio protocol hierarchy and channels to provide a particular service, and determining the specific parameters and operating methods of each. RB is SRB (signaling RB) and DRB (data) It can be divided into two categories: RB). The SRB is used as a passage for transmitting RRC messages on the control plane, and the DRB is used as a passage for transmitting user data on the user plane.

With reference to Figure 3- (a), the RLC and MAC tiers (ending at eNB on the network side) can perform functions such as scheduling, ARQ and HARQ. The PDCP hierarchy (ending with eNB on the network side) can perform user plane functions such as header compression, integrity protection and encryption.

With reference to Figure 3- (b), the RLC / MAC hierarchy (ending at eNB on the network side) can perform the same function due to the control plane. The RRC hierarchy (ending at eNB on the network side) can perform functions such as broadcasting, paging, RRC connection management, RB control, mobility functions and UE measurement reporting and control. The NAS control protocol (terminating at the gateway MME on the network side) provides features such as SAE bearer management, authentication, LTE_IDLE mobility management, LTE_IDLE paging initiation and security control for signaling between the gateway and the UE. Can be carried out.

The RRC state indicates whether the RRC hierarchy of the terminal is logically connected to the RRC hierarchy of E-UTRAN. The RRC state is divided into two, such as the RRC connection state (RRC_CONNECTED) and the RRC idle state (RRC_IDLE). If an RRC connection between the terminal's RRC hierarchy and the E-UTRAN's RRC hierarchy is configured, the terminal will be in the RRC connection state, otherwise the terminal will be in the RRC idle state. Since the RRC_CONNECTED terminal has an E-UTRAN and RRC connection set, the E-UTRAN can grasp the existence of the RRC_CONNECTED terminal and can effectively control the terminal. On the other hand, E-UTRAN cannot grasp the terminal of RRC_IDLE, and the core network (CN; core network) is a region larger than the cell. Area) Manage terminals in units. That is, the terminal of RRC_IDLE is only known to exist in units of larger areas, and the terminal must move to RRC_CONNECTED in order to receive normal mobile communication services such as voice or data communication.

In the RRC_IDLE state, while the terminal specifies the DRX (discontinuous reception) set by the NAS, the terminal can receive the broadcast of system information and paging information. In addition, the terminal is assigned an ID (identification) that uniquely specifies the terminal in the tracking area, and can execute PLMN (public land mobile network) selection and cell reselection. Also, in the RRC_IDLE state, the RRC context is not stored in eNB.

In the RRC_CONNECTED state, the terminal has an E-UTRAN RRC connection and RRC context in E-UTRAN and is capable of sending and / or receiving data from the eNB. The terminal can also report channel quality information and feedback information to the eNB. In the RRC_CONNECTED state, E-UTRAN can know the cell to which the terminal belongs. Thus, the network can send and / or receive data from the terminal and GERAN (GSM® EDGE radio access) via terminal mobility (handover and network assisted cell change (NACC)). It is possible to control inter-RAT (radio access technology) cell change instruction) to network) and perform cell measurement for adjacent cells.

In the RRC_IDLE state, the terminal specifies the paging DRX cycle. Specifically, the terminal monitors the paging signal at a specific paging occasion for each terminal specific paging DRX cycle. The paging opportunity is the time interval during which the paging signal is transmitted. The terminal has its own paging opportunity.

The paging message is transmitted across all cells belonging to the same tracking area. If the terminal moves from one tracking area to another, the terminal sends a TAU (tracking area update) message to the network to update the location.

When the user first powers on the terminal, the terminal first searches for the appropriate cell and then stays in RRC_IDLE in that cell. When an RRC connection needs to be established, a terminal that remains in RRC_IDLE can establish an E-UTRAN RRC and RRC connection and move to RRC_CONNECTED via the RRC connection procedure. The terminal staying at RRC_IDLE receives an uplink data transmission due to a user's call attempt, etc., or receives a paging message from E-UTRAN and needs to send a response message to it. And RRC connection needs to be established.

It is known that different cause values are mapped to the signature sequence used to send a message between the terminal and the eNB. In addition, CQI (channel quality indicator) or path loss and cause or message size are known to be candidates for inclusion in the initial preamble.

If the terminal wants to access the network and decides to send the message, the message can be linked to a purpose and the cause value can be determined. Also, the ideal message size can be determined by identifying all additional information and alternative sizes that differ from each other. Scheduling request messages that can be stripped or replaced with additional information can be used.

The terminal obtains the necessary information for the transmission of the preamble, UL interference, pilot transmission power, the SNR required to detect the preamble at the receiver, or a combination thereof. This information must allow the calculation of the initial transmit power of the preamble. It is advantageous to send UL messages near the preamble in terms of frequency to ensure that the same channel is used for sending the message.

To ensure that the network receives the preamble with minimal SNR, the terminal must consider UL interference and UL path loss. UL interference can only be determined on the eNB and must be broadcast by the eNB and received by the terminal prior to preamble transmission. UL path loss can be considered similar to DL path loss and can be estimated by the terminal from the received RX signal strength once the transmit power of some of the cell's pilot signals is known to the terminal. ..

The UL SNR required for preamble detection generally depends on the eNB configuration, such as the number of Rx antennas and receiver performance. It has the advantage of transmitting a somewhat static pilot transmit power, separating the required UL SNR from changing UL interference, and transmitting the required possible power offset between the message and the preamble. is there.

The initial transmission power of the preamble can be roughly calculated by the following formula.

Transmission power = TransmitPilot + RxPilot + UL interference + offset + SNRRequired

Therefore, any combination of SNRRequired, ULInterference, TransmitPilot and offset can be broadcast. In principle, only one value should be broadcast. This is essential in current UMTS systems, even though UL interference in 3GPP LTE is primarily more constant adjacent cell interference than UMTS systems.

As mentioned above, the terminal determines the initial UL transmit power for the transmission of the preamble. The eNB receiver can estimate the absolute received power as well as the relative received power compared to cell interference. The eNB considers a preamble detected if the received signal power compared to the interference is greater than the threshold known to the eNB.

Terminal pre were initially estimated without transmission power of amble suitable executes power ramping so as to be able to detect the preamble. If no ACK or NACK is received by the terminal before the next random access attempt, most of the other preambles will be sent. To increase the probability of detection, the preambles can be transmitted to different UL frequencies and / or the transmission power of the preambles can be increased. Therefore, the actual transmission power of the detected preamble does not have to correspond to the initial transmission power of the preamble initially calculated by the UE.

The terminal must always determine a possible UL transport format. The MCS used by the terminal and the transport format that can contain a large number of resource blocks are mainly determined by two parameters. Specifically, the two parameters are the SNR of the eNB and the size of the message required to be sent.

The actual maximum or payload of the terminal message size, and the minimum SNR required, respectively, correspond to the transport format. In UMTS, the initial preamble transmit power estimated prior to the transmission of the preamble, the required offset between the preamble and the transport block, the maximum allowed or available terminal transmit power, the fixed offset and additional Margins can be considered to determine what transport format for transmission can be selected. The preamble in UMTS need not include any information for the transport format selected by the terminal, as the network does not require time and frequency resource reservations. Therefore, the transport format is displayed with the message sent.

When receiving the preamble, after selecting the correct transport format, the eNB must be aware of the size of the message the terminal intends to send and the SNR selected by the terminal in order to reserve the required time and frequency resources. Must be. Therefore, since the terminal considers some of the same measurements for determining the path loss or initial preamble transmit power measured mostly in DL, the terminal transmit power compared to the maximum permissible or available terminal transmit power is to the eNB. Due to the unknown, the eNB cannot estimate the SNR selected by the terminal, according to the received preamble.

eNB can calculate the difference by comparing the path loss estimated by DL and the path loss estimated by UL. However, if power ramping is used and the terminal transmit power for the preamble does not correspond to the initially calculated terminal transmit power, this calculation is not possible. Moreover, the precision of the actual terminal transmit power and the transmit power intended for the terminal to transmit is very low. Therefore, it is suggested to code the path loss or the cause value of UL with the encoding or signature of the CQI estimate of downlink and message size.

Self-organizing networks (SON) improvements are needed not only for the new features and new deployments considered in 3GPP LTE-rel-12, but also for the interoperability of existing features. In 3GPP LTE rel-11, mobility robustness optimization (MRO) has been improved to identify the type of device that failed. Other SON use cases need similar improvements. For example, mobility load balancing (MLB) cannot distinguish between terminals that support cell range expansion (CRE) and those that do not.

Numerous vertical and horizontal beams are generated through the active antennas to diversify their placement. Dynamic cell splitting / coupling is possible to handle changing load conditions via the active antenna. For example, depending on the actual traffic mix, traffic location and user demand, the beam can be adjusted to accurately distribute the capacity. Thereby, active antennas have a high fixed placement of picocells, but nevertheless, networks are particularly useful in suburban and rural areas where congestion can be faced. SON can automate network placement based on active antennas.

New features for SON improvement and deployment based on the active antenna system (AAS) were discussed. AAS deployable scenarios and additional SON functionality required for AAS need to be discussed.

<p> The present invention provides a method and an apparatus for transmitting a cell formation instruction in a wireless communication system. INDUSTRIAL APPLICABILITY The present invention informs an adjacent eNB (eNodeB) of a plan for cell shaping or cell un-shaping, or informs an adjacent eNB of an event that cell formation or deformation has been completed. I will provide a.</p>

<p> In one aspect, a method of transmitting a cell shaping instruction by a first eNB (evolved Node B) in a wireless communication system is provided. The method comprises transmitting a cell formation instruction instructing cell formation of a cell managed by the first eNB in an active antenna system (AAS) to a second eNB. This means that the main coverage of the cell remains unchanged, but the edge of the cell can be adjusted by load demand.</p><p> The cell formation instruction indicates that the cell formation of the cell has been completed. The method further comprises performing cell formation of the cell before transmitting the cell formation instruction to the second eNB.</p><p> The cell formation instruction indicates that cell formation of the cell is executed. The method further comprises performing cell formation of the cell after transmitting the cell formation instruction to the second eNB.</p><p> In another aspect, a method of transmitting a cell un-shaping instruction by a first eNB (evolved Node B) in a wireless communication system is provided. The method comprises transmitting a cell deformation instruction instructing the cell deformation of the cell managed by the first eNB in the active antenna system (AAS) to the second eNB. Deformation means that the coverage of the cell returns to the original coverage.</p><p> The cell formation release instruction indicates that the cell formation release of the cell has been completed. The method further comprises performing cell deformation of the cell before transmitting the cell deformation instruction to the second eNB.</p><p> The cell formation release instruction indicates that the cell formation release of the cell is executed. The method further comprises executing the cell deformation of the cell after transmitting the cell deformation instruction to the second eNB.</p><p> In another aspect, a method of rejecting a first eNB (evolved Node B) handover procedure in a wireless communication system is provided. The method determines to execute cell deformation of the cell managed by the first eNB, and immediately after deciding to execute cell deformation of the cell, a handover request message is sent from the second eNB. The release of the cell means that the coverage of the cell returns to the original coverage, which includes receiving and transmitting a handover preparation failure message including cause information instructing the release of the cell of the cell.<u style="single"> The present specification also provides, for example, the following items.</u><u style="single">(Item 1)</u><u style="single"> In a method of transmitting a cell shaping instruction by a first eNB (evolved Node B) in a wireless communication system,</u><u style="single"> Including sending a cell formation instruction instructing cell formation of a cell managed by the first eNB in an active antenna system (AAS) to a second eNB.</u><u style="single"> The method characterized in that the cell formation means that the main coverage of the cell remains unchanged, but the edge of the cell can be adjusted by load demand. ..</u><u style="single">(Item 2)</u><u style="single"> The method according to item 1, wherein the cell formation instruction indicates that cell formation of the cell has been completed.</u><u style="single">(Item 3)</u><u style="single"> The method of item 2, further comprising performing cell formation of the cell before transmitting the cell formation instruction to the second eNB.</u><u style="single">(Item 4)</u><u style="single"> The method according to item 1, wherein the cell formation instruction indicates that cell formation of the cell is executed.</u><u style="single">(Item 5)</u><u style="single"> The method according to item 4, further comprising performing cell formation of the cell after transmitting the cell formation instruction to the second eNB.</u><u style="single">(Item 6)</u><u style="single"> In a method of transmitting a cell un-shaping instruction by a first eNB (evolved Node B) in a wireless communication system,</u><u style="single"> Including sending a cell formation release instruction to the second eNB instructing the cell formation release of the cell managed by the first eNB in the active antenna system (AAS).</u><u style="single"> The method characterized in that the cell formation release means that the coverage of the cell returns to the original coverage.</u><u style="single">(Item 7)</u><u style="single"> The method according to item 6, wherein the cell formation release instruction indicates that the cell formation release of the cell has been completed.</u><u style="single">(Item 8)</u><u style="single"> 7. The method of item 7, further comprising performing cell deformation of the cell before transmitting the cell deformation instruction to the second eNB.</u><u style="single">(Item 9)</u><u style="single"> The method according to item 6, wherein the cell formation release instruction indicates that the cell formation release of the cell is executed.</u><u style="single">(Item 10)</u><u style="single"> 9. The method of item 9, further comprising performing cell deformation of the cell after transmitting the cell deformation instruction to the second eNB.</u><u style="single">(Item 11)</u><u style="single"> In the method of rejecting the handover procedure by the first eNB (evolved Node B) in the wireless communication system,</u><u style="single"> Decided to perform cell deformation of the cell managed by the first eNB;</u><u style="single"> Immediately after deciding to perform cell deformation of the cell, a handover request message is received from the second eNB;</u><u style="single"> Including sending a handover preparation failure message including cause information instructing the cell to be released from the cell</u><u style="single"> The method characterized in that the cell formation release means that the coverage of the cell returns to the original coverage.</u><u style="single">(Item 12)</u><u style="single"> Deformation of the cell;</u><u style="single"> The method according to item 11, further comprising transmitting a cell formation release instruction to the second eNB after executing the cell formation release of the cell.</u><u style="single">(Item 13)</u><u style="single"> The method according to item 12, wherein the cell formation release instruction indicates that the cell formation release of the cell has been completed.</u><u style="single">(Item 14)</u><u style="single"> A cell formation release instruction is transmitted to the second eNB; and</u><u style="single"> The method according to item 11, further comprising executing the cell formation release of the cell after transmitting the cell formation release instruction.</u><u style="single">(Item 15)</u><u style="single"> The method according to item 14, wherein the cell formation release instruction indicates that the cell formation release of the cell is executed.</u></p>

<p> It is possible to notify the adjacent eNB of cell formation or cell formation release.</p>

<figref num="1">The structure of the LTE system is shown.</figref><figref num="2">It is a block diagram of a general E-UTRAN and EPC structure.</figref><figref num="3">It is a block diagram of the user plane protocol stack and the control plane protocol stack of the LTE system.</figref><figref num="4">An example of the physical channel structure is shown.</figref><figref num="5">The scenario of beam formation adjustment for AAS is shown.</figref><figref num="6">The scenario of cell formation adjustment for AAS is shown.</figref><figref num="7">The scenario of cell partition adjustment for AAS is shown.</figref><figref num="8">An example of a method of transmitting an instruction according to an embodiment of the present invention is shown.</figref><figref num="9">Another example of a method of transmitting an instruction according to an embodiment of the present invention is shown.</figref><figref num="10">Another example of a method of transmitting an instruction according to an embodiment of the present invention is shown.</figref><figref num="11">An example of cell formation operation between adjacent eNBs is shown.</figref><figref num="12">An example of a method of transmitting a cell formation instruction according to an embodiment of the present invention is shown.</figref><figref num="13">An example of a method of transmitting a cell formation release instruction according to an embodiment of the present invention is shown.</figref><figref num="14">An example of a method of rejecting the handover procedure according to the embodiment of the present invention is shown.</figref><figref num="15">It is a block diagram of the wireless communication system which embodies the embodiment of this invention.</figref>

The following technologies include CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), etc. It can be used for various wireless communication systems such as. CDMA can be embodied in wireless technologies such as UTRA (universal terrestrial radio access) and CDMA2000. TDMA is GSM (registered trademark) (global system for mobile communications) / GPRS (general packet radio service) / EDGE (enhanced data rates for) It can be embodied in wireless technologies such as GSM® evolution). OFDMA can be embodied in wireless technologies such as IEEE (institute of electrical and electronics engineers) 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802.20, E-UTRA (evolved UTRA), etc. .. IEEE802.16m is an evolution of IEEE802.16e and provides backward compatibility with systems based on IEEE802.16. UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long term evolution) uses E-UTRA (evolved-UMTS terrestrial radio access) E-UMTS (evolved) It is a part of UMTS) and adopts OFDMA for downlink and SC-FDMA for uplink. LTE-A (advanced) is an evolution of 3GPP LTE.

In order to clarify the explanation, LTE-A will be mainly described, but the technical idea of the present invention is not limited to this.

An active antenna system (AAS) is a base station equipped with an antenna array system (AAS) in which the radiation pattern can be dynamically adjusted. AAS will introduce an alternative antenna system to what was traditionally installed in base stations. The interaction between the antenna array system in the AAS and the transmitter and receiver may differ from conventional base stations and conventional antenna systems.

The AAS deployment scenario is explained. You can refer to Section 5 of 3GPP TR 37.840 V12.0.0 (2013-03).

1) Tilt and radiation pattern control

Antennas are typically manufactured with a fixed beam width, and antenna manufacturers typically offer a limited number of beam width variations within their conventional production line. Traditionally, base station equipment often introduces a physical tilt into the antenna in order to direct the main lobe of the antenna response towards the ground. Antenna tilt is selected to optimize the desired cell coverage and minimize interference from / to adjacent cells. Some equipment uses a remote electrical tilt (RET) device that allows adjustment of the phase shift to facilitate remote control of the antenna tilt angle.

AAS can dynamically control not only the beam width of the radiation pattern but also the altitude and defense angle via electronic means. Electronic control can be used in conjunction with mechanical control. The AAS emission pattern can be adjusted to change the specific placement scenario and, where possible, the traffic pattern. The AAS emission pattern can be independently optimized for different links, such as independent uplinks and downlinks, for coverage and beam formation gain purposes.

The concept of tilt and beamwidth control can be extended by cell partitioning techniques where cells are vertically or horizontally divided by adjusting the antenna pattern. For example, one cell partition can be located close to the BS and the other cell partition can be located far away from the BS.

2) MIMO (multiple-input multiple-output)

MIMO is a general term that includes a variety of spatial processing techniques such as beam formation, diversity, and spatial multiplexing. A brief description of each is as follows.

-Beam formation: Use of a dedicated beam formed towards the terminal when data demodulation using a dedicated reference signal is supported by the terminal

-Diversity: Use of diversity technology for joint optimization in the spatial and frequency domains, for example through the use of SFBC (spatial-frequency block code) or FSTD (frequency switching transmit diversity) or a combination of both.

-Spatial multiplexing: Multiple signal streams transmitted to one terminal (SU-MIMO) or multiple terminals (MU-MIMO) using multiple spatial layers generated by the combination of available antennas.

3) Differentiate antenna operation at different carrier frequencies

AAS supports the use of different antennas for different radio access technologies (RATs) on different carrier frequencies. For example, AAS can generate four virtual antennas for LTE carriers and two antennas for HSPA (high-speed packet access) or GSM® carriers.

4) Send / receive by RB (or terminal)

Each terminal can obtain its own beam that tracks the movement of the terminal. Current specifications for supporting spatial multiplexing, beam formation and transmission diversity include the ability to schedule transmission and reception to one terminal within one resource block. For example, this allows individual terminals to form beams with adjustments to mobility.

AAS base stations can be located in wide area, medium range and local area coverage.

-Wide coverage deployment scenarios are typically found in outdoor macro environments where the base station antenna is located above the antenna stanchions, roof tops, or street level. AAS base stations designed for wide area coverage are called macro AAS.

-Intermediate range coverage placement scenarios are commonly found in field micro-environments where AAS base stations are below the top of the roof. An AAS base station designed for intermediate range coverage is called a micro AAS.

-Local area base station placement scenarios are typically found in rooms where the antenna is located on the ceiling or wall (office, subway station, etc.). Deployment scenarios for local area coverage can also be found in outdoor hotspot areas such as markets, boulevards, and train stations. An AAS base station designed for local area coverage is called a pico AAS.

Conventionally, a beam pattern in which the base station is fixed is assumed, but the radiation pattern of the AAS base station can be dynamically adjusted. Coexistence of conventional base stations and AAS base stations based on uncoordinated arrangements can be considered. Analytical methods based on existing results can be used to study coexistence requirements and can be supplemented with additional simulations if necessary. The initial scenario below is confirmed for the purpose of studying the spatial properties of AAS BS:

-E-UTRA macro AAS base station located with other E-UTRA macro AAS base stations

-E-UTRA macro AAS base station, which was previously located with the E-UTRA macro base station

Based on the deployment / coexistence scenarios described above, AAS deployment scenarios can be categorized into three aspects, as described in Table 1 below.

<tables num="1"><img file="JP6441925B2_D0001.tif" /></tables>

Referring to Table 1, the cells divided into the inner part and the outer part in relation to the cell division are considered as the basic placement scenario. Assuming more accurate and adaptive beam adjustment, this is a scenario in which transmission / reception for each terminal is possible by tracking the movement of each terminal.

In relation to the frequency and RAT allocation for each cell partition, there are three possible options: 1) assign the same frequency to all partitions, 2) assign different frequencies to each partition, 3) A different RAT is assigned to each partition. Of the three options, those that assign different RATs to each partition have more effort in terms of network than the other options (eg, inter-RAT handover, cell ID assignment, and use cases are discussed further. Required) is required.

In connection with the coexistence scenario, if an interworking SON mechanism is developed between AAS base stations located together with each other, it can then be used as a case for AAS base stations located with conventional base stations. .. However, in this case compatibility issues must be considered.

Therefore, it is preferable to first focus on the AAS deployment scenario below.

-Cells divided into inner and outer areas,

-Assign the same frequency to all partitions of the cell, or assign different frequencies to each partition, and

-Macro AAS base station located with other macro AAS base stations

The AAS basic deployment scenario is explained. When many terminals are concentrated, scenarios including beam shaping, cell shaping, and cell partitioning have been discussed for AAS operations that can be applied to optimize capacity. Such a scenario assumes high traffic demands from high density terminals. The terminals can be temporarily or permanently concentrated in space. AAS-based placement is used to optimize capacity.

Figure 5 shows a beam formation adjustment scenario for AAS. Beam formation introduces an adaptive or reconfigurable antenna system in which the coverage of each cell remains unchanged. With reference to Figure 5, the eNB1 configures the antenna towards the traffic hotspot. There is no cell boundary interference due to beam formation, and there is no terminal mobility cooperation at traffic hotspots. Also, there is no serving / adjacent cell update and / or functional reconfiguration in each eNB. Also, there is no configuration update in OAM (operations, management and maintenance). The same physical cell ID (PCI) is used for all cell coverage. Such adjustments are considered as a fast time scale (by radio resource management (RRM)). If beam formation causes a remodeling of cell coverage, the trigger for the change is an OAM reconfiguration (eg, collected KPIs (key performance)). indicator) base). Alternatively, if cell coverage is unaffected, the control unit is a base station (execution-based).

FIG. 6 shows a scenario of cell formation adjustment for AAS. Cell formation introduces an adaptive or reconfigurable antenna system in which the main coverage of each cell remains unchanged, but cell boundaries can be adjusted by load demand. .. Referring to FIG. 6, cell 1 is formed around the traffic hotspot. There is no cell boundary interference due to cell formation, and there is no terminal mobility cooperation at traffic hotspots. Also, there is no serving / adjacent cell update and / or functional reconfiguration in each eNB. Also, there is no configuration update in OAM. The same PCI is used for all cell coverage. Such adjustments are considered a medium time scale (hourly or even rarely). The trigger for the change is an OAM reconfiguration (eg, KPI-based collected). Alternatively, if changes are planned in advance, the control unit is a base station (execution-based).

Figure 7 shows a cell partition adjustment scenario for AAS. Cell splitting modifies the antenna system to include more antenna beams and introduces high-step sectorization (vertical, horizontal or a combination thereof) to the selected base station. Each antenna beam covers a smaller area before the change. However, the main coverage of the combined beam corresponds to the main cell coverage before splitting. Referring to FIG. 7, cell 1 is divided into cell 1a and cell 1b to support traffic hotspots. Cell boundary interference between cell 1a and cell 1b can occur, and the mobility of terminals connected to cell 1 at the traffic hotspot can be changed. In addition, serving / neighboring cell updates including ANR (automatic neighbor relation), PCI, neighbor cell list (NCL), mobility robustness optimization (MOR), and improved inter-cell interference cooperation. (eICIC; enhanced inter-cell interference Functional reconfiguration, including coordination), can be performed on each eNB. Also, there may be new configuration updates in OAM. Each beam broadcasts different PCIs. The cell splitting procedure is considered a long term time scale (every hour or even rarely several times a day). The trigger for the change is an OAM reconfiguration (eg, KPI-based collected). Alternatively, the control unit is a base station (execution-based) if the cell coverage is unaffected and the split is planned in advance. Cell splitting instructions are required at OAM and adjacent eNBs.

Hereinafter, a cell formation scenario will be focused on according to an embodiment of the present invention.

Based on the approaches mentioned above, there are some issues that currently require improvements to the standard for MRO mechanisms. That is, since the cell formation function causes a dynamic change in the cell coverage area, the terminal needs to distinguish between a cell that supports the cell formation function and a general cell by AAS. Even if the terminal is handed over to the formed portion of the cell, the terminal must leave the cell due to a dynamic change in cell coverage. Therefore, when the eNB determines the handover of the terminal, the eNB needs to know whether the target cell supports the cell formation function by AAS.

Therefore, according to one embodiment of the present invention, the eNB can indicate whether the cell supports the cell forming function by AAS. Upon receiving the corresponding instruction, the serving eNB can know whether the adjacent cell to which the terminal can be handed over supports the cell formation function.

FIG. 8 shows an example of a method of transmitting an instruction according to an embodiment of the present invention. Referring to FIG. 8, the adjacent eNB broadcasts an instruction to its own cell to the terminal via a wireless channel. Upon receiving the corresponding instruction, the terminal reports the received instruction to the serving eNB. Therefore, the serving eNB can know whether the adjacent cell supports the cell formation instruction.

FIG. 9 shows another example of a method of transmitting an instruction according to an embodiment of the present invention. Referring to FIG. 9, the adjacent eNB broadcasts an instruction to its own cell to the terminal via a wireless channel. If the received instruction contains information that the adjacent cell supports the cell formation function by AAS, the terminal does not report the measurement result to the serving eNB. Therefore, the terminal cannot be handed over to an adjacent cell.

FIG. 10 shows another example of a method of transmitting an instruction according to an embodiment of the present invention. Referring to FIG. 10, the adjacent eNB transmits an instruction to its own cell to the serving eNB of the terminal via the X2 interface. Therefore, the serving eNB can know whether the adjacent cell supports the cell formation instruction.

The serving eNB can take into account the instructions obtained from the terminal or the adjacent eNB when deciding whether to hand over the terminal to the cell associated with the instruction.

Also, according to one embodiment of the invention, AAS can reserve PCI for cells that support the cell forming function. The eNB can broadcast the PCI range information reserved in the adjacent eNB. Table 2 shows an example of PCI allocation for cells that support the cell formation function by AAS according to an embodiment of the present invention. For example, if an operator reserves K + 1 PCIs for a cell that supports the cell formation function by AAS, an example of PCI allocation is as follows.

<tables num="2"><img file="JP6441925B2_D0002.tif" /></tables>

Referring to Table 2, PCIs from N to N + K are reserved for cells that support the cell formation function by AAS, and the remaining PCIs are reserved for general cells. The PCI reserved for cells that support the cell formation function by AAS and the PCI reserved for general cells do not overlap.

Further, according to an embodiment of the present invention, when the cell (cell 1) is in a high traffic load state, the eNB (eNB1) that manages the cell 1 receives the terminal of the cell 1 so that the adjacent eNB (eNB2) Can be required to form a cell (cell 2) of an adjacent eNB towards cell 1.

FIG. 11 shows an example of cell formation operation between adjacent eNBs. Referring to FIG. 11, cell 1 managed by eNB1 is formed at the cell boundary toward cell 2 managed by eNB2. The main coverage of cell 1 does not change. By forming cell 1 towards cell 2 and accepting the terminals in cell 2, the eNB2 can escape the high load condition when the amount of traffic (or the number of terminals) required in cell 2 is high. it can. Further, when the cell 1 is in a high load state, the eNB 2 can form the cell 2 toward the cell 1 and accept the terminal of the cell 1.

The problem is that the actual cell coverage before cell formation and the coverage area after cell formation may differ. Therefore, when an eNB plans cell formation or cell un-shaping of its own cell, the plan must be notified to the adjacent eNB. Alternatively, the eNB must notify the adjacent eNB that its cell has completed cell formation or cell formation release. Hereinafter, cell formation means that the cell main coverage remains unchanged, but the cell boundaries can be adjusted by load demand. Deformation of a cell means that the coverage of the cell returns to the original coverage. That is, cell formation is an operation from FIG. 11- (a) to FIG. 11- (b), and cell formation release is an operation from FIG. 11- (b) to FIG. 11- (a).

FIG. 12 shows an example of a method of transmitting a cell formation instruction according to an embodiment of the present invention.

Referring to FIG. 12- (a), in step S100, eNB1 decides to perform cell formation and performs cell formation. In step S101, eNB1 transmits a cell formation instruction instructing that cell formation has been performed. Therefore, eNB1 can notify eNB2 that it has completed cell formation.

With reference to FIG. 12- (b), in step S110, eNB1 decides to perform cell formation. In step S111, the eNB1 transmits a cell formation instruction instructing the cell formation to be performed. Therefore, the eNB1 can inform the eNB2 of the cell formation plan after making the cell formation decision. In step S112, eNB1 performs cell formation.

FIG. 13 shows an example of a method of transmitting a cell formation release instruction according to an embodiment of the present invention.

Referring to FIG. 13- (a), in step S200, the eNB1 determines to execute the cell deformation and executes the cell deformation. In step S201, the eNB1 transmits a cell formation release instruction instructing that the cell formation release has been executed. Therefore, the eNB1 can notify the eNB2 that it has completed the cell formation release.

With reference to FIG. 13- (b), in step S210, eNB1 decides to perform cell deformation. In step S211 the eNB1 transmits a cell formation release instruction instructing the cell formation release to be executed. Therefore, the eNB1 can inform the eNB2 of the cell formation release plan after making the cell formation release decision. In step S212, eNB1 performs cell deformation.

Further, when the eNB receives the handover request message from the adjacent eNB immediately after the eNB decides to release the cell formation, the eNB needs to reject the handover request in order to prevent the handover failure, and gives the adjacent eNB an appropriate reason for refusal. I need to let you know.

FIG. 14 shows an example of a method of rejecting the handover procedure according to the embodiment of the present invention.

According to FIG. 14- (a), in step S300, eNB1 decides to perform cell deformation. In step S301, the eNB 2 determines the handover, thereby transmitting a handover request message to the eNB 1 in step S302. That is, the eNB 1 receives the handover request message from the eNB 2 immediately after deciding to execute the cell formation release. Therefore, in step S303, the eNB1 transmits a handover preparation failure message to the eNB2. At this time, the cause information instructing that the target cell (for example, the cell of eNB1) is planning to release the cell formation can be transmitted together. In step S304, eNB1 performs cell deformation. In step S305, the eNB1 transmits a cell formation release instruction instructing that the cell formation release has been executed. Therefore, the eNB1 can notify the eNB2 that it has completed the cell formation release.

According to FIG. 14- (b), in step S310, eNB1 decides to perform cell deformation. In step S311 the eNB 2 determines the handover, thereby transmitting a handover request message to the eNB 1 in step S312. That is, the eNB 1 receives the handover request message from the eNB 2 immediately after deciding to execute the cell formation release. Therefore, in step S313, the eNB 1 transmits a handover preparation failure message to the eNB 2. At this time, the cause information instructing that the target cell (for example, the cell of eNB1) is planning to release the cell formation can be transmitted together. In step S314, the eNB 1 transmits a cell formation release instruction instructing the cell formation release to be executed. Therefore, the eNB1 can inform the eNB2 of the cell formation release plan after making the cell formation release decision. In step S315, eNB1 performs cell deformation.

FIG. 15 is a block diagram of a wireless communication system embodying an embodiment of the present invention.

The first eNB 800 can include a processor 810, a memory 820 and an RF unit (radio frequency unit) 830. Processor 810 can be configured to embody the functions, processes and / or methods described herein. The hierarchy of wireless interface protocols can be embodied by processor 810. The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 830 is connected to the processor 810 to transmit and / or receive radio signals.

The second eNB 900 can include a processor 910, a memory 920 and an RF unit 930. Processor 910 can be configured to embody the functions, processes and / or methods described herein. The hierarchy of wireless interface protocols can be embodied by processor 910. The memory 920 is connected to the processor 910 and stores various information for driving the processor 910. The RF unit 930 is connected to the processor 910 to transmit and / or receive radio signals.

Processors 810, 910 can include application-specific integrated circuits (ASICs), other chipsets, logic circuits and / or data processing devices. The memories 820 and 920 can include ROM (read-only memory), RAM (random access memory), flash memory, memory cards, storage media and / or other storage devices. The RF units 830 and 930 can include a baseband circuit for processing a radio frequency signal. When the embodiments are embodied in software, the techniques described above can be embodied in modules (processes, functions, etc.) that perform the functions described above. The module is stored in memory 820, 920 and can be executed by processors 810, 910. The memories 820, 920 are inside or outside the processors 810, 910 and can be connected to the processors 810, 910 by various well-known means.

In the exemplary system described above, the methods that can be embodied by the features of the invention described above have been described based on flow diagrams. For convenience, the method has been described in a series of steps or blocks, but the claimed features of the invention are not limited to the order of the steps or blocks, and some steps may be in different steps and in a different order as described above. Or it can occur at the same time. Also, those skilled in the art can delete the steps shown in the flow diagram without being exclusive, including other steps, or one or more steps in the flow diagram without affecting the scope of the invention. I can understand that.