KR20100091873A - Method for recognizing ue capability - Google Patents

Abstract

PURPOSE: A method for recognizing terminal capability is provided to transmit information for terminal capability in a wireless communication system. CONSTITUTION: A base station divides a preamble based on a terminal category into a plurality of groups(S1205). The base station broadcasts information about a parameter about the preamble and the preamble group to a terminal(S1210). The terminal arbitrarily selects a preamble from a specific preamble group(S1215). The terminal transmits the preamble for random access to the base station(S1220). The base station recognizes a category of the terminal and terminal capability from the preamble(S1225).

Description

How to recognize terminal capability {METHOD FOR RECOGNIZING UE CAPABILITY}

The present invention relates to a wireless communication system. The present invention relates to a wireless communication system supporting at least one of SC-FDMA, MC-FDMA and OFDMA. In particular, the present invention relates to a method for recognizing terminal capabilities in a wireless communication system.

1 shows a network structure of an Evolved Universal Mobile Terrestrial System (E-UMTS). The E-UMTS system is an evolution from the WCDMA UMTS system and is being standardized by the 3rd Generation Partnership Project (3GPP). E-UMTS is also called a Long Term Evolution (LTE) system. For details of technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of the "3rd Generation Partnership Project; Technical Specification Group Radio Access Network", respectively.

Referring to FIG. 1, an E-UMTS is mainly composed of an access gateway (AG) located at an end of a user equipment (UE), a base station, and an network (E-UTRAN) and connected to an external network. Typically, a base station can transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service. The AG may be divided into a part that handles user traffic and a part that handles control traffic. In this case, a new interface may be used to communicate with each other between the AG for processing new user traffic and the AG for controlling traffic. One or more cells exist in one base station. An interface for transmitting user traffic or control traffic may be used between base stations. CN (Core Network) may be composed of a network node for the user registration of the AG and the terminal. An interface for distinguishing between E-UTRAN and CN may be used. AG manages the mobility of the terminal in units of a tracking area (TA). The TA is composed of a plurality of cells, and when the UE moves from one TA to another, the AG notifies the AG of the change of the TA.

2 shows a network structure of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The E-UTRAN system is an evolution from the existing UTRAN system. The E-UTRAN consists of base stations (eNBs) and the eNBs are connected via an X2 interface. X2 user plane interface (X2-U) is defined between eNBs. The X2-U interface provides non guaranteed delivery of user plane PDUs. An X2 control plane interface (X2-CP) is defined between two neighboring eNBs. X2-CP performs functions such as context transfer between eNBs, control of user plane tunnel between source eNB and target eNB, delivery of handover related messages, and uplink load management. The eNB is connected to the terminal through a wireless interface and is connected to the Evolved Packet Core (EPC) through the S1 interface. The S1 user plane interface (S1-U) is defined between the eNB and the S-GW (Serving Gateway). The S1 control plane interface (S1-MME) is defined between the eNB and the Mobility Management Entity (MME). The S1 interface performs an evolved packet system (EPS) bearer service management function, a non-access stratum (NAS) signaling transport function, network sharing, MME load balancing function, and the like.

3 illustrates a control plane and a user plane (U-Plane, User-Plane) structure of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard. The air interface protocol consists of a physical layer, a data link layer, and a network layer horizontally, and vertically a user plane and control signal for data information transmission. (Signaling) It is divided into control plane for transmission. The protocol layer of FIG. 3 is based on the lower three layers of the Open System Interconnection (OSI) reference model, which is well known in communication systems, and includes L1 (first layer), L2 (second layer), and L3 (first layer). Three layers).

The control plane refers to a path through which control messages used by the terminal and the network to manage a call are transmitted. The user plane refers to a path through which data generated at an application layer, for example, voice data or Internet packet data, is transmitted. Hereinafter, each layer of the control plane and the user plane of the radio protocol will be described.

The physical layer, which is the first layer, provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to the upper layer of the medium access control layer through a transport channel. Data moves between the medium access control layer and the physical layer through the transport channel. Data moves between the physical layer between the transmitting side and the receiving side through the physical channel. The physical channel is modulated by Orthogonal Frequency Division Multiplexing (OFDM) in downlink and modulated by SC-FDMA in uplink and utilizes time and frequency as radio resources.

The medium access control (MAC) layer of the second layer provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The functionality of the RLC layer may be implemented as a functional block inside the MAC. In this case, the RLC layer may not exist. The PDCP (Packet Data Convergence Protocol) layer of the second layer performs a header compression function to reduce unnecessary control information in order to efficiently transmit an IP packet such as IPv4 or IPv6 over a narrow bandwidth interface. .

The radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration, re-configuration, and release of radio bearers (RBs) are performed. It is in charge of controlling logical channels, transport channels and physical channels. RB means a service provided by the second layer for data transmission between the UE and the E-UTRAN. To this end, the RRC layer exchanges RRC messages between the terminal and the network. If there is an RRC connected (RRC Connected) between the RRC layer of the terminal and the RRC layer of the wireless network, the terminal is in the RRC connected mode (Connected Mode), otherwise it is in the RRC idle mode (Idle Mode).

The non-access stratum (NAS) layer above the RRC layer performs functions such as session management and mobility management.

One cell constituting the eNB is set to one of the bandwidth, such as 1.25, 2.5, 5, 10, 15, 20Mhz to provide a downlink or uplink transmission service to multiple terminals. Different cells may be configured to provide different bandwidths.

The downlink transmission channel for transmitting data from the network to the UE includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a downlink shared channel (SCH) for transmitting user traffic or control messages. have. Traffic or control messages of a downlink multicast or broadcast service may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the terminal to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or a control message.

It is located above the transport channel, and the logical channel mapped to the transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and an MTCH (multicast). Traffic Channel).

4 shows an example of a physical channel structure used in an E-UMTS system. A physical channel consists of several subframes on the time axis and several subcarriers on the frequency axis. Here, one subframe consists of a plurality of symbols on the time axis. One subframe consists of a plurality of resource blocks, and one resource block consists of a plurality of symbols and a plurality of subcarriers. In addition, each subframe may use specific subcarriers of specific symbols (eg, the first symbol) of the corresponding subframe for the L1 / L2 control channel. 4 shows an L1 / L2 control information transmission area and a data transmission area. The E-UMTS system uses a radio frame of 10 ms and one radio frame consists of 10 subframes. In addition, one subframe consists of two consecutive slots. One slot is 0.5ms long. In addition, one subframe includes a plurality of OFDM symbols, and some symbols (eg, first symbols) of the plurality of OFDM symbols may be used to transmit L1 / L2 control information. The transmission time interval (TTI), which is a unit time for transmitting data, is 1 ms.

Except for specific control signals or specific service data, the base station and the terminal generally transmit data through physical downlink shared channels (PDSCHs), which are physical channels using downlink-shared channels (DL-SCH), which are mostly transport channels. And receive. Data of the PDSCH is transmitted to which UE (one or a plurality of UEs), and information on how the UEs should receive and decode the PDSCH data is included in the PDCCH (Physical Downlink Control CHannel).

For example, a specific PDCCH has a Cyclic Redundancy Check Masking (RNC) with a Radio Network Temporary Identity (RNTI) of "A", a radio resource (for example, frequency location) of "B" and a transmission of "C". It is assumed that information about data transmitted using format information (eg, transport block size, modulation, coding information, etc.) is transmitted through a specific subframe. In this case, one or more terminals in the cell monitor the PDCCH using the RNTI information that they have, and if there is one or more terminals having an “A” RNTI, the terminals receive the PDCCH and the received PDCCH. The PDSCH indicated by " B " and " C " is received through the information. That is, the PDCCH transmits downlink scheduling information for a specific UE, and the PDSCH transmits downlink data corresponding to the downlink scheduling information. In addition, the PDCCH may transmit uplink scheduling information for a specific UE.

5 shows a process of transmitting terminal capability information. The base station needs UE capability information for management of radio resources. In addition, the terminal capability information is required for the network to manage the terminal (eg, mobility support, etc.). The terminal capability information includes various information for managing / operating radio resources for the terminal. For example, the terminal capability information may include power control related information, code resource information, encryption related information, and the like. Referring to FIG. 5, after the RRC connection is established, the base station transmits a UE capability enquiry message to the terminal, and the terminal transmits UE capability information to the base station as a response to the message. .

Conventionally, terminal capability information has been delivered to a base station only after an RRC connection is established between the base station and the terminal. That is, when the terminal attempts to initially access the base station, radio resource management in consideration of the terminal capability has not been performed. Therefore, in order to efficiently manage radio resources, a method of transmitting terminal capability before RRC connection establishment is required.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a method for delivering information about the terminal capabilities in a wireless communication system.

Another object of the present invention is to provide a method for transmitting information on terminal capability using a random access procedure.

Still another object of the present invention is to provide a method of transmitting information about the number of antennas of a terminal using a random access procedure.

Technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

In one aspect of the present invention, a method for performing random access of a terminal in a mobile communication system, the method comprising: transmitting a preamble for a random access to a base station; Receiving a second message from the base station including resource allocation information in response to the preamble; Transmitting a third message to the base station according to the resource allocation information; And receiving a conflict resolution message from the base station, wherein the third message is provided with a method of performing random access including information on terminal capability.

In another aspect of the present invention, a terminal configured to perform random access in a mobile communication system, the terminal configured to generate a preamble for random access for transmission to a base station, received from the base station in response to the preamble A processor configured to process a second message including resource allocation information, and configured to generate a third message for transmission to the base station according to the resource allocation information, the processor configured to process a conflict resolution message received from the base station; And a radio frequency (RF) unit configured to transmit information received from the processor to the base station, and to transmit information received from the base station to the processor, wherein the processor is configured to generate the third message. A terminal is provided that is configured to include information about the capability of the terminal in the third message.

Here, the third message may be scrambled using a first temporary identifier related to the terminal capability. In this case, the first temporary identifier may be modified according to a predetermined method related to the terminal capability from the second temporary identifier included in the second message. Also, the first temporary identifier may be modified by applying a predetermined offset related to the terminal capability to the second temporary identifier. As another example, the second message may include a plurality of second temporary identifiers associated with the terminal category, and the first temporary identifier may be selected from the plurality of second temporary identifiers in consideration of the terminal capability.

Here, the third message may include a Radio Resource Control (RRC) signaling message indicating information on the terminal capability.

Here, the information about the terminal capability may include 1 bit information for terminal identification. In addition, the information on the terminal capability may include information on the category of the terminal. In addition, the information on the terminal capability may include information on the number of antennas of the terminal.

Here, the information about the terminal capability may be indicated by the length of the message 3.

Herein, the information about the terminal capability may be indicated by a multi-antenna transmission scheme applied to the message 3. In this case, the multi-antenna transmission scheme may include at least one of Space-Time Block Coding, Space-Frequency Block Coding, and SORTD (Space Orthogonal Resource Transmit Diversity). have.

According to the embodiments of the present invention, the following effects are obtained.

First, information about terminal capability may be transmitted in a wireless communication system.

Second, information on terminal capability may be delivered using a random access procedure.

Third, information about the number of antennas of the terminal may be transmitted using a random access procedure.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

The construction, operation, and other features of the present invention will be readily understood by the preferred embodiments of the present invention described with reference to the accompanying drawings. The embodiments described below are examples in which the technical features of the present invention are applied to a 3GPP system.

Recently, 3GPP has been working on standardization of follow-up technology for LTE. In the present specification, the above technique is referred to as "LTE-Advanced" or "LTE-A". For convenience, the 3GPP LTE system is referred to herein as an LTE system or a legacy system. In addition, the terminal supporting the LTE system is referred to as an LTE terminal or a legacy terminal. Correspondingly, the 3GPP LTE-A system is referred to as LTE-A system or evolved system. In addition, a terminal supporting the LTE-A system is referred to as an LTE-A terminal or an evolved terminal.

6 is a configuration diagram of a wireless communication system having a general multiple antenna. Increasing the number of transmitting antennas to N _{T and the} number of receiving antennas to N _R may increase the channel transmission capacity in proportion to the number of antennas. The transmission rate may theoretically increase as the rate of increase ( R _i ) multiplied by the maximum transmission rate ( R _o ) when using a single antenna.

Multiple Input Multiple Output (MIMO) technology may be classified into spatial multiplexing and spatial diversity according to whether the data transmitted through each antenna is identical. Spatial multiplexing is a method of transmitting different data simultaneously through multiple transmit antennas. The transmitting side transmits different data through each transmitting antenna, and the receiving side distinguishes various transmission data through appropriate interference cancellation and signal processing. Therefore, the data rate can be improved in proportion to the number of transmit antennas. The spatial diversity scheme is a method of obtaining transmit diversity gain by transmitting the same data through multiple transmit antennas. Space diversity techniques include Space Time Block Coding (STBC), Space Frequency Block Coding (SFBC), and Space Orthogonal Resource Transmit Diversity (SORTD). However, the spatial diversity technique does not improve the transmission rate but improves the transmission reliability. MIMO technology is classified into an open loop scheme (eg, BLAST, STTC scheme, etc.) and a closed loop scheme (eg, TxAA, etc.) according to whether feedback information regarding a channel state is transmitted from a receiver side to a transmitter side.

The communication method in the multi-antenna system will be described in detail using mathematical modeling. Assume that there are N _T transmit antennas and N _R receive antennas.

는 다음과 같다.Transmission signal through each transmit antenna

Is as follows.

는 전력이 조정된 전송 정보를 나타내고,

는 i번째 송신 안테나와 j번째 정보간의 가중치를 나타낸다.

는 프리코딩 행렬이라고도 불린다. 프리코딩 행렬은 전송 정보를 전송 채널 상황 등에 따라 각 안테나에 적절히 분배해 주는 역할을 한다.From here,

Denotes power-adjusted transmission information,

Denotes a weight between the i th transmit antenna and the j th information.

Is also called a precoding matrix. The precoding matrix plays a role in properly distributing transmission information to each antenna according to transmission channel conditions.

는 다음과 같다.Meanwhile, the reception signal through each reception antenna

Is as follows.

는 전송 안테나 j로부터 수신 안테나 i를 거치는 채널을 나타낸다.

는 채널 행렬이라고 불린다.

은 수신 안테나 각각에 더해지는 백색잡음(AWGN; Additive White Gaussian Noise)을 나타낸다.From here,

Denotes a channel passing from the transmitting antenna j to the receiving antenna i .

Is called the channel matrix.

Denotes Additive White Gaussian Noise (AWGN) added to each of the receiving antennas.

7 shows a random access procedure. The random access procedure is used for transmitting short length data upward. For example, the random access process is performed when initial access in RRC_IDLE, initial access after a radio link failure, handover requiring a random access process, and generation of uplink / downlink data requiring a random access process during RRC_CONNECTED. Some RRC messages, such as an RRC connection request message, a cell update message, and an URA update message, are also transmitted using a random access procedure. The logical channels Common Control Channel (CCCH), Dedicated Control Channel (DCCH), and Dedicated Traffic Channel (DTCH) may be mapped to the transport channel RACH. The transport channel RACH is mapped to the physical channel physical random access channel (PRACH). When the MAC layer of the UE instructs the UE physical layer to transmit PRACH, the UE physical layer first selects one of an access slot and 64 preamble sequences and transmits the PRACH preamble upward.

Referring to FIG. 7, when initially accessing a network, a UE acquires downlink synchronization through a downlink synchronization channel, and a system through a physical-broadcast channel (P-BCH) and a dynamic-broadcast channel (D-BCH). System essential parameters and RACH parameters are obtained by receiving the information (SI-x information) (S710). Thereafter, the terminal generates a random access preamble (also referred to as message 1) from a randomly selected preamble sequence and transmits the random access preamble to the base station (S720). When the base station detects a random access preamble from the terminal, the base station transmits a random access response message (also referred to as message 2) to the terminal (S730). In detail, downlink scheduling information on the random access response message may be CRC masked by a random access-RNTI (RA-RNTI) and transmitted on an L1 / L2 control channel (PDCCH). The UE that receives the downlink scheduling signal masked by the RA-RNTI may receive and decode a random access response message from the PDSCH. Thereafter, the terminal checks whether the random access response message includes random access response information indicated to the terminal. Whether the random access response information indicated to the presence of the self may be determined by whether there is a random access preamble ID (RAID) for the preamble transmitted by the terminal. The random access response information includes a timing advance (TA) indicating timing offset information for synchronization, radio resource allocation information used for uplink, and a temporary identifier (eg, Temporary Cell-RNTI; TC-) for terminal identification. RNTI) and the like. Upon receiving the random access response information, the terminal transmits an uplink message (also referred to as message 3) to an uplink shared channel (SCH) according to radio resource allocation information included in the response information (S740). Message 3 is scrambled using TC-RNTI. After receiving the message 3 from the terminal, the base station transmits a contention resolution (also called message 4) message to the terminal (S750).

8 shows a MAC PDU structure of a random access response message (message 2).

Referring to FIG. 8, a MAC PDU consists of a MAC header and a MAC payload. The MAC header consists of one or more MAC subheaders (eg, E / R / RAID subheaders) and the MAC payload consists of one or more MAC RARs. Each MAC subheader corresponds to each MAC RAR.

9 shows the structure of a MAC RAR. Referring to FIG. 9, the MAC RAR is composed of a TA field, an UL grant field, and a TC-RNTI field. MAC RARs are arranged in octets (bytes). The contents indicated by each field are as follows.

TA field: Indicates an uplink transmission timing required for synchronization (11 bits).

UL grant field: Represents resource allocation information for uplink transmission (21 bits).

TC-RNTI field: This indicates an identifier temporarily used by the UE until collision resolution passes or another random access procedure is started (16 bits).

10 shows the structure of a MAC PDU in message 3. FIG.

Referring to FIG. 10, MAC PDUs sequentially include a MAC header, a MAC control element, a MAC SDU, and optionally padding. The rest of the MAC header constitutes the MAC payload. Although FIG. 10 illustrates both the MAC control element and the MAC SDU, they may not be included or may be included in the MAC PDU. If the MAC PDU includes a plurality of MAC control elements or MAC SDUs, the MAC header may include a corresponding plurality of MAC PDU subheaders. The MAC PDU subheader may consist of an R / R / E / LCID field or an R / R / E / LCID / F / L field. R represents reserved bits. E is an extension field and indicates whether there is another field in the MAC header. The LCID is a Logical channel ID field that identifies the type of logical channel or corresponding MAC control element of the corresponding MAC SDU. L indicates the length of the corresponding MAC SDU as a length field, F indicates the size of the L field as a format field. The MAC control element includes information regarding a buffer status report, a C-RNTI, a DRX command, a UE collision resolution identifier, a timing advance, a power headroom, and the like.

Terminal capability identification using message 1

11 shows an example of identifying a terminal capability using an RA-preamble sequence according to an embodiment of the present invention. The RA-preamble sequence is basically divided into cyclic shifts of the same root Zadoff-Chu sequence, and is distinguished using another root Zadoff-Chu sequence when the sequence is insufficient. In case of LTE, the number of preamble sequences that can be used by a terminal in each cell is 64, and the terminal acquires a root index through system information. When the random access procedure is started, the terminal selects one of 64 preamble sequences and transmits the RA-preamble to the base station. The number of preamble sequences is one example, and the number of preamble sequences is not limited to 64. For convenience, the preamble sequence and the preamble are used interchangeably herein and may be interpreted according to the context.

Referring to FIG. 11, the RA-preamble is divided into a plurality of groups in consideration of the capability category of the terminal. For example, the first M preambles may be allocated to capability category 1, and the next N preambles may be allocated to capability category 2. FIG. In this way, the entire preamble can be assigned to multiple capability categories. In this embodiment, it is assumed that the capability category of the terminal is four. In order to simplify the system, only two terminal capability categories may be set. In this specification, the terminal capability category means that the transmission and reception capabilities of the terminal are classified. In this specification, the terminal capability category is mixed with a terminal category, a capability category or a category. The terminal categories are mapped to one or more terminal capabilities, and the mapping relationship between each category and the terminal capabilities may be variously set. For example, category 1 may indicate a terminal supporting LTE, and category 2-4 may indicate a terminal supporting LTE-A. By more subdividing the categories for LTE-A, it is possible to more accurately distinguish the capabilities of LTE-A terminals. As another example, the terminal category may be associated with the number of antennas of the terminal. Although not limited thereto, the terminal categories 1, 2, 3, and 4 may indicate that the number of antennas of the terminal is 1, 2, 4, and 8, respectively.

12 illustrates a flowchart of transmitting terminal capability using an RA-preamble according to an embodiment of the present invention.

Referring to FIG. 12, the base station divides the preamble into a plurality of groups based on the terminal category (S1205). The relationship between the preamble group and the terminal category may be fixed or semi-static in the cell. The information on the preamble and the information on the preamble group may be broadcast to the terminal through the system information (S1210). After receiving the information on the preamble group, the UE randomly selects a preamble from a specific preamble group corresponding to its category (S1215). Thereafter, the terminal transmits a preamble for the random access to the base station (S1220). After receiving the preamble transmitted from the terminal, the base station recognizes the category of the terminal and the terminal capability according to the preamble (S1225). As an example, the base station may recognize the number of antennas of the terminal from the preamble. Thereafter, the base station transmits a random access response message including uplink scheduling information to the corresponding terminal in response to the preamble (S1230). In this case, the base station may allocate uplink resources in consideration of the terminal capability. For example, when the terminal has a plurality of antennas, the base station may configure uplink scheduling information in consideration of the number of antennas of the terminal, MIMO scheme, and the like. The terminal performs uplink transmission to the base station using the allocated uplink resource (S1240). When uplink resources are allocated in consideration of multiple antennas, the UE may transmit message 3 through the MIMO scheme (S1250). Thereafter, the base station transmits a collision resolution message to the terminal and the random access procedure ends (S1260).

Terminal capability identification using temporary identifier

FIG. 13 illustrates an example of identifying a terminal capability using a Temporary Cell-Radio Network Temporary Identifier (TC-RNTI) according to an embodiment of the present invention. The TC-RNTI is included in the random access response (RAR) and used as a temporary identifier in the random access procedure. The RAR is generated in the MAR layer and included in message 2 transmitted by the base station. In LTE, TC-RNTI is represented by 16 bits and one TC-RNTI is included in one RAR.

Referring to FIG. 13, the entire TC-RNTI is divided into a plurality of groups in consideration of the capability category of the terminal. In this case, the terminal may transmit the terminal capability to the base station by performing a random access procedure using the TC-RNTI corresponding to the terminal. This embodiment assumes five terminal categories, and each terminal category is associated with a TC-RNTI of a predetermined group. The method of mapping the terminal category and the TC-RNTI is not particularly limited. This embodiment exemplifies a case in which a TC-RNTI having a value of 60 to 1024 is assigned to category A, and a TC-RNTI having a value of 1025 to 2048 is assigned to category B. FIG. In this way, the required number of TC-RNTIs can be flexibly allocated to each category. As another example, although not shown, TC-RNTI having a value of 1 to 5 may be sequentially assigned to categories A to E, and TC-RNTI having a value of 6 to 10 may be sequentially allocated. In this case, the TC-RNTIs allocated to each category are separated from each other by 5 units. The categories indicate one or more terminal capabilities, and a mapping relationship between each category and the terminal capabilities may be variously set. For example, when each category is associated with the number of antennas of the terminal, categories A, B, C, D, and E may indicate that the number of antennas of the terminal is 1, 2, 3, 4, and 8, respectively.

The above-described example is for explaining an embodiment of the present invention, and the number of categories, the range of the assigned TC-RNTI, the terminal capability mapped to the category, etc. may be freely changed. For example, in consideration of system complexity and TC-RNTI resources, only two capability categories may be set.

14 shows an example of a MAC RAR according to an embodiment of the present invention. The basic structure is the same as that illustrated in FIG. Description of each field is made with reference to FIG. 9. This embodiment is based on the premise that the base station informs the terminal of the plurality of TC-RNTIs associated with the terminal capability. In this case, the terminal may transmit the terminal capability to the base station by using a specific TC-RNTI corresponding to itself among the plurality of TC-RNTIs received from the base station.

Referring to FIG. 14, the MAC RAR has five TC-RNTI fields. In this embodiment, five TC-RNTI fields are octets 5-6 (TC-RNTI_0 field), octets 7-8 (TC-RNTI_1 field), octets 9-10 (TC-RNTI_2 field), and octets 11-12 (TC -RNTI_3 field) and octets 13-14 (TC-RNTI_4 field). The TC-RNTI entering each TC-RNTI field is selected from each TC-RNTI group corresponding to the terminal category. Referring to FIG. 13, the TC-RNTI_0 field may include any one of values of 60 to 1024, and the TC-RNTI_1 field may include any one of values of 1025 to 2048. In this way, the TC-RNTI_2 to TC-RNTI_4 fields each contain one TC-RNTI value corresponding to the terminal categories C to E. FIG.

In case of LTE, since the MAC RAR includes only one TC-RNTI field, the LTE terminal can read only the TC-RNTI_0 field and cannot read the TC-RNTI_1 to TC-RNTI_4 fields. That is, the added TC-RNTI field can be read only by the LTE-A terminal. Therefore, it is preferable to associate the existing TC-RNTI_0 field with the capability common to the LTE terminal and the LTE-A terminal, and the TC-RNTI_1 to TC-RNTI_4 fields with the capability added in the LTE-A terminal. For example, assuming that the LTE-A UE uses 1, 2, 3, 4, or 8 antennas, the TC-RNTI included in the TC-RNTI_0 field represents a case where the number of antennas of the UE is 1 and TC- The TC-RNTI included in the RNTI_1 to TC-RNTI_4 fields may be used to indicate a case where the number of antennas of the terminal is plural.

15 illustrates a flowchart of transmitting terminal capability using TC-RNTI according to an embodiment of the present invention.

Referring to FIG. 15, the terminal transmits a preamble for a random access to a base station (S1520). Thereafter, the base station transmits a random access response message including uplink scheduling information to the corresponding terminal in response to the preamble (S1530). In this case, the MAR RAR in the response message includes a plurality of TC-RNTIs. Each TC-RNTI is associated with a different terminal category. For example, the MAR RAR may have a structure as illustrated in FIG. 14. The terminal selects a specific TC-RNTI corresponding to its capability from among the plurality of TC-RNTIs (S1535). Thereafter, the terminal transmits a message 3 scrambled with a specific TC-RNTI in uplink (S1540). After receiving the message 3 from the terminal, the base station checks the TC-RNTI used for the scramble of the message 3 to recognize the category of the terminal and the terminal capability accordingly (1545). Thereafter, the base station transmits a collision resolution message to the terminal and the random access procedure ends (S1550).

16 is a flowchart illustrating a terminal capability transmission using a TC-RNTI according to another embodiment of the present invention. The basic process is similar to FIG. The difference from FIG. 15 is that the MAR RAR contains only one TC-RNTI.

Referring to FIG. 16, the terminal transmits a preamble for a random access to a base station (S1620). Thereafter, the base station transmits a random access response message including uplink scheduling information to the corresponding terminal in response to the preamble (S1630). In this case, the MAR RAR in the response message includes only one TC-RNTI. After receiving the MAC RAR, the UE transforms the TC-RNTI in a predetermined manner in consideration of its category to generate the TC-RNTI_MOD (S1635). The modification of the TC-RNTI is not particularly limited and may be predefined between the terminal and the base station or shared in advance through system information. As an example, the UE may apply a constant offset to the received TC-RNTI. For example, assuming that there are three capability categories, the first category may be offset 0, the second category is offset 1, and the third category may be offset 2. Thereafter, the terminal transmits a message 3 scrambled with TC-RNTI_MOD on the uplink (S1640). After receiving the message 3 from the terminal, the base station checks the TC-RNTI_MOD used for the scrambling of the message 3 to recognize the category of the corresponding terminal and the terminal capability accordingly (1645). As an example, the base station may identify the TC-RNTI_MOD used for the scramble of message 3 using a plurality of TC-RNTIs to which different offsets are applied. Thereafter, the base station transmits a collision resolution message to the terminal and the random access procedure ends (S1650).

Terminal capability identification using message 3

17 shows an example of identifying a terminal capability by signaling using message 3 according to an embodiment of the present invention. Message 3 is the first message transmitted by scheduling in the random access procedure. Transmission of message 3 supports HARQ (Hybrid Automatic Repeat and reQuest). The size of the transport block sent in message 3 is determined by the UL grant in message 2 and is at least 80 bits. Message 3 may include an RRC signaling message (eg, an RRC connection request message). For convenience, the payload of message 3 is assumed to include both the MAC header and the CRC.

Referring to FIG. 17, the LTE terminal generates message 3 according to an existing procedure. That is, message 3 of the LTE terminal does not include information about the terminal capability. On the other hand, the LTE-A terminal may include information on the terminal capability in message 3. The information about the terminal capability may include a terminal type (eg, 1 bit identification information), a terminal category, the terminal capability itself (eg, the number of antennas), and the like. The form / method in which the information about the terminal capability is included in the message 3 is not particularly limited. For example, the information about the terminal capability may be included in a MAC subheader, a MAC control element, a MAC SDU (ie, an RRC signaling message), and the like. In addition, the information about the terminal capability may be additionally included in the message 3 format defined in LTE. For example, the information about the terminal capability may be simply added to the end of the MAC PDU of the message 3. In this case, the information on the terminal capability preferably has a predetermined size to assist the CRC check of the base station. Further information about the terminal capabilities may be indicated using the length of message 3.

Specifically, one specific bit of the MAC subheader may be used for indicating the LTE-A terminal. In this case, a specific element corresponding to the MAC subheader may be defined in the MAC payload to include more detailed information about the terminal capability. As another example, one or more bits (eg, reserved bits) in the MAC subheader may be used to indicate the terminal category. As another example, an RRC signaling message indicating information about UE capability may be included in one or more MAC SDUs. As another example, a padding bit having a predetermined length may be added according to the terminal capability.

For convenience, FIG. 17 illustrates a case in which information about terminal capability is included in a MAC payload. In this case, since the length of the message 3 is different according to the terminal type, the base station can distinguish between the LTE terminal and the LTE-A terminal through the CRC double check. Thereafter, the base station can check additional information about the terminal capability included in message 3. For example, the base station may identify the terminal type through the CRC double check (CRC0 and CRC1) and check the number of antennas of the terminal from the additional information in the message 3.

18 is a flowchart illustrating a terminal capability delivery using message 3 according to an embodiment of the present invention.

Referring to FIG. 18, the terminal transmits a preamble for the random access to the base station (S1820). The base station transmits a random access response message including uplink scheduling information to the corresponding terminal in response to the preamble (S1830). The terminal prepares to transmit the message 3 according to the uplink scheduling information. In this case, the terminal includes information on the terminal capability in message 3 (S1835). A detailed method of configuring message 3 may refer to FIG. 17. Thereafter, the terminal transmits a message 3 including information on the terminal capability in the uplink (S1840). After receiving the message 3 from the terminal, the base station uses the information included in the message 3 to recognize the capability category of the corresponding terminal and the terminal capability accordingly (1845). Thereafter, the base station transmits a collision resolution message to the terminal and the random access procedure ends (S1850).

blind Detection Terminal capability identification

FIG. 19 illustrates a flowchart for transmitting terminal capability using blind detection according to an embodiment of the present invention.

Referring to FIG. 19, the terminal transmits a preamble (message 1) for random access to the base station (S1920). In this case, the terminal transmits message 1 using a predetermined MIMO scheme in consideration of the number of antennas. For example, when the terminal has a plurality of antennas, the message 1 may be transmitted by applying a spatial multiplexing or transmit diversity scheme. Specifically, when the number of antennas is 2, 4, or 8, message 1 may be transmitted using a specific precoding matrix shared between the base station and the terminal. In addition, in consideration of system complexity, a type of a terminal may be classified into a single antenna or multiple antennas only, and a predefined 2Tx MIMO scheme may be used regardless of the number of antennas when the number of transmitting antennas is plural. After receiving the message 1, the base station performs blind detection on a possible MIMO scheme and compares cross correlation metrics (S1925). If the corresponding metric exceeds a certain threshold value for a specific MIMO scheme, the base station may obtain information on the number of antennas of the terminal from the used MIMO scheme. If the metric does not exceed a certain threshold value for a specific MIMO scheme, the base station may assume that no signal by the MIMO scheme is detected and perform blind detection using another MIMO scheme as much as possible. Thereafter, the base station transmits a random access response message (message 2) configured in consideration of the terminal capability to the terminal (S1930). In this case, the base station may allocate uplink resources in consideration of multiple antennas. In addition, the base station may designate a transmission mode in consideration of multiple antennas. The terminal transmits message 3 to the base station using the allocated uplink resource (S1940). If the message 2 includes information on the transmission mode, the terminal transmits the message 3 using the indicated transmission mode. On the other hand, if there is no information about the transmission mode in the message 2, the terminal may transmit the message 3 using a predetermined transmission mode. Thereafter, the base station transmits a collision resolution message to the terminal and the random access procedure ends (S1950).

20 illustrates a flowchart of transmitting terminal capability using blind decoding according to an embodiment of the present invention. 20 is similar to the method illustrated in FIG. 19 in that the multi-antenna transmission scheme is applied to message 3 instead of message 1. FIG. However, since message 3 includes a CRC, the base station identifies the terminal capability based on the CRC check through blind decoding.

Referring to FIG. 20, the terminal transmits a preamble (message 1) for random access to the base station (S2020). After receiving the message 1, the base station transmits a random access response message (message 2) including the uplink scheduling information to the terminal (S2030). The terminal transmits message 3 to the base station using the allocated uplink resource (S2040). In this case, the terminal transmits message 3 using a predetermined MIMO scheme in consideration of the number of antennas. For example, when the terminal has a plurality of antennas, the message 1 may be transmitted by applying a spatial multiplexing or transmit diversity scheme. Specifically, when the number of antennas is 2, 4, or 8, message 3 may be transmitted using a specific precoding matrix shared between the base station and the terminal. In addition, in consideration of system complexity, a type of a terminal may be classified into a single antenna or multiple antennas only, and a predefined 2Tx MIMO scheme may be used regardless of the number of antennas when the number of transmitting antennas is plural. After receiving the message 3, the base station performs blind decoding on a possible MIMO scheme and checks the CRC (S2045). In the case of CRC OK, the base station may obtain information on the number of antennas of the terminal from the used MIMO scheme. If CRC ERROR, the base station performs blind decoding using another MIMO scheme as much as possible. Thereafter, the base station transmits a collision resolution message to the terminal and the random access procedure ends (S2050).

default Mode  Terminal capability identification

In the legacy random access procedure, the procedure up to message 4 is followed as it is, and after that, the base station can determine the terminal capability (eg, capability category, number of antennas, etc.) by additional handshaking. For example, after receiving the message 4, the UE may transmit information on the number of its antennas when transmitting data through the PUSCH. Thereafter, the base station recognizes the number of antennas of the terminal and designates a transmission mode corresponding thereto, so that the terminal can transmit a signal through multiple antennas.

21 illustrates a block diagram of a transceiver in accordance with an embodiment of the present invention. The transceiver may be part of a base station or a terminal.

Referring to FIG. 21, the transceiver 2500 includes a processor 2510, a memory 2520, an RF module 2530, a display module 2540, and a user interface module 2550. The transceiver 2500 is shown for convenience of description and some modules may be omitted. In addition, the transceiver 2500 may further include necessary modules. In addition, some modules in the transceiver 2500 may be classified into more granular modules. The processor 2520 is configured to perform an operation according to the embodiment of the present invention illustrated with reference to the drawings. Detailed operation of the processor 2520 may refer to the contents described with reference to FIGS. 1-20. The memory 2520 is connected to the processor 2510 and stores an operating system, an application, program code, data, and the like. The RF module 2530 is connected to the processor 2510 and performs a function of converting a baseband signal into a wireless signal or converting a wireless signal into a baseband signal. To this end, the RF module 2530 performs analog conversion, amplification, filtering and frequency up-conversion, or a reverse process thereof. The display module 2540 is connected to the processor 2510 and displays various information. The display module 2540 may use well-known elements such as, but not limited to, a liquid crystal display (LCD), a light emitting diode (LED), and an organic light emitting diode (OLED). The user interface module 2550 is connected to the processor 2510 and may be configured with a combination of well-known user interfaces such as a keypad and a touch screen.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with any other component or feature. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

In this document, the embodiments of the present invention have been mainly described with reference to the data transmission / reception relationship between the terminal and the base station. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the term "terminal" may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

The present invention can be applied to a wireless communication system. The present invention can be applied to a wireless communication system supporting at least one of SC-FDMA, MC-FDMA, and OFDMA. Specifically, the present invention can be applied to a method for recognizing terminal capability in a wireless communication system.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.

1 shows a network structure of an Evolved Universal Mobile Terrestrial System (E-UMTS).

2 shows a schematic structure of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN).

3 shows a structure of a radio interface protocol between a terminal and an E-UTRAN.

4 shows an example of a physical channel structure used in an E-UMTS system.

5 illustrates a method of transmitting terminal capability when connecting to a network.

6 shows a schematic structure of a multiple input multiple output (MIMO) system.

7 shows an example of a method of performing a random access procedure.

8 illustrates a structure of a medium access control protocol data unit (MAC PDU) of a random access response message.

9 shows a structure of MAC random access response (RAR).

10 shows the MAC PDU structure of message 3. FIG.

11 shows an example of identifying a terminal capability using an RA-preamble according to an embodiment of the present invention.

12 illustrates a flowchart of transmitting terminal capability using an RA-preamble according to an embodiment of the present invention.

FIG. 13 illustrates an example of identifying a terminal capability using a Temporary Cell-Radio Network Temporary Identifier (TC-RNTI) according to an embodiment of the present invention.

14 shows an example of a MAC RAR according to an embodiment of the present invention.

15-16 illustrate a flow diagram for transmitting terminal capability using TC-RNTI according to an embodiment of the present invention.

17 illustrates an example of identifying terminal capability using message 3 according to an embodiment of the present invention.

18 is a flowchart illustrating a terminal capability delivery using message 3 according to an embodiment of the present invention.

19-20 illustrate a flow diagram for transmitting terminal capability using blind detection / decoding according to an embodiment of the present invention.

21 illustrates a transceiver that can be applied to an embodiment of the present invention.

Claims (13)

In the method of performing random access of a terminal in a mobile communication system, Transmitting a preamble for a random access to a base station; Receiving a second message from the base station including resource allocation information in response to the preamble; Transmitting a third message to the base station according to the resource allocation information; And Receiving a conflict resolution message from the base station, The third message is a method of performing random access including information on terminal capability. The method of claim 1, And wherein the third message is scrambled using a first temporary identifier related to the terminal capability. The method of claim 2, And wherein the first temporary identifier is modified according to a predetermined method related to the terminal capability from a second temporary identifier included in the second message. The method of claim 3, And wherein the first temporary identifier is modified by applying a predetermined offset related to the terminal capability to the second temporary identifier. The method of claim 1, And the second message includes a plurality of second temporary identifiers associated with a terminal category, and the first temporary identifier is selected from the plurality of second temporary identifiers in consideration of the terminal capability. The method of claim 1, And the third message includes a Radio Resource Control (RRC) signaling message indicating information on the terminal capability. The method of claim 1, The information on the terminal capability comprises a 1-bit information for identifying the terminal. The method of claim 1, The information on the terminal capability includes the information on the category of the terminal. The method of claim 1, The information on the terminal capability includes the information on the number of antennas of the terminal. The method of claim 1, The information on the terminal capability is indicated by the length of the message 3, characterized in that the random access method. The method of claim 1, The information about the terminal capability is indicated by a multi-antenna transmission scheme applied to the message 3. The method of claim 1, The multi-antenna transmission scheme includes at least one of space-time block coding, space-frequency block coding, and space orthogonal resource transmit diversity (SORTD). How to perform random access. A terminal configured to perform random access in a mobile communication system, Generate a preamble for random access for transmission to a base station, and process a second message including resource allocation information received from the base station in response to the preamble, the base station according to the resource allocation information A processor configured to generate a third message for sending a message, the processor configured to process a conflict resolution message received from the base station; And A radio frequency (RF) unit, configured to transmit information received from the processor to the base station, and configured to transmit information received from the base station to the processor, The processor is configured to include information in the third message about the capability of the terminal in generating the third message.

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