JP5462908B2 - Radio resource allocation method in radio communication system - Google Patents

Description

  The present invention relates to a radio communication system, and more particularly to a radio resource allocation method in a radio communication system.

  Wireless communication systems that use multiple carrier schemes, such as Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier-Frequency Division Multiple Access (SC-FDMA), A resource is a set of consecutive subcarriers and is defined by a time-frequency domain in a two-dimensional space. One time-frequency region is divided into rectangles determined by time coordinates and subcarrier coordinates. That is, one time-frequency region is divided into rectangles defined by at least one symbol on the time axis and a large number of subcarriers on the frequency axis. This time-frequency domain may be assigned to the uplink of a specific terminal (User Equipment; UE), or the base station (eNode B) may transmit the time-frequency domain to a specific terminal in the downlink. it can. In order to define this time-frequency domain in two-dimensional space, the number of OFDM symbols and the number of consecutive subcarriers starting at an offset from the reference point in the frequency domain must be given. .

  The Evolved Universal Mobile Telecommunications System (E-UMTS), which is currently under discussion, uses 10 ms radio frames, and one radio frame is composed of 10 subframes. One subframe is composed of two consecutive slots. The length of one slot is 0.5 ms. One subframe is composed of a large number of OFDM symbols, and a part of the large number of OFDM symbols (for example, the first symbol) is used to transmit L1 / L2 control information.

  FIG. 1 is a diagram showing an example of a physical channel structure used in an E-UMTS system. One subframe includes an L1 / L2 control information transmission area (hatched part) and a data transmission area (unhatched part). ).

  FIG. 2 is a diagram for explaining a general method of transmitting data by E-UMTS. In E-UMTS, a hybrid automatic repeat request (HARQ) technique, which is one of data retransmission techniques, is used in order to improve throughput and perform smooth communication.

  Referring to FIG. 2, the base station performs downlink scheduling via a DL L1 / L2 control channel, eg, Physical Downlink Control Channel (PDCCH), to transmit data to the terminal according to the HARQ technique. Information (Downlink Scheduling Information, hereinafter referred to as DL scheduling information) is transmitted. The DL scheduling information includes a terminal identifier or a group identifier of each terminal (UE Id or Group Id), position and interval information of radio resources allocated for transmission of downlink data, modulation scheme, payload size, Transmission parameters such as MIMO related information, HARQ process information, redundant version, information identifying whether or not new data is included, and the like are included.

  A terminal identifier (or group identifier), for example, a radio network temporary identifier (RNTI) is used to inform a terminal about which DL scheduling information transmitted through the PDCCH in the above process. Is sent. RNTI can be classified into individual RNTI and shared RNTI. The dedicated RNTI is used for data transmission / reception with a terminal whose information is registered in the base station. Shared RNTI transmits / receives information commonly used by a plurality of terminals, such as system information, when communicating with each terminal that is not assigned an individual RNTI because no information is registered in the base station Used when. For example, RA-RNTI or TC-RNTI used in a random access process through a random access channel (RACH) is an example of a shared RNTI. The terminal identifier or group identifier is transmitted in the form of a cyclic redundancy check (CRC) mask in DL scheduling information transmitted via the PDCCH.

  Each terminal existing in a specific cell monitors the PDCCH through the L1 / L2 control channel using its own RNTI information, and if CRC decoding is successful in its own RNTI, Receive DL scheduling information. The terminal receives downlink data transmitted to itself through a physical downlink shared channel (PDSCH) indicated by the received DL scheduling information.

  Scheduling schemes can be classified into dynamic scheduling schemes and persistent or semi-persistent scheduling schemes. The dynamic scheduling scheme is a scheme in which scheduling information is transmitted to the terminal via the DPCCH whenever it is necessary to allocate uplink or downlink resources for a specific terminal. The persistent scheduling scheme refers to a scheme in which downlink or uplink scheduling information is statically allocated to a terminal at the time of initial call setting such as when setting up a radio bearer at a base station.

  In the case of the persistent scheduling method, the terminal does not receive allocation of DL scheduling information or UL scheduling information from the base station every time data is transmitted or received, but uses scheduling information previously allocated to the base station. For example, when the base station is preset in a specific terminal to receive downlink data with a period of “C” in a transmission format of “B” through a radio resource of “A” through an RRC signal in a radio bearer setting process, The terminal can receive downlink data transmitted from the base station using “A”, “B”, and “C” information. Similarly, when the terminal transmits data to the base station, it is possible to transmit the uplink data using radio resources predetermined by the uplink scheduling information allocated in advance. The persistent scheduling method is a scheduling method that is often applied to services with regular traffic characteristics such as voice calls.

  The AMR codec used in a voice call, that is, voice data generated through the voice codec has special characteristics. That is, the audio data is classified into two sections, a sound section and a silent section. A voiced section means a voice data section generated while a person is actually speaking, and a silent section is a voice data section generated while a person is not speaking. For example, a voice packet including voice data in a voiced section is generated every 20 ms, and a silent packet (SID) including voice data in a silent section is generated every 160 ms.

  When the persistent scheduling method is used for a voice call, the base station sets radio resources in accordance with the sound period. That is, the base station preliminarily sets radio resources for transmitting / receiving uplink or downlink data at intervals of 20 ms to the terminal at a call setting stage using the characteristic that a voice packet is generated every 20 ms. The terminal receives downlink data or transmits uplink data using radio resources set in advance every 20 ms interval.

  In a wireless communication system, communication can be performed by simultaneously applying a dynamic scheduling method and a persistent scheduling method to one terminal. For example, when a voice call based on the VoIP service is performed by the HARQ method, the persistent scheduling method is applied to the initial transmission packet, and the dynamic scheduling method is applied to the retransmission packet. Further, when the terminal uses two or more services at the same time, the persistent scheduling method is applied to one service, and the dynamic scheduling method is applied to other services. In this case, from the terminal's standpoint, the scheduling information transmitted to itself is according to which scheduling method, for initial transmission packet or retransmission packet, or for which service It is necessary to have a system that can clearly identify whether it is a product.

  Accordingly, it is an object of the present invention to provide a radio resource allocation method in a radio communication system that substantially prevents one or more problems due to limitations and disadvantages in the art.

  An object of the present invention is to provide a radio resource allocation method in a radio communication system that can efficiently use radio resources in the radio communication system.

  Another object of the present invention is to provide a method in which a terminal can clearly identify scheduling information according to each scheduling method in a wireless communication system in which radio resources are allocated by a number of scheduling methods.

  In one aspect of the present invention, a network of a wireless communication system is for allocating radio resources to terminals according to a number of scheduling schemes, and a first terminal identifier is allocated to allocate radio resources to terminals according to a first scheduling scheme. First scheduling information including the second scheduling information is transmitted to the terminal, and second scheduling information including a second terminal identifier is transmitted to the terminal to allocate radio resources to the terminal according to a second scheduling scheme.

  In another aspect of the present invention, when the scheduling information received from the network includes the first terminal identifier, the terminal transmits uplink data using the radio resource allocated by the first scheduling scheme. And receive downlink data. If the scheduling information includes a second terminal identifier, the terminal transmits uplink data or receives downlink data using radio resources allocated by the second scheduling scheme. .

  Advantageous Effects of Invention According to the present invention, radio resources can be efficiently used in a radio communication system, and a terminal can clearly identify scheduling information according to each scheduling scheme in a radio communication system that allocates radio resources by a number of scheduling schemes. it can.

It is the figure which showed an example of the physical channel structure used with an E-UMTS system. It is a figure for demonstrating the general method which transmits data by E-UMTS. It is the figure which showed the network structure of E-UMTS. It is a schematic block diagram of E-UTRAN. It is a protocol block diagram of the control plane in the radio | wireless interface protocol structure between a terminal (UE) and E-UTRAN. It is a protocol block diagram of the user plane in the radio | wireless interface protocol structure between a terminal (UE) and E-UTRAN. 5 is a flowchart illustrating a procedure of a data transmission method according to an embodiment of the present invention.

  Hereinafter, the configuration, operation, and other features of the present invention can be easily understood by embodiments of the present invention described with reference to the accompanying drawings. Each example described below is an example in which the technical features of the present invention are applied to E-UMTS.

  FIG. 3 is a diagram illustrating a network structure of E-UMTS. The E-UMTS system is a system developed from the existing WCDMA UMTS system, and basic standardization work is currently underway in the 3rd Generation Partnership Project (3GPP). E-UMTS is also called Long Term Evolution (LTE) system.

  Referring to FIG. 3, an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) is composed of base stations (hereinafter abbreviated as eNode B or eNB), and each eNB is connected via an X2 interface. Connected to each other. The eNB is connected to a terminal (User Equipment; hereinafter abbreviated as UE) via a radio interface, and is connected to an evolved packet core (EPC) via an S1 interface. The EPC includes a Mobility Management Entity (MME) / System Architecture Evolution (SAE) gateway.

  Each layer of the radio interface protocol between the terminal and the network is based on L1 (Layer 1) based on the lower three layers of the Open System Interconnection (OSI) standard model widely known in communication systems. ), L2 (layer 2) and L3 (layer 3), among these, the physical layer belonging to layer 1 (L1) provides an information transmission service using a physical channel and is located in layer 3 The radio resource control (Radio Resource Control; hereinafter abbreviated as RRC) layer performs a role of controlling radio resources between the terminal and the network. For this purpose, the RRC layer exchanges RRC messages between the terminal and the network. The RRC layer is distributed and arranged in network nodes such as Node B and AG, or is independently arranged in Node B or AG.

  FIG. 4 is a schematic configuration diagram of E-UTRAN. In FIG. 4, the shaded portion indicates a functional entity of the user plane, and the non-hatched portion indicates a functional entity of the control plane.

  5A and 5B are diagrams illustrating a structure of a radio interface protocol between a terminal (UE) and an E-UTRAN, in which FIG. 5A is a protocol configuration diagram of a control plane and FIG. 5B is a user plane protocol. It is a block diagram. 5A and 5B includes a physical layer, a data link layer, and a network layer in the horizontal direction, and a user plane for data information transmission and a control plane for control signal transmission in the vertical direction. Become. Each of the protocol layers in FIG. 5A and FIG. 5B is based on the lower three layers of the Open System Interconnection (OSI) reference model widely known in the communication system. Layer 2) and L3 (layer 3).

  The physical layer which is Layer 1 provides an information transmission service to an upper layer using a physical channel. The physical layer is connected to a higher level medium access control (hereinafter abbreviated as MAC) layer via a transport channel, and the MAC layer and the physical layer are connected via the transport channel. The data in between moves. Data is transferred between physical layers different from each other, that is, between physical layers on the transmission side and the reception side via a physical channel. In E-UMTS, the physical channel is modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, thereby using time and frequency as radio resources.

  The MAC layer, which is Layer 2, provides a service to a radio link control (Radio Link Control; hereinafter abbreviated as RLC) layer, which is an upper layer, via a logical channel. The Layer 2 RLC layer supports reliable data transmission. The layer 2 PDCP layer is a header that reduces unnecessary control information so that data transmitted using IP packets such as IPv4 and IPv6 is efficiently transmitted in a wireless section with a relatively small bandwidth. Perform the compression function.

  The RRC layer located at the bottom of layer 3 is defined only by the control plane, and is associated with the setting of a radio bearer (hereinafter abbreviated as RB), reconfiguration and release, and a logical channel and a transport channel. And is responsible for controlling physical channels. At this time, RB means a service provided by layer 2 for data transfer between the terminal and the UTRAN.

  The downlink transport channel for transmitting data from the network to the terminal includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and user traffic and control. There is a downlink shared channel (SCH) for transmitting messages. Downlink multicast or broadcast service traffic or control messages may be transmitted via the downlink SCH or via another downlink multicast channel (MCH). On the other hand, as an uplink transport channel for transmitting data from a terminal to a network, there are an RACH for transmitting an initial control message and an uplink SCH for transmitting user traffic and control messages.

  The logical channels that are above the transport channel and are mapped to the transport channel include a broadcast channel (BCCH), a paging control channel (PCCH), and a common control channel (CCCH). Multicast Control Channel (MCCH) and Multicast Traffic Channel (MTCH).

  In the E-UMTS system, the OFDM scheme is used in the downlink and the SC-FDMA scheme is used in the uplink. An OFDM system that is a multi-carrier scheme is a system that allocates resources in units of a number of subcarriers in which a part of carrier waves is grouped, and uses OFDMA as a connection scheme.

  FIG. 6 is a flowchart illustrating a procedure of a data transmission method according to an embodiment of the present invention. The embodiment of FIG. 6 relates to an example in which a terminal (UE) receives an SRB packet by a dynamic scheduling method while receiving voice data (VoIP packet) by a persistent scheduling method. In the following, description will be made only when necessary for understanding one embodiment of the present invention, and description of general procedures necessary for communication between other networks and terminals will be omitted.

  Referring to FIG. 6, the base station (eNB) allocates two terminal identifiers to the terminal [S61]. Examples of the two terminal identifiers include C-RNTI and SPS-C-RNTI (Semi-Persistent Scheduling RNTI), but are not limited thereto, and other terminal identifiers such as temporary C-RNTI or RA-RNTI may be used. The two terminal identifiers are allocated to the terminal by a network in a random access process, a call setup process, or a radio bearer (RB) setup process. The two terminal identifiers are assigned simultaneously or individually.

  The base station transmits first scheduling information to the terminal to allocate radio resources for voice data transmission / reception [S62]. The first scheduling information may include uplink and downlink scheduling information. The first scheduling information includes SPS-C-RNTI to indicate that the scheduling information is allocated according to a persistent scheduling scheme. The SPS-C-RNTI is included in the form of a CRC mask in at least a part of the first scheduling information. The first scheduling information is set to have a format (first format) different from the scheduling information based on the dynamic scheduling method. The terminal decodes the first scheduling information according to a first format, and when the SPS-C-RNTI is included in the first scheduling information, the first scheduling information is a persistent scheduling scheme. It recognizes that it is scheduling information by. The first scheduling information includes information related to a position of a radio resource allocated to the terminal, an allocation cycle, and an allocation interval. The terminal transmits uplink data or receives downlink data using radio resources allocated at a period allocated at an allocation interval according to the first scheduling information.

  The base station transmits an initial transmission VoIP packet (V1) to the terminal via the PDSCH according to the first scheduling information [S63]. The initial transmission VoIP packet (V1) means a voice packet that is not a retransmission packet when the HARQ scheme is applied. When the terminal does not normally receive the initial transmission VoIP packet (V1), that is, when decoding of the initial transmission VoIP packet fails, the terminal performs a negative uplink acknowledgment signal (NACK) with physical uplink control. It transmits to the said base station via a channel (Physical Uplink Control Channel; PUCCH) [S64]. The terminal receives the initial transmission VoIP packet (V1) or transmits NACK (or ACK) using the first scheduling information.

  When the terminal receives the initial transmission VoIP packet (V1) or transmits a NACK (or ACK), a static scheduling method is applied, but the base station does not transmit a retransmission VoIP packet. A dynamic scheduling scheme is applied. Therefore, in order to receive a retransmission packet after the terminal transmits a NACK to the base station, scheduling information must first be received. Therefore, the terminal monitors the PDCCH of the L1 / L2 control channel.

  In FIG. 6, the base station transmits second scheduling information to the terminal via PDCCH [S65]. The second scheduling information is information for allocating uplink and downlink channel resources to the terminal using a dynamic scheduling scheme, and may include DL scheduling information and UL scheduling information. The second scheduling information includes C-RNTI to indicate that the second scheduling information is allocated by a dynamic scheduling scheme. The C-RNTI is included in the form of a CRC mask in at least a part of the second scheduling information. The second scheduling information is set to have scheduling information based on a static scheduling scheme, that is, a format (second format) different from the first scheduling information. The terminal decodes the second scheduling information according to a second format, and when the second scheduling information includes C-RNTI, the second scheduling information is scheduled according to a dynamic scheduling scheme. Recognize information. The second scheduling information includes a HARQ process identifier.

  The base station transmits an initial transmission SRB packet (S1) to the terminal according to the second scheduling information [S66]. The initial transmission SRB packet (S1) means an SRB packet that is not a retransmission packet when the HARQ scheme is applied. When the terminal does not normally receive the initial transmission SRB packet (S1), that is, when decoding of the initial transmission SRB packet fails, the terminal sends a negative acknowledgment signal (NACK) via PUCCH. Transmit to the base station [S67]. The terminal receives the initial transmission SRB packet (S1) or transmits NACK (or ACK) using the second scheduling information.

  The base station transmits third scheduling information including SPS-C-RNTI to the terminal via PDCCH to transmit a retransmission packet (V2) for the initial transmission VoIP packet (V1). [S68]. If the terminal receives the third scheduling information including the SPS-C-RNTI, the terminal receives a retransmission VoIP packet (V2) transmitted from the base station using the third scheduling information. [S69]. The terminal combines the received retransmission VoIP packet (V2) and the initial transmission VoIP packet (V1) by the HARQ method to restore the VoIP packet [S70]. If the restoration of the VoIP packet is successful, the terminal transmits a reception acknowledgment signal (ACK) to the base station [S71]. The VoIP packet means a data packet to be transmitted from the base station to the terminal, and the initial transmission VoIP packet (V1) and the retransmission are transmitted based on the VoIP packet in order to transmit by the HARQ method. The packet is divided into VoIP packets (V2) and transmitted to the terminal.

  The third scheduling information may include information related to a point in time when the base station transmits the initial transmission VoIP packet (V1). For example, the third scheduling information may include information indicating a transmission time interval (TTI) at which the initial transmission VoIP packet (V1) is transmitted. The terminal determines that the retransmission VoIP packet (V2) is a retransmission packet for the initial transmission VoIP packet according to information related to the time point when the initial transmission VoIP packet (V1) included in the third scheduling information is transmitted. It can be easily recognized.

  The base station transmits fourth scheduling information including C-RNTI to the terminal via PDCCH to transmit a retransmission packet (S2) for the initial transmission SRB packet (S1) [S72. ]. When the terminal receives the fourth scheduling information including the C-RNTI, the terminal receives a retransmission SRB packet (S2) transmitted from the base station using the fourth scheduling information [ S73]. The terminal combines the received retransmission SRB packet (S2) and the initial transmission SRB packet (S1) by the HARQ method to restore the SRB packet [S74]. If the restoration of the SRB packet is successful, the terminal transmits a reception acknowledgment signal (ACK) to the base station [S75]. The SRB packet means a data packet to be transmitted from the base station to the terminal, and the initial transmission SRB packet (S1) and the retransmission are transmitted based on the SRB packet for transmission by the HARQ scheme. It is divided into SRB packets (S2) and transmitted to the terminal. The fourth scheduling information includes the same HARQ process identifier as that included in the second scheduling information.

  In the embodiment of FIG. 6, the first to fourth scheduling information includes an initial transmission packet or a data packet transmitted from the base station to the terminal according to the first to fourth scheduling information. Identification information that can identify whether the packet is a transmission packet can be further included. The identification information may be included in the first to fourth scheduling information in such a manner that specific fields of the first to fourth scheduling information are set to predetermined values. For example, by setting specific values such as 1, 2 and 3 in the Redundancy Version (RV) field included in the first to fourth scheduling information, the first retransmission packet, the second retransmission packet, It can be shown that it is a transmission packet and a third retransmission packet. In addition to the RV field, other fields included in the first to fourth scheduling information, for example, HARQ process ID field, format field, MCS field, new data indicator field, TPC field, cyclic shift field for DMRS , TX antenna field, CQI request field, etc. can be used as the identification information by setting at least one field to a specific value.

  In each of the embodiments described above, the constituent elements and features of the present invention are combined in a predetermined form. Each component or feature must be considered optional unless explicitly stated otherwise. Each component or feature is implemented in a form that is not combined with other components or features. It is also possible to combine some components and / or features to form an embodiment of the present invention. The order of each operation described in each embodiment of the present invention can be changed. Some configurations and features of one embodiment can be included in other embodiments and replaced with corresponding configurations or features of other embodiments. It is obvious that claims which do not have an explicit citation relationship in the claims can be combined to constitute an embodiment, or can be included as new claims by amendment after application.

  In this document, each embodiment of the present invention has been described with a focus on the data transmission / reception relationship between the terminal and the base station. The specific operations described in this document as being performed by a base station are sometimes performed by its higher order nodes. That is, it is obvious that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station are performed by the base station or another network node other than the base station. The “base station” is replaced with terms such as a fixed station, Node B, eNode B (eNB), and access point. Further, “terminal” is replaced with terms such as user equipment (UE), a mobile station (Mobile Station; MS), a mobile subscriber station (MSS), and the like.

  Embodiments according to the present invention may be implemented by various means such as hardware, firmware, software, or a combination thereof. When implemented in hardware, one embodiment of the present invention includes one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), and digital signal processors. (Digital Signal Processing Device; DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), Processor, Controller, Microcontroller, Microprocessor, etc.

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

  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 characteristics of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects, but should be considered as exemplary. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes that come within the equivalent scope of the invention are included in the scope of the invention.

  The present invention can be used in a wireless communication system such as a mobile communication system and a portable Internet system.

Claims (10)

A method for receiving data at a user equipment in a wireless communication system, comprising:
Receiving first scheduling information from the network and receiving an initial packet from the network based on the first scheduling information;
If the user equipment fails to successfully decode the initial packet, sending a NACK to the network;
Receiving second scheduling information from the network and receiving a retransmission packet from the network based on the second scheduling information;
Restoring the packet associated with the initial packet and the retransmission packet by combining the retransmission packet with the initial packet;
The first scheduling information and the second scheduling information may either have a C-RNTI that indicates that the first scheduling information and the second scheduling information is related to the dynamic scheduling mode, or,
The first scheduling information and the second scheduling information have a SPS-C-RNT I indicating that the first scheduling information and the second scheduling information are related to a semi-persistent scheduling mode. .   The method of claim 1, wherein the C-RNTI and the SPS-C-RNTI are assigned to the user equipment before receiving the scheduling information.   The method of claim 1, wherein the scheduling information is received on a PDCCH.   The method of claim 1, wherein each of the first scheduling information and the second scheduling information further comprises a HARQ process identifier.   The first scheduling information and the second scheduling information each further includes an indicator indicating whether a corresponding packet is an initial packet or a retransmission packet. the method of. A user apparatus for receiving data in a wireless communication system,
Receiving first scheduling information from the network, receiving an initial packet from the network based on the first scheduling information;
If the user equipment fails to successfully decode the initial packet, it sends a NACK to the network;
Receiving second scheduling information from the network, receiving a retransmission packet from the network based on the second scheduling information;
Configured to recover the packet associated with the initial packet and the retransmission packet by combining the retransmission packet with the initial packet;
The first scheduling information and the second scheduling information may either have a C-RNTI that indicates that the first scheduling information and the second scheduling information is related to the dynamic scheduling mode, or,
The first scheduling information and the second scheduling information have a SPS-C-RNT I indicating that the first scheduling information and the second scheduling information are related to a semi-persistent scheduling mode. apparatus.   The user apparatus according to claim 6, wherein the C-RNTI and the SPS-C-RNTI are allocated to the user apparatus before receiving the scheduling information.   The user equipment according to claim 6, wherein the scheduling information is received on a PDCCH.   The user apparatus according to claim 6, wherein each of the first scheduling information and the second scheduling information further includes a HARQ process identifier.   7. The method of claim 6, wherein each of the first scheduling information and the second scheduling information further includes an indicator indicating whether a corresponding packet is an initial packet or a retransmission packet. User equipment.

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