JP2011029893A - Radio resource allocation device and radio resource allocation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contribute to the prevention of the deterioration of the efficiency of radio resource utilization by appropriately limiting a radio resource amount allocated for retransmission. <P>SOLUTION: This radio resource allocation device includes: a radio resource using amount recording part 3 for recording a radio resource amount used for the transmission of physical layer packets for each physical layer packet; and a retransmission maximum radio resource amount determination part 4 for determining the upper limit value of the radio resource amount allocated for the retransmission of one physical layer packet on the basis of the radio resource amount used for the transmission of the physical layer packet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio resource allocation device and a radio resource allocation method.

  In recent years, for example, “LTE (Long Term Evolution)”, which is one of the standards of 3GPP (Third Generation Partnership Project), is known as a next-generation mobile communication system that realizes high-speed and broadband wireless transmission (for example, Non-Patent Document 1). In LTE, an orthogonal frequency division multiple access (OFDMA) system is used as a wireless transmission system in the downlink (link from the base station to the terminal station). The OFDMA scheme is one of multicarrier transmission schemes in which communication is performed using wideband signals composed of a plurality of subcarriers whose frequencies are orthogonal to each other, and by using different subcarriers for each user (terminal station). Implement multiple access between one base station and multiple users.

  In LTE, in order to improve packet error rate characteristics in the physical layer, “HARQ (Hybrid ARQ (Automatic Repeat reQuest))” is used as a packet retransmission method. In HARQ, there are roughly two types of packet transmission methods and packet combining methods on the receiving side: “Chase combining” and “IR (Incremental Redundancy)”, and LTE uses the IR method.

  FIG. 2 is a conceptual diagram for explaining a packet transmission method of the IR method. In the IR method, error correction encoded data obtained by encoding transmission information with an error correction code is stored in a physical layer packet (referred to as a transport block). The error correction encoded data in the transport block can decode all transmission information before error correction encoding from a part of the error correction encoded data.

  In the IR method, the error correction encoded data in the transport block is partially transmitted. This is intended in the hope that the error correction function on the receiving side will succeed in decoding all transmission information in the transport block with only a part of the error correction encoded data in the transport block. As a result, when all transmission information in the transport block is successfully decoded in the first transmission (initial transmission), the second and subsequent transmissions (retransmission) are not performed. On the other hand, if the transmission information in the transport block fails to be decoded in the initial transmission, the second transmission (the first retransmission) is performed, and then all the transmission information in the transport block is successfully decoded. Repeat retransmission until

As shown in FIG. 2, in each transmission of initial transmission and retransmission, the transmission start location in the transport block is designated, and the transmission data amount (the amount indicated by the width of the arrow in FIG. 2) from the transmission start location. Error correction encoded data is transmitted. Here, the IR method has the following features (1) and (2).
(1) The size of the transport block is determined from the amount of radio resources used in the initial transmission, the modulation scheme, and the channel coding rate.
(2) In each transmission of initial transmission and retransmission, the transmission data amount is determined from the amount of radio resources and the modulation method used in each transmission.

3GPP TS 36.212, “Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding”

  However, in the conventional transmission data amount determination method described above, radio resources may be wasted in retransmission. The amount of radio resources to be used for retransmission is determined according to the amount of radio resources that can be used at the time of retransmission, but because a large amount of radio resources can be used, a large amount of radio resources are allocated for retransmission and retransmitted. Even if the transmission data amount is increased, only the transmission information stored in the transport block of the size determined at the time of initial transmission can be transmitted. That is, since the upper limit of the amount of transmission information that can be transmitted is determined, the radio resource utilization efficiency decreases as the amount of radio resources allocated for retransmission increases.

  The present invention has been made in view of such circumstances, and its purpose is to provide a radio that can contribute to prevention of a decrease in radio resource utilization efficiency by appropriately limiting the amount of radio resources allocated for retransmission. A resource allocation apparatus and a radio resource allocation method are provided.

  In order to solve the above problem, a radio resource allocation device according to the present invention is an error correction encoded data of transmission information, and an error capable of decoding all of the transmission information from a part of the error correction encoded data A recording that records the amount of radio resources used for transmission of physical layer packets for each physical layer packet in a radio resource allocation apparatus that allocates radio resources used for transmission of physical layer packets in which correction encoded data is stored And a radio resource amount determining means for determining an upper limit value of a radio resource amount allocated for retransmission of one physical layer packet based on a radio resource amount used for transmission of the physical layer packet. Features.

  In the radio resource allocation device according to the present invention, the radio resource amount determining means determines the upper limit value based only on the radio resource amount used for the initial transmission.

  In the radio resource allocation device according to the present invention, the radio resource amount determination means determines the upper limit value based on a total amount of used radio resource amounts.

The radio resource allocation device according to the present invention is characterized in that an adjustment coefficient for adjusting the upper limit value is provided for each destination user of the physical layer packet.
In the radio resource allocation device according to the present invention, the adjustment coefficient is a value corresponding to the priority of the destination user.
In the radio resource allocation device according to the present invention, the adjustment coefficient is a value corresponding to a frequency characteristic of a radio wave propagation path from a transmission station transmitting a physical layer packet to a destination user.

  The radio resource assignment device according to the present invention is characterized in that a value specific to the radio communication system is provided as an adjustment coefficient for adjusting the upper limit value.

  The radio resource allocation method according to the present invention is a physical information storing error correction encoded data of transmission information, in which error correction encoded data capable of decoding all of the transmission information from a part of the error correction encoded data is stored. A radio resource allocation method for allocating radio resources to be used for transmitting layer packets, the step of recording the amount of radio resources used for transmitting physical layer packets for each physical layer packet; Determining an upper limit value of a radio resource amount to be allocated for retransmission based on a radio resource amount used for transmission of the physical layer packet.

  According to the present invention, it is possible to appropriately limit the amount of radio resources allocated for retransmission. Thereby, the effect that it can contribute to the fall prevention of radio | wireless resource utilization efficiency is acquired.

It is a block diagram which shows the structure of the radio | wireless resource allocation apparatus 1 which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating the packet transmission method of IR method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a radio resource allocation device 1 according to an embodiment of the present invention. The radio resource allocation device 1 according to the present embodiment performs downlink radio resource allocation in an LTE-compliant radio communication system. In the wireless communication system according to the present embodiment, HARQ is used as a retransmission method for physical layer packets (transport blocks), and an IR method is used as a packet transmission method and a packet synthesis method on the reception side. Therefore, the radio resource allocation device 1 uses a radio resource allocation method that conforms to the HARQ and IR methods. In LTE, a radio resource called a resource block (RB) is defined, and RB is a minimum unit of radio resource allocation. The RB includes resources in the frequency direction and resources in the time direction. In the following description, the transport block is referred to as a packet.

In FIG. 1, the radio resource allocation device 1 includes a radio resource allocation unit 2, a radio resource usage amount recording unit 3, and a retransmission upper limit radio resource amount determination unit 4.
The radio resource allocation unit 2 refers to retransmission packet information when scheduling radio resource allocation for a certain radio frame. The retransmission packet information is information related to radio resource allocation for the retransmission packet, such as an identifier (ID), a size, a retransmission deadline, and the like of a packet to be retransmitted (hereinafter referred to as a retransmission packet).

  Based on the retransmission packet information, the radio resource allocation unit 2 determines a retransmission packet (hereinafter referred to as an allocation target retransmission packet) that requires radio resource allocation in a scheduling target radio frame. The radio resource allocating unit 2 acquires the upper limit value of the radio resource amount to be allocated to the allocation target retransmission packet from the retransmission upper limit radio resource amount determining unit 4.

  The radio resource allocation unit 2 allocates radio resources to the allocation target retransmission packet with the upper limit value of the radio resource amount acquired from the retransmission upper limit radio resource amount determination unit 4 as an upper limit. As a result, the amount of radio resources allocated to the allocation target retransmission packet is limited to the upper limit value of the radio resource amount.

  The radio resource allocation unit 2 outputs radio resource allocation information as a radio resource allocation result. The radio resource allocation information includes a packet ID and a radio resource usage amount for each packet to which radio resources are allocated. The radio resource usage amount included in the radio resource allocation information is the radio resource amount used for transmission of the radio frame to be scheduled. From this radio resource usage amount and modulation scheme, the transmission data amount of the packet transmitted in the radio frame to be scheduled is determined.

  The radio resource usage recording unit 3 receives the radio resource allocation information output from the radio resource allocation unit 2 and records the radio resource usage for each packet ID. ACK / NACK information is input to the radio resource usage amount recording unit 3. The ACK / NACK information is reply information of a delivery confirmation signal (acknowledgment signal (ACK) or negative acknowledgment signal (NACK)) returned from the wireless terminal to the base station for each packet, and either the packet ID or ACK or NACK is returned. Information indicating whether or not The radio resource usage amount recording unit 3 acquires the packet ID of the packet for which the ACK is returned from the ACK / NACK information, and deletes the radio resource usage amount record related to the acquired packet ID. This is because a packet to which an ACK is returned is not retransmitted, and it is not necessary to record the amount of radio resource usage related to the packet.

  The retransmission upper limit radio resource amount determination unit 4 determines the upper limit value of the radio resource amount to be allocated to the retransmission packet based on the radio resource amount used in the transmission of the retransmission packet. The retransmission upper limit radio resource amount determination unit 4 acquires the packet ID of the packet for which the NACK is returned from the ACK / NACK information, and records the radio resource usage amount related to the acquired packet ID from the radio resource usage amount recording unit 3. get. The packet to which NACK is returned is a retransmission packet.

  The retransmission upper limit radio resource amount determination unit 4 determines the upper limit value of the radio resource amount based on the record of the radio resource usage amount acquired from the radio resource usage amount recording unit 3 regarding the retransmission packet.

  Hereinafter, a method for determining the upper limit value of the radio resource amount for the retransmission packet will be described with reference to examples.

  In the first embodiment, the retransmission upper limit radio resource amount determination unit 4 determines the upper limit value of the radio resource amount based only on the radio resource amount used for the initial transmission. First, the retransmission upper limit radio resource amount determination unit 4 acquires the initial radio resource use amount from the record of the radio resource usage amount related to the retransmission packet whose upper limit value is to be determined. The retransmission upper limit radio resource amount determination unit 4 sets the acquired initial transmission radio resource usage as the upper limit value of the radio resource amount. Thereby, the amount of radio resources allocated to the allocation target retransmission packet is limited to be equal to or less than the amount of radio resource used in the initial transmission of the packet.

  The amount of radio resources used for the initial transmission can be expected to achieve a desired error rate at least at the time of the initial transmission. For this reason, in the first embodiment, the radio resource usage amount for the initial transmission is an upper limit value of an appropriate radio resource amount for retransmission.

  The second embodiment is a modification of the first embodiment. The retransmission upper limit radio resource amount determination unit 4 sets a value obtained by multiplying an initial transmission radio resource usage amount related to a retransmission packet whose upper limit value is determined by an adjustment coefficient as an upper limit value of the radio resource amount. The adjustment coefficient is a coefficient (positive real number) for adjusting the upper limit value of the radio resource amount. Needless to say, the case of “adjustment coefficient = 1” corresponds to the first embodiment. Further, when the technical idea of the first embodiment is followed, the adjustment coefficient is a positive real number of 1 or less.

Examples of the adjustment coefficient include the following.
(Example of adjustment factor 1)
The adjustment coefficient adjusts the upper limit value of the radio resource amount for each destination user of the packet. Examples 1-1 and 1-2 in this case will be given.
(Example 1-1) The value is set according to the priority of the user. For example, when a user is classified into a priority user and a non-priority user, the adjustment coefficient applied to the non-priority user is set to a value smaller than the adjustment coefficient applied to the priority user.
(Example 1-2) A value corresponding to the frequency characteristics of the radio wave propagation path from the base station (transmitting station) to the destination user is used. For example, an adjustment coefficient to be applied to a user who has obtained only a frequency characteristic less than a desired transmission standard is smaller than an adjustment coefficient to be applied to a user who has obtained a good frequency characteristic equal to or higher than the desired transmission standard. To do.
(Example of adjustment factor 2)
The adjustment coefficient is a value unique to the wireless communication system. For example, the adjustment coefficient is determined based on the operation policy of the wireless communication system.

  In the third embodiment, the retransmission upper limit radio resource amount determination unit 4 determines the upper limit value of the radio resource amount based on the total amount of used radio resources. First, the retransmission upper limit radio resource amount determination unit 4 acquires the total amount of radio resource usage from the record of the radio resource usage associated with the retransmission packet for which the upper limit value is to be determined. The retransmission upper limit radio resource amount determination unit 4 determines the upper limit value of the radio resource amount based on the acquired total amount of radio resource usage. For example, a value obtained by subtracting the total amount from the value obtained by multiplying the total amount of radio resource usage by an adjustment coefficient is set as the upper limit value of the radio resource amount. In this case, the adjustment coefficient is a real number larger than 1. Note that examples of adjustment coefficients are the same as those in Examples 1 and 2 given in Example 2 above. In the third embodiment, an upper limit value can be set according to the total amount of radio resources used so far.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, the present invention is applicable to various wireless communication systems that use HARQ as a retransmission method for physical layer packets and use the IR method as a packet transmission method and a packet synthesis method on the reception side.

DESCRIPTION OF SYMBOLS 1 ... Radio resource allocation apparatus, 2 ... Radio resource allocation part, 3 ... Radio resource usage recording part, 4 ... Retransmission upper limit radio | wireless resource amount determination part

Claims (8)

Radio resource used for transmission of physical layer packet storing error correction encoded data of transmission information and error correction encoded data in which all of the transmission information can be decoded from a part of the error correction encoded data In the radio resource allocation apparatus that performs allocation,
Recording means for recording the amount of radio resources used for transmission of the physical layer packet for each physical layer packet;
Radio resource amount determination means for determining an upper limit value of a radio resource amount to be allocated for retransmission of one physical layer packet based on a radio resource amount used for transmission of the physical layer packet;
A radio resource allocation device comprising:   The radio resource allocation apparatus according to claim 1, wherein the radio resource amount determination unit determines the upper limit value based only on a radio resource amount used for initial transmission.   The radio resource allocation apparatus according to claim 1, wherein the radio resource amount determining means determines the upper limit value based on a total amount of used radio resources.   The radio resource allocation device according to any one of claims 1 to 3, wherein an adjustment coefficient for adjusting the upper limit value is provided for each destination user of the physical layer packet.   The radio resource allocation apparatus according to claim 4, wherein the adjustment coefficient is a value corresponding to a priority level of a destination user.   The radio resource allocation apparatus according to claim 4, wherein the adjustment coefficient is a value corresponding to a frequency characteristic of a radio wave propagation path from a transmission station that transmits a physical layer packet to a destination user.   The radio resource allocation device according to any one of claims 1 to 3, wherein a value unique to a radio communication system is provided as an adjustment coefficient for adjusting the upper limit value. Radio resource used for transmission of physical layer packet storing error correction encoded data of transmission information and error correction encoded data in which all of the transmission information can be decoded from a part of the error correction encoded data A radio resource allocation method for performing allocation,
For each physical layer packet, recording the amount of radio resources used to transmit the physical layer packet;
Determining an upper limit value of a radio resource amount to be allocated for retransmission of one physical layer packet based on a radio resource amount used for transmission of the physical layer packet;
A radio resource allocating method comprising:

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