JP5302807B2 - RADIO RESOURCE ALLOCATION DEVICE, RADIO RESOURCE ALLOCATION METHOD, AND COMPUTER PROGRAM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of radio resource utilization when allocating radio resources to a terminal station using one of a plurality of radio resource allocation methods having different restrictions in the radio frame of the downlink of an OFDMA system. <P>SOLUTION: This radio resource allocation device includes: an RB allocation part 15 for allocating the radio resources to a terminal station using one of the plurality of radio resource allocation methods having the different restrictions; and an allocation type 0 execution part 11 for giving the radio resource satisfying a condition for satisfying the restriction of an allocation type 2 (localized) priority when selecting the radio resource allocated to the terminal station according to an allocation type 0. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

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

  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 a wideband signal 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.

FIG. 6 is a diagram illustrating a configuration example of a downlink radio frame of the OFDMA scheme. The radio frame shown in FIG. 6 is based on LTE. In FIG. 6, one radio frame is composed of a plurality of subframes. One subframe is composed of two slots. In LTE, a radio resource called a resource block (RB) is defined. As shown in FIG. 7, one slot has a configuration in which N _RB RBs are connected in the frequency direction. For example, when the subcarrier interval is 15 kHz, one RB is “12 subcarriers in the frequency direction × 7 OFDMA symbols in the time direction” or “12 subcarriers in the frequency direction × 6 OFDMA in the time direction”. Any configuration of "symbol" is possible. In the OFDMA scheme, arrangement information indicating in which RB a packet addressed to each user is arranged is determined for each subframe. The transmitter of the base station determines radio resources to be used for downlink packet transmission according to the arrangement information. The receiver of each terminal station receives a packet addressed to itself within the subframe according to the arrangement information.

  In LTE, four allocation types (Allocation types) 0, 1, 2 (localized), and 2 (distributed) are defined as allocation methods of RBs in a subframe to terminal stations (see, for example, Non-Patent Document 2). ). Each allocation type has different restrictions. When an RB is allocated to a terminal station, the RB must be allocated to the terminal station under the constraint according to any allocation type. Hereinafter, each allocation type will be briefly described.

FIG. 8 to FIG. 11 are examples of RB allocation to a terminal station according to each allocation type. In the examples of FIGS. 8 to 11, the frequency bandwidth (system bandwidth) used by the mobile communication system is 10 MHz, and the number of RBs per slot is 50 (N _RB = 50). These 50 RBs are assigned RB numbers from 0 to 49, respectively. RBs having consecutive RB numbers continue on the logical frequency axis. Whether it is continuous on the actual physical frequency axis depends on the allocation type.

[Allocation type 0]
In allocation type 0, RBs are allocated to terminal stations in units of radio resource groups called resource block groups (RBGs). The RBG is composed of a plurality of RBs that are continuous on the logical frequency axis, and is mapped in the same sequence on the physical frequency axis. In the example of FIG. 8, the RBG is composed of three consecutive RBs on the frequency axis (that is, the RBG size is 3), and RBs are allocated to the terminal station in units of the RBGs.

[Allocation type 1]
In allocation type 1, RBs are allocated to terminal stations in units of RBs in the same subset (Subset). In the example of FIG. 9, three subsets (the number of subsets is the same as the RBG size) are provided, and RBs are allocated to the same terminal station in units of RBs in the same subset. In each subset, RBs are arranged in order in units of RBGs. Further, the arrangement of RBs on the logical frequency axis is mapped in the same arrangement on the physical frequency axis.

[Allocation type 2 (localized)]
In allocation type 2 (localized), RBs are allocated to terminal stations in units of RBs on the logical frequency axis. However, all RBs assigned to the same terminal station need to be continuous on the frequency axis. Then, as illustrated in FIG. 10, mapping is performed on the physical frequency axis in the same manner as on the logical frequency axis. According to allocation type 2 (localized), only the start point and end point of RB allocation need be represented on the logical frequency axis, and the amount of RB allocation information notified to the terminal station can be reduced.

[Allocation type 2 (distributed)]
In allocation type 2 (distributed), RBs are allocated to terminal stations in units of RBs on the logical frequency axis. However, all RBs assigned to the same terminal station need to be continuous on the frequency axis. Then, as illustrated in FIG. 11, mapping is performed with a predetermined pattern on the physical frequency axis.

3GPP TS 36.211, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation” 3GPP TS 36.213, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation”

  However, if the above-described allocation type is used in a fixed manner, the degree of freedom of RB allocation is considerably limited, and RB utilization efficiency may be reduced. In particular, in allocation type 0, if the number of RBs required by the terminal station does not become an integer multiple of the RBG size, a surplus is generated in the RB allocated in units of RBGs, resulting in a decrease in RB utilization efficiency.

  The present invention has been made in view of such circumstances, and the object of the present invention is to select one of a plurality of resource block (radio resource) allocation methods each having different restrictions in an OFDMA downlink radio frame. An object of the present invention is to provide a radio resource allocating device, a radio resource allocating method, and a computer program capable of improving resource block utilization efficiency when allocating resource blocks to terminal stations using such a method.

  In order to solve the above problem, a radio resource allocation device according to the present invention is a radio resource allocation device that allocates radio resources to a terminal station in a downlink radio frame of an orthogonal frequency division multiple access scheme, Radio resource allocating means for allocating radio resources to the terminal station using any one of a plurality of radio resource allocating methods each having different constraints, and radio resources allocated to the terminal station according to the first radio resource allocating method And a first radio resource allocation method executing unit that prioritizes a radio resource that satisfies a condition for satisfying the constraints of the second radio resource allocation method.

  In the radio resource allocating device according to the present invention, the first radio resource allocating method executing means includes a plurality of radio resources having the same priority as the means for selecting a radio resource according to the priority of the radio resources according to the terminal station. And a means for selecting a radio resource that satisfies a condition for satisfying the constraints of the second radio resource allocation method.

  In the radio resource allocation device according to the present invention, the first radio resource allocation method allocates radio resources to terminal stations in units of radio resource groups composed of a plurality of radio resources continuous on the frequency axis. The second radio resource allocation method allocates radio resources continuous on the frequency axis to the terminal station in units of radio resources, and a condition for satisfying the constraints of the second radio resource allocation method Is continuous with the already selected radio resource group on the frequency axis.

  In the radio resource allocating device according to the present invention, the radio resource allocating means is a radio resource allocated to a terminal station among radio resources included in a radio resource group selected by the first radio resource allocating method executing means. And radio resources consecutive on the frequency axis are preferentially allocated to the terminal station.

  In the radio resource allocation device according to the present invention, the first radio resource allocation method allocates radio resources to terminal stations in units of radio resource groups composed of a plurality of radio resources continuous on the frequency axis. In the second radio resource allocation method, radio resources are allocated to a terminal station in units of radio resources in the same subset among a plurality of subsets in which radio resources are sequentially arranged in units of radio resource groups. The condition for satisfying the restriction of the second radio resource allocation method is that, when all already selected radio resource groups belong to the same subset, they belong to the subset. .

  A radio resource allocation device according to the present invention is a radio resource allocation device that allocates radio resources to a terminal station in a downlink radio frame of an orthogonal frequency division multiple access scheme, and each of the radio resource allocation devices has different constraints. A radio resource allocating means for allocating radio resources to the terminal station using any one of the methods, and a second radio when selecting a radio resource to be allocated to the terminal station according to the first radio resource allocating method. First radio resource allocation method execution means that prioritizes radio resources that satisfy the conditions for satisfying the constraints of the resource allocation method or the third radio resource allocation method, and the first radio resource allocation method includes: Nothing consisting of multiple radio resources that are continuous on the axis A radio resource is allocated to a terminal station in units of resource groups, and the second radio resource allocation method is to allocate radio resources continuous on the frequency axis to a terminal station in units of radio resources, The condition for satisfying the constraints of the second radio resource allocation method is to continue with the already selected radio resource group on the frequency axis, and the third radio resource allocation method is a unit of radio resource group. In order to satisfy the restrictions of the third radio resource allocation method, radio resources are allocated to terminal stations in units of radio resources in the same subset among a plurality of subsets in which radio resources are arranged in order. This condition is that all sub-resource groups that have already been selected belong to the same subset. It is to belong to the bets, the first radio resource allocation method execution means, priority conditions for satisfying the constraints of the second radio resource allocation method, characterized in that.

  A radio resource allocation method according to the present invention is a radio resource allocation method for allocating radio resources to a terminal station in a downlink radio frame of an orthogonal frequency division multiple access scheme, and a plurality of radio resources each having different constraints A step of allocating radio resources to the terminal station using any one of the allocation methods, and a second radio resource allocation when selecting a radio resource to be allocated to the terminal station according to the first radio resource allocation method Prioritizing radio resources that satisfy a condition for satisfying the constraints of the method.

A computer program according to the present invention is a computer program for allocating radio resources to a terminal station in a downlink radio frame of an orthogonal frequency division multiple access scheme, and a plurality of radio resource allocation methods each having different restrictions Assigning radio resources to the terminal station using any of the methods, and selecting a radio resource to be assigned to the terminal station according to the first radio resource assignment method, the second radio resource assignment method A computer program for causing a computer to execute the step of giving priority to radio resources that satisfy the conditions for satisfying the constraints.
As a result, the above-described radio resource allocation device can be realized using a computer.

  According to the present invention, in an OFDMA downlink radio frame, resource blocks are allocated to a terminal station using any one of a plurality of resource block (radio resource) allocation methods each having different constraints. In this case, it is possible to improve the resource block utilization efficiency. Thereby, the effect that it can contribute to the improvement of the frequency utilization efficiency of a mobile communication system is acquired.

It is a block diagram which shows schematic structure of the radio base station apparatus 1 of the OFDMA system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless frame control part 4 shown in FIG. It is a block diagram which shows the structure of the allocation type 0 execution part 11 shown in FIG. It is a flowchart which shows the flow of the RBG selection process which concerns on one Embodiment of this invention. It is an RB allocation example for demonstrating the RB allocation process which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the radio frame of the downlink of an OFDMA system. It is a conceptual diagram which shows the structure of the slot in the radio | wireless frame shown in FIG. It is an example of RB allocation to the terminal station by LTE allocation type 0. It is an example of RB allocation to the terminal station by LTE allocation type 1. It is an example of RB allocation to the terminal station by LTE allocation type 2 (localized). It is an example of RB allocation to the terminal station by LTE allocation type 2 (distributed).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of an OFDMA wireless base station apparatus 1 according to an embodiment of the present invention. This radio base station apparatus 1 is based on LTE. FIG. 1 shows a schematic configuration related to transmission in the downlink (link from the base station to the terminal station).

  In FIG. 1, the radio base station apparatus 1 includes a packet buffer 2, an OFDMA transmission unit 3, and a radio frame control unit 4. The packet buffer 2 temporarily stores packets to be transmitted to each terminal station. The OFDMA transmission unit 3 arranges a packet to be transmitted to each terminal station in a resource block (RB) in a radio frame and transmits the radio by the OFDMA method. The radio frame control unit 4 determines an RB to be allocated to each terminal station for each radio frame, and passes RB allocation information indicating which RB is allocated to which terminal station to the OFDMA transmission unit 3. The OFDMA transmitter 3 arranges transmission packets addressed to each terminal station for RBs in the radio frame according to the RB allocation information.

  The radio frame control unit 4 uses transmission packet information, CQI (Channel Quality Indicator) and QoS (Quality of Service) in RB allocation to the terminal station. The transmission packet information includes the amount of packets stored in the packet buffer 2, the size of each packet, and the arrival time of each packet at the packet buffer 2 for each destination terminal station. QoS is information indicating the quality of service requested by the terminal station, and is sent from the terminal station to the radio base station apparatus 1.

  CQI is information representing the frequency characteristics of a downlink propagation path. The terminal station estimates the frequency characteristics of the downlink propagation path, and transmits the estimation result to the radio base station apparatus 1 as CQI. There are two types of CQI, “Wideband CQI” and “Subband CQI”. “Wideband CQI” is a value for the entire frequency band corresponding to the system bandwidth. “Subband CQI” is a value for a subband. A subband is composed of continuous RBs on the frequency axis, and its size is determined by the system bandwidth. For example, when the system bandwidth is 10 MHz, the subband size is 6 RBs. The radio frame control unit 4 can know the frequency characteristics of the downlink propagation path with the terminal station that is the CQI transmission source by CQI. However, the accuracy of the frequency characteristic is in subband units.

  Based on the transmission packet information, the CQI, and the QoS, the radio frame control unit 4 determines a terminal station that allocates RBs in a certain radio frame and determines which RB is allocated to the terminal station. The radio frame control unit 4 performs RB allocation to the terminal station using any one of allocation types 0, 1, 2 (localized) and 2 (distributed) compliant with LTE.

  FIG. 2 is a block diagram showing a configuration of the radio frame controller 4 shown in FIG. In FIG. 2, the radio frame control unit 4 includes an allocation type 0 execution unit 11, an allocation type 1 execution unit 12, an allocation type 2 (localized) execution unit 13, an allocation type 2 (distributed) execution unit 14, and an RB allocation unit 15. It has a free RB management unit 16, a terminal reservation RB management unit 17, and an allocation target terminal determination unit 18.

  The allocation type 0 execution unit 11 selects an RB to be allocated to the terminal station in resource block group (RBG) units according to the allocation type 0. The allocation type 1 execution unit 12 selects an RB to be allocated to the terminal station in units of RBs according to the allocation type 1. The allocation type 2 (localized) execution unit 13 selects an RB to be allocated to the terminal station in units of RBs according to the allocation type 2 (localized). The allocation type 2 (distributed) execution part 14 selects RB allocated to a terminal station per RB according to allocation type 2 (distributed).

  The RB allocation unit 15 determines an RB to be allocated to the allocation target terminal station. The free RB management unit 16 manages the allocation status (allocated or not allocated) of each RB. The free RB management unit 16 holds information (free RB information) indicating an unallocated RB (free RB). The terminal reservation RB management unit 17 manages RBs reserved for each terminal station. The terminal reservation RB management unit 17 holds information indicating the reserved RB (terminal reservation RB information) for each terminal station.

  The allocation target terminal determination unit 18 determines a terminal station to which an RB is allocated based on transmission packet information, CQI, and QoS, and also determines a priority related to the allocation target terminal station. The priority is a priority order of each subband targeted for an allocation target terminal station. The priority of the subband suitable for the terminal station to be allocated can be determined by the priority. The allocation target terminal determination unit 18 grasps the propagation path characteristics of each subband from the CQI related to the allocation target terminal station, and assigns priorities to the subbands. Furthermore, the allocation target terminal determination unit 18 calculates the allowable delay time or required throughput of transmission data based on the transmission packet information and QoS related to the allocation target terminal station, and reflects the calculation result on the subband priority. Let The allocation target terminal determination unit 18 notifies the RB allocation unit 15 of the terminal number and priority of the allocation target terminal station.

  The RB assigning unit 15 uses the execution units 11 to 14 of each allocation type based on the notified priority to the assignment target terminal station notified of the terminal number and the like from the assignment target terminal determining unit 18. The RB to be allocated is determined so that the utilization efficiency is increased. At this time, if the RB allocation result by a certain allocation type satisfies the constraints of the other allocation type and there is a possibility that the RB utilization efficiency may be improved, the RB allocation information of the original allocation type is stored in the other allocation type. Change to

  For example, when the RB allocation information in RBG units according to allocation type 0 satisfies the restriction of allocation type 2 (localized) allocated in RB units and there is a possibility that the RB usage efficiency may increase, RB allocation in allocation type 0 Change information to allocation type 2 (localized). Alternatively, if the RB allocation information in units of RBGs according to allocation type 0 satisfies the constraints of allocation type 1 allocated in units of RBs and there is a possibility that RB usage efficiency may increase, the allocation type 0 RB allocation information is allocated. Change to type 1. Note that there is a possibility that the RB usage efficiency may increase because RB allocation by allocation type 0 is performed in units of RBGs. For example, in the transmission packet information, there is no transmission packet that can fully use the RBG, and the RBG This is a case where a transmission packet can be transmitted with only some of the RBs.

  For this reason, in RB allocation of RBG units by allocation type 0, it is desirable to select an RBG so as to satisfy the restrictions of allocation type 1 or allocation type 2 (localized) if possible. Furthermore, it is desirable to select the RBG so as to satisfy the restriction of allocation type 2 (localized) that allows the terminal station to easily maintain a continuous frequency band with a good radio environment. Hereinafter, the allocation type 0 execution unit 11 according to this embodiment based on this idea will be described in detail.

  FIG. 3 is a block diagram showing a configuration of allocation type 0 execution unit 11 shown in FIG. In FIG. 3, the allocation type 0 execution unit 11 includes a priority determination unit 20, a first RBG condition determination unit 21, a second RBG condition determination unit 22, a third RBG condition determination unit 23, and a reserved RBG information storage unit 24. And a control unit 25.

  The RB allocation instruction and priority are input from the RB allocation unit 15 to the allocation type 0 execution unit 11. The RB allocation instruction is for instructing RB allocation to a terminal station to be allocated (terminal number is u, hereinafter referred to as terminal station u), and has a terminal number “u”. The priority is a priority order of each subband for the terminal station u. The priority of the subband suitable for the terminal station u can be known from the priority.

  Also, the free RB information is input from the free RB management unit 16 to the allocation type 0 execution unit 11. The free RB information has an RB number of an unallocated RB (free RB). The free RB information indicates which RB is free.

  FIG. 4 is a flowchart showing a flow of RBG selection processing of the allocation type 0 execution unit 11 according to the present embodiment. The operation of the allocation type 0 execution unit 11 shown in FIG. 3 will be described below with reference to FIG.

  First, when an RB allocation instruction is input from the RB allocation unit 15, the control unit 25 instructs the priority determination unit 20 to select an RBG selection target subband.

  Next, in step S1, the priority determination unit 20 selects one RBG selection target subband in order from the highest priority according to the priority indicated by the priority.

  Next, in step S2, the priority determination unit 20 refers to the free RB information, and checks whether all RBs belonging to the RBG are free for each RBG belonging to the RBG selection target subband selected in step S1. When all the RBs belonging to the RBG are free, the RBG can be reserved. Furthermore, the priority determination unit 20 refers to the reservation RBG information G (u) of the terminal station u, and among the reservable RBGs belonging to the RBG selection target subband, the RBG number not included in the reservation RBG information G (u) Check if there are any available RBGs. The reserved RBG information G (u) has the RBG number of the RBG reserved for the terminal station u. The reserved RBG information G (u) is stored in the reserved RBG information storage unit 24. From the reserved RBG information G (u), it is possible to grasp the RBG reserved in the terminal station u.

  As a result of the investigation, if there is a reservable RBG that is not included in the reservation RBG information G (u) among the RBGs belonging to the RBG selection target subband (step S2, YES), the process proceeds to step S3. If there is no such reservable RBG (NO in step S2), the process proceeds to step S13. In step S13, the priority determination unit 20 determines whether all subbands have been checked. As a result, if all the subbands are checked, the process proceeds to step S14, and if there are any subbands that have not been checked, the process returns to step S1.

  In the description after step S3, the reservable RBG indicates a reservable RBG that is not included in the reserved RBG information G (u).

  Next, in step S3, the priority determination unit 20 determines whether there are a plurality of reservable RBGs belonging to the RBG selection target subband. As a result, if there are a plurality of reservable RBGs belonging to the RBG selection target subband, the process proceeds to step S5, and if there is only one, the process proceeds to step S4.

  In step S4, the priority determination unit 20 adds the RBG number of the reservable RBG belonging to the RBG selection target subband to the reserved RBG information G (u) of the terminal station u. As a result, the RBG number of the only reservable RBG belonging to the RBG selection target subband is added to the reserved RBG information G (u). The priority determination unit 20 notifies the control unit 25 that one RBG number has been added to the reservation RBG information G (u).

  In step S5, the priority determination unit 20 sends the RBG number group 101 including the RBG numbers of all the reservable RBGs belonging to the RBG selection target subband to each of the RBG condition determination units 21, 22, and 23, and to the control unit 25. On the other hand, it is notified that there are a plurality of reservable RBGs belonging to the RBG selection target subband. Thereby, the control unit 25 instructs the first RBG condition determining unit 21 to determine the RBG condition. When receiving an RBG condition determination instruction from the control unit 25, the first RBG condition determination unit 21 determines whether there is an RBG number that satisfies the first RBG condition for the RBG number group 101. The first RBG condition is that any RBG number already included in the reserved RBG information G (u) is a serial number. The RB groups included in the RBGs having consecutive RBG numbers are continuous on the frequency axis. The first RBG condition is a condition for satisfying the constraint of allocation type 2 (localized).

  As a result of the determination in step S5, if the first RBG condition is satisfied for the RBG number group 101 (step S6, YES), the process proceeds to step S7, and if the first RBG condition is not satisfied (step In the case of S6, NO), the process proceeds to step S8.

  In step S7, the first RBG condition determining unit 21 adds the smallest RBG number among the RBG numbers satisfying the first RBG condition in the RBG number group 101 to the reserved RBG information G (u). As a result, there is a possibility that all the RBG numbers included in the reserved RBG information G (u) are serial numbers, and it can be expected that the reservation type can be changed to allocation type 2 (localized). The first RBG condition determining unit 21 notifies the control unit 25 that one RBG number has been added to the reserved RBG information G (u).

  In step S8, the first RBG condition determining unit 21 notifies the control unit 25 that the first RBG condition is not satisfied. Thereby, the control unit 25 instructs the second RBG condition determination unit 22 to determine the RBG condition. When receiving the RBG condition determination instruction from the control unit 25, the second RBG condition determination unit 22 determines whether there is an RBG number that satisfies the second RBG condition for the RBG number group 101. The second RBG condition is that when all the RBG numbers included in the reserved RBG information G (u) belong to the same subset, they belong to the subset. The second RBG condition is a condition for satisfying the constraint of allocation type 1. The subset number of the subset to which the RBG number belongs is the remainder when the RBG number is divided by the RBG size. In this embodiment, since the RBG size is 3, the remainder (0, 1 or 2) when the RBG number is divided by 3 is the subset number of the subset to which the RBG number belongs (see FIG. 9).

  As a result of the determination in step S8, if the second RBG condition is satisfied for the RBG number group 101 (YES in step S9), the process proceeds to step S10, and if the second RBG condition is not satisfied (step In the case of S9, NO), the process proceeds to step S11.

  In step S10, the second RBG condition determining unit 22 adds the smallest RBG number among the RBG numbers satisfying the second RBG condition in the RBG number group 101 to the reserved RBG information G (u). As a result, there is a possibility that all the RBG numbers included in the reserved RBG information G (u) belong to the same subset, and it can be expected that the allocation type 1 can be changed. The second RBG condition determination unit 22 notifies the control unit 25 that one RBG number has been added to the reservation RBG information G (u).

  In step S11, the second RBG condition determination unit 22 notifies the control unit 25 that the second RBG condition is not satisfied. Thereby, the control unit 25 instructs the third RBG condition determining unit 23 to determine the RBG condition. When the third RBG condition determination unit 23 receives an RBG condition determination instruction from the control unit 25, the third RBG condition determination unit 23 adds an RBG number satisfying the third RBG condition in the RBG number group 101 to the reserved RBG information G (u). . The third RBG condition is that the RBG number is the smallest. That is, the third RBG condition determining unit 23 adds the smallest RBG number in the RBG number group 101 to the reserved RBG information G (u). The third RBG condition determining unit 23 notifies the control unit 25 that one RBG number has been added to the reserved RBG information G (u).

  Next, in step S12, the control unit 25 determines the end of the RBG reservation related to the terminal station u. The determination condition is that either all transmission packets addressed to the terminal station u can be transmitted or that a predetermined RB addition end condition is satisfied. As a result of the determination, if the determination condition is satisfied, the process proceeds to step S14. If the determination condition is not satisfied, the process returns to step S2.

  Next, in step S <b> 14, the control unit 25 reads the reserved RBG information G (u) from the reserved RBG information storage unit 24 and outputs it to the RB allocation unit 15.

  The above is the description of the allocation type 0 execution unit 11 according to the present embodiment.

  According to the present embodiment, when there are a plurality of reservable RBGs belonging to the RBG selection target subband in the RB allocation in RBG units by allocation type 0, there is a possibility that the restriction of allocation type 1 or allocation type 2 (localized) is satisfied. In order to remain, a reservationable RBG belonging to the RBG selection target subband is selected. As a result, it can be expected that the allocation type can be changed to allocation type 1 or allocation type 2 (localized), in which RB utilization efficiency may be higher than allocation type 0. Furthermore, priority is given to the possibility of satisfying the constraint of allocation type 2 (localized), and by selecting a reservable RBG belonging to the RBG selection target subband, a continuous radio environment is favorable for the terminal station. The possibility of changing to allocation type 2 (localized) that easily maintains the frequency band can be left more.

  It should be noted that it is difficult to accurately select a reservable RBG suitable for frequency characteristics for the terminal station u from among a plurality of reservable RBGs belonging to the RBG selection target subband. This is because the accuracy of the frequency characteristic represented by the CQI is limited to the subband unit, so that the frequency characteristic of the RBG unit finer than the subband unit cannot be easily determined. In view of such circumstances, in the present embodiment, allocation type 1 or allocation type 2 (localized), in which RB usage efficiency may be higher than allocation type 0, in order to prevent a decrease in RB usage efficiency due to allocation type 0. In order to leave the possibility of the change to RBG, an attempt is made to select a reservable RBG from among a plurality of reservable RBGs belonging to the RBG selection target subband.

Returning to FIG.
Upon receiving the reservation RBG information G (u) of the terminal station u from the allocation type 0 execution unit 11, the RB allocation unit 15 receives the terminal reservation RB information J (u) related to the terminal station u based on the reservation RBG information G (u). ) Is generated. The terminal reservation RB information J (u) has the RB number of the RB reserved for the terminal station u. The terminal reservation RB information J (u) is held in the terminal reservation RB management unit 17.

In the generation of the terminal reservation RB information J (u), the RB allocating unit 15 corresponds to the number of required RBs of the terminal station u from among the reservation candidates RB included in the RBG of the RBG number included in the reservation RBG information G (u). And the RB number of the selected RB is included in the terminal reservation RB information J (u). At this time, the RB allocating unit 15 selects n RB groups (RB numbers are j ₁ , j ₂ ,..., J _n ) consecutive on the frequency axis among the reservation candidates RB on the frequency axis. Focusing on the end RB (j ₁ , j _n ), RB (j ₁ −1) is reserved in the terminal station u (that is, the RB number “j ₁ −1)” is stored in the terminal reserved RB information J (u). The RB number “j ₁ ” is added to the terminal reservation RB information J (u), and RB (j _n +1) is reserved in the terminal station u (that is, the RB number “j _n +1”). Is included in the terminal reservation RB information J (u)), the RB number “j _n ” is added to the terminal reservation RB information J (u). The RB group whose RB number is a serial number is continuous on the frequency axis. As a result, there is a possibility that a continuous RB on the frequency axis is reserved for the terminal station u, and the possibility of changing from allocation type 0 to allocation type 2 (localized) can be increased. It becomes like this.

  For example, as shown in FIG. 5A, if RBs (RB numbers 3, 4, 5, 9, and 10) reserved for the terminal station u are not continuous on the frequency axis, allocation type 0 Since it cannot be changed to allocation type 2 (localized), among RBs (RB numbers 9, 10, and 11) reserved in units of RBGs, RBs (RB number 11) that are not reserved in the terminal station u are set to other terminals. The station cannot use it. However, as shown in FIG. 5 (2), if the RBs (RB numbers 3, 4, 5, 6, and 7) reserved for the terminal station u are continuous on the frequency axis, the allocation type Since it is possible to change from 0 to allocation type 2 (localized), among RBs (RB numbers 6, 7, and 8) reserved in units of RBG, other RBs (RB number 8) that are not reserved for the terminal station u Terminal stations can be used. Thereby, it can contribute to the improvement of frequency utilization efficiency.

  Based on the generated terminal reservation RB information J (u), the RB allocating unit 15 determines whether the allocation type 0 can be changed to the allocation type 2 (localized), and if so, the allocation type 2 (localized) ) To determine the RB to be assigned to the terminal station u. The RB allocating unit 15 determines whether the allocation type 0 can be changed to the allocation type 1 when the allocation type 0 cannot be changed to the allocation type 2 (localized). RB to be allocated to the terminal station u is determined. If the RB allocation unit 15 cannot change from allocation type 0 to allocation type 1 or allocation type 2 (localized), the RB allocation unit 15 determines an RB to be allocated to the terminal station u while maintaining the allocation type 0.

  The RB allocation unit 15 updates the free RB information held by the free RB management unit 16 according to the allocation type and the terminal reservation RB information J (u). For example, in the example of FIG. 5 (1), since the allocation type cannot be changed, the allocation type 0 remains as five RBs (RB numbers 3, 4, 5, 9, 10) reserved for the terminal station u. In addition, the RB number “3,4,5,9,10,11” of a total of 6 RBs of one RB (RB number 11) that is not reserved in the terminal station u but is reserved in RBG units. Is deleted from the free RB information.

  On the other hand, in the example of FIG. 5 (2), since the allocation type can be changed to allocation type 2 (localized), five RBs (RB numbers 3 and 3) reserved for the terminal station u in allocation type 2 (localized). 4, 5, 6, 7) are deleted from the free RB information. In this case, for one RB (RB number is 8) that is not reserved in the terminal station u but is secured in RBG units by allocation type 0, the RB number “8” remains in the free RB information, and the free RB Is available as

  According to the above-described embodiment, when RB is allocated to the terminal station, first, RB is allocated to the terminal station with allocation type 0, and thereafter, allocation type 0 to allocation type 1 or allocation type 2 (localized). You can try to change. As a result, if the unnecessary RB can be released by changing to allocation type 1 or allocation type 2 (localized) for the terminal station to which an unnecessary RB has been assigned by allocation type 0, the released RB is released. Can be allocated to other terminal stations, so that the RB utilization efficiency is improved. Thereby, it becomes possible to contribute to the improvement of the frequency utilization efficiency of the mobile communication system. Furthermore, by giving priority to the change from allocation type 0 to allocation type 2 (localized), it is possible to easily maintain a continuous frequency band having a good wireless environment for the terminal station.

  Note that the radio frame control unit 4 according to the present embodiment may be realized by dedicated hardware, or is configured by a memory and a CPU (central processing unit), and functions of the radio frame control unit 4. The function may be realized by the CPU executing a program for realizing the above.

  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.

DESCRIPTION OF SYMBOLS 1 ... Radio base station apparatus, 2 ... Packet buffer, 3 ... OFDMA transmission part, 4 ... Radio frame control part, 11 ... Allocation type 0 execution part, 12 ... Allocation type 1 execution part, 13 ... Allocation type 2 (localized) execution , 14 ... Allocation type 2 (distributed) execution unit, 15 ... RB allocation unit, 16 ... Empty RB management unit, 17 ... Terminal reservation RB management unit, 18 ... Assignment target terminal determination unit, 20 ... Priority determination unit, 21 ... 1st RBG condition determination unit, 22 ... 2nd RBG condition determination unit, 23 ... 3rd RBG condition determination unit, 24 ... reserved RBG information storage unit, 25 ... control unit

Claims (8)

The radio resource allocation to the terminal station in the downlink radio frame of the orthogonal frequency division multiple access scheme is performed using any one of a plurality of radio resource allocation methods with different restrictions on how to select the radio resource to be allocated. A radio resource allocation device to perform,
When selecting the radio resources (reservation radio resource) to reserve to assign to the assignment target terminal station according to a first of said radio resource allocation method, satisfies to satisfy the constraints of the second of the radio resource allocation method First radio resource allocation method executing means for prioritizing radio resources;
When the reserved radio resource selected for the allocation target terminal station by the first radio resource allocation method executing means satisfies the restriction of the second radio resource allocation method, the reserved radio resource is used to Radio resource allocation means for allocating radio resources to the allocation target terminal station by a second radio resource allocation method ;
A radio resource allocation device comprising: The first radio resource allocation method executing means includes:
Means for selecting a radio resource according to the priority of the radio resource related to the allocation target terminal station;
From the priority of the same plurality of radio resources, means for selecting a satisfying radio resources to satisfy the constraints of the second radio resource allocation method,
The radio resource allocating device according to claim 1, comprising: The first radio resource assignment method is a method of assigning radio resources to a terminal station in a unit of a radio resource group composed of a plurality of radio resources continuous on a frequency axis.
The second radio resource allocation method allocates radio resources continuous on the frequency axis to a terminal station in units of radio resources,
Conditions for satisfying the constraints of the second radio resource allocation method is already continuously on a frequency axis selected radio resource group to the assignment target terminal station,
The radio resource allocating device according to claim 1 or 2, wherein The radio resource allocating means uses a plurality of radio resource groups continuous on the frequency axis among radio resource groups selected for the allocation target terminal station by the first radio resource allocation method executing means , The radio resource allocation apparatus according to claim 3, wherein radio resource allocation to the allocation target terminal station is performed by the second radio resource allocation method . The first radio resource assignment method is a method of assigning radio resources to a terminal station in a unit of a radio resource group composed of a plurality of radio resources continuous on a frequency axis.
The second radio resource allocation method allocates radio resources to a terminal station in units of radio resources in the same subset among a plurality of subsets in which radio resources are sequentially arranged in units of radio resource groups. Yes,
Conditions for satisfying the constraints of the second radio resource allocation method, when the already all radio resources groups selected with respect to the allocation target terminal station belonging to the same subset, is to belong to the subset ,
The radio resource allocating device according to claim 1 or 2, wherein Radio resource allocation to a terminal station in a downlink radio frame of an orthogonal frequency division multiple access scheme is performed using any one of a plurality of radio resource allocation methods with different restrictions on how to select the radio resource to be allocated A radio resource allocation device,
When selecting the radio resources (reservation radio resource) to reserve to assign to the assignment target terminal station according to a first of said radio resource allocation method, a second of said radio resource allocation method or the third the radio resource assignment method for the First radio resource allocation method executing means for prioritizing radio resources satisfying the conditions for satisfying the constraints;
When the reserved radio resource selected for the allocation target terminal station by the first radio resource allocation method executing means satisfies the restriction of the second radio resource allocation method, the reserved radio resource is used to Radio resources are allocated to the allocation target terminal station by a second radio resource allocation method, and the reserved radio resource selected for the allocation target terminal station by the first radio resource allocation method executing unit is the third radio resource allocation method. Radio resource allocating means for allocating radio resources to the allocation target terminal station by the third radio resource allocating method using the reserved radio resource when the restriction of the radio resource allocating method is satisfied ,
The first radio resource assignment method is a method of assigning radio resources to a terminal station in a unit of a radio resource group composed of a plurality of radio resources continuous on a frequency axis.
The second radio resource allocation method allocates radio resources continuous on the frequency axis to a terminal station in units of radio resources,
The condition for satisfying the constraints of the second radio resource allocation method is that already consecutive selected radio resource group and frequency axis with respect to the assignment target terminal station,
The third radio resource allocation method allocates radio resources to a terminal station in units of radio resources in the same subset among a plurality of subsets in which radio resources are sequentially arranged in units of radio resource groups. Yes,
Conditions for satisfying the constraints of the third radio resource allocation method, when the already all radio resources groups selected with respect to the allocation target terminal station belonging to the same subset is that belonging to the subset ,
The first wireless resource allocation method execution means, priority conditions for satisfying the constraints of the second radio resource allocation method,
A radio resource allocation device. In any one of a plurality of radio resource allocation methods, the radio resource allocation to the terminal station in the downlink radio frame of the orthogonal frequency division multiple access scheme is different from each other in the restriction on how to select the radio resource to be allocated. A radio resource allocation method to perform,
When selecting the radio resources (reservation radio resource) to reserve to assign to the assignment target terminal station according to a first of said radio resource allocation method, satisfies to satisfy the constraints of the second of the radio resource allocation method A first radio resource allocation method execution step that prioritizes radio resources ;
When the reserved radio resource selected for the allocation target terminal station by the first radio resource allocation method executing step satisfies the restriction of the second radio resource allocation method, the reserved radio resource is used to A radio resource allocation step of allocating radio resources to the allocation target terminal station by a second radio resource allocation method ;
A radio resource allocating method comprising: The radio resource allocation to the terminal station in the downlink radio frame of the orthogonal frequency division multiple access scheme is performed using any one of a plurality of radio resource allocation methods with different restrictions on how to select the radio resource to be allocated. A computer program for performing
When selecting the radio resources (reservation radio resource) to reserve to assign to the assignment target terminal station according to a first of said radio resource allocation method, satisfies to satisfy the constraints of the second of the radio resource allocation method A first radio resource allocation method execution step that prioritizes radio resources ;
When the reserved radio resource selected for the allocation target terminal station by the first radio resource allocation method executing step satisfies the restriction of the second radio resource allocation method, the reserved radio resource is used to A radio resource allocation step of allocating radio resources to the allocation target terminal station by a second radio resource allocation method ;
A computer program for causing a computer to execute.

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