JP2013179417A - Wireless resource allocation device, wireless resource allocation method and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allocate wireless resources efficiently to a mobile station performing contention free transmission and a mobile station performing contention base transmission, when performing single carrier transmission.SOLUTION: The wireless resource allocation device includes a contention base object allocation unit 12 for allocating a part of continuous frequency resources, out of the frequency resources available for single carrier transmission, to the contention base transmission sequentially from the end, and a contention free object allocation unit 11 for allocating frequency resources to the contention free transmission. The contention free object allocation unit 11 allocates some of the frequency resources, remaining after allocating the frequency resources to the contention base transmission, to the contention free transmission.

Description

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

  Conventionally, "LTE (Long Term Evolution)" is known as one of the standards studied by 3GPP (Third Generation Partnership Project). In LTE, SC-FDMA (Single-Carrier Frequency Division Multiple Access) which is single carrier transmission is used as an uplink (from a mobile station to a base station) communication method. SC-FDMA is single carrier transmission, so it has high power utilization efficiency and is suitable for uplink transmission. Furthermore, scheduling gain can be obtained by scheduling radio resources to be allocated to mobile stations in the same cell in the frequency direction.

  In LTE, a base station schedules radio resources to be used by each mobile station, both in the uplink and in the downlink (from the base station to the mobile station). For example, in uplink scheduling, the mobile station first transmits a scheduling request (SR) to the base station. After the base station performs uplink transmission path estimation, as a result, the base station notifies a scheduling grant to the mobile station using the downlink control channel. The scheduling grant includes information such as a transmission mode, a resource block (RB: Resource Block) that is a radio resource allocated to the mobile station, and MCS (Modulation and Coding Scheme). Thus, since the base station centrally manages radio resources for the mobile station, radio interference between terminals belonging to the same cell does not occur, and stable communication can be performed. A transmission method in which a mobile station performs radio transmission after scheduling so that radio resources (RB) used by each mobile station do not overlap is called contention-free transmission.

  In 3GPP, LTE-Advanced, an advanced form of LTE, is being studied. In LTE-Advanced, contention-based uplink transmission has been proposed (see Non-Patent Document 1, for example). In contention-based transmission, scheduling of radio resources used by a mobile station is not performed. For this reason, according to the contention-based transmission, it is possible to expect a reduction in transmission delay time for scheduling and a reduction in overhead by not having to separately transmit the scheduling result to each mobile station through the downlink control channel. However, in contention-based transmission, a plurality of mobile stations may use the same radio resource (RB), which may cause an event in which a packet collision occurs and a reception success rate decreases. When packet collision occurs, use a communication method that is resistant to radio wave interference between users, such as Interleave Division Multiple Access (IDMA). The influence can be reduced.

  In the prior art described in Non-Patent Document 1, in an LTE-Advanced wireless communication system, a mobile station that performs contention-free transmission for scheduling radio resources used by a mobile station, and a mobile station that performs contention-based transmission RBs that are not used by mobile stations that perform contention-free transmission are used for contention-based transmission. By assigning unused RBs for contention-free transmission to contention-based transmission, it is possible to perform contention-based transmission without reducing the scheduling gain of a mobile station that performs contention-free transmission.

“Contention based uplink transmissions”, 3GPP TSG RAN WG2 meeting # 66bis, R2-093812.

  However, the conventional technique described in Non-Patent Document 1 described above has a disadvantage for single carrier transmission. In single carrier transmission, it is necessary to transmit signals using continuous RBs. However, if unused RBs are fragmented in contention-free transmission, continuous RBs are transmitted to mobile stations performing contention-based transmission. There is a risk that the required number of cannot be secured.

  The present invention has been made in consideration of such circumstances, and when performing single carrier transmission, radio resources are efficiently used for a mobile station that performs contention-free transmission and a mobile station that performs contention-based transmission. It is an object to provide a radio resource assignment device, a radio resource assignment method, and a computer program that can be assigned to a computer program.

  In order to solve the above problems, a radio resource allocation device according to the present invention is a radio in which a mobile station that performs contention-based transmission and a mobile station that performs contention-free transmission simultaneously perform single carrier transmission to a base station. A radio resource allocation apparatus in a communication system, a first allocation unit that allocates a part of continuous frequency resources among frequency resources that can be used for single carrier transmission to contention-based transmission in order from the end, and contention-free transmission A second allocation unit that allocates frequency resources to the contention-free transmission from among the remaining frequency resources excluding the frequency resources allocated to the contention-based transmission. It is characterized by that.

  The radio resource allocating device according to the present invention is characterized in that the first allocator allocates contention-based transmission from an end frequency band among frequency resources that can be used for single carrier transmission.

  In the radio resource allocating device according to the present invention, the first allocating unit changes a frequency resource amount allocated to contention-based transmission according to radio resource usage of a mobile station that performs contention-free transmission. To do.

  The radio resource allocation device according to the present invention includes a control unit that controls the first allocation unit and the second allocation unit, wherein the second allocation unit targets all frequency resources that can be used for single carrier transmission. The first allocation of frequency resources to the mobile station performing contention-free transmission is performed, and the control unit determines that “frequency resources continuous on the frequency axis” are unallocated in the allocation result of the first phase. If the one with the maximum frequency band is sufficient for contention-based transmission, frequency resources that are continuous on the frequency axis are allocated to contention-based transmission, which is insufficient for contention-based transmission. In some cases, the first assigning unit assigns the contention-based transmission, and the first assigning unit To perform allocation for the contention-free transmissions on the assigned portion is based on the allocation result of the first allocation unit, characterized in that.

  In the radio resource allocation device according to the present invention, the first allocation unit allocates frequency resources exclusively between adjacent sectors.

  In the radio resource allocation device according to the present invention, the first allocation unit allocates the same frequency resource between adjacent sectors.

  In the radio resource allocation device according to the present invention, the first allocation unit sets the allocation timing once in a plurality of subframes.

  The radio resource allocation method according to the present invention is a radio resource allocation method in a radio communication system in which a mobile station that performs contention-based transmission and a mobile station that performs contention-free transmission simultaneously perform single carrier transmission to a base station. Then, among the frequency resources that can be used for single carrier transmission, a first allocation step that allocates a part of continuous frequency resources to contention-based transmission in order from the end, and a second allocation that allocates frequency resources to contention-free transmission And in the second allocating step, allocation is made to contention-free transmission from the remaining frequency resources excluding frequency resources allocated to contention-based transmission.

A computer program according to the present invention performs radio resource allocation processing in a radio communication system in which a mobile station that performs contention-based transmission and a mobile station that performs contention-free transmission simultaneously perform single carrier transmission to a base station. A first allocation step in which a part of continuous frequency resources among frequency resources that can be used for single carrier transmission is allocated to contention-based transmission in order from the end, and frequency resources are allocated to contention-free transmission. A computer program for causing a computer to execute a second allocation step, wherein the content of the remaining frequency resources excluding the frequency resources allocated for contention-based transmission in the second allocation step is stored. Deployment free allocated to the transmission, characterized in that.
As a result, the above-described radio resource allocation device can be realized using a computer.

  According to the present invention, when performing single carrier transmission, it is possible to efficiently allocate radio resources to a mobile station that performs contention-free transmission and a mobile station that performs contention-based transmission.

It is a schematic block diagram of the radio | wireless communications system which concerns on one Embodiment of this invention. It is a block diagram of the radio | wireless resource allocation apparatus 10 which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating Example 1 of the radio | wireless resource allocation method which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating Example 2 of the radio | wireless resource allocation method which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a radio communication system according to an embodiment of the present invention. In FIG. 1, the wireless communication system includes a base station 1 and mobile stations 2a, 2b, 2c, and 2d. In this wireless communication system, single carrier transmission is performed in the uplink. Also, mobile stations that perform contention-free transmission and mobile stations that perform contention-based transmission can coexist in the cell 100 of the base station 1.

  Here, for convenience of explanation, it is assumed that the mobile stations 2a and 2b perform contention-free transmission and the mobile stations 2c and 2d perform contention-based transmission. The mobile stations 2a and 2b that perform contention-free transmission comply with LTE, and SC-FDMA is used for the uplink communication scheme. On the other hand, the mobile stations 2c and 2d that perform contention-based transmission use IDMA for the uplink communication scheme. Hereinafter, a mobile station that performs contention-free transmission is referred to as an LTE terminal, and a mobile station that performs contention-based transmission is referred to as an IDMA terminal.

  The base station 1 detects from the category information of each mobile station 2a, 2b, 2c, 2d that LTE terminals 2a, 2b and IDMA terminals 2c, 2d exist under its own station 1.

  FIG. 2 is a configuration diagram of the radio resource allocation device 10 according to the present embodiment. The radio resource allocation device 10 is provided in the base station 1. In FIG. 2, the radio resource allocation device 10 includes a contention free target allocation unit 11, a contention base target allocation unit 12, and a control unit 13. The contention-free target assigning unit 11 assigns radio resources to LTE terminals. The contention base target assignment unit 12 assigns radio resources to IDMA terminals. The control unit 13 controls the contention-free target allocation unit 11 and the contention-based target allocation unit 12.

  Hereinafter, a radio resource allocation method performed by the radio resource allocation apparatus 10 according to the present embodiment will be described by giving examples.

  FIG. 3 is a conceptual diagram for explaining Example 1 of the radio resource allocation method according to the present embodiment. FIG. 3 shows a configuration example of uplink radio resources in the radio communication system of FIG. In FIG. 3, the radio resource is composed of RBs having a certain frequency resource and a certain time resource. The total RB number N is determined by the system bandwidth.

In the configuration example of FIG. 3, RBs corresponding to fixed frequency bands at both ends of all frequency bands of the system bandwidth are used for the uplink control channel (PUCCH). The number of RBs used for PUCCH is “N _PUCCH ÷ 2” at one end of the entire frequency band, and a total of N _{PUCCH at} both ends. Therefore, the number of RBs that can be used for the uplink common channel is “N−N _PUCCH ”.

In the first embodiment, N _CB-PUSCH RBs are reserved as RBs for allocating to IDMA terminals in order from the frequency band at the end of all frequency bands of the uplink common channel. The RB for allocation to this IDMA terminal may be secured from the frequency band at either end of the entire frequency band of the uplink common channel.

As a result, the remaining “N−N _PUCCH− N _CB-PUSCH ” RBs are allocated to the LTE terminal, excluding the allocation RBs, in the entire frequency band of the uplink common channel. . FIG. 3 shows an example of RB allocation. In FIG. 3, N _CB-PUSCH RBs are assigned to IDMA terminals 2c and 2d in order from the frequency band at the end of the entire frequency band of the uplink common channel (uplink common channel use band). . These N _CB-PUSCH RBs can be used by the IDMA terminals 2c and 2d without scheduling. For the LTE terminals 2a and 2b, the remaining "N-N _PUCCH- N _CB " of the entire frequency band of the uplink common channel (uplink common channel use band) excluding the RB for allocation to the IDMA terminal. _-PUSCH "RBs are scheduled and allocated.

The allocation information of N _CB-PUSCH RBs for allocation to IDMA terminals may be broadcast as system information, or notified to IDMA terminals using a contention-based transmission message (for example, scheduling grant). May be.

The number N _CB-PUSCH of RBs assigned to IDMA terminals may be constant or variable. For example, N _CB-PUSCH may be changed according to the traffic volume of the LTE terminal. Specifically, N _CB-PUSCH is increased when the RB usage of LTE terminals (the degree of RBs allocated to LTE terminals among all RBs) is lower than a predetermined threshold. On the other hand, when the RB usage of the LTE terminal is higher than the threshold, N _CB-PUSCH is decreased. Thereby, the throughput of the IDMA terminal can be improved without reducing the throughput of the LTE terminal.

  The second embodiment is a modification of the first embodiment. In the second embodiment, RBs assigned to IDMA terminals are exclusively assigned between adjacent sectors. FIG. 4 is a conceptual diagram for explaining Example 2 of the radio resource allocation method according to the present embodiment. In the example of FIG. 4, the IDMA terminal 2c is in sector A, the IDMA terminal 2d is in sector B, and sector A and sector B are adjacent. In FIG. 4, a certain number of RBs are allocated to the IDMA terminal 2c in sector A in order from the frequency band at one end of the uplink common channel use band. Then, a certain number of RBs are assigned to the IDMA terminal 2d in sector B in order from the frequency band at the other end of the uplink common channel use band. Thereby, the RB assigned to the IDMA terminal 2c in sector A and the RB assigned to the IDMA terminal 2d in sector B do not overlap. For the LTE terminal, scheduling is allocated to the remaining RBs excluding RBs for allocation to the IDMA terminals 2c and 2d in the uplink common channel use band.

  According to the second embodiment, the radio wave interference received by the LTE terminal becomes close to white noise, and the reception characteristics of the LTE terminal can be improved.

  The third embodiment is a modification of the first embodiment. In the third embodiment, the same RB is allocated to IDMA terminals between adjacent sectors. For example, in FIG. 3, IDMA terminal 2c is in sector A, IDMA terminal 2d is in sector B, and sector A and sector B are adjacent. A certain number of RBs are assigned to the IDMA terminals 2c and 2d in order from the frequency band at the end of the uplink common channel use band. As a result, the RB assigned to the IDMA terminal 2c in sector A is the same as the RB assigned to the IDMA terminal 2d in sector B. For the LTE terminal, scheduling is allocated to the remaining RBs excluding RBs for allocation to the IDMA terminals 2c and 2d in the uplink common channel use band.

  According to the third embodiment, since the IDMA terminal has only interference from the IDMA terminal, interference from other sectors can be removed and reception characteristics of the IDMA terminal can be improved.

  In the fourth embodiment, scheduling for LTE terminals is first performed for the uplink common channel use band. As a result of this scheduling, among the RB groups that are unallocated in the uplink common channel use band and are composed of a plurality of RBs that are continuous on the frequency axis, the RB group with the maximum number of RBs (unallocated maximum RB group) ) Check the RB number N '.

Next, the number of RBs N _REQ required for transmission by the IDMA terminal is compared with the number of RBs N ′. As a result of this comparison, if “N ′ ≧ N _REQ ”, the unallocated maximum RB group is allocated to the IDMA terminal.

On the other hand, if “N ′ <N _REQ ” as a result of the comparison, the radio resource allocation method according to the first, second, or third embodiment described above is performed. That is, N _CB-PUSCH RBs are allocated to the IDMA terminal in order from the frequency band at the end of the uplink common channel use band. For LTE terminals, scheduling is performed for the remaining “N-N _PUCCH- N _CB-PUSCH ” RBs, excluding RBs allocated to IDMA terminals, in the uplink common channel usage band. assign.

  In the fifth embodiment, first, by the radio resource allocation method of the first, second, or third embodiment, an RB group (referred to as a reserved RB group) composed of a plurality of RBs consecutive on the allocation frequency axis is secured in the IDMA terminal. To do. Next, scheduling is performed and assigned to the LTE terminal with respect to the remaining RBs excluding the RBs for allocation to the IDMA terminal in the uplink common channel use band. Next, for the IDMA terminal, a reserved RB group and an RB group that is unallocated as a result of scheduling among the RBs allocated to the LTE terminal and that is continuous on the frequency axis (Referred to as an unassigned RB group).

  The IDMA terminal performs uplink transmission using one of the allocated RB groups. As a method for selecting this RB group, for example, an IDMA terminal having a large traffic and a large number of required RBs uses a reserved RB group, and an IDMA terminal having a small traffic and a small number of required RBs uses an unassigned RB group.

  The sixth embodiment is a modification of the first to fifth embodiments. In the sixth embodiment, the timing for assigning RBs to IDMA terminals is once in N subframes. However, N is an integer of 2 or more. That is, for an IDMA terminal, RBs are assigned only once to N subframes instead of being assigned to each subframe. For example, when 10 RBs are assigned per 10 subframes, 1 RB is not assigned to each subframe, but 2 RBs are assigned only once every 2 subframes. As a result, the number of RBs allocated in one subframe can be increased, and an effect of improving the transmission characteristics of the IDMA terminal can be expected. The sixth embodiment is effective when a transmission delay is allowed.

  An IDMA terminal can also be applied to an ABS (Almost Blank Subframe) that is applied in an environment where a macro station and a pico station exist. Since the signal spectral density of the IDMA terminal is low, radio wave interference given to the terminal of the pico station can be kept low.

  The seventh embodiment is a modification of the first to sixth embodiments. In the seventh embodiment, when there are a plurality of “RB groups composed of a plurality of RBs continuous on the frequency axis” that can be used by an IDMA terminal, a plurality of RB groups are hopped and used. For example, RBs separated on the frequency axis are hopped and used in time slot units. As a result, the packet error rate can be reduced by the frequency diversity gain. Alternatively, RB groups separated on the frequency axis are hopped and used in subframe units. As a result, diversity gain between retransmission packets can be obtained, and the number of retransmissions can be reduced.

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.
Further, a program for realizing the function of the radio resource allocation device 10 shown in FIG. 2 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. The radio resource allocation process may be performed. Here, the “computer system” may include an OS and hardware such as peripheral devices.
“Computer-readable recording medium” refers to a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), and a built-in computer system. A storage device such as a hard disk.

Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... Base station, 2a, 2b, 2c, 2d ... Mobile station, 10 ... Radio | wireless resource allocation apparatus, 11 ... Contention free object allocation part (2nd allocation part), 12 ... Contention base object allocation part (1st Allocation unit), 13 ... control unit

Claims (9)

A radio resource allocation apparatus in a radio communication system in which a mobile station that performs contention-based transmission and a mobile station that performs contention-free transmission simultaneously perform single carrier transmission to a base station,
A first allocation unit that allocates a part of continuous frequency resources among the frequency resources that can be used for single carrier transmission to contention-based transmission in order from the end;
A second allocation unit that allocates frequency resources for contention-free transmission,
The second allocation unit allocates contention-free transmissions from the remaining frequency resources excluding frequency resources allocated to contention-based transmissions.
A radio resource allocation device.   The radio resource allocation device according to claim 1, wherein the first allocation unit allocates contention-based transmission from an end frequency band among frequency resources that can be used for single carrier transmission.   3. The radio according to claim 1, wherein the first allocation unit changes a frequency resource amount allocated to contention-based transmission according to a radio resource usage of a mobile station performing contention-free transmission. Resource allocation device. A control unit for controlling the first allocation unit and the second allocation unit;
The second allocating unit performs the first stage allocation of frequency resources to mobile stations performing contention-free transmission for all frequency resources that can be used for single carrier transmission,
The control unit has the highest frequency band among the “frequency resources continuous on the frequency axis” that is unallocated in the allocation result of the first stage,
When contention-based transmission is sufficient, frequency resources that are continuous on the frequency axis are allocated to contention-based transmission.
If the contention-based transmission is insufficient, the first assignment unit is assigned to the contention-based transmission, and the second assignment unit is based on the assignment result of the first assignment unit. To assign the contention-free transmission
The radio resource allocation apparatus according to claim 1, wherein the radio resource allocation apparatus is a radio resource allocation apparatus.   The radio resource allocation apparatus according to any one of claims 1 to 4, wherein the first allocation unit allocates frequency resources exclusively between adjacent sectors.   5. The radio resource allocation device according to claim 1, wherein the first allocation unit allocates the same frequency resource between adjacent sectors. 6.   The radio resource allocation apparatus according to any one of claims 1 to 6, wherein the first allocation unit sets the timing of allocation once in a plurality of subframes. A radio resource allocation method in a radio communication system in which a mobile station performing contention-based transmission and a mobile station performing contention-free transmission simultaneously perform single carrier transmission to a base station,
A first allocation step of allocating a part of continuous frequency resources among the frequency resources that can be used for single carrier transmission to contention-based transmission in order from the end;
A second allocation step of allocating frequency resources for contention-free transmission,
In the second allocation step, contention-free transmission is allocated from the remaining frequency resources excluding frequency resources allocated to contention-based transmission.
A radio resource allocation method characterized by the above. A computer program for performing radio resource allocation processing in a radio communication system in which a mobile station that performs contention-based transmission and a mobile station that performs contention-free transmission simultaneously performs single carrier transmission to a base station,
A first allocation step of allocating a part of continuous frequency resources among the frequency resources that can be used for single carrier transmission to contention-based transmission in order from the end;
A computer program for causing a computer to execute a second allocation step of allocating frequency resources for contention-free transmission;
In the second allocation step, contention-free transmission is allocated from the remaining frequency resources excluding frequency resources allocated to contention-based transmission.
A computer program characterized by the above.

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