JP4848381B2 - RADIO RESOURCE ALLOCATION DEVICE, RADIO RESOURCE ALLOCATION METHOD, AND COMPUTER PROGRAM - Google Patents

Description

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

  In recent years, standards related to the third generation (3G) cellular system successor system (next generation cellular system) have been studied. The standardization organization of The next-generation cellular system uses an Orthogonal Frequency Division Multiple Access (OFDMA) system as a multiple access system.

  In a radio system using the OFDMA scheme (hereinafter referred to as “OFDMA system”), a plurality of subcarriers within a usable frequency band can be allocated to a mobile terminal. Further, the allocation content can be changed in the time direction. Therefore, in general, in an OFDMA system, flexible radio resource allocation is possible using two-dimensional radio resources on the frequency axis and the time axis. Also, in radio wave propagation environments with frequency selective fading, the quality (SINR: Signal to Interference and Noise Ratio) differs depending on the subcarrier. Can be improved. In addition, when there are a plurality of mobile terminals, if the best subcarrier varies depending on the mobile terminal, good performance can be obtained for each mobile terminal, and excellent performance can be obtained in the entire system due to the multiuser diversity effect. In code division multiple access (CDMA), which is used by many 3G cellular systems, all mobile terminals share all of the available frequency band, so only the multi-user diversity effect in the time axis direction can be obtained. However, in the OFDMA system, a multiuser diversity effect can be obtained not only in the time axis direction but also in the frequency axis direction. In general, a method of assigning subcarriers suitable for each mobile terminal using frequency selective fading is called frequency scheduling or subband scheduling.

  In the conventional techniques described in Non-Patent Documents 1 and 2, as shown in FIG. 4, all subcarriers (for example, 1024 subcarriers in a bandwidth of 10 MHz) are divided into a plurality of subcarrier groups (for example, one subcarrier group). Is composed of 16 subcarriers) and defines a resource block composed of one subcarrier group and a radio frame in the time axis direction (for example, the frame length is about 1 millisecond). The resource block is a radio resource represented by frequency × time. In the frequency axis direction, all subcarriers are divided into units called subbands (for example, one subband is made up of 128 subcarriers), and line quality information is acquired in units of subbands. In the cellular systems targeted in Non-Patent Documents 1 and 2, when performing subband scheduling, a subcarrier group (that is, a subband) with good channel quality is selected, and one or more resource blocks in the subband are selected. Is assigned to the mobile terminal.

  In a centralized wireless access system such as the cellular system targeted in Non-Patent Documents 1 and 2, the WiMAX system standardized by IEEE 802.16, and the Evolved UTRA system being standardized by 3GPP, A radio resource management function called a scheduler provided in the station implements subband scheduling. For this reason, the base station needs to acquire channel quality information (eg, SINR: Signal to Interference and Noise Ratio) of each subband by measurement or the like. In the downlink (the channel in the direction from the base station to the mobile terminal), the base station broadcasts the pilot channel (Pilot channel) embedded in each resource block to all mobile terminals, so that each mobile terminal The channel quality of the block can be estimated and the channel quality information can be notified to the base station. As a result, the base station can acquire line quality information for all the used frequency bands. Note that the cellular systems targeted in Non-Patent Documents 1 and 2 notify the line quality information in units of subbands.

On the other hand, in the uplink (the line in the direction from the mobile terminal to the base station), the mobile terminal transmits only the pilot channel included in the resource block allocated from the base station. Only the line quality information about can be acquired. In order to solve this problem, in the cellular systems targeted in Non-Patent Documents 1 and 2, a specific subband (hereinafter referred to as “specific subband”) is defined, and the specific subband is hopped for each radio frame. By measuring the pilot channel transmitted from a specific subband,
Line quality information for each subband is acquired.

  In addition, a technique for hopping subbands other than a specific subband within the entire use frequency band (that is, changing a subcarrier to be used for each radio frame) (in Non-Patent Documents 1 and 2, global hopping (GH)) There is also known a technique called local hopping (LH) in which hopping is performed only within a subband rather than hopping over the entire available frequency band as in global hopping.

Further, as a technique related to frequency scheduling, in the conventional technique described in Patent Document 1, an open loop is used for a high-speed mobile terminal, and a closed loop is used for a low-speed mobile terminal. Yes. This reduces the negative effects of feedback delay between the mobile terminal and the base station for high-speed mobile terminals, while using feedback between the closed-loop mobile terminal and the base station for low-speed mobile terminals. More accurate frequency scheduling.
3GPP2 C.S0084-001-0 v2.0 “Physical Layer for Ultra Mobile Broadband (UMB) Air Interface Specification” 3GPP2 C.S0084-002-0 v2.0 “Medium Access Control Layer for Ultra Mobile Broadband (UMB) Air Interface Specification” C30-20070212-033R2, “Update on hopping and scrambling sequences” JP 2006-60814 A

  However, in the above-described conventional cellular system, the hopping mode used for each radio frame can be set to global hopping or local hopping, but the uplink hopping mode is uniquely determined by the parameters of the radio channel structure used in the downlink. It will be decided. Since the hopping performed in the uplink and the radio channel structure used in the downlink are inherently independent, it can be said that the conventional cellular system is not appropriately operated.

  In addition, a specific subband is used to transmit various control channels including a pilot channel. If a specific subband is used in each radio frame in order to obtain channel quality information for each subband, data traffic is reduced. Radio resources to be transmitted are tight, and data traffic accommodation efficiency is reduced. However, if a specific subband is transmitted intermittently instead of every radio frame in order to increase data traffic accommodation efficiency, it takes time to acquire line quality information of all subbands, and the line quality information itself is old. As a result, the reliability of the line quality information decreases, and the significance of acquiring the line quality information for each subpound using a specific subband is diminished.

  The present invention has been made in consideration of such circumstances, and its purpose is to provide radio resources for global hopping and local hopping (for global hopping and local hopping in the uplink of a radio access system using the OFDMA scheme). (All resource blocks in a radio frame for hopping) are adaptively allocated, and line quality information for each subband is acquired and subband scheduling is performed without transmitting a specific subband for each radio frame. An object of the present invention is to provide a possible radio resource allocation device, radio resource allocation method, and computer program.

  In order to solve the above problems, a radio resource allocation apparatus according to the present invention is a radio resource allocation apparatus in a radio access system of an orthogonal frequency division multiple access scheme, and traffic characteristics for evaluating characteristics of new traffic generated in a mobile terminal. Evaluation means, and radio resource allocation determination means for determining whether to allocate the new traffic to a global hopping radio resource or a local hopping radio resource, wherein the radio resource allocation determination means is based on the evaluation result In the case where the new traffic should be allocated to the global hopping radio resource, and the new traffic should not be allocated to the global hopping radio resource, the channel quality information of all subbands has already been acquired for the mobile terminal. And In, and assigns the new traffic to a particular sub-band of the radio resource for local hopping.

  In the radio resource allocating device according to the present invention, the radio resource allocation determining unit is configured such that the channel quality of the global hopping radio resource is superior to the channel quality necessary to accommodate the packet length of the new traffic, or It is characterized in that it is determined that new traffic should be allocated to the global hopping radio resource when the moving speed of the mobile terminal related to the new traffic is faster than a threshold.

  In the radio resource allocating device according to the present invention, the radio resource allocation determining means can determine the local hopping radio resource only when there is one or more subbands that are end allocation and exceed the channel quality of the global hopping radio resource. It is characterized by assigning new traffic to a specific subband.

  In the radio resource allocating device according to the present invention, the radio resource allocation judging means is the highest channel quality among the end allocations when there is one or more subbands exceeding the channel quality of the global hopping radio resource. New traffic is allocated to subbands having

  In the radio resource allocating device according to the present invention, the radio resource allocation determining unit may allocate local traffic to the global hopping radio resource when there is no free space in the global hopping radio resource. If new traffic is allocated to the local hopping radio resource, the local hopping radio resource is allocated.

  In the radio resource allocating device according to the present invention, the radio resource allocation determining means is that effective channel quality information is obtained for all subbands, and the channel quality of unallocated subbands is used for transmission of new traffic. It is characterized in that it is determined that it can be allocated to a local hopping radio resource when both conditions of being of a required predetermined quality or higher are satisfied.

  A radio resource allocation method according to the present invention is a radio resource allocation method in an orthogonal frequency division multiple access radio access system, in which a base station evaluates characteristics of new traffic generated in a mobile terminal; Determining whether to allocate the new traffic to the global hopping radio resource based on the evaluation result, and when the base station should not allocate the new traffic to the global hopping radio resource, the mobile terminal And allocating the new traffic to a specific subband of the local hopping radio resource when the channel quality information of all subbands has already been acquired.

A computer program according to the present invention is a computer program for performing a radio resource allocation process in a radio access system of an orthogonal frequency division multiple access method, the step of evaluating characteristics of new traffic generated in a mobile terminal, and the evaluation Determining whether the new traffic should be allocated to the global hopping radio resource based on the result; and if the new traffic should not be allocated to the global hopping radio resource, the channel quality of all subbands for the mobile terminal Allocating the new traffic to a specific subband of the local hopping radio resource when the information has already been acquired, and causing the computer to execute.
As a result, the above-described radio resource allocation device can be realized using a computer.

  According to the present invention, in the uplink of a radio access system using the OFDMA system, radio resources for global hopping and local hopping are adaptively allocated, and a specific subband is transmitted without transmitting each radio frame. The effect that the line quality information for each band can be acquired is obtained. As a result, it is possible to perform subband scheduling without constraining radio resources for data traffic transmission.

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. This radio resource allocation device 1 is provided in a base station of a radio access system using the OFDMA system, and allocates radio resources in the uplink. In FIG. 1, the radio resource allocation device 1 includes an information input unit 11, a traffic characteristic evaluation unit 12, a radio resource allocation determination unit 13, and a radio resource allocation information output unit 14.

  The information input unit 11 inputs various information used for the radio resource allocation process. The input information includes information on the traffic that flows from each mobile terminal to the uplink (presence of newly generated traffic, packet length, etc.), information on the moving speed of each mobile terminal, and information on each sub-band of the uplink of each mobile terminal. Information on channel quality (for example, SINR), number of required radio resources for uplink of each mobile terminal, information on radio frames for uplink global hopping and local hopping. Information received from the mobile terminal is sent to the base station via a control channel or signaling.

  The traffic characteristic evaluation unit 12 performs characteristic evaluation of traffic newly generated in each mobile terminal (hereinafter referred to as “new traffic”). The radio resource allocation determination unit 13 determines which radio resource (global hopping radio resource or local hopping radio resource) is allocated to the new traffic. The radio resource allocation information output unit 14 outputs information on radio resources allocated to new traffic.

  Next, the operation of the radio resource assignment device 1 shown in FIG. 1 will be described.

FIG. 2 is a flowchart of radio resource allocation processing according to the present embodiment.
First, as a preparatory step, the ratio between the global hopping radio frame and the local hopping radio frame is set to an initial value when the radio access system is activated. As the initial value, for example, a past statistical value can be used.

In FIG. 2, the processing starts when the resource allocation timing comes. The resource allocation timing is set to a cycle that is an integer multiple of 1 or more of the radio frame.
In step S1, it is determined based on the traffic information of each mobile terminal whether or not new traffic exists in the buffer in the mobile terminal. As a result, when there is new traffic, the subsequent processing (steps S2 to S9) is performed on all new traffic existing in the buffer. If there is no new traffic, the wireless resource allocation process is waited until the next resource allocation timing.

  In step S2, characteristics relating to new traffic are evaluated. Specifically, evaluation is performed regarding the packet length of the new traffic and the moving speed of the mobile terminal that transmits the new traffic. For packet length, compare the channel quality of the global hopping radio resource with the channel quality standard required to accommodate the packet length, and determine whether the channel quality of the global hopping radio resource is better. judge. The line quality information is that of the mobile terminal. It is determined whether or not the moving speed is faster than a preset threshold value.

  In step S3, it is determined whether new traffic is allocated to the global hopping radio resource according to the evaluation result of step S2. In this determination, in the evaluation result of step S2, one of the conditions “condition 1: the channel quality of the global hopping radio resource is superior” or “condition 2: the moving speed is faster than the threshold” If the condition is satisfied, it is determined that the radio resource for global hopping should be allocated. If it is determined that it should be allocated to the global hopping radio resource, the process proceeds to step S4, and if not, the process proceeds to step S7.

  In step S4, it is determined whether there is a global hopping radio resource. As a result, when there is a global hopping radio resource, the process proceeds to step S5, and it is determined that the global hopping radio resource is allocated. On the other hand, if there is no global hopping radio resource, the process proceeds to step S6.

  In step S6, the new traffic is stored in the buffer until the next radio resource allocation timing.

In step S7, it is determined whether or not channel quality information of all subbands has already been acquired for the mobile terminal related to the new traffic. At this time, only the line quality information acquired within a predetermined time is valid. If the line quality information of all subbands has already been acquired, the process proceeds to step S8.
On the other hand, if the channel quality information of all the subbands has not been acquired yet, the process proceeds to step S4 to allocate global hopping radio resources. As a result, early acquisition of line quality information of all subbands is attempted.

In step S8, it is determined whether or not to allocate to a specific subband of the local hopping radio resource. In this determination, it is determined whether or not the channel quality exceeds the channel quality of the global hopping radio resource in the vacant (that is, end-assigned) subband. As a result, if there is one or more subbands that are end allocation and exceed the channel quality of the global hopping radio resource, the process proceeds to step S9, and it is determined to allocate to the subband having the highest channel quality.
On the other hand, if there is no corresponding unallocated subband as a result of step S8, the process proceeds to step S4 to allocate a global hopping radio resource. This is because there is no merit by allocating to the local hopping radio resource when there is no subband exceeding the channel quality of the global hopping radio resource in the end allocation.

Next, another embodiment of the radio resource allocation process will be described with reference to FIG. The configuration of the radio resource allocation device is the same as that in FIG.
FIG. 3 is a flowchart of radio resource allocation processing according to another embodiment of the present invention. The radio resource allocation process in FIG. 3 is obtained by changing a part of the radio resource allocation process in FIG. 2, and the steps corresponding to those in FIG.

  When it is determined in step S4 in FIG. 3 whether or not there is a global hopping radio resource, if the global hopping radio resource does not exist, the process proceeds to step S21.

In step S21, it is determined whether it can be allocated to the local hopping radio resource. In this determination, when both of the following two conditions 1 and 2 are satisfied, it is determined that the local hopping radio resource can be allocated.
(Condition 1) Effective channel quality information is obtained for all subbands. Valid line quality information is acquired within a certain time.
(Condition 2) The channel quality of the unassigned subband is equal to or higher than a predetermined quality required for transmission of the new traffic.

  As a result of step S21, if it can be allocated to the local hopping radio resource, the process proceeds to step S22, and if not, the process proceeds to step S6.

In step S22, it is determined to allocate to the local hopping radio resource. At this time, when there are one or more subbands satisfying the two conditions 1 and 2 in step S21, the following two allocation methods 1 and 2 are listed.
(Assignment method 1) A subband having the lowest channel quality is selected and assigned from subbands having a channel quality of “predetermined channel quality required for transmission of the new traffic + α” or higher. Here, α is a parameter representing the margin of channel quality.
(Assignment method 2) A subband having the highest channel quality is selected and assigned.

  As described above, in the radio resource allocation process of FIG. 3, if it is determined that the global hopping radio resource should be allocated and the global hopping radio resource is not available, if it can be allocated to the local hopping radio resource, The resource is allocated to the local hopping radio resource without waiting for the next resource allocation timing.

  According to the above-described embodiment, in the uplink of a radio access system using the OFDMA scheme, a global hopping radio frame is used without using many specific subbands for acquiring channel quality information for each subband. Thus, the effect that the channel quality information of each subband can be obtained efficiently is obtained. Thereby, it is possible to perform subband scheduling. Moreover, the effect that the global hopping radio resource and the local hopping radio resource can be used effectively is obtained.

Further, a program for realizing each step shown in FIG. 2 or FIG. 3 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed, thereby performing wireless communication. Resource allocation processing 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.

  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.

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. 5 is a flowchart of radio resource allocation processing according to an embodiment of the present invention. 7 is a flowchart of radio resource allocation processing according to another embodiment of the present invention. It is a figure which shows the structural example of the radio | wireless resource in the radio | wireless frame of an OFDMA system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Radio | wireless resource allocation apparatus, 11 ... Information input part, 12 ... Traffic characteristic evaluation part, 13 ... Radio | wireless resource allocation determination part, 14 ... Radio | wireless resource allocation information output part

Claims (8)

In a radio resource allocation apparatus in a radio access system of an orthogonal frequency division multiple access method,
A traffic characteristic evaluation means for evaluating characteristics of new traffic generated in a mobile terminal;
Radio resource allocation determining means for determining whether to allocate the new traffic to a global hopping radio resource or a local hopping radio resource,
The radio resource allocation determining means includes
Determining whether to allocate the new traffic to a global hopping radio resource based on the evaluation result;
In the case where the new traffic should not be allocated to the global hopping radio resource, when the channel quality information of all subbands has already been acquired for the mobile terminal, the new traffic is assigned to the specific subband of the local hopping radio resource. Assign traffic,
A radio resource allocation device. The radio resource allocation determination unit is configured such that when the channel quality of the global hopping radio resource is superior to the channel quality necessary to accommodate the packet length of the new traffic, or the moving speed of the mobile terminal related to the new traffic is When it is faster than the threshold, it is determined that new traffic should be allocated to the radio resource for global hopping.
The radio resource allocating device according to claim 1. The radio resource allocation determination unit allocates new traffic to a specific subband of the local hopping radio resource only when there is one or more subbands that are unallocated and exceed the line quality of the global hopping radio resource.
The radio resource allocating device according to claim 1. The radio resource allocation determination means allocates new traffic to a subband having the highest channel quality among the subbands in the case of one or more subbands exceeding the channel quality of the global hopping radio resource in the end allocation.
The radio resource allocating device according to claim 3. The radio resource allocation determining unit may allocate local traffic to the local hopping radio resource if new traffic should be allocated to the global hopping radio resource and the global hopping radio resource is not available. Allocate new traffic to radio resources for
The radio resource allocating device according to claim 1. The radio resource allocation determining means both that valid channel quality information is obtained for all subbands, and that the channel quality of unallocated subbands is equal to or higher than a predetermined quality required for transmission of new traffic. When satisfying the condition, it is determined that it can be allocated to the local hopping radio resource,
The radio resource allocating device according to claim 5. A radio resource allocation method in a radio access system of an orthogonal frequency division multiple access method,
The base station evaluating the characteristics of new traffic generated in the mobile terminal; and
A base station determining whether to allocate the new traffic to a global hopping radio resource based on the evaluation result; and
When the base station should not allocate the new traffic to the global hopping radio resource, when the base station has already acquired the channel quality information of all subbands for the mobile terminal, Assigning the new traffic to a band;
A radio resource allocating method comprising: A computer program for performing radio resource allocation processing in an orthogonal frequency division multiple access wireless access system,
Evaluating the characteristics of new traffic generated at the mobile terminal;
Determining whether to allocate the new traffic to a global hopping radio resource based on the evaluation result;
In the case where the new traffic should not be allocated to the global hopping radio resource, when the channel quality information of all subbands has already been acquired for the mobile terminal, the new traffic is assigned to the specific subband of the local hopping radio resource. Assigning traffic; and
A computer program for causing a computer to execute.

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