JP2008205537A - Allocation method and base station apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration in communication quality even when being interfered. <P>SOLUTION: While forming time slots by frequency multiplexing of a plurality of subchannels, a frame formed by the time multiplexing of a plurality of time slots is regulated. A time slot priority determination part 40 and a wireless resource allocation part 38 specify different time slots out of a plurality of time slots forming a frame, the different time slots being correspond to the number of channels to be allocated to one terminal apparatus. A subchannel priority determination part 42 and the wireless resource allocation part 38 specify a subchannel in each of specified time slots. A modem part 24, a base band processing part 22 and an RF part 20 execute communication with one terminal apparatus by two or more allocated subchannels. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an allocation technique, and more particularly to an allocation method for allocating time slots to terminal apparatuses and a base station apparatus using the allocation method.

In a wireless communication system, a base station device may connect a plurality of terminal devices. One of the forms when the base station apparatus connects a plurality of terminal apparatuses is TDMA / TDD. In TDMA / TDD, a frame is formed by a plurality of time slots, and a plurality of frames are continuously arranged. Further, some of the plurality of time slots included in one frame are used for the uplink, and the remaining time slots are used for the downlink. In the prior art using such TDMA / TDD, the number of time slots used for the uplink in one frame and the number of time slots used for the downlink are determined as traffic. It is set according to the difference (see, for example, Patent Document 1).
JP-A-8-186533

  In general, effective use of limited frequency resources is desired in wireless communication. In particular, as the communication speed increases, the demand is further increased. One technique for meeting this demand is the OFDMA (Orthogonal Frequency Division Multiple Access) scheme, which can be combined with the TDMA / TDD described above. OFDMA is a technique for frequency-multiplexing a plurality of terminal devices using OFDM.

  In such OFDMA, a subchannel is formed by a plurality of subcarriers, and a multicarrier signal is formed by a plurality of subchannels. Further, the base station apparatus performs communication with the terminal apparatus by assigning at least one subchannel to the terminal apparatus. Further, in order to further increase the communication speed with the terminal device, the base station device allocates a plurality of subchannels to the terminal device. At this time, in order to simplify the processing, the base station apparatus generally assigns adjacent subchannels to one terminal apparatus in succession. Under such circumstances, when the same frequency band as that of the base station apparatus grounded in the vicinity is used, a plurality of continuous subchannels may be affected by interference collectively. As a result, the communication quality for the terminal device to which such a subchannel is assigned deteriorates.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an allocation technique that suppresses deterioration in communication quality even when receiving interference.

  In order to solve the above problems, a base station apparatus according to an aspect of the present invention defines a frame formed by time multiplexing of a plurality of time slots while forming a time slot by frequency multiplexing of a plurality of subchannels. And an allocating unit that allocates two or more of the plurality of subchannels to one terminal device, and an execution unit that executes communication with one terminal device using the two or more subchannels allocated by the allocating unit. The assigning unit is a time slot corresponding to the number of subchannels to be assigned to one terminal apparatus, and a first specifying unit for specifying different time slots among a plurality of time slots to form a frame; A second specifying unit that specifies a subchannel in each of the time slots specified by the first specifying unit.

  According to this aspect, since the subchannels are specified after specifying different time slots among the plurality of time slots, the subchannels are distributed in the time direction and the frequency direction, and communication quality is improved even when interference is received. Deterioration can be suppressed.

  A calculation unit that calculates the number of subchannels that can be allocated to a terminal device in units of time slots, and a grant unit that gives priority to each of a plurality of time slots that increases as the number calculated by the calculation unit increases. And may further be provided. The first specifying unit may specify a time slot based on the priority assigned by the assigning unit. In this case, since the priority is set so as to increase as the number of subchannels that can be allocated to the terminal apparatus increases, it is possible to preferentially use a time slot that has a large number of subchannels that can be allocated.

  The calculation unit may execute the calculation when the time slot allocation changes, and the assigning unit may change the priority when the calculation is performed by the calculation unit. In this case, since the priority changes when the time slot allocation changes, processing according to the time slot allocation status can be executed.

  The second specifying unit may preferentially specify non-adjacent subchannels when specifying a plurality of subchannels for one time slot. In this case, since subchannels that are not adjacent are preferentially specified, the subchannels to be allocated can be distributed in the frequency direction.

  Another aspect of the present invention is an allocation method. In this method, while a time slot is formed by frequency multiplexing of a plurality of subchannels, a frame formed by time multiplexing of a plurality of time slots is defined, and two or more of the plurality of subchannels are defined as one terminal. An allocation method to be assigned to a device, which is a time slot corresponding to the number of subchannels to be assigned to one terminal device, and specifies different time slots among a plurality of time slots to form a frame, A subchannel is specified in each of the specified time slots.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, deterioration of communication quality can be suppressed even when interference is received.

  Before describing the present invention specifically, an outline will be given first. Embodiments of the present invention relate to a communication system including a base station device and at least one terminal device. In the communication system, each frame is formed by time-division multiplexing a plurality of time slots, and each time slot is formed by frequency-division multiplexing a plurality of subchannels. Each subchannel is formed by a multicarrier signal. Here, OFDM signals are used as multicarrier signals, and OFDMA is used as frequency division multiplexing.

  The base station apparatus performs communication with the plurality of terminal apparatuses by assigning each of the plurality of subchannels included in each time slot to the terminal apparatus. In order to improve the communication speed with a predetermined terminal device, the base station device allocates a plurality of subchannels to the terminal device. On the other hand, in consideration of effective use of frequencies, the same frequency band is also used in neighboring base station apparatuses. At this time, if subchannels having the same timing and the same frequency are used, interference occurs between terminal apparatuses. Under such circumstances, if a plurality of adjacent subchannels are assigned to one terminal device, the interference affects the plurality of subchannels collectively. In order to cope with this, the base station apparatus according to the present embodiment executes the following processing.

  When assigning a plurality of subchannels to one terminal apparatus, the base station apparatus assigns subchannels in each of a plurality of time slots. At that time, the base station apparatus preferentially uses a time slot having a small number of already assigned subchannels. In one time slot, the base station apparatus preferentially assigns subcarriers that are not adjacent to the already assigned subchannel. By assigning subchannels in this way, even if any of the subcarriers is affected by interference, it is possible to reduce the possibility of interference being exerted on other subcarriers.

  FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a first terminal device 12a, a second terminal device 12b, and a third terminal device 12c, which are collectively referred to as a base station device 10 and a terminal device 12.

  The base station device 10 has a terminal device 12 connected to one end via a wireless network and a wired network (not shown) connected to the other end. Further, the terminal device 12 is connected to the base station device 10 via a wireless network. The base station apparatus 10 performs communication with the plurality of terminal apparatuses 12 by assigning communication channels to the plurality of terminal apparatuses 12. Specifically, the terminal apparatus 12 transmits a channel allocation request signal to the base station apparatus 10, and the base station apparatus 10 allocates a communication channel to the terminal apparatus 12 in response to the received request signal.

  In addition, the base station apparatus 10 transmits information on the communication channel assigned to the terminal apparatus 12, and the terminal apparatus 12 performs communication with the base station apparatus 10 while using the assigned communication channel. As a result, the data transmitted from the terminal device 12 is output to the wired network via the base station device 10 and finally received by a communication device (not shown) connected to the wired network. Data is also transmitted in the direction from the communication device to the terminal device 12.

  Here, the base station apparatus 10 allocates a plurality of communication channels to one terminal apparatus 12 in order to improve the communication speed with the terminal apparatus 12. Further, although not shown, another base station device exists around the base station device 10. Another base station apparatus uses the same frequency band as the frequency band used by the base station apparatus 10. Therefore, if base station apparatus 10 and another base station apparatus allocate the same subchannel at the same timing, interference occurs between subcarriers. The base station apparatus 10 according to the present embodiment executes processing for reducing the influence of such interference, which will be described later.

  In the above description, the communication channel is specified by the combination of the subchannel and the time slot described above. In addition, since the base station apparatus 10 has a plurality of time slots and a plurality of subchannels, the base station apparatus 10 executes OFDMA using a plurality of subchannels while executing TDMA using the plurality of time slots.

  2A to 2C show a frame configuration in the communication system 100. FIG. The horizontal direction in the figure corresponds to the time axis. The frame is formed by 8 time slots. The eight time slots are composed of four upstream time slots and four downstream time slots. Here, four uplink time slots are indicated as “first uplink time slot” to “fourth uplink time slot”, and four downlink time slots are indicated as “first downlink time slot” to “fourth downlink time slot”. . Further, the illustrated frame is repeated continuously. The configuration of the frame is not limited to that shown in FIG. 2A. For example, the frame configuration may be configured by four time slots or 16 time slots. The configuration will be described with reference to FIG. For the sake of brevity, it is assumed that the upstream time slot and the downstream time slot have the same configuration. For this reason, only one of the uplink time slot and the downlink time slot may be described, but the same description is valid for the other time slot.

  FIG. 2B shows the configuration of one time slot in FIG. The vertical direction in the figure corresponds to the frequency axis. As shown in the figure, one time slot is formed by “16” subchannels from “first subchannel” to “16th subchannel”. In addition, the plurality of subchannels are frequency division multiplexed. Since each time slot is configured as shown in FIG. 2B, the above-described communication channel is specified by the combination of the time slot and the subchannel. Also, the frame configuration corresponding to one subchannel in FIG. 2B may be as shown in FIG. Note that the number of subchannels arranged in one time slot may not be “16”.

  FIG. 2 (c) shows the configuration of one subchannel in FIG. 2 (b). Similar to FIG. 2A and FIG. 2B, the horizontal direction in the figure corresponds to the time axis, and the vertical direction in the figure corresponds to the frequency axis. Further, numbers “1” to “29” are assigned to the frequency axis, and these indicate subcarrier numbers. In this way, the subchannel is composed of multicarrier signals, and in particular is composed of OFDM signals. “TS” in the figure corresponds to a training symbol and is constituted by a known value. Further, it is assumed that a control signal may be included in “TS”. “GS” corresponds to a guard symbol, and no substantial signal is arranged here. “PS” corresponds to a pilot symbol, and is configured by a known value. “DS” corresponds to a data symbol and is data to be transmitted. “GT” corresponds to a guard time, and no substantial signal is arranged here.

  In this embodiment, a plurality of subchannels are allocated to one terminal device 12. At that time, each of the plurality of time slots shown in FIG. 2A is selected. In addition, when a plurality of subchannels are allocated to each selected time slot, a subchannel to be allocated is specified so as not to be an adjacent subchannel among the plurality of subchannels illustrated in FIG. The As a result, in this embodiment, distributed subchannels are used for each of the time domain and the frequency domain.

  FIG. 3 shows an arrangement of subchannels in the communication system 100. In FIG. 3, the frequency axis is shown on the horizontal axis, and the spectrum for the time slot shown in FIG. 2B is shown. As described above, 16 subchannels from the first subchannel to the 16th subchannel are frequency division multiplexed in one time slot. Each subchannel is configured by a multicarrier signal, here, an OFDM signal.

  FIG. 4 shows the configuration of the base station apparatus 10. The base station apparatus 10 includes a first RF unit 20a, a second RF unit 20b, an NRF unit 20n, a baseband processing unit 22, a modem unit 24, an IF unit 26, a radio control unit 28, and a storage unit 30. including. The radio control unit 28 includes a control channel determination unit 32, a communication quality determination unit 34, a time slot priority determination unit 40, a subchannel priority determination unit 42, and a radio resource allocation unit 38.

  As a reception process, the RF unit 20 performs frequency conversion on a radio frequency multicarrier signal received from a terminal device 12 (not shown) to generate a baseband multicarrier signal. Here, the multicarrier signal is formed as shown in FIG. 3, and corresponds to the uplink time slot of FIG. Further, the RF unit 20 outputs a baseband multicarrier signal to the baseband processing unit 22. In general, a baseband multicarrier signal is formed by an in-phase component and a quadrature component, and therefore should be transmitted by two signal lines. For the sake of clarity, a single signal line is used here. Only. The RF unit 20 also includes an AGC and an A / D conversion unit.

  As a transmission process, the RF unit 20 performs frequency conversion on the baseband multicarrier signal input from the baseband processing unit 22 to generate a radiofrequency multicarrier signal. Further, the RF unit 20 transmits a radio frequency multicarrier signal. The RF unit 20 transmits a multicarrier signal while using the same radio frequency band as the received multicarrier signal. That is, as shown in FIG. 2A, TDD (Time Division Duplex) is used. The RF unit 20 also includes a PA (Power Amplifier) and a D / A conversion unit.

  The baseband processing unit 22 inputs a baseband multicarrier signal from each of the plurality of RF units 20 as a reception operation. Since the baseband multicarrier signal is a time domain signal, the baseband processing unit 22 converts the time domain signal to the frequency domain by FFT and performs adaptive array signal processing on the frequency domain signal. To do. Further, the baseband processing unit 22 executes timing synchronization, that is, FFT window setting, and also deletes the guard interval. Since a known technique may be used for timing synchronization and the like, description thereof is omitted here. The baseband processing unit 22 outputs the result of adaptive array signal processing to the modem unit 24.

  As a transmission operation, the baseband processing unit 22 receives a multi-carrier signal in the frequency domain from the modulation / demodulation unit 24 and performs dispersion processing using weight vectors. The baseband processing unit 22 converts the frequency domain signal into the time domain by IFFT, and outputs the converted time domain signal to the RF unit 20. The baseband processing unit 22 also adds a guard interval, but the description is omitted here. Here, the frequency domain signal includes a plurality of subchannels as shown in FIG. 2B, and each of the subchannels includes a plurality of subcarriers as in the vertical direction of FIG. 2C. For the sake of clarity, it is assumed that the signals in the frequency domain are arranged in the order of subcarrier numbers to form a serial signal.

  The modem unit 24 performs demodulation on the multi-carrier signal in the frequency domain from the baseband processing unit 22 as reception processing. The multicarrier signal converted into the frequency domain has components corresponding to each of the plurality of subcarriers as shown in FIGS. Demodulation is performed in units of subcarriers. The modem unit 24 outputs the demodulated signal to the IF unit 26. Further, the modem unit 24 performs modulation as transmission processing. The modem unit 24 outputs the modulated signal to the baseband processing unit 22 as a multi-carrier signal in the frequency domain.

  The IF unit 26 receives the demodulation result from the modulation / demodulation unit 24 as a reception process, and separates the demodulation result for each terminal device 12. That is, the demodulation result is composed of a plurality of subchannels as shown in FIG. Therefore, when one subchannel is assigned to one terminal apparatus 12, the demodulation result includes signals from a plurality of terminal apparatuses 12. The IF unit 26 separates such a demodulation result for each terminal device 12. The IF unit 26 outputs the separated demodulation result to a wired network (not shown). At that time, the IF unit 26 performs transmission according to information for identifying the destination, for example, an IP (Internet Protocol) address.

  Further, the IF unit 26 inputs data for the plurality of terminal devices 12 from a wired network (not shown) as a transmission process. The IF unit 26 assigns data to subchannels and forms a multicarrier signal from a plurality of subchannels. That is, the IF unit 26 forms a multicarrier signal composed of a plurality of subchannels as shown in FIG. The subchannel to which data is to be assigned is determined in advance as shown in FIG. 2 (c), and an instruction related thereto is received from the radio control unit 28. The IF unit 26 outputs the multicarrier signal to the modem unit 24.

  The communication quality determination unit 34 receives a frequency domain multicarrier signal from the baseband processing unit 22 via a signal line (not shown). Here, the frequency domain multi-carrier signal may be a result of adaptive array signal processing. Further, the communication quality determination unit 34 measures the signal strength based on the multi-carrier signal in the frequency domain. The multicarrier signal is, for example, a channel assignment request transmitted by a terminal device 12 (not shown). Furthermore, the communication quality determination unit 34 specifies an empty subchannel while referring to a table stored in the storage unit 30 and indicating a subchannel already allocated. Note that, as shown in FIGS. 2A to 2C, the subchannels are arranged not only in the frequency axis direction but also in the time axis direction. Therefore, the communication quality determination unit 34 specifies an empty subchannel in each time slot while changing the time slot.

  The communication quality determination unit 34 measures the signal strength in the specified empty subchannel. When there are a plurality of empty subchannels, measurement is performed for each of the plurality of empty subchannels. The measurement result corresponds to the signal intensity of the U wave. The signal strength of the aforementioned multicarrier signal corresponds to the signal strength of the D wave. The communication quality determination unit 34 calculates D / U for each subchannel based on the signal intensity of the D wave and the signal intensity of the U wave. In addition, the communication quality determination unit 34 stores the calculation result in the storage unit 30 while associating the calculation result with the subchannel.

  The time slot priority order determination unit 40 compares each D / U stored in the storage unit 30 with a threshold value, and extracts a D / U having a value larger than the threshold value. Here, the subchannel corresponding to the extracted D / U becomes a candidate for allocation. Also, the time slot priority order determination unit 40 searches for a subchannel that has already been assigned to the terminal device 12 while referring to the table stored in the storage unit 30. Following this, the time slot priority order determination unit 40 counts the number of already assigned subchannels in units of time slots, and stores the result in the storage unit 30. FIG. 5A shows the data structure of the search result stored in the storage unit 30. As shown, the number of subchannels in use is shown for each time slot number. Returning to FIG. When no subchannel is allocated to the terminal device 12, the time slot priority order determination unit 40 may calculate the number of allocation candidates already extracted for each subchannel. Both processes correspond to calculating the number of subchannels that can be allocated to the terminal device 12 in units of time slots.

  The time slot priority order determination unit 40 assigns a priority to each of the plurality of time slots so as to increase as the number of already assigned subchannels decreases. This is equivalent to giving priority to each of a plurality of time slots so that the higher the number of unassigned subchannels, the higher the priority. In the case of FIG. 5A, priorities are given in the order of time slot numbers “1”, “3”, “4”, “2”. When the number of allocation candidates already extracted is calculated in units of subchannels, the time slot priority determining unit 40 gives priority to each of a plurality of time slots so that the priority increases as the number of candidates increases. Give. The above operation can also be said to give priority to each of a plurality of time slots so as to increase as the number of subchannels that can be allocated increases. The time slot priority order determination unit 40 stores the assigned priority order in the storage unit 30.

  After determining the priority of the time slot in the time slot priority determining unit 40, the sub channel priority determining unit 42 gives priority to the empty subchannel included in each time slot. Prior to giving priority, the sub-channel priority determining unit 42 refers to the storage unit 30 and acquires the usage status of the sub-channel in each time slot. FIG. 5B shows the data structure of the search result stored in the storage unit 30. Here, the usage status for one time slot is shown, and an empty subchannel number, the resource being used by the user, and the resource being used by another user are shown. The user busy resource corresponds to a subchannel already assigned to the terminal apparatus 12, and the other user busy resource corresponds to a subchannel already assigned to another terminal apparatus 12. Returning to FIG.

  Note that such data may not be stored in the storage unit 30, and information on the terminal device 12 assigned to each subchannel may be stored in the storage unit 30. In that case, the subchannel priority order determination unit 42 outputs the result as shown in FIG. 5B by calculation based on the information. When specifying a plurality of subchannels for one time slot, the subchannel priority determining unit 42 assigns a priority to a subcarrier with a small number and not adjacent to each other. To do. For example, in the case of FIG. 5B, the time slot priority determining unit 40 assigns the highest priority to the subchannel number “1”. As a result of the above processing, the priorities are subchannel numbers “1”, “3”, “11”, “12”, “16”, “17”, “6”, “7”, “13”. . In addition, the subchannel priority order determination unit 42 executes the above processing for other time slots. Further, the subchannel priority order determination unit 42 stores the processing result in the storage unit 30. Note that the time slot priority determination unit 40 and the subchannel priority determination unit 42 execute the calculation again and change the priority when the time slot assignment changes.

  The radio resource allocating unit 38 transmits the sub slot to the terminal device 12 based on the time slot priority assigned by the time slot priority determining unit 40 and the sub channel priority assigned by the sub channel priority determining unit 42. Assign channels. That is, while a time slot is formed by frequency multiplexing of a plurality of subchannels, a frame formed by time multiplexing of a plurality of time slots is defined, and the radio resource allocating unit 38 selects two of the plurality of subchannels. The above is assigned to one terminal device 12. Specifically, the radio resource allocation unit 38 identifies a time slot based on the priority of the time slot.

  In the case of the priority based on FIG. 5A, for example, if the number of subchannels to be allocated is “3”, the radio resource allocation unit 38 determines the time slot numbers “1”, “3”, “4”. The time slots are specified in the order of "." If the number of subchannels to be allocated is “8”, the radio resource allocation unit 38 sets the time slot numbers “1”, “3”, “4”, “2”, “1”, “3”, “3”, “ Time slots are specified in the order of “4” and “2”. As a premise, when a time slot is specified once, one subchannel is allocated in the time slot.

  If there are no more empty subchannels in a predetermined time slot, the time slot specification is skipped. For example, if the number of subchannels to be allocated is “8”, but there is only one free subchannel in the time slot “3”, the radio resource allocation unit 38 sets the time slot numbers “1”, “3”, “4”. ”,“ 2 ”,“ 1 ”,“ 4 ”,“ 2 ”,“ 1 ”in this order. As described above, the radio resource allocation unit 38 is a time slot corresponding to the number of subchannels to be allocated to one terminal apparatus 12, and different time slots among a plurality of time slots to form a frame. Is identified.

  After identifying the time slot, the radio resource allocation unit 38 identifies the subchannel based on the priority of the subchannel in each of the identified time slots. As described above, since the priority is given to be higher for non-adjacent sub-channels, it can be said that the radio resource allocation unit 38 preferentially specifies non-adjacent sub-channels. Finally, the radio resource allocation unit 38 allocates the identified subchannel to the terminal device 12. Also, the radio resource allocation unit 38 notifies the allocated subchannel to the terminal device 12 (not shown) via the modem unit 24, the baseband processing unit 22, and the RF unit 20. Further, the modem unit 24, the baseband processing unit 22, and the RF unit 20 execute communication with one terminal device 12 through two or more subchannels allocated by the radio resource allocation unit 38.

  The control channel determination unit 32 assigns control signals to subchannels. Here, the control signal is a signal including information used for controlling communication with the terminal device 12. In addition, the control channel determination unit 32 notifies the radio resource allocation unit 38 of the selected subchannel. The radio resource allocation unit 38 allocates a subchannel to the control signal according to the notification from the radio resource allocation unit 38.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it is realized by a program having a communication function loaded in the memory. Describes functional blocks realized by collaboration. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  The operation of the communication system 100 configured as above will be described. FIG. 6 is a flowchart showing a subchannel allocation procedure in the base station apparatus 10. The communication quality determination unit 34 measures the received power of the allocated user (S10). Here, the allocated user corresponds to the terminal apparatus 12 to be allocated with the subchannel. Further, the communication quality determination unit 34 sets the time slot number to “1” (S12), and if there is an empty subchannel (Y in S14), calculates the D / U (S16). If the time slot number is equal to or less than the number of slots (Y in S18), or if there is no free subchannel (N in S14), 1 is added to the time slot number (S20), and the process returns to step 14.

  If the time slot number is not equal to or less than the number of slots (N in S18), if there is a D / U check OK resource (Y in S22), the time slot priority determining unit 40 sets the time slot number to "1" ( S24). The time slot priority order determination unit 40 calculates the number of subchannels used by the user (S26). If the time slot number is equal to or less than the number of slots (Y in S28), 1 is added to the time slot number (S30), and the process returns to step 26. When the time slot number is not equal to or less than the number of slots (N in S28), the time slot priority order determination unit 40 assigns a priority order according to the calculation result (S32). The subchannel priority order determination unit 42 selects the first priority slot (S34).

  The subchannel priority order determination unit 42 executes subchannel priority selection processing (S36). If the required lease number is not secured (N in S38) and there is an assignable time slot (Y in S40), the radio resource allocating unit 38 moves to the next time slot according to the priority (S42). Return to 36. On the other hand, if the required lease number is secured (Y in S38) and there is no assignable time slot (N in S40), the radio resource allocation unit 38 ends the process. On the other hand, if there is no D / U check OK resource (N in S22), the radio resource allocation unit 38 notifies the allocation failure (S44), and the process ends.

  FIG. 7 is a flowchart showing a subchannel priority selection procedure in the base station apparatus 10. The process in FIG. 7 corresponds to step 36 in FIG. The subchannel priority order determination unit 42 sets the subchannel number to 1 (S60). If the subchannel number is equal to or less than the number of subchannels (Y in S62), there is an empty subchannel (Y in S64), and the adjacent subchannel is not being used by the user (N in S66), the subchannel is selected. (S70). If there is no free subchannel (N in S64), or if the user is using an adjacent subchannel (Y in S66), the subchannel priority determining unit 42 adds 1 to the subchannel number (S68), Return to step 62. On the other hand, if the subchannel number is not less than the number of subchannels (N in S62), the process is terminated.

  According to the embodiment of the present invention, since the subchannels are specified after specifying different time slots among the plurality of time slots, the subchannels to be allocated can be distributed in the time direction and the frequency direction. Further, since the subchannels to be allocated are distributed in the time direction and the frequency direction, it is possible to reduce the possibility that all subchannels are affected by interference at the same time. In addition, since the possibility that interference is simultaneously exerted on all subchannels is reduced, deterioration of communication quality can be suppressed even when interference is received. In addition, since the priority is set so as to increase as the number of subchannels that can be allocated to the terminal apparatus increases, it is possible to preferentially use time slots that have a large number of subchannels that can be allocated. In addition, since the priority is changed when the time slot assignment changes, processing according to the time slot assignment situation can be executed. In addition, since non-adjacent subchannels are specified preferentially, the subchannels to be allocated can be distributed in the frequency direction.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. It is a figure which shows the frame structure in the communication system of FIG. It is a figure which shows the frame structure in the communication system of FIG. It is a figure which shows the frame structure in the communication system of FIG. It is a figure which shows arrangement | positioning of the subchannel in the communication system of FIG. It is a figure which shows the structure of the base station apparatus of FIG. FIGS. 5A and 5B are diagrams showing the data structure of the search results stored in the storage unit of FIG. 6 is a flowchart showing a subchannel allocation procedure in the base station apparatus of FIG. 6 is a flowchart showing a subchannel priority selection procedure in the base station apparatus of FIG.

Explanation of symbols

  10 base station apparatus, 12 terminal apparatus, 20 RF section, 22 baseband processing section, 24 modulation / demodulation section, 26 IF section, 28 radio control section, 30 storage section, 32 control channel determination section, 34 communication quality determination section, 38 radio 100 resource allocation unit, 40 time slot priority determination unit, 42 subchannel priority determination unit, 100 communication system

Claims (6)

While a time slot is formed by frequency multiplexing of a plurality of subchannels, a frame formed by time multiplexing of a plurality of time slots is defined, and an allocation in which two or more of the plurality of subchannels are allocated to one terminal device And
An execution unit that executes communication with the one terminal device by two or more subchannels allocated in the allocation unit;
The allocation unit is
A first specifying unit that specifies time slots corresponding to the number of subchannels to be allocated to the one terminal device and that is different from a plurality of time slots to form a frame;
A second specifying unit for specifying a subchannel in each of the time slots specified by the first specifying unit;
A base station apparatus comprising: A calculation unit that calculates the number of subchannels that can be allocated to the terminal device in units of time slots;
A grant unit that gives priority to each of the plurality of time slots so that the higher the number calculated in the calculation unit is,
The base station apparatus according to claim 1, wherein the first specifying unit specifies a time slot based on the priority assigned by the assigning unit. The calculation unit performs the calculation when the time slot allocation changes,
The base station apparatus according to claim 2, wherein the assigning unit changes the priority when the calculation is performed by the calculating unit.   The base according to any one of claims 1 to 3, wherein when the second specifying unit specifies a plurality of subchannels for one time slot, the second specifying unit preferentially specifies non-adjacent subchannels. Station equipment. While a time slot is formed by frequency multiplexing of a plurality of subchannels, a frame formed by time multiplexing of a plurality of time slots is defined, and an allocation in which two or more of the plurality of subchannels are allocated to one terminal device A method,
A time slot corresponding to the number of subchannels to be allocated to the one terminal device, and a different time slot among a plurality of time slots to form a frame is specified, and in each of the specified time slots, An allocation method characterized by specifying a subchannel. A step of defining a frame formed by time multiplexing of a plurality of time slots while forming a time slot by frequency multiplexing of a plurality of subchannels, and assigning two or more of the plurality of subchannels to one terminal device When,
Performing communication with the one terminal device by two or more assigned subchannels,
The assigning step comprises:
A time slot corresponding to the number of subchannels to be allocated to the one terminal apparatus, and specifying a different time slot among a plurality of time slots to form a frame;
Identifying a subchannel in each of the identified time slots;
A program that causes a computer to execute.

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