JP2008193549A - Allocation method and base station device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an influence of a terminal device which moves fast. <P>SOLUTION: The base station device 10 generates a frame by time multiplexing of a plurality of time slots while generating time slots by frequency multiplexing of a plurality of subchannels. A communication quality decision unit 34 detects the extent of variation of a radio transmission line to a terminal device. A time slot specifying unit 36 specifies one of the plurality of time slots forming the frame according to the detected extent of variation. A radio resource allocating unit 38 allocates at least one of the plurality of subchannels forming the specified time slot to the terminal device. <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. Under such circumstances, when the terminal device moves at high speed, the Doppler frequency of the signal from the terminal device increases. When the Doppler frequency is increased, orthogonality between subchannels is not established, and interference with other subchannels is increased. When the interference increases, not only the reception characteristic for the terminal apparatus deteriorates, but also the reception characteristic for the terminal apparatus to which the subchannel affected by the interference is assigned deteriorates.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an allocation technique that reduces the influence of a terminal device that moves at high speed.

  In order to solve the above problems, a base station apparatus according to an aspect of the present invention is a base station apparatus that forms a frame by time multiplexing of a plurality of time slots while forming a time slot by frequency multiplexing of a plurality of subchannels. A detection unit that detects the degree of fluctuation of the wireless transmission path with the terminal device, and any one of a plurality of time slots that form a frame according to the degree of fluctuation detected by the detection unit And a allocating unit for allocating at least one of a plurality of subchannels forming the time slot specified by the specifying unit to the terminal device.

  The “degree of fluctuation of the wireless transmission path with the terminal device” is an extent to which the wireless transmission path changes with time, and is indicated by the moving speed of the terminal device and the Doppler frequency. According to this aspect, since the subchannel included in the time slot is assigned after the time slot is specified according to the detected degree of fluctuation, the influence of the terminal device moving at high speed can be reduced.

  The specifying unit predefines a time slot in which terminal devices whose degree of variation is larger than the threshold value should be aggregated, and when the degree of variation detected in the detecting unit is larger than the threshold value, the time slot May be specified. In this case, since the terminal devices whose degree of variation is larger than the threshold value are collected in a predetermined time slot, the influence of the terminal devices moving at high speed can be reduced.

  The specifying unit predefines a range of the degree of variation for each of the plurality of time slots, and after specifying the range including the degree of variation detected by the detecting unit, the specific unit is associated with the specified range A time slot may be specified. In this case, since the time slot is associated with each of the range of the degree of fluctuation, the influence of the terminal device moving at high speed can be reduced.

  The specifying unit may specify a time slot associated with a range of the smallest fluctuation degree with respect to the control signal. In this case, since the control signal is assigned to the time slot associated with the range of the smallest variation, the influence of the terminal device moving at a high speed on the control signal can be reduced.

  Another aspect of the present invention is an allocation method. In this method, a time slot is formed by frequency multiplexing of a plurality of subchannels, while a frame is formed by time multiplexing of a plurality of time slots, and when the degree of fluctuation of a wireless transmission path with a terminal device is detected The terminal device identifies one of a plurality of time slots forming a frame according to the detected degree of variation, and at least one of the plurality of subchannels forming the specified time slot is a terminal device Assign to.

  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, the influence of a terminal device that moves at high speed can be reduced.

  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. As described above, since OFDMA is performed for each of the plurality of subchannels, orthogonality is required between the plurality of subchannels. A signal included in a predetermined time slot in the uplink is transmitted from a plurality of terminal devices. However, uplink conditions, for example, Doppler frequencies, are generally different for each of a plurality of terminal apparatuses. In particular, if the Doppler frequency in a signal from a predetermined terminal apparatus is large, the signal gives interference to other subchannels. As a result, reception characteristics in other subchannels are deteriorated. In order to cope with this, the base station apparatus according to the present embodiment executes the following processing.

  The base station apparatus estimates the moving speed of the terminal apparatus. Further, the base station apparatus assigns subchannels included in a specific time slot to a terminal apparatus having a high moving speed. On the other hand, a terminal device having a low moving speed is assigned to a subchannel included in another time slot. As a result, the terminal devices having a high moving speed interfere with each other, but the influence of the interference received by the terminal devices having a low moving speed is reduced.

  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, each of the plurality of terminal devices 12 moves in different directions at different speeds. That is, the base station apparatus 10 receives signals from a plurality of terminal apparatuses 12, but the Doppler frequency in each signal is different.

  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.

  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 identification unit 36, 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.

  As a transmission operation, the baseband processing unit 22 converts the frequency domain signal to the time domain by IFFT on the frequency domain multicarrier signal input from the modem unit 24, and converts the converted time domain signal to the RF unit. 20 output. 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 derives the degree of fluctuation of the radio transmission path with the terminal device 12 based on the frequency domain multicarrier signal. Here, the degree of fluctuation of the wireless transmission path with the terminal device 12 is, for example, the moving speed or Doppler frequency of the terminal device 12. FIG. 5 shows an outline of a moving speed estimation technique in the communication quality determination unit 34. FIG. 5 shows a constellation for pilot symbols among a plurality of subcarriers included in a multicarrier signal. As shown, the horizontal axis represents the in-phase (I) component, and the vertical axis represents the quadrature (Q) component. The points shown in the figure are signal points, and the plurality of signal points correspond to a plurality of symbols on the time axis as shown in the direction of the horizontal axis in FIG.

  The communication quality determination unit 34 derives phase differences at different symbols on the time axis as illustrated. For example, the communication quality determination unit 34 derives the absolute value of the phase difference between adjacent symbols on the time axis and integrates the absolute values. Such an integrated value corresponds to the final phase difference. Returning to FIG. Furthermore, the communication quality determination unit 34 performs the same process for another pilot symbol. The communication quality determination unit 34 derives an error in phase difference between a plurality of pilot symbols. In addition, a correspondence between the error value and the moving speed is stored as a table in the storage unit 30 described later, and the communication quality determination unit 34 derives the moving speed from the error value while referring to the table. To do. For example, the table defines a relationship in which the movement speed increases as the error increases.

  When subchannel allocation is performed for a new terminal device 12, the communication quality determination unit 34 derives a moving speed based on a channel allocation request signal received from the terminal device 12. On the other hand, when the subchannel switching is executed for the terminal device 12 to which the subchannel has already been assigned, the communication quality determination unit 34 derives the moving speed based on the data signal received from the terminal device 12.

  The storage unit 30 stores information regarding the frame. As described above, a frame is formed by time multiplexing of a plurality of time slots, and the time slot is formed by frequency multiplexing of a plurality of subchannels, and information on the frame is, for example, a predetermined subchannel is allocated. This is information regarding the terminal device 12. In addition, the storage unit 30 stores the result of carrier sense performed for each subchannel. Here, the carrier sense is performed in the RF unit 20 by a known technique. Furthermore, the storage unit 30 predefines a range of moving speed for each of the plurality of time slots.

  FIG. 6 shows the relationship between the conditions stored in the storage unit 30 and the time slots. As illustrated, a condition column 200 and a time slot column 202 are stored. In the condition column 200, a plurality of threshold values “a”, “b”, and “c” are defined to have a relationship of “a” <“b” <“c”. These threshold values define the range of moving speed. Here, the lower part of the condition column 200 corresponds to a higher moving speed range. In the time slot column 202, a time slot associated with the moving speed range is defined. The fastest moving speed range is associated with the fourth time slot. Returning to FIG.

  The time slot specifying unit 36 receives the value of the moving speed from the communication quality determining unit 34. The time slot specifying unit 36 specifies any one of a plurality of time slots forming a frame according to the received moving speed. That is, the time slot specifying unit 36 specifies the time slot associated with the specified range after specifying the range including the moving speed while referring to the table stored in the storage unit 30. The time slot specifying unit 36 outputs the specified time slot to the radio resource allocating unit 38.

  The radio resource allocation unit 38 allocates at least one of the plurality of subchannels forming the time slot specified by the time slot specifying unit 36 to the terminal device 12. At that time, the radio resource allocating unit 38 extracts empty subchannels included in the identified time slot while referring to information on the frame stored in the storage unit 30. In addition, the radio resource allocation unit 38 specifies the subchannel with the lowest interference wave level among the extracted free subchannels while referring to the carrier sense result stored in the storage unit 30. Note that carrier sense may be performed when a subchannel is specified. The radio resource allocation unit 38 determines the allocation of the identified subchannel and transmits the result as a notification of allocation to the terminal device 12 via the modem unit 24, the baseband processing unit 22, and the RF unit 20. Further, the radio resource allocation unit 38 reflects the allocated result in the storage unit 30.

  When there is no empty subchannel in the time slot specified by the time slot specifying unit 36, the radio resource allocating unit 38 specifies again the time slot specified so that the moving speed range is lower than the time slot. . Further, the time slot specifying unit 36 extracts empty subchannels included in the specified time slot. Here, the time slot defined so that the moving speed range is lower than that of the time slot corresponds to the third time slot when “the time slot” is the fourth time slot of FIG. . If there is an empty subchannel, the time slot specifying unit 36 performs subchannel allocation as described above. If the allocation is impossible, the time slot specifying unit 36 may transmit the allocation rejection to the terminal device 12 via the modem unit 24, the baseband processing unit 22, and the RF unit 20.

  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. Such a control signal is more important than a data signal. Therefore, the control channel determination unit 32 identifies the time slot associated with the range of the lowest moving speed with respect to the control signal while referring to the storage unit 30, and a plurality of times included in the identified time slot Select one of the subchannels. 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. 7 is a sequence diagram showing a subchannel assignment procedure in communication system 100. The first terminal apparatus 12a transmits a subchannel allocation request signal to the base station apparatus 10 (S10). The base station apparatus 10 estimates the moving speed of the first terminal apparatus 12a based on the allocation request signal (S12), and identifies the time slot based on the estimated moving speed (S14). The base station apparatus 10 allocates the subchannel included in the identified time slot to the first terminal apparatus 12a (S16). The base station apparatus 10 transmits an allocation notification of the allocated result to the first terminal apparatus 12a (S18). Thereafter, the base station apparatus 10 and the first terminal apparatus 12a perform communication while using the assigned subchannel.

  FIG. 8 is a flowchart showing a subchannel allocation procedure in the base station apparatus 10. The communication quality determination unit 34 estimates the moving speed (S30). The time slot specifying unit 36 specifies a time slot based on the estimated moving speed (S32). If there is an empty subchannel in the identified time slot (Y in S34), the RF unit 20 performs carrier sense (S36). If subchannel allocation is possible (Y in S38), the radio resource allocation unit 38 executes allocation and notifies the result (S40). On the other hand, when there is no empty subchannel in the specified time slot (N in S34) or when subchannel allocation is not possible (N in S38), if there is a higher group (Y in S42), the time slot specifying unit 36 Specifies a time slot (S44).

  Here, the upper group corresponds to a range where the moving speed is lower than that of the current group. If there is an empty subchannel in the identified time slot (Y in S46), the RF unit 20 performs carrier sense (S48). If subchannel allocation is possible (Y in S50), the radio resource allocation unit 38 executes allocation and notifies the result (S52). If there is no empty subchannel in the identified time slot (N in S46) or if subchannel allocation is not possible (N in S50), the process returns to step 42. On the other hand, if there is no higher group (N in S42), the radio resource allocation unit 38 rejects the allocation (S54).

  Hereinafter, modifications of the present invention will be described. In the embodiment, the storage unit 30 associates time slots with each of the moving speed ranges. However, in the modification, the storage unit 30 predefines time slots in which the terminal devices 12 whose moving speed is higher than the threshold value should be aggregated. In other words, there is a rule that only the terminal devices 12 that are likely to interfere with other terminal devices 12 are grouped into one time slot. The base station apparatus 10 according to the modification is the same type as that in FIG.

  FIG. 9 shows the relationship between the conditions and the time slots stored in the storage unit 30 according to the modification of the present invention. As illustrated, a condition column 200 and a time slot column 202 are stored. In the condition column 200, one threshold value “c” is defined. In the time slot column 202, a time slot associated with the condition in the condition column 200 is defined. The fourth time slot is associated with the terminal device 12 whose moving speed is faster than the threshold value. Returning to FIG. The time slot specifying unit 36 specifies the fourth time slot when the estimated moving speed is higher than the threshold value.

  According to the embodiment of the present invention, since the subchannel included in the time slot is assigned after the time slot is specified according to the estimated moving speed, the influence of the terminal device moving at high speed can be reduced. Further, since the time slots are associated with the respective moving speeds, different time slots can be specified for the terminal apparatus moving at a low speed and the terminal apparatus moving at a high speed. Further, since different time slots are specified for the terminal device moving at a low speed and the terminal device moving at a high speed, the influence of the terminal device moving at a high speed can be reduced with respect to the terminal device moving at a low speed. In addition, since terminal devices whose moving speed is larger than the threshold value are collected in a predetermined time slot, the influence of the terminal device moving at high speed can be reduced. Further, since the control signal is assigned to the time slot associated with the smallest moving speed, the influence of the terminal device moving at high speed on the control signal can be reduced.

  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. .

  In the embodiment of the present invention, the communication quality determination unit 34 measures the variation of the phase with respect to the pilot symbol as the degree of variation of the radio transmission path. However, the present invention is not limited to this. For example, the degree of fluctuation such as the Doppler frequency may be applied by a known technique. According to this modification, the degree of freedom in design can be improved.

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. It is a figure which shows the outline | summary of the estimation technique of the moving speed in the communication quality determination part of FIG. It is a figure which shows the relationship between the conditions memorize | stored in the memory | storage part of FIG. 4, and a time slot. FIG. 2 is a sequence diagram showing a subchannel allocation procedure in the communication system of FIG. 1. 6 is a flowchart showing a subchannel allocation procedure in the base station apparatus of FIG. It is a figure which shows the relationship between the conditions memorize | stored in the memory | storage part which concerns on the modification of this invention, and a time slot.

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, 36 time A slot identifying unit; 38 a radio resource allocating unit; 100 a communication system;

Claims (6)

A base station apparatus that forms a frame by time multiplexing of a plurality of time slots while forming a time slot by frequency multiplexing of a plurality of subchannels,
A detection unit for detecting the degree of fluctuation of the wireless transmission path with the terminal device;
A specifying unit for specifying any one of a plurality of time slots forming a frame according to the degree of variation detected by the detection unit;
A base station apparatus comprising: an allocating section that allocates at least one of a plurality of subchannels forming a time slot identified by the identifying section to the terminal apparatus.   The specifying unit preliminarily defines a time slot in which terminal devices whose degree of variation is larger than a threshold value should be aggregated, and when the degree of variation detected in the detecting unit is larger than the threshold value, The base station apparatus according to claim 1, wherein a time slot is specified.   The specifying unit predefines a range of the degree of variation for each of a plurality of time slots, specifies a range including the degree of variation detected by the detection unit, and then associates the range with the specified range. The base station apparatus according to claim 1, wherein the specified time slot is specified.   The base station apparatus according to claim 3, wherein the specifying unit specifies a time slot associated with a range of a degree of the smallest variation with respect to the control signal.   When a time slot is formed by frequency multiplexing of a plurality of subchannels and a frame is formed by time multiplexing of a plurality of time slots, the detected fluctuation is detected when the degree of fluctuation of the wireless transmission path with the terminal device is detected. According to the degree of, specify any one of a plurality of time slots forming a frame, and assign at least one of a plurality of subchannels forming the specified time slot to the terminal device An allocation method characterized by Detecting the degree of fluctuation of the wireless transmission path with the terminal device;
While a time slot is formed by frequency multiplexing of a plurality of subchannels, a frame is formed by time multiplexing of a plurality of time slots. A step to identify one of them,
Assigning at least one of a plurality of subchannels forming a specified time slot to the terminal device;
A program that causes a computer to execute.

Images