JP2009027530A - Band control method and controller utilizing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a band control method and a controller using the same with which divided bands can be allocated to a terminal device in such a way as to be suited to variation in bandwidths even when the bandwidths are varied in a case where a plurality of kinds of priorities are specified. <P>SOLUTION: An IF section 50 transfers a packet signal input from a network to a base station device. A control section 54 specifies a plurality of kinds of priorities for packet signals to be transferred at the IF section 50, divides a band at the base station device in a predetermined ratio while associating the bands with the plurality of kinds of priorities, respectively, and controls transfer of packet signals of the respective priorities within a range of the divided band. When a decrease in the band at the base station device is detected, the control section 54 changes the ratio in dividing the band so as to reduce the decrease of the band for high-priority packet signals. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a band control technique, and more particularly to a band control method for controlling bands associated with different priorities and a control apparatus using the same.

In a communication system, when various types of data are transmitted, service quality is defined and scheduling is performed in consideration of the service quality. Service quality may be defined by frame priority. For example, when data corresponds to VoIP (Voice over IP), a frame including this is defined as a high priority frame, and when data corresponds to FTP (File Transfer Protocol), this is included. The frame is defined as a low priority frame (see, for example, Patent Document 1).
JP 2005-252897 A

  There are various types of wireless communication access methods. For example, one of them is the TDMA (Time Division Multiple Access) method. In the TDMA, the base station apparatus divides the band on the time axis, thereby forming a plurality of time slots. The base station apparatus performs communication with the terminal apparatus by assigning each of the plurality of time slots to the terminal apparatus. This corresponds to the base station device dividing the band and allocating the divided band to the terminal device. When a plurality of types of priorities are defined, the base station apparatus reserves a band in advance while associating with each priority. That is, the bandwidth is associated with each priority at a predetermined ratio. Further, the base station apparatus allocates a band to the terminal apparatus within the reserved band. In wireless communication, the propagation environment generally varies. When the base station apparatus switches the modulation method or the like according to the propagation environment, the bandwidth of the base station apparatus also varies. As a result, as the bandwidth decreases, the bandwidth that should be allocated to high priority packet signals also decreases.

  The present invention has been made in view of such a situation, and an object of the present invention is to divide a divided band so as to be suitable for fluctuation even when the bandwidth fluctuates when a plurality of types of priorities are defined. It is to provide a communication technology to be assigned to.

  In order to solve the above problems, a control device according to an aspect of the present invention includes a communication unit that transfers a packet signal input from a network to a base station device, and a plurality of types of packet signals that are to be transferred in the communication unit. The priority is defined, and the bandwidth in the base station apparatus is divided at a predetermined ratio while corresponding to each of the plurality of types of priorities, and the packet signal of each priority is within the divided bandwidth range. And a control unit for controlling transfer. When the control unit detects a decrease in the bandwidth at the base station apparatus, the control unit changes the ratio at which the bandwidth is divided so that the decrease in the bandwidth with respect to the high priority packet signal is reduced.

  Another aspect of the present invention is a bandwidth control method. In this method, a plurality of types of priorities are defined for a packet signal to be transferred in the step of transferring the packet signal input from the network to the base station device and the step of transferring. A step of dividing the bandwidth of the base station device at a predetermined ratio while controlling the transfer of packet signals of each priority within the range of the divided bandwidth. In the controlling step, when a decrease in the bandwidth at the base station apparatus is detected, the ratio at which the bandwidth is divided is changed so that the decrease in the bandwidth for the packet signal having a high priority is reduced.

  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.

  ADVANTAGE OF THE INVENTION According to this invention, even if a bandwidth fluctuates when a plurality of types of priorities are defined, a divided band can be allocated to a terminal device so as to be suitable for the fluctuation.

  Before describing the present invention specifically, an outline will be given first. An embodiment of the present invention relates to a communication system including a plurality of base station devices, a plurality of terminal devices, and a control device. The terminal device is connected to one of a plurality of base station devices via a wireless network, and performs wireless communication with the base station device. Since the terminal apparatus and the base station apparatus support the link adaptation function, the bandwidth between the two varies depending on the propagation environment. As a result, the bandwidth of the base station apparatus also varies. On the other hand, in the communication system, multiple types of priorities are defined as service quality. In addition, the band in the base station apparatus is divided while being associated with each of a plurality of types of priorities. When link adaptation is performed and the bandwidth at the base station apparatus is reduced, the bandwidth corresponding to the high priority is also reduced. As a result, service quality corresponding to high priority may not be satisfied. In order to solve such a problem, the communication system according to the present embodiment is configured as follows.

  The control device acquires the bandwidth at the base station device. Further, the control device estimates a bandwidth to be associated with a high priority from the acquired bandwidth. Further, the control device changes the ratio at the time of dividing the band when the estimated reduction amount of the bandwidth is large with respect to the past bandwidth associated with the high priority. That is, the control device changes the ratio so that the bandwidth for the high priority is maintained.

  FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a base station device 10, a first terminal device 12 a, a second terminal device 12 b, a third terminal device 12 c, a network 14, and a control device 16 that are collectively referred to as a terminal device 12.

  The base station apparatus 10 connects the terminal apparatus 12 to one end via a wireless network, and connects the wired network 14 to the other end. 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 base station device 10 broadcasts a broadcast signal, and the terminal device 12 recognizes the presence of the base station device 10 by receiving the broadcast signal. Thereafter, 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 network 14 via the base station device 10 and finally received by a communication device (not shown) connected to the network 14. Data is also transmitted in the direction from the communication device to the terminal device 12. 1 shows one base station apparatus 10, the communication system 100 may include a plurality of base station apparatuses 10, and the terminal apparatus 12 communicates with one of the base station apparatuses 10. If a channel is assigned, communication can be executed.

  Here, the communication system 100 corresponds to an OFDMA (Orthogonal Frequency Division Multiple Access) system. OFDMA is a technique for frequency-multiplexing a plurality of terminal devices using OFDM. In such OFDMA, a plurality of subcarriers form a subchannel, and the plurality of subchannels are frequency division multiplexed. Further, by combining with TDMA, the multicarrier signal is divided into a plurality of time slots on the time axis. That is, 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.

  In the above description, the communication channel is specified by the combination of the subchannel and the time slot described above. As a result, the base station apparatus 10 performs communication with the terminal apparatus 12 by assigning a subchannel in at least one time slot to the terminal apparatus 12. Note that the base station apparatus 10 and the terminal apparatus 12 support link adaptation, and the transmission rate is adjusted according to the propagation environment between them. As a result, the entire bandwidth of the base station apparatus 10 varies depending on link adaptation. Since link adaptation may be a known technique, the description thereof is omitted here.

  The control device 16 is connected to the base station device 10. The control device 16 is also connected to another base station device 10 (not shown). As a result, one paging area is formed by the plurality of base station devices 10 connected to the control device 16. That is, the control device 16 generates a calling signal when it is a transmission from a communication device (not shown) and receives a transmission to the terminal device 12. The control device 16 transmits a call signal to each of the plurality of base station devices 10 via the network 14. Therefore, it can be said that the control device 16 controls the paging area.

  Moreover, although mentioned later for details, the control apparatus 16 controls the traffic with respect to the base station apparatus 10. FIG. Here, in the communication system 100, a plurality of types of service qualities are defined, and a priority is defined for each of the plurality of types of service qualities. For example, high priority is defined for data having a short allowable delay time and a wide required bandwidth, such as a video conference. On the other hand, a low priority is defined for data having a long allowable delay time, such as file transfer. Here, for the sake of clarity, two priorities are considered as priorities, and they are indicated as a high priority and a low priority. The control device 16 divides the band in the base station device 10 for each of high priority data and low priority data while considering the priority. Note that the division ratio is defined in advance. Although details will be described later, when the bandwidth of the base station apparatus 10 changes due to link adaptation or the like, particularly when the bandwidth decreases, the control apparatus 16 adjusts the ratio at the time of division.

  2A to 2C show a frame configuration in the communication system 100. FIG. The horizontal direction in the figure corresponds to the time axis. A frame is formed by time multiplexing of eight time slots. The eight time slots are composed of four downstream time slots and four upstream 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. Furthermore, a super frame is formed by continuing a plurality of frames shown in FIG. Here, as an example, it is assumed that a super frame is formed by “20” frames.

  FIG. 2B shows the configuration of one time slot in FIG. The vertical direction in the figure corresponds to the frequency axis. As illustrated, one time slot is formed by frequency multiplexing of “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”. Here, it is assumed that the allocation of the subchannel in the uplink time slot and the allocation of the subchannel in the downlink time slot are the same. Further, it is assumed that at least one notification signal is assigned in units of superframes. For example, a broadcast signal is allocated to one subchannel in one time slot among a plurality of downlink time slots included in the superframe.

  FIG. 2 (c) shows the configuration of one subchannel of FIG. 2 (b), and FIG. 2 (c) corresponds to the aforementioned packet signal. 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. “SS” corresponds to a signal symbol. “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 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 multi-carrier 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 the network 14 (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.

  The IF unit 26 inputs data for the plurality of terminal devices 12 from the network 14 (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, IF section 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 radio control unit 28 controls the operation of the base station device 10. The radio control unit 28 defines time slots formed by frequency multiplexing of a plurality of subchannels and frames formed by time multiplexing of a plurality of time slots, as shown in FIGS. . Further, the radio control unit 28 instructs the modem unit 24 and the like to form a packet signal, and notifies the broadcast signal from the modem unit 24 via the RF unit 20. The control channel determination unit 32 assigns the broadcast signal to the subchannel. Here, the notification signal is a signal including information used for controlling communication with the terminal device 12. It can be said that the importance of such a notification signal is higher than that of a packet signal including data. The control channel determination unit 32 selects a predetermined subchannel while referring to the storage unit 30. 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 broadcast signal according to the notification from the control channel determination unit 32. The storage unit 30 stores information on subchannels assigned to the terminal device 12 and information on control channels in cooperation with the radio control unit 28. Also, after transmitting the broadcast signal, the radio resource allocation unit 38 receives a subchannel allocation request from the terminal device 12 (not shown) from the RF unit 20 via the modem unit 24. Note that ranging processing is performed between the base station apparatus 10 and the terminal apparatus 12 before receiving the subchannel allocation request, but the description thereof is omitted here. The subchannel allocation request is also called a radio resource acquisition request. The radio resource allocation unit 38 allocates a subchannel to the terminal device 12 that has received the allocation request.

  Here, the radio resource assignment unit 38 assigns the subchannels included in the uplink time slot and the downlink time slot to the terminal device 12. In particular, the subchannel allocation in the uplink time slot and the subchannel allocation in the downlink time slot are made symmetrical. Note that the radio resource allocation unit 38 refers to information such as the MAC protocol type and the upper layer protocol type included in the radio resource acquisition request at the time of subchannel allocation, but details thereof are omitted here. Further, the radio resource allocation unit 38 transmits an allocation notification from the modem unit 24 to the terminal device 12 via the RF unit 20. The allocation notification is also called radio resource allocation.

  The assignment notification includes information on the assigned subchannel and time slot. After the above processing is performed, the wireless control unit 28 causes the RF unit 20 to cause the modem unit 24 to perform communication with the terminal device 12 to which the subchannel is assigned. As described above, a plurality of types of priorities are defined in the data, and the radio resource assignment unit 38 considers the priorities when assigning subchannels. That is, the bandwidth corresponding to each priority is determined, and the radio resource allocation unit 38 allocates subchannels within the determined bandwidth range. As will be described later, the radio resource allocating unit 38 receives information on a determined bandwidth from the control device 16 (not shown) via the IF unit 26.

  Through the control in the radio control unit 28 as described above, the base station device 10 assigns subchannels to each of the plurality of terminal devices 12 and executes communication therewith. Here, as described above, since the communication system 100 supports link adaptation, the modem unit 24 supports multiple types of modulation schemes and multiple types of coding rates. Further, since the transmission rate between each terminal apparatus 12 varies due to link adaptation, the bandwidth of the entire base station apparatus 10 in which they are combined also varies. For example, when the multi-value number of the modulation scheme for one terminal device 12 is changed so as to be small, the radio control unit 28 maintains the same transmission rate for the terminal device 12. Increase the number of subchannels to be allocated to As a result, other terminal devices 12 cannot be allocated to the increased subchannels, and the bandwidth of the entire base station device 10 is reduced. If the transmission process is described in detail, the IF unit 26 receives data from the control device 16 (not shown), and the modem unit 24, the baseband processing unit 22, and the RF unit 20 store the data in a packet signal and transmit it. To do.

  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.

  FIG. 5 shows the configuration of the control device 16. The control device 16 includes an IF unit 50, a buffer unit 52, and a control unit 54. The control unit 54 includes a detection unit 56 and a determination unit 58. The control device 16 mainly performs position registration, call signal generation, and band division control. First, location registration will be described. The IF unit 50 is connected to the base station apparatus 10 (not shown) via the network 14 (not shown). When the IF unit 50 receives a location registration request from the terminal device 12 (not shown), the buffer unit 52 stores the received location registration. The IF unit 50 transmits a location registration response to the location registration request to the terminal device 12. Note that the location registration function may be included in the exchange (not shown) instead of being included in the control device 16.

  Next, generation of a call signal will be described. Further, the IF unit 50 receives a call to the terminal device 12 from a communication device (not shown) via the network 14 (not shown). The detection unit 56 detects the call received by the IF unit 50 and creates a call signal. Since the paging signal may be generated by a known technique, the description is omitted here. IF section 50 transmits the generated call signal to base station apparatus 10 (not shown). The base station apparatus 10 includes other base station apparatuses 10 shown in FIG.

  Finally, band division control will be described. The IF unit 50 receives a packet signal from the network 14 (not shown). The packet signal is a packet signal to be transmitted to the terminal device 12 (not shown) via the base station device 10 (not shown). The IF unit 50 outputs the received packet signal to the buffer unit 52. The buffer unit 52 stores the received packet signal, and outputs the packet signal to the IF unit 50 after a predetermined period has elapsed. Here, the predetermined period is controlled by the control unit 54. The IF unit 50 transfers the received packet signal to the base station apparatus 10.

  As described above, the control unit 54 defines a plurality of types of priorities for the packet signal or data, and assigns a band in the base station apparatus 10 to a predetermined band while associating with each of the plurality of types of priorities. Divide by percentage. For example, the bandwidth at the base station apparatus 10 is 10 Mbps, and high priority data (hereinafter referred to as “high priority packet signal”) and low priority data (hereinafter referred to as “low priority packet signal”). On the other hand, the ratio for dividing the bandwidth is defined as “6: 4”. At that time, the control unit 54 allocates 6 Mbps to the high priority packet signal and 4 Mbps to the low priority packet signal. In addition, the control unit 54 controls the transfer of packet signals of each priority within the divided band range.

  That is, when a plurality of high priority packet signals are stored in the buffer unit 52, the control unit 54 reads out the high priority packet signals within a range of 6 Mbps. Through the processing as described above, the control unit 54 controls traffic when transferring to the base station apparatus 10. Furthermore, when detecting a decrease in the bandwidth at the base station apparatus 10, the control unit 54 changes the ratio at which the bandwidth is divided so that the decrease in the bandwidth with respect to the high priority packet signal is reduced. In the following, this process will be described in more detail.

  The detection unit 56 acquires a bandwidth in the base station device 10. For example, the detection unit 56 calculates the bandwidth based on the data amount of the packet signal transmitted from the IF unit 50 to the base station apparatus 10. Alternatively, the IF unit 50 periodically receives information on the number of subchannels allocated in the base station apparatus 10 and the transmission speed per subchannel from the base station apparatus 10 and calculates the bandwidth based on the received information. To do. As described above, since the base station apparatus 10 performs link adaptation, the transmission rate varies. Therefore, the detection unit 56 receives information over a certain period of time and derives the bandwidth while averaging the information. That is, the detection unit 56 derives an average bandwidth “X”.

  The detection unit 56 also estimates the bandwidth allocated to the high priority packet signal by multiplying the average bandwidth “X” by the ratio “0.6” of the high priority packet signal. Here, the estimated bandwidth is “0.6X”. On the other hand, when the past bandwidth is “W”, the detection unit 56 also derives the bandwidth allocated to the high priority packet signal in the past. Here, the derived bandwidth is “0.6 W”. Further, the detection unit 56 derives a difference “0.6W−0.6X” between the newly estimated bandwidth “0.6X” and the previously derived bandwidth “0.6 W”. If the difference is a positive value, it can be said that the bandwidth has decreased. Also, the difference value at that time can be said to be a reduction amount of the band. That is, the detection unit 56 detects the amount of decrease in the bandwidth at the base station device 10. Since the above processing is periodically executed, the detection unit 56 stores the value of X and uses that value as W after a predetermined period. That is, the part for storing X is configured by FIFO.

  The determination unit 58 receives the amount of decrease detected by the detection unit 56. Further, the determination unit 58 predefines the threshold “Th”. Furthermore, when the reduction amount is larger than the threshold value, that is, when “0.6W−0.6X> Th” is established, the determination unit 58 determines the change of the ratio. The change of the ratio may be adjusted one by one, for example, from “6: 4” to “7: 3”. That is, the determination unit 58 determines the ratio so that the ratio to the high priority packet signal increases as the bandwidth decreases. The control unit 54 controls traffic according to the ratio determined by the determination unit 58. Even when the bandwidth increases, the ratio is adjusted by performing the same operation so that the ratio to the high priority packet signal decreases.

  FIGS. 6A to 6C show an outline of band division in the control device 16. FIG. 6A shows a past band, which corresponds to the state of the above-described bandwidth “W”. Here, the bandwidth “W” is “10 Mbps”, and the ratio between the bandwidth for the high priority packet signal and the bandwidth for the low priority packet signal is defined as “6: 4”. Therefore, as illustrated, 6 Mbps is assigned to the high priority packet signal, and 4 Mbps is assigned to the low priority packet signal. FIG. 6B shows the current band, which corresponds to the aforementioned bandwidth “X”. FIG. 6B corresponds to the case where the division ratio is not adjusted unlike the present embodiment. Here, since the bandwidth “X” is “5 Mbps”, 3 Mbps is allocated to the high priority packet signal.

  Therefore, in the case of FIG. 6B, the bandwidth for the high priority packet signal is reduced by 3 Mbps compared to the case of FIG. As a result, the high priority packet signal corresponding to 3 Mbps is further stored in the buffer unit 52 of FIG. 5, and the delay with respect to the high priority packet signal is increased. FIG. 6C shows the current bandwidth as in FIG. 6B, and the bandwidth “X” is also “5 Mbps”. However, the ratio of division is changed by the determination unit 58 in FIG. 5, and the ratio of the band for the high priority packet signal and the band for the low priority packet signal is set to “9: 1”. As a result, 4.5 Mbps is assigned to the high priority packet signal. Therefore, even if the overall bandwidth is greatly reduced from “10 Mbps” to “5 Mbps”, the reduction of the bandwidth for the high priority packet signal is suppressed to 1.5 Mbps.

  The operation of the communication system 100 configured as above will be described. FIG. 7 is a flowchart showing a packet signal transfer procedure in the control device 16. The IF unit 50 receives the packet signal from the network 14 (S10), and stores the packet signal in the buffer unit 52. If the predetermined period has not elapsed (N in S12), the process waits. On the other hand, if a predetermined period has elapsed (Y in S12), the control unit 54 causes the IF signal 50 to be transmitted to the packet signal stored in the buffer unit 52 in a band corresponding to the priority (S14).

  FIG. 8 is a flowchart showing a procedure for changing the band division in the control device 16. The detection unit 56 acquires the bandwidth of the base station device 10 via the IF unit 50 (S30). Further, the detection unit 56 estimates the bandwidth for the high priority packet signal (S32). If the reduction amount of the bandwidth with respect to the high priority packet signal is larger than the threshold value (Y of S34), the determination unit 58 determines the change of the ratio (S36). On the other hand, if the amount of bandwidth reduction for the high priority packet signal is not greater than the threshold (N in S34), step 36 is skipped and the process is terminated.

  FIG. 9 is a flowchart showing a bandwidth allocation procedure in the base station apparatus 10. If the IF unit 26 receives an instruction to change the ratio from the control device 16 (Y in S50), the wireless control unit 28 changes the ratio (S52). On the other hand, if the IF unit 26 does not receive an instruction to change the ratio from the control device 16 (N in S50), step 52 is skipped. The radio control unit 28 allocates a band to the packet signal according to the ratio (S54).

  According to the embodiment of the present invention, when the bandwidth at the base station apparatus is reduced, the ratio of dividing the bandwidth is changed so that the reduction of the bandwidth with respect to the high priority packet signal is reduced. It is possible to suppress a decrease in the bandwidth for the signal. Further, when a plurality of types of priorities are defined, even if the bandwidth fluctuates, the divided bands can be allocated to the terminal device so as to be suitable for the fluctuation. Even when the bandwidth is reduced, the bandwidth for the low priority packet signal can be secured. Further, since the control device controls the bandwidth corresponding to a plurality of types of priorities, the processing of the base station device can be simplified. Moreover, since the bandwidth for the high priority packet signal is estimated based on the bandwidth of the base station device, the types of information to be acquired from the base station device can be reduced. In addition, since the types of information to be acquired from the base station device are reduced, the processing of the base station device can be simplified. In addition, since the types of information to be acquired from the base station device are reduced, it is possible to suppress deterioration in transmission efficiency.

  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. It is a figure which shows the structure of the control apparatus of FIG. FIGS. 6A to 6C are diagrams showing an outline of band division in the control device of FIG. It is a flowchart which shows the transfer procedure of the packet signal in the control apparatus of FIG. It is a flowchart which shows the change procedure of the band division in the control apparatus of FIG. 5 is a flowchart showing a bandwidth allocation procedure in the base station apparatus of FIG.

Explanation of symbols

  10 base station apparatus, 12 terminal apparatus, 14 network, 16 control 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, 38 Radio resource allocation unit, 50 IF unit, 52 buffer unit, 54 control unit, 56 detection unit, 58 determination unit, 100 communication system.

Claims (4)

A communication unit that transfers a packet signal input from the network to the base station device;
A plurality of types of priorities are defined for packet signals to be transferred in the communication unit, and the band in the base station apparatus is divided at a predetermined ratio while corresponding to each of the plurality of types of priorities. And a control unit for controlling the transfer of packet signals of each priority within the divided bandwidth range,
The control unit, when detecting a decrease in a band in the base station apparatus, changes a ratio when dividing the band so that a decrease in the band with respect to a high priority packet signal is reduced. apparatus. The controller is
A detection unit for detecting a decrease in bandwidth in the base station device;
When the amount of decrease detected in the detection unit is greater than a threshold value, a determination unit that determines a change in the ratio;
The control device according to claim 1, further comprising: Transferring the packet signal input from the network to the base station device;
A plurality of types of priorities are defined for the packet signal to be transferred in the transferring step, and the bandwidth in the base station apparatus is set at a predetermined ratio while corresponding to each of the plurality of types of priorities. Dividing and controlling the transfer of packet signals of each priority within the divided bandwidth range,
The controlling step is characterized in that, when detecting a decrease in bandwidth in the base station apparatus, the ratio at the time of dividing the bandwidth is changed so that the decrease in bandwidth with respect to a high priority packet signal is reduced. Bandwidth control method. Transferring the packet signal input from the network to the base station device;
A plurality of types of priorities are defined for the packet signal to be transferred in the transferring step, and the bandwidth in the base station apparatus is set at a predetermined ratio while corresponding to each of the plurality of types of priorities. Dividing and controlling the transfer of packet signals of each priority within the divided bandwidth range,
In the controlling step, when detecting a decrease in the bandwidth at the base station apparatus, the computer is executed to change a ratio at which the bandwidth is divided so that a decrease in the bandwidth with respect to a packet signal having a high priority is reduced. Program to make.

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