WO2009113623A1 - 無線通信方法、無線通信システム、基地局、及び端末局 - Google Patents
無線通信方法、無線通信システム、基地局、及び端末局 Download PDFInfo
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- WO2009113623A1 WO2009113623A1 PCT/JP2009/054786 JP2009054786W WO2009113623A1 WO 2009113623 A1 WO2009113623 A1 WO 2009113623A1 JP 2009054786 W JP2009054786 W JP 2009054786W WO 2009113623 A1 WO2009113623 A1 WO 2009113623A1
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- 238000000034 method Methods 0.000 title claims description 58
- 230000005540 biological transmission Effects 0.000 claims abstract description 154
- 238000005259 measurement Methods 0.000 claims description 9
- 238000012545 processing Methods 0.000 description 18
- 238000012544 monitoring process Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 6
- 238000011144 upstream manufacturing Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 2
- 108700026140 MAC combination Proteins 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access
- H04W74/08—Non-scheduled access, e.g. ALOHA
- H04W74/0866—Non-scheduled access, e.g. ALOHA using a dedicated channel for access
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
- H04W72/21—Control channels or signalling for resource management in the uplink direction of a wireless link, i.e. towards the network
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access
- H04W74/04—Scheduled access
Definitions
- the present invention relates to a radio communication method, a radio communication system, a base station, and a terminal station that enable dynamic band allocation.
- this network includes a base station 2 connected to a wired network 1 and a large number of wireless terminals 3-1, 3-2,. , An integer).
- the wireless terminals 3-1, 3-2,..., 3-N are directly accommodated in the base station 2.
- each of the wireless terminals 3-1 and 3-2 has established one wireless link 5 with the base station 2.
- the wireless terminal 3-N has established two wireless links 5 with the base station 2.
- the wireless terminals 3-1, 3-2,..., 3-N in this network are battery-activated.
- the wireless terminals 3-1, 3-2,..., 3-N are low power consumption / low function terminals having only a minimum function such as data measurement and measurement data transmission.
- the traffic from the wireless terminals 3-1, 3-2,..., 3-N has (1-1) a small amount of data, (1-2) a relatively long transmission interval, (1-3) data Regarding the occurrence, it has a feature of high periodicity.
- Many such wireless terminals 3-1, 3-2,..., 3-N exist under one base station 2. Therefore, as traffic characteristics, there are many periodic traffics of uplink (information transmission from the wireless terminals 3-1, 3-2,..., 3-N to the base station 2 on the wired network 1 side).
- the overall traffic volume tends to increase. Furthermore, the purpose of this network is to collect data from as many wireless terminals 3-1, 3-2,..., 3-N as possible, so that as many wireless terminals as possible can be transmitted to one base station 2. It is necessary to efficiently accommodate the terminals 3-1, 3-2,..., 3-N. Therefore, in these networks, a single base station 2 efficiently accommodates a large number of low-function wireless terminals 3-1, 3-2,..., 3-N, while having high throughput and low transmission delay time.
- MAC Media Access Control
- FIG. 2 shows an example of a MAC frame in TDMA-TDD (Time Division Multiple Access-Time Division Duplex).
- the MAC frame has a fixed length and is divided into an uplink and a downlink.
- the downlink includes a broadcast area (or section, the same applies hereinafter) and a demand assignment area.
- the uplink includes a demand assignment (DA) area and a random access (RA) area.
- DA demand assignment
- RA random access
- the demand assignment area is a band allocation area for each of the wireless terminals 3-1, 3-2,..., 3-N or each wireless link, and is an area that can be accessed without contention (no contention).
- the random access area is an area used by a plurality of wireless terminals 3-1, 3-2,..., 3-N by random access, and is a contention-based access area.
- Bch Broadcast control channel
- RFch Random access Feedback channel
- Fch Frerame control channel
- Cch Control channel: control channel
- Dch Data channel: data channel
- Rch Random access channel
- Bch is used for frame synchronization and for reporting the attributes (base station ID (identifier), etc.) of the base station 2 to the radio terminals 3-1, 3-2,..., 3-N.
- Fch is a wireless terminal 3-1, 3-2,..., 3 in a demand assignment area in which bandwidth allocation is performed in units of wireless terminals 3-1, 3-2,. -Information on bandwidth allocation for each N or for each radio link (for example, ID, allocation channel, allocation for identifying the wireless terminals 3-1, 3-2, ..., 3-N or the radio link 5 to which the bandwidth is allocated (Location, allocated amount, etc.).
- RFch to notify random access information (random access result of previous frame, random access parameters (Initial Window Size: IWS) and PF (Persistent Factor), starting position of random access in this frame, number of slots, etc.) Used.
- Cch is used to transmit and receive control information for each wireless terminal or each wireless link such as a bandwidth request (Resource Request: RREQ) and ARQ (Automatic Repeat Request).
- Dch is used to send and receive data.
- Rch is a channel for random access, and is used by the radio terminals 3-1, 3-2,..., 3-N or a radio link for random access transmission of the RREQ to the base station 2.
- FIG. 3 shows an example of an uplink data transmission sequence using this method.
- the base station 2 transmits Bch, RFch, and Fch to the wireless terminals 3-1, 3-2,..., 3-N in order from the top of the MAC frame.
- the wireless terminals 3-1, 3-2,..., 3 -N subordinate to the base station 2 can know the start position of random access and the number of slots in the frame by receiving the RFch.
- the wireless terminals 3-1, 3-2,..., 3-N ,..., 3-N or RREQ bandwidth request
- the wireless terminals 3-1, 3-2,..., 3-N indicate the back-off time that is the transmission standby time based on the Exponential (exponential function) back-off algorithm.
- -2, ..., 3-N autonomously determined to avoid collision with Rch from N.
- a uniform random value (integer) within 0 (WS) is generated from 0.
- the random value is set as the number of back-off slots.
- the time required for the number of back-off slots to pass is defined as the back-off time.
- IWS notified by RFch is used as WS.
- the wireless terminals 3-1, 3-2,..., 3 -N transmit RREQ to the base station 2 in the Rch slot immediately after completion of standby when the back-off time is completed. If there is a collision with Rch from other wireless terminals 3-1, 3-2,..., 3-N, the RREQ is retransmitted by applying the Exponential backoff algorithm. When the RREQ is correctly received, the base station 2 notifies successful reception of the RREQ using the RFch of the next frame, and allocates Dch corresponding to the bandwidth request value from the RREQ.
- an ARQ (ARQ-ACK / ARQ-NACK) Cch for transmitting an arrival confirmation for the Dch to the wireless terminal 2 is assigned.
- the wireless terminals 3-1, 3-2,..., 3-N receive CRQ for ARQ-ACK, the data transmission processing is completed.
- the RREQ is retransmitted by applying the Exponential back-off algorithm.
- the present invention has been made in view of the above circumstances, and an object of the present invention is to reduce overhead associated with a collision by reducing random access traffic, and to connect a base station and a radio connected to the base station via a radio line.
- An object of the present invention is to provide a radio communication method, a radio communication system, a base station, and a terminal station that can improve throughput characteristics and delay characteristics between terminals.
- the present invention has been made to solve the above-described problems.
- a wireless communication method a plurality of terminal stations are connected to a base station through a common wireless line.
- the bandwidth for bandwidth allocation in the uplink communication band in the radio frame is managed as a demand assignment section, and the remaining band is managed as a random access section, and the upstream communication band required for the bandwidth request information from the terminal station
- the terminal station performs random access transmission of bandwidth request information to the random access section after the back-off time elapses, and allocates from the base station when the transmission is successful.
- the base station is configured to transmit the terminal data for each terminal station or between the terminal station and the base station. Even if a bandwidth request for random access is not received from the terminal station in the demand assignment section that exists in a specific period of high transmission frequency of the transmission data specified for each link, for each terminal station or the wireless Band allocation is performed for each link, and the terminal station transmits band request information or the transmission data in the band for which the base station has allocated the band.
- the specific period is set to start or end based on an instruction from the outside of the base station.
- the specific period is set to start time or end time corresponding to a signal exchange sequence for each wireless link.
- the specific period is set to start time corresponding to bandwidth allocation for the terminal station or the wireless link.
- the specific period is a time-out of an internal timer set at the start time, or the demand assignment section where the base station exists in the specific period.
- the specific period is based on measurement information of the transmission data transmitted to the base station for each terminal station or for each wireless link, Alternatively, the end time is estimated and set.
- bandwidth allocation for each terminal station or each wireless link in the demand assignment section existing in the specific period satisfies a specified timing or a specified condition. It is done at the timing.
- a plurality of terminal stations are connected to a base station through a common wireless channel, and the base station is for bandwidth allocation among uplink communication bands in a wireless frame. Is assigned as a demand assignment interval, and the remaining bandwidth is managed as a random access interval, and a requested uplink communication bandwidth is assigned to the demand assignment interval in response to bandwidth request information from the terminal station.
- wireless communication is performed such that, after the back-off time elapses, bandwidth request information is randomly accessed and transmitted in a random access section, and when transmission is successful, the transmission data is transmitted using a bandwidth allocated from the base station.
- the base station specifies the transmission data specified for each terminal station or for each radio link between the terminal station and the base station. Even if a bandwidth request for random access is not received from the terminal station in the demand assignment section existing in a specific period with high transmission frequency, bandwidth allocation is performed for each terminal station or each radio link, and the terminal The station transmits band request information or the transmission data in a band to which the base station has assigned a band.
- a plurality of terminal stations are connected to the base station through a common radio channel, and the base station is used for bandwidth allocation in the uplink communication band in the radio frame.
- the bandwidth is managed as a demand assignment section, and the remaining bandwidth is managed as a random access section, and a requested uplink communication band is allocated to the demand assignment section in response to the bandwidth request information from the terminal station.
- a plurality of terminal stations are connected to a base station through a common radio channel, and the base station is used for bandwidth allocation in an uplink communication band in a radio frame.
- the bandwidth is managed as a demand assignment section, and the remaining bandwidth is managed as a random access section, and the requested upstream communication bandwidth is allocated to the demand assignment section in response to the bandwidth request information from the terminal station.
- the base station specified for each terminal station or for each radio link between the terminal station and the base station Even when a bandwidth request for random access is not transmitted in the demand assignment section existing in a specific period with high transmission frequency of communication data, the base station performs bandwidth allocation for each terminal station or each wireless link.
- the bandwidth request information or the transmission data is transmitted in the bandwidth.
- a period during which uplink data transmission frequency is high is specified for each radio terminal or radio link that is a terminal station, and for the specified period (specific period), the radio terminal Alternatively, a bandwidth for uplink data transmission to the radio link is allocated. Therefore, random access traffic can be reduced when the base station performs bandwidth allocation for uplink transmission in advance.
- 6 is a flowchart of a process for releasing a bandwidth allocation link for uplink transmission according to an embodiment of the present invention.
- 4 is a flowchart of bandwidth allocation processing for uplink transmission according to an embodiment of the present invention.
- 6 is a flowchart of a registration determination process for a bandwidth allocation link for uplink transmission according to an embodiment of the present invention.
- 6 is a flowchart of a process for releasing a bandwidth allocation link for uplink transmission according to an embodiment of the present invention.
- the basic configuration of the wireless system according to the embodiment of the present invention is the same as the conventional one. That is, as shown in FIG. 1, it is composed of a base station 2 connected to the wired network 1 and a large number of wireless terminals 3-1, 3-2,. Wireless terminals 3-1, 3-2,..., 3 -N serving as terminal stations are directly accommodated in the base station 2. In this case, a server 4 is connected to the wired network 1. Further, the base station 2 and the plurality of wireless terminals 3-1, 3-2,..., 3-N are connected by wireless links 5, respectively.
- the base station 2 dynamically allocates a band in response to a request from the wireless terminals 3-1, 3-2,..., 3-N, the TDMA-TDD shown in FIG. A case where the MAC frame in FIG.
- a plurality of wireless terminals 3-1, 3-2,... is connected to the base station 2 by (consisting of each wireless link 5).
- the base station 2 manages a band for band allocation among uplink communication bands in a MAC frame that is a radio frame as a demand assignment section, and manages the remaining bands as a random access section. Then, the base station 2 allocates the requested upstream communication bandwidth to the demand assignment section for the bandwidth request information from the wireless terminals 3-1, 3-2,.
- the wireless terminals 3-1, 3-2,..., 3-N transmit the band request information to the slots in the random access section after the back-off time has elapsed.
- the wireless terminals 3-1, 3-2,..., 3-N transmit the band request information at random after the back-off time has elapsed. If the transmission is successful, the base station 2 allocates the upstream communication band to the demand assignment section, and the wireless terminals 3-1, 3-2,..., 3-N transmit using the allocated band. Send data. In the embodiment of the present invention, as described below, it is possible to specify a period in which the transmission frequency of uplink transmission data is high.
- the base station 2 performs dynamic bandwidth allocation for allocating bandwidth for uplink data transmission to the wireless terminals 3-1, 3-2,..., 3-N or the wireless link 5.
- uplink transmission data is provided for each radio terminal 3-1, 3-2,..., 3-N or for each radio link 5.
- the period in which the transmission frequency of the message is high is specified as the “specific period”.
- an uplink data transmission band for the wireless terminals 3-1, 3-2,..., 3-N or the wireless link 5 is allocated to the specific period. This eliminates the need for RREQ (bandwidth request) transmission using random access from the wireless terminals 3-1, 3-2,..., 3-N, and reduces the amount of random access traffic.
- This specific period is a time corresponding to one or more frames of the MAC frame in FIG.
- FIG. 4 and 5 are diagrams showing an example of an access sequence when the bandwidth allocation method according to the embodiment of the present invention is applied to the wireless system of FIG.
- the specific period is set as one MAC frame (MAC Frame (1)) as an example.
- RREQ Cch is assigned to the corresponding wireless terminal 3-1, 3-2,..., 3 -N or the wireless link 5 as an uplink (UL) transmission allocated band.
- DA uplink
- an ARQ Cch may be assigned to that Cch.
- the transmission data Dch is assigned to the corresponding wireless terminals 3-1, 3-2,..., 3-N or the wireless link 5 as the allocated bandwidth for uplink transmission.
- the allocated bands (channels) for uplink (UL) transmission in a specific period include the following (i) and (ii).
- FIG. 6 shows a basic configuration example of the base station 2.
- the base station 2 includes a transmission unit 21, a reception unit 22, a radio control unit 23, and a band allocation unit 24 in order to realize radio communication.
- the base station 2 includes a connection control unit 25 in order to manage communication with the wired side including the wired network 1 of FIG. 1, the transmission unit 21 and the reception unit 22 that perform wireless communication with the wireless terminals 3-1, 3-2,..., 3-N perform transmission and reception in units of wireless channels.
- the radio control unit 23 performs radio frame generation / decomposition, control of the transmission unit 21 and the reception unit 22, and band management for each radio link.
- the bandwidth allocation unit 24 performs scheduling.
- the base station 2 determines a specific period according to an instruction from the wired network 1, for example, the server 4.
- the connection control unit 25 receives an instruction from the wired network 1, specifies the wireless link 5 corresponding to the instruction, and notifies the wireless control unit 23 of a start / end instruction for a specified period for the specified wireless link 5. To do.
- the timing at which the instruction from the wired network 1 is received may be used as the start / end instruction for the specific period, or the start / end timing of the specific period included in the instruction from the wired network 1 may be used as the start / end instruction for the specific period. It is good.
- the timing may be time, or may represent time or information that can be calculated, for example, a frame number of a MAC frame.
- the start / end of the specific period is the received time or the instructed time
- the frame number is the frame in which the instruction is received or the instructed frame.
- the wireless control unit 23 sets the start of the specific period by receiving the start instruction from the connection control unit 25 and sets the end of the specific period by receiving the end instruction.
- FIG. 7 shows a control flow of the base station 2. In FIG. 7, the structure of the base station 2 of FIG. 6 is shown. In FIG. 7, the flow of information when a specific period is determined by an instruction from the connection control unit 25 or the wired network 1 is indicated by a broken line.
- a broken line (f1) indicates the present embodiment, and the connection control unit 25 instructs the wireless control unit 23 to start and end the specific period in response to an instruction from the server 4 (see FIG. 1) of the wired network 1. Shows when to do.
- the base station 2 specifies the data exchange sequence performed in the radio link 5 from the known data exchange sequence group. By doing so, the specific period is determined.
- the connection control unit 25 receives data from the wireless side or the wired side, identifies the first data of the data exchange sequence from the data type in the data, and thus extracts the corresponding sequence from the known data exchange sequence group.
- the wireless control unit 23 is instructed to specify the reception timing of the first data of the corresponding sequence as the start of the specific period and the reception timing of the last data as the end of the specific period.
- the wireless control unit 23 sets the start of the specific period by receiving the start instruction from the connection control unit 25 and sets the end of the specific period by receiving the end instruction.
- FIG. 7 shows a control flow of the base station 2.
- a broken line (f2) indicates the present embodiment, and shows a case where the connection control unit 25 instructs the start and end of the specific period.
- the reception timing may be time, information representing time, or information from which time can be calculated, for example, a frame number of a MAC frame. In the case of time, the start / end of the specific period is the received time, and in the case of the frame number, it is the received frame.
- a radio link monitoring unit 26 is provided between the receiving unit 22 and the radio control unit 23, and the communication status and bandwidth of the radio link 5 at the base station 2 Monitor the allocation status and determine a specific period. That is, the start of the specific period is made according to the band allocation timing (for example, Dch allocation in the present embodiment) for the radio link 5 to be monitored. At this time, the Dch to be monitored may be (2-1) uplink Dch only, (2-2) downlink Dch only, or (2-3) uplink and downlink Dch. On the other hand, the end of the specific period may be the following cases (a) to (c).
- the conditions described in (a) to (c) above may be used alone or in combination.
- the timing at which the number of times of transmission of the bandwidth allocation information or transmission data for the allocated bandwidth reaches the specified number, or the reception timing of the bandwidth allocation information for the allocated bandwidth is terminated.
- the bandwidth allocation timing, the timeout timing, the timing when the specified number is reached, and the reception timing may be time, or may be information representing the time or calculating the time, for example, the frame number of the MAC frame.
- the bandwidth allocation time, the timeout time, the time when the specified number is reached, and the reception time In the case of the frame number, the bandwidth allocation frame, the time-out frame, the specified number
- the received frame is the received frame.
- a radio traffic measurement unit 27 is provided between the reception unit 22 and the radio control unit 23, and uplink transmission data of the radio link 5 at the base station 2.
- (Dch) traffic may be measured, and the specific period may be estimated based on the measurement result. At this time, the specific period is determined from the following measurement information.
- the wireless terminals 3-1, 3-2 to 3-N transmit the transmission data with the data generation information added thereto, and the base station 2 receives the data before receiving the data.
- the data generation interval is calculated by taking the difference from the data generation information.
- a specific period for the next data is determined at the time of data (Dch) reception based on a fixed interval or an occurrence interval measured for a specified number of data.
- the start of the specific period is defined as the last received data occurrence information + minimum occurrence interval
- the end of the specific period is defined as the last received data occurrence information + longest occurrence interval.
- the base station 2 stores the reception information of the data, and calculates the reception interval of the transmission data at the base station 2 by taking the difference from the reception information of the previous data. Then, a specific period for the next data is determined at the time of data (Dch) reception based on a predetermined interval or a reception interval measured for a specified number of data. At this time, the start of the specific period is defined as reception information of the last received data + minimum reception interval, and the end of the specific period is defined as reception information of the last received data + longest reception interval.
- the generation information and the reception information may be time information, or information representing time or calculating time, for example, a frame number of a MAC frame (fixed length). When the generation information and the reception information are defined by time, the generation information and the reception information are respectively the generation time and the reception time.
- the above (III) is a combination of the above configuration (I) and (II).
- the configuration / operation of (I) is applied to the start of a specific period, and the end is determined by monitoring of (II).
- the start is determined by the monitoring in (II) above, and the configuration / operation of (I) is applied for the end.
- the configurations of (I) and (II) are combined for the setting at the start and end.
- (A) includes, for example, every frame, every specified number of frames, and after the specified number of frames from the start of a specific period.
- (B) applies (A) when the specified condition is satisfied.
- the specified condition the wireless terminals 3-1, 3-2,. 5, when there is data allocation of downlink (information transmission from the base station 2 to the wireless terminals 3-1, 3-2,..., 3-N), For example.
- FIG. 10 shows a sequence example at the time of authentication processing applied in the first and second embodiments.
- the wireless terminals 3-1, 3-2,..., 3-N perform authentication processing to start wireless communication after establishing synchronization with the base station 2.
- the wireless terminals 3-1, 3-2,..., 3-N acquire the MAC-ID that is an ID for the base station 2 to identify the wireless terminal 2 in the wireless section.
- a MAC-ID assignment request is randomly accessed and transmitted to the base station 2 (step S11).
- the wireless terminal 2 receives the MAC-ID assignment response from the base station 2 (step S12).
- an authentication processing sequence (authentication request, authentication response, authentication completion) which is one of known data exchange sequences is performed. That is, the wireless terminals 3-1, 3-2,..., 3-N transmit an authentication request to the base station 2 (step S13). Then, the wireless terminals 3-1, 3-2,..., 3-N receive an authentication response from the base station 2 (step S14). Then, the wireless terminals 3-1, 3-2,..., 3-N transmit authentication completion to the base station 2 (step S15). This process is performed at the initiative of the connection control unit 25, and data to be exchanged is sequential.
- Bandwidth allocation for uplink (UL) transmission is performed for this sequence.
- the determination of the specific period can be applied based on monitoring of the data exchange sequence of the radio link 5 (corresponding to FIG. 7) or based on monitoring of the bandwidth allocation status of the radio link 5 (corresponding to FIG. 8).
- the connection control unit 25 in FIG. 7 issues a start instruction after receiving the authentication request that is the first data in the authentication processing sequence.
- the wireless control unit 23 is notified (step S16).
- the connection control unit 25 notifies the end instruction after receiving the authentication completion, which is the last data in the authentication processing sequence (step S17).
- the wireless control unit 23 regards the start instruction and the end instruction as the start and end of the specific period.
- the wireless link 5 that performs the authentication process is monitored, and the start of the Dch bandwidth allocation for the wireless link 5 is set as the start of the specific period.
- the base station 2 counts the number of unaccessed bandwidths assigned to the wireless link 5 in a specific period, and when the specified value is reached, the communication of the wireless link 5 is considered to be completed, and the specific period ends.
- the end time is not determined at the start of the specific period (when a method other than the method for determining the specific period by estimation is used), and the specific period is set for the authentication processing sequence.
- a case where frame allocation is performed will be described.
- the bandwidth allocation method for uplink (UL) transmission in the specific period described above is set to each frame in (A) above, and the bandwidth allocated for uplink (UL) transmission is set to RREQ in (i) above.
- An allocation process in the case of allocating one Cch per frame as a Cch for (bandwidth request) will be described.
- FIG. 11 shows registration determination processing for a bandwidth allocation link for uplink (UL) transmission.
- step Sa1 It is determined whether or not the wireless link 5 for which the specific period has started can be registered as a bandwidth allocation link for uplink (UL) transmission (step Sa1). If registration is possible, an RREQ Cch band is allocated to the radio link 5 until the specific period ends (step Sa2). At this time, the Cch band for RREQ is regarded as a priority reserved band.
- the priority reserved bandwidth is a bandwidth that is always secured.
- the priority reserved total bandwidth value (the RREQ Cch bandwidth for the wireless link 5 added to the already registered priority reserved bandwidth) and its maximum value (preset value) are obtained. Compare. If it is equal to or less than the maximum value, the bandwidth for RREQ is determined as a priority secured bandwidth in step Sa2, and the link is registered as a bandwidth allocation link for uplink (UL) transmission. At the time of scheduling by the bandwidth allocation unit 24, Cch for RREQ is allocated to all links registered as bandwidth allocation links for uplink (UL) transmission. When the maximum value is exceeded, the added Cch band is subtracted from the priority secured total band value and returned to the value before comparison.
- Fig. 12 shows the cancellation processing of the bandwidth allocation link for uplink (UL) transmission. This process is performed at the end of the specific period, and the link is released from the bandwidth allocation link for uplink (UL) transmission (step Sb1). Then, the priority total bandwidth value is updated by subtracting the RREQ bandwidth for the link from the priority total bandwidth value (step Sb2).
- the end time is not determined at the start of the specific period (when a method other than the method for determining the specific period by estimation is used), and the specific period is set for the authentication processing sequence.
- An example of assignment when assignment conditions are provided will be described.
- a case will be described in which a bandwidth allocation method for uplink (UL) transmission in a specific period matches the allocation condition (B).
- the allocation condition is when downlink Dch transmission occurs, and the UL transmission band is allocated only once after the same frame. In FIG. 10, it corresponds to the message transmission of the authentication response.
- an allocation process when the allocated bandwidth for uplink (UL) transmission is Dch for data transmission of (ii) will be described.
- the allocated bandwidth is not Dch for RREQ but Dch for data transmission, but is not limited to this.
- the exchanged message has a fixed length and is sequential as in the authentication processing sequence, direct allocation of Dch is possible.
- a radio link that has started a specific period is registered as a bandwidth allocation link for uplink (UL) transmission.
- the radio link whose specific period has ended is released from the uplink (UL) transmission bandwidth allocation link.
- the allocation to the priority reserved bandwidth described in the first embodiment is performed, and then the allocated bandwidth is subtracted to calculate an allocatable bandwidth (remaining bandwidth).
- the bandwidth allocation processing for uplink (UL) transmission shown in FIG. 13 is performed for all links of the bandwidth allocation link for uplink (UL) transmission.
- it is determined whether or not the allocation condition is met is met (step Sc1). If they match, it is determined whether the bandwidth for uplink (UL) transmission can be secured by comparing the remaining bandwidth with the allocated bandwidth for uplink (UL) transmission (step Sc2).
- the allocated bandwidth value for uplink (UL) transmission is equal to or less than the remaining bandwidth value, allocation is possible, and as the bandwidth allocation processing for uplink (UL) transmission, Dch for data transmission to the corresponding radio link 5 Is assigned (step Sc3). At this time, the remaining bandwidth is updated by subtracting the allocated bandwidth value from the remaining bandwidth value.
- step Sc1 if the allocation condition is not satisfied (“No” in step Sc1), the bandwidth allocation processing for uplink (UL) transmission to the radio link is not performed.
- step Sc4 bandwidth allocation for uplink (UL) transmission in the next and subsequent frames.
- This process secures the allocated bandwidth for the uplink (UL) bandwidth allocation link satisfying the allocation condition as the priority secured bandwidth (described in the first embodiment) after the next frame, and allocates it reliably after the next frame.
- the priority is reserved.
- the allocated bandwidth for uplink (UL) transmission is Dch for data transmission, but it can also be applied to Cch for RREQ.
- the end time is determined at the start of the specific period (when the method for determining the specific period by estimation is used), and data uplink (UL) transmission is performed in the communication of the radio link 5.
- the determination of the specific period is performed based on traffic estimation using the generation information (II).
- the data generation interval is calculated by taking the difference from the previous data generation information.
- the generation period of the next data is predicted from the measured generation interval, and the prediction period is set as the specific period.
- the generation intervals are measured by wireless terminals 3-1, 3-2,..., 3-N attaching generation information to data and transmitting the data. Hold for minutes and calculate.
- the start of the specific period is defined as the last received data generation information + the shortest generation interval.
- the end of the specific period is defined as the last received data generation information + the longest generation interval.
- a threshold that is an upper limit value of the specific period may be provided for the specific period in the present embodiment, and the following uplink (UL) transmission band allocation may be performed for the radio link 5 that is equal to or less than the threshold. .
- UL uplink
- the bandwidth allocation method for uplink (UL) transmission in a specific period is set to each frame of (A) above, and the allocated bandwidth for uplink (UL) transmission is set to Cch for RREQ in (i) above.
- An allocation process when one Cch is allocated for each frame will be described.
- FIG. 14 shows registration determination processing for a bandwidth allocation link for uplink (UL) transmission. First, it is determined whether or not the wireless link 5 whose specific period has started can be registered as a bandwidth allocation link for uplink (UL) transmission (step Sd1). If registration is possible, an RREQ Cch band is allocated to the radio link in all frames in a specific period.
- the CREQ band for RREQ is regarded as a priority reserved band.
- the priority reserved bandwidth it is determined whether or not the priority reserved bandwidth can be secured in all the frames in the specific period.
- the method described in the first embodiment can be used to determine the priority reserved bandwidth. If the RREQ bandwidth can be determined as the priority secured bandwidth in all frames, the link is registered as a bandwidth allocation link for uplink (UL) transmission (step Sd2). At the time of scheduling by the bandwidth allocation unit 24, Cch for RREQ is allocated to all links registered as bandwidth allocation links for uplink (UL) transmission.
- FIG. 15 shows a process for releasing a bandwidth allocation link for uplink (UL) transmission. This process is performed when the specific period expires or when the specific period ends midway. At the time of uplink reception, the link is released from the bandwidth allocation link for uplink (UL) transmission (step Se1). Then, it is determined whether or not the specific period has expired (step Se2). When the specific period has expired (“Yes” in step Se2), the processing illustrated in FIG. 15 is terminated.
- step Se2 If it ends in the middle of a specific period (“No” in step Se2), that is, if a bandwidth request is received by random access, or if a bandwidth request is received by bandwidth allocation for uplink transmission, unallocated
- the priority secured total bandwidth value is updated by subtracting the RREQ bandwidth for the link from the priority secured total bandwidth value for the frame (step Se3).
- the above embodiment is a communication method in the case where, for example, a plurality of wireless terminals 3-1, 3-2,..., 3-N share a wireless line composed of a plurality of wireless links 5.
- DSA dynamic slot
- a demand assignment section and a random access section are set in the uplink section in the MAC frame.
- the wireless terminals 3-1, 3-2,..., 3-N transmit a bandwidth allocation request to the base station 2 in the random access section.
- the wireless terminals 3-1, 3-2,..., 3-N transmit the transmission data in the allocated bandwidth to the base station 2. Send to.
- the wireless terminals 3-1, 3-2,..., 3 -N repeat transmitting the bandwidth allocation request again after the back-off time has elapsed. Then, a period in which the transmission frequency of uplink transmission data is high is analyzed and determined for each of the wireless terminals 3-1, 3-2,..., 3-N or for each wireless link 5. In this specific period, the base station 2 allocates a demand assign band to the wireless terminals 3-1, 3-2 to 3 -N or the wireless link 5. That is, the base station 2 identifies (specific period) a period in which the uplink data transmission frequency is high for each of the radio terminals 3-1, 3-2,.
- an uplink data transmission band for the wireless terminals 3-1, 3-2,..., 3-N or the wireless link 5 is allocated to the period.
- a method for determining the specific period a method based on an instruction from the outside, a method of monitoring a bandwidth allocation state or estimating traffic in the base station 2 can be used.
- the base station 2 since the base station 2 performs bandwidth allocation for uplink (UL) transmission in advance, the wireless terminals 3-1, 3-2,. It is not necessary to transmit a bandwidth allocation request. Therefore, random access (RA) traffic can be reduced. That is, according to the embodiment of the present invention, there is an effect that data collision in a random access section can be suppressed even during a period in which traffic is concentrated, and throughput can be improved.
- each said embodiment was demonstrated based on the frame structure of the prior art shown in FIG. 2, it is not limited to this.
- the present invention can be applied even to a frame in which the order of Bch, RFch, Fch, etc. is switched.
- Each configuration of the above-described embodiment of the present invention (each block shown in FIGS. 6 to 9) can be realized by a combination of a computer and its peripheral devices and a program executed by the computer. Changes such as division and integration of the components can be made as appropriate.
- the present invention can reduce overhead due to collision by reducing random access traffic, and improve throughput characteristics and delay characteristics between a base station and a radio terminal connected to the base station by a radio channel. It can be applied to a wireless communication method, a wireless communication system, a base station, a terminal station, and the like.
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Abstract
Description
本願は、2008年3月12日に、日本に出願された特願2008-062531号に基づき優先権を主張し、その内容をここに援用する。
図1に示すように、本ネットワークは、有線ネットワーク1に接続された基地局2と、広域に点在する多数の無線端末3-1、3-2、・・・、3-N(Nは、整数)から構成される。無線端末3-1、3-2、・・・、3-Nは、基地局2に直接収容される。図1では、無線端末3-1、3-2は、基地局2とそれぞれ1つの無線リンク5を確立している。また、無線端末3-Nは、基地局2と2つの無線リンク5を確立している。
なお、有線ネットワーク1に接続される基地局2は複数であってもよい。
図2に、TDMA-TDD(Time Division Multiple Access - Time Division Duplex)におけるMACフレームの一例を示す。MACフレームは、固定長であり、上りリンクと下りリンクの2つに分かれている。下りリンクは、報知領域(あるいは区間、以下同じ)とデマンドアサイン領域で構成されている。上りリンクは、デマンドアサイン(DA)領域とランダムアクセス(RA)領域で構成されている。
デマンドアサイン領域は、無線端末3-1、3-2、・・・、3-N或いは無線リンク毎の帯域割当領域であり、コンテンションフリー(競合なし)でアクセス可能な領域である。一方、ランダムアクセス領域は、複数の無線端末3-1、3-2、・・・、3-Nがランダムアクセスにより使用する領域であり、コンテンションベースのアクセス領域である。また、データや制御情報を送受信するために、Bch(Broadcast control channel:ブロードキャスト制御チャネル)、RFch(Random access Feedback channel:ランダムアクセスフィードバックチャネル)、Fch(Frame control channel:フレーム制御チャネル)、Cch(Control channel:制御チャネル)、Dch(Data channel:データチャネル)、Rch(Random access channel:ランダムアクセスチャネル)が使用される。Bchは、フレーム同期用で、かつ、無線端末3-1、3-2、・・・、3-Nに基地局2の属性(基地局ID(識別子)等)を報知するために用いられる。Fchは、無線端末3-1、3-2、・・・、3-N単位或いは無線リンク単位で帯域割当を行うデマンドアサイン領域での無線端末3-1、3-2、・・・、3-N毎或いは無線リンク毎の帯域割当に関する情報(例えば、帯域を割り当てた無線端末3-1、3-2、・・・、3-Nあるいは無線リンク5を特定可能なID、割当チャネル、割当位置、割当量等)を通知するために用いられる。RFchは、ランダムアクセス情報(前フレームのランダムアクセス結果、ランダムアクセスパラメータ(Initial Window Size: IWS)とPF(Persistent Factor)、本フレームでのランダムアクセスの開始位置及びスロット数等)を通知するために用いられる。Cchは、帯域要求(Resource Request: RREQ)やARQ(Automatic Repeat Request)等の無線端末毎あるいは無線リンク毎の制御情報を送受信するために使用される。Dchはデータを送受信するために使用される。Rchは、ランダムアクセスのためのチャネルであり、無線端末3-1、3-2、・・・、3-N或いは無線リンクが上記RREQを基地局2へランダムアクセス送信するために使用される。
図3は、この方法を用いたアップリンクのデータ送信シーケンスの一例を示している。本例では、基地局2は、MACフレーム(MAC Frame)の先頭から順にBch、RFch、Fchを無線端末3-1、3-2、・・・、3-Nに送信する。基地局2配下の無線端末3-1、3-2、・・・、3-Nは、RFchを受信することで、そのフレームでのランダムアクセスの開始位置、スロット数を知ることができる。無線端末3-1、3-2、・・・、3-Nは、基地局2にデータを送信する場合、送信データのための帯域を要求するために、無線端末3-1、3-2、・・・、3-Nあるいは無線リンク5を特定するIDを含むRREQ(帯域要求)をRchで送信する。このとき、無線端末3-1、3-2、・・・、3-NはExponential(指数関数)バックオフアルゴリズムに基づいた送信待機時間であるバックオフ時間を、他無線端末3-1、3-2、・・・、3-NからのRchとの衝突を回避するために自律的に決定する。このアルゴリズムでは、0からWS(Window Size)内の一様乱数値(整数)を生成する。そして、その乱数値を、バックオフスロット数とする。そして、そのバックオフスロット数の経過に要する時間を、バックオフ時間とする。また、最初のランダムアクセス時には、RFchで通知されているIWSをWSとして用いる。
無線端末3-1、3-2、・・・、3-Nは、バックオフ時間が完了した時点で、RREQを待機完了直後のRchスロットで基地局2に送信する。もし、他の無線端末3-1、3-2、・・・、3-NからのRchと衝突した場合、Exponentialバックオフアルゴリズムを適用してRREQを再送する。基地局2では、RREQを正しく受信できた場合に、次フレームのRFchでRREQの受信成功を通知し、RREQから帯域要求値に相当するDchを割り当てる。また、そのDchを割り当てた次のフレームにおいて、そのDchに対する到達確認を無線端末2に送信するためのARQ(ARQ - ACK / ARQ - NACK)用のCchを割り当てる。
無線端末3-1、3-2、・・・、3-Nは、ARQ - ACK用のCchを受信した場合は、そのデータの送信処理を完了する。一方、ARQ - NACK用のCchを受信した場合は、Exponentialバックオフアルゴリズムを適用してRREQを再送する。
太田厚、布房夫、望月伸晃ほか、"5GHz帯アドバンスドワイヤレスアクセス(AWA)システムの開発-MAC/DCL機能"、2000年電子情報通信学会ソサイエティ大会、B-5-39、P. 327、2000年
2・・・基地局、
3-1、3-2~3-N・・・無線端末、
4・・・サーバ、
5・・・無線リンク、
21・・・送信部、
22・・・受信部、
23・・・無線制御部、
24・・・帯域割当部、
25・・・コネクション制御部、
26・・・無線リンク監視部、
27・・・無線トラヒック測定部
なお、以下の説明では、基地局2が無線端末3-1、3-2、・・・、3-Nからの要求に応じて帯域を動的に割り当てる際に、図2に示すTDMA-TDDにおけるMACフレームを用いる場合について説明する。
本発明の実施形態においては、以下に述べるようにして、アップリンクの送信データの送信頻度が高い期間を特定できる。また、基地局2は、その特定した期間のデマンドアサイン区間に、無線端末3-1、3-2、・・・、3-Nからランダムアクセスでの帯域要求を受信していない場合でも、当該無線端末3-1、3-2、・・・、3-N或いは無線リンク5に対するアップリンクのデータ送信用の帯域を割り当てる動的帯域割当を行う。
一方、図5では、アップリンク送信用の割当帯域として、送信データ用のDchを、該当する無線端末3-1、3-2、・・・、3-N或いは無線リンク5に対して、デマンドアサイン(DA)領域に割り当てている。図4では、特定期間において、CchでRREQ(帯域要求)を送信することで、ランダムアクセス(RA)領域への送信を行わないようにしている。一方、図5では、Dchで送信データを直接送信することで、ランダムアクセス(RA)領域への送信を行わないようにしている。本例において示したように、特定期間におけるアップリンク(UL)送信用の割当帯域(チャネル)としては、以下の(i)、(ii)がある。
(ii) 送信データ用のDch
(II) 基地局2での監視/推定に基づいて決定する場合、
(III) (I)と(II)を組み合わせる場合
このとき、有線ネットワーク1からの指示を受信したタイミングを特定期間の開始/終了指示としてもよいし、有線ネットワーク1からの指示に含まれる特定期間の開始/終了タイミングを特定期間の開始/終了指示としてもよい。なお、タイミングは、時間でもよいし、時間を表す、或いは、時間を算出できる情報、例えば、MACフレームのフレーム番号でもよい。時間の場合、特定期間の開始/終了は、受信した時間、或いは指示された時間となり、フレーム番号は、指示を受信したフレーム、或いは、指示されたフレームとなる。
無線制御部23は、コネクション制御部25から開始指示を受信することで特定期間の開始を設定し、終了指示を受信することで特定期間の終了を設定する。図7に基地局2の制御フローを示す。図7では、図6の基地局2の構成を示している。また、図7では、コネクション制御部25或いは有線ネットワーク1からの指示により特定期間を決定する際の情報の流れを破線で示している。破線(f1)は、本実施形態を示しており、有線ネットワーク1のサーバ4(図1参照)からの指示を契機に、コネクション制御部25が特定期間の開始と終了を無線制御部23へ指示する場合を示している。
上記(II)のうちで、無線リンク5毎のデータ交換シーケンスを監視する場合においては、基地局2は、既知のデータ交換シーケンス群から、その無線リンク5で行われているデータ交換シーケンスを特定することにより、特定期間を決定する。例えば、コネクション制御部25は、無線側あるいは有線側からのデータを受信し、データ中のデータ種別からデータ交換シーケンスの最初のデータを識別することで、既知のデータ交換シーケンス群から、該当シーケンスを特定し、該当シーケンスの最初のデータの受信タイミングを特定期間の開始に、最後のデータの受信タイミングを特定期間の終了とし、無線制御部23へ指示する。無線制御部23は、コネクション制御部25から開始指示を受信することで特定期間の開始を設定し、終了指示を受信することで特定期間の終了を設定する。図7に基地局2の制御フローを示す。破線(f2)は、本実施形態を示しており、コネクション制御部25が特定期間の開始と終了を指示する場合を示している。
なお、受信タイミングは、時間でもよいし、時間を表す、或いは、時間を算出できる情報、例えば、MACフレームのフレーム番号でもよい。時間の場合、特定期間の開始/終了は、受信した時間となり、フレーム番号の場合は、受信したフレームとなる。
(b) 本実施形態による基地局2が特定期間において割り当てを行ったアップリンク送信用の帯域に対する該当する無線端末からのアクセス状況に基づいて判定する場合、
(c) ランダムアクセスでの帯域要求の受信タイミングとする場合
上記(b)では、割当帯域に対する、帯域割当情報又は送信データの送信がない回数が規定数に達したタイミングや、割当帯域に対する帯域割当情報の受信タイミングを終了とする。
なお、帯域割当タイミング、タイムアウトのタイミング、規定数に達したタイミング、受信タイミングは、時間でもよいし、時間を表す、或いは、時間を算出できる情報、例えば、MACフレームのフレーム番号でもよい。時間の場合、帯域割当が行われた時間、タイムアウト時間、規定数に達した時の時間、受信時間であり、フレーム番号の場合は、帯域割当が行われたフレーム、タイムアウトしたフレーム、規定数に達したフレーム、受信フレームとなる。
(3-2) 送信データの受信情報、
(3-2)に関しては、基地局2は、当該データの受信情報を記憶し、前のデータの受信情報との差分をとることで、送信データの基地局2での受信間隔を算出する。そして、一定間隔、あるいは、規定のデータ数分測定した受信間隔をもとに、データ(Dch)受信時に、次のデータ用の特定期間を決定する。このとき特定期間の開始を、最後に受信したデータの受信情報+最小の受信間隔とし、特定期間の終了を、最後に受信したデータの受信情報+最長の受信間隔とする。
なお、発生情報及び受信情報は、時間情報でもよいし、時間を表す、あるいは時間を算出できる情報、例えば、MACフレーム(固定長)のフレーム番号でもよい。
発生情報および受信情報は、時間で規定される場合、それぞれ、発生時間、受信時間となり、フレームで規定される場合、発生フレーム、受信フレームとなる。
(B) 規定条件を満たすタイミング
(B)は、規定した条件を満たす場合に、(A)を適用するものであり、例えば、規定条件としては、無線端末3-1、3-2、・・・、3-N或いは無線リンク5に対して、ダウンリンク(基地局2から無線端末3-1、3-2、・・・、3-Nへの情報の伝送)のデータ割当がある場合や、コネクション制御部25から指示がある場合などである。
最初に、無線端末3-1、3-2、・・・、3-Nは、無線区間において、基地局2が無線端末2を特定するためのIDであるMAC-IDを取得するために、MAC-ID割当要求を基地局2にランダムアクセス送信する(ステップS11)。そして、無線端末2は、基地局2からのMAC-ID割当応答を受信する(ステップS12)。
そして、既知のデータ交換シーケンスの1つである認証処理シーケンス(認証要求、認証応答、認証完了)を実施する。つまり、無線端末3-1、3-2、・・・、3-Nは、基地局2に認証要求を送信する(ステップS13)。そして、無線端末3-1、3-2、・・・、3-Nは、基地局2から認証応答を受信する(ステップS14)。そして、無線端末3-1、3-2、・・・、3-Nは、基地局2に認証完了を送信する(ステップS15)。本処理は、コネクション制御部25主導で行われ、かつ、交換されるデータはシーケンシャルである。
上記(II)の内のデータ交換シーケンスの監視に基づく場合では、図10に示すように、図7のコネクション制御部25は、認証処理シーケンスの最初のデータである認証要求を受信後に開始指示を無線制御部23に通知する(ステップS16)。また、コネクション制御部25は、認証処理シーケンスの最後のデータである認証完了受信後に終了指示を通知する(ステップS17)。このとき、無線制御部23は、開始指示と終了指示を特定期間の開始と終了とみなす。一方、上記(II)の無線リンク5の帯域割当状況の監視に基づく場合では、認証処理を行う無線リンク5を監視し、当該無線リンク5に対するDch帯域割当の開始を特定期間の開始とする。また、当該無線リンク5に対して、基地局2が特定期間において割り当てる割当帯域に対する未アクセス数をカウントし、規定値に達した場合に、当該無線リンク5の通信終了とみなし、特定期間の終了とする。
本実施形態では、特定期間の開始時に、終了時が決まっていない場合(推定による特定期間の決定方法以外を用いる場合)であり、認証処理シーケンスに対して特定期間を設定し、その特定期間で毎フレーム割当を行う場合について説明する。
本実施形態では、上述した特定期間におけるアップリンク(UL)送信用の帯域割当方法を上記(A)の内の毎フレームとし、アップリンク(UL)送信用の割当帯域を上記(i)のRREQ(帯域要求)用のCchとし、毎フレーム1つのCchを割り当てる場合の割当処理について説明する。
図11に、アップリンク(UL)送信用の帯域割当リンクの登録判定処理を示す。特定期間が開始した無線リンク5に対して、アップリンク(UL)送信用の帯域割当リンクとして登録可否を判定する(ステップSa1)。
登録可であれば、特定期間が終了するまで、当該無線リンク5に対してRREQ用のCch帯域を割り当てる(ステップSa2)。この際、RREQ用のCch帯域を優先確保帯域とみなす。ここで、優先確保帯域とは、必ず確保される帯域のことである。
本実施形態では、特定期間の開始時に、終了時が決まっていない場合(推定による特定期間の決定方法以外を用いる場合)であり、認証処理シーケンスに対して特定期間を設定し、その特定期間で、かつ、割当条件を持たす場合の割当例について説明する。
本実施形態では、特定期間におけるアップリンク(UL)送信用の帯域割当方法が上記(B)の割当条件に一致する場合について説明する。割当条件は、ダウンリンクのDch送信発生時とし、同一フレーム以降で、UL送信用の帯域を1度だけ割り当てる。図10では、認証応答のメッセージ送信時に該当する。また、アップリンク(UL)送信用の割当帯域を上記(ii)のデータ送信用のDchとした場合の割当処理について説明する。
本例では、割当帯域をRREQ用のCchではなく、データ送信用のDchとしているが、これに限定されるものではない。例えば、認証処理シーケンスのように、交換されるメッセージが固定長であり、かつ、シーケンシャルである場合にはDchの直接割当が可能である。特定期間が開始した無線リンクをアップリンク(UL)送信用の帯域割当リンクとして登録する。また、特定期間が終了した無線リンクをアップリンク(UL)送信用の帯域割当リンクから解除する。
なお、本例では、アップリンク(UL)送信用の割当帯域をデータ送信用のDchとしているが、RREQ用のCchでも適用可能である。
本実施形態では、特定期間の開始時に、終了時が決まっている場合(推定による特定期間の決定方法を用いる場合)であり、無線リンク5の通信のうちで、データのアップリンク(UL)送信(図3の「data」がデータに相当)への適用について説明する。特定期間の決定に関しては、上記(II)の発生情報を用いたトラヒック推定をもとに行なう。データの受信時に、前のデータの発生情報との差分をとることで、データの発生間隔を算出する。そして、測定した発生間隔から、次のデータの発生期間を予測し、その予測期間を特定期間とする。発生間隔の測定は、無線端末3-1、3-2、・・・、3-Nがデータに発生情報を付与して送信し、基地局2でデータの発生間隔を一定区間或いは一定データ数分保持し、算出する。そして、特定期間の開始を、最後の受信データの発生情報+最短の発生間隔とする。また、特定期間の終了を、最後の受信データの発生情報+最長の発生間隔とする。
そして、特定期間が満了したか否かについて判定する(ステップSe2)。
特定期間が満了している場合(ステップSe2で「Yes」)、図15に示す処理を終了する。
もし、特定期間の途中で終了する場合(ステップSe2で「No」)、すなわち、ランダムアクセスで帯域要求を受信した場合、或いは、アップリンク送信用の帯域割当で帯域要求を受信した場合、未割当フレームに対して、優先確保総帯域値から当該リンク用のRREQ用の帯域を減算することで優先確保総帯域値を更新する(ステップSe3)。
Claims (10)
- 複数の端末局が共通の無線回線により基地局と接続され、前記基地局は、無線フレーム内の上り通信用帯域のうち帯域割当用の帯域をデマンドアサイン区間、残りの帯域をランダムアクセス区間として管理し、前記端末局からの帯域要求情報に対して要求分の上り通信用帯域を前記デマンドアサイン区間に割り当て、前記端末局は、送信データが発生した場合、バックオフ時間経過後に帯域要求情報をランダムアクセス区間にランダムアクセス送信し、送信に成功した場合には前記基地局から割り当てられた帯域を用いて前記送信データを送信する無線通信方法において、
前記基地局は、前記端末局毎又は前記端末局と当該基地局間の無線リンク毎に特定された前記送信データの送信頻度の高い特定期間に存在する前記デマンドアサイン区間に、前記端末局からランダムアクセスでの帯域要求を受信していない場合でも、当該端末局毎又は当該無線リンク毎の帯域割当を行い、
前記端末局は、前記基地局が帯域割当を行った帯域にて帯域要求情報又は前記送信データを送信する無線通信方法。 - 前記特定期間は、前記基地局の外部からの指示に基づいて開始時、あるいは終了時が設定される請求項1に記載の無線通信方法。
- 前記特定期間は、無線リンク毎の信号交換シーケンスに対応して開始時、あるいは、終了時が設定される請求項1に記載の無線通信方法。
- 前記特定期間は、前記端末局又は前記無線リンクに対する帯域割当に対応して開始時が設定される請求項1に記載の無線通信方法。
- 前記特定期間は、開始時に設定する内部のタイマのタイムアウト時、あるいは、前記基地局が前記特定期間に存在する前記デマンドアサイン区間に、前記端末局からランダムアクセスでの帯域要求を受信していない場合でも、前記端末局毎又は前記無線リンク毎に前記基地局が帯域割当を行った帯域に対する前記帯域要求情報又は前記送信データのアクセス状況に応じて、或いは、ランダムアクセスでの帯域要求受信時に、終了時が設定される請求項1に記載の無線通信方法。
- 前記特定期間は、前記端末局毎又は前記無線リンク毎に前記基地局へ伝送される前記送信データの測定情報に基づいて開始時、あるいは終了時が推定され設定される請求項1に記載の無線通信方法。
- 前記特定期間に存在する前記デマンドアサイン区間における前記端末局毎又は前記無線リンク毎の帯域割当が、規定タイミング、あるいは、規定条件を満たすタイミングで行われる請求項1に記載の無線通信方法。
- 複数の端末局が共通の無線回線により基地局と接続され、前記基地局は、無線フレーム内の上り通信用帯域のうち帯域割当用の帯域をデマンドアサイン区間、残りの帯域をランダムアクセス区間として管理し、前記端末局からの帯域要求情報に対して要求分の上り通信用帯域を前記デマンドアサイン区間に割り当て、前記端末局は、送信データが発生した場合、バックオフ時間経過後に帯域要求情報をランダムアクセス区間にランダムアクセス送信し、送信に成功した場合には前記基地局から割り当てられた帯域を用いて前記送信データを送信する無線通信システムにおいて、
前記基地局は、前記端末局毎又は前記端末局と当該基地局間の無線リンク毎に特定された前記送信データの送信頻度の高い特定期間に存在する前記デマンドアサイン区間に、前記端末局からランダムアクセスでの帯域要求を受信していない場合でも、当該端末局毎又は当該無線リンク毎の帯域割当を行い、
前記端末局は、前記基地局が帯域割当を行った帯域にて帯域要求情報又は前記送信データを送信する無線通信システム。 - 複数の端末局が共通の無線回線により基地局と接続され、前記基地局は、無線フレーム内の上り通信用帯域のうち帯域割当用の帯域をデマンドアサイン区間、残りの帯域をランダムアクセス区間として管理し、前記端末局からの帯域要求情報に対して要求分の上り通信用帯域を前記デマンドアサイン区間に割り当て、前記端末局は、送信データが発生した場合、バックオフ時間経過後に帯域要求情報をランダムアクセス区間にランダムアクセス送信し、送信に成功した場合には前記基地局から割り当てられた帯域を用いて前記送信データを送信する無線通信システムにおける基地局において、
前記端末局毎又は前記端末局と当該基地局間の無線リンク毎に特定された前記送信データの送信頻度の高い特定期間に存在する前記デマンドアサイン区間に、前記端末局からランダムアクセスでの帯域要求を受信していない場合でも、当該端末局毎又は当該無線リンク毎の帯域割当を行い、
前記端末局から前記帯域割当を行った帯域にて送信された帯域要求情報又は前記送信データを受信する基地局。 - 複数の端末局が共通の無線回線により基地局と接続され、前記基地局は、無線フレーム内の上り通信用帯域のうち帯域割当用の帯域をデマンドアサイン区間、残りの帯域をランダムアクセス区間として管理し、前記端末局からの帯域要求情報に対して要求分の上り通信用帯域を前記デマンドアサイン区間に割り当て、前記端末局は、送信データが発生した場合、バックオフ時間経過後に帯域要求情報をランダムアクセス区間にランダムアクセス送信し、送信に成功した場合には前記基地局から割り当てられた帯域を用いて前記送信データを送信する無線通信システムにおける端末局において、
前記基地局によって当該端末局毎又は当該端末局と前記基地局間の無線リンク毎に特定された前記送信データの送信頻度の高い特定期間に存在する前記デマンドアサイン区間に、ランダムアクセスでの帯域要求を送信していない場合でも、当該端末局毎又は当該無線リンク毎に基地局が帯域割当を行った帯域にて帯域要求情報又は前記送信データを送信する端末局。
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