JP2003110575A - Multi-rate compatible wireless base station device - Google Patents

Abstract

(57) [Summary] [Purpose] By giving priority control to multi-rate control to a plurality of transmission queues having different data transmission rates, high-speed data frames are transmitted with higher priority than low-rate data frames, and high-speed data frames are transmitted. It is an object of the present invention to improve the performance of a wireless terminal that receives a message, and to enhance the performance of the entire wireless LAN system. [MEANS FOR SOLVING PROBLEMS] In a multi-rate compatible wireless base station apparatus which is a wireless base station apparatus for relaying data between a wired network and a wireless network, means for creating a transmission rate management table for managing a data transmission rate for each wireless terminal. A transmission rate-specific transmission queue for storing a data frame addressed to a wireless terminal for each of a plurality of different data transmission rates, a means for setting a priority corresponding to the number of opportunities to transmit data, and managing the priority Means for creating a priority management table for each transmission rate for

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a wireless base station transmits data to a wireless terminal under the control of the wireless base station, changes the data transmission rate according to the communication environment with the wireless terminal. Relates to a wireless base station device of a wireless packet communication system for selectively switching,

In particular, by using priority control for transmitting a data frame transmitted at a high transmission rate more preferentially than a data frame transmitted at a low transmission rate, the data transmission rate can be adjusted according to the data transmission rate. The present invention relates to a wireless base station device of a wireless packet communication system that provides performance.

[0003]

2. Description of the Related Art As a wireless communication system in which a transmitting station dynamically switches a data transmission rate according to a communication environment between a wireless base station and a wireless terminal, IEEE802.
The IEEE 802.11 system defined by the 11th Committee is conventionally known.

In this IEEE 802.11 system,
CSMA / CA in which a plurality of wireless terminals transmit data while carrying out carrier sensing so that frame collision does not occur
(Carrier Sense Multip1e A
ccess with Collision Avoi
DCF (Distributed)
Coordination Function distributed control procedure) is defined as an access control method.

In the IEEE 802.11 system, each wireless terminal and wireless base station transmit data only when they have a data transmission right according to a random access procedure.

In the IEEE802.11 system, the data frame is transmitted by a wireless base station that has transmitted the data frame and a wireless terminal or a wireless base station that is the destination of the ACK frame, which is an affirmative response to the data transmission by each wireless terminal. If it is received from, the transmission is successful. On the other hand, the data frame transmission fails if the ACK frame is not received.

FIG. 9 is a diagram showing an example of conventional multi-rate control during data transmission. In the conventional multi-rate control shown in FIG. 9, as wireless access control, IEEE
The DCF of the E802.11 system is used. The wireless base station 100 transmits data frames to the wireless terminals 200 and 201 under its control.

Data transmission from the radio base station 100 to the radio terminal 200 has failed several times in succession. On the other hand, the data transmission from the wireless base station 100 to the wireless terminal 201 has succeeded a plurality of times in succession.

The radio base station 100 has a plurality of data transmission rates R1, R2 and R3. Wireless terminal 2
First data frame D1 addressed to 00 and wireless terminal 20
The first data D6 to 1 are both transmitted at the transmission rate R2.

The radio base station 100 continuously fails to transmit the data frames D1 to D4 to the radio terminal 200. Therefore, the next data frame D5 is transmitted at the lower data transmission rate R3 than the data transmission rate R2 when the data frames D1 to D4 are transmitted.

This is because the transmission from the data frame D1 to the data frame D4 has failed continuously, so that the data frame is surely transmitted at a lower data rate to improve the performance in the wireless packet communication. is there.

On the other hand, the radio base station 100 includes a radio terminal 20.
Data frame D6 to data frame D8 addressed to 1
Up to consecutive successes. Therefore, the next data frame D9 is transmitted at the data transmission rate R1 which is higher than the data transmission rate R2 when the data frames D6 to D8 are transmitted.

This is because the transmission from the data frame D6 to the data frame D8 has been continuously succeeded, so that the data frame is transmitted at a higher data rate to improve the performance in the wireless packet communication. .

As described above, in the conventional multi-rate control, the radio base station autonomously looks at the channel state to judge whether data can be transmitted, and transmits the data. That is, as described above, the radio base station
Data frames are transmitted at a high data rate to wireless terminals in a good environment for data transmission, while data frames are reliably transmitted at a low data rate to wireless terminals in a bad environment for data transmission. As a result, high performance was achieved in wireless packet communication.

As a priority control method during data transmission, the IEEE standardized by the IEEE 802 committee
A method using E802.1D Annex H is conventionally known. FIG. 10 is a diagram showing this method, that is, a conventional priority control method during data transmission. IEEE802.1 D Annex H is a protocol on a wired system, and is targeted for Ethernet (registered trademark).

IEEE 802.1 D Annex H
In a communication system complying with the standard, a data relay device (hereinafter referred to as a bridge) has a maximum of seven transmission queues for temporarily storing data to be relayed, and each transmission queue is dependent on the quality of service to be provided. Priority is set. Further, a field indicating the priority of the frame is set in the data frame to be transmitted / received.

The bridge stores the data frame in an appropriate transmission queue according to the priority based on the priority set in the relayed data frame. The bridge is
Data is extracted from the transmission queue according to the specified algorithm, and the extracted data is transmitted.

The algorithm at this time is not particularly specified, but a typical one is WFQ (Wei).
ghted Fair Queuing) and WRR (W
Eighted Round Robin), CBQ
An algorithm based on an existing method such as (Class Based Queuing) is used.

As described above, in the conventional priority control method, the priority control according to the service quality of the data is performed by providing the bridge with the transmission queue according to the service quality.

As described above, conventionally, the performance of the entire wireless system has been improved by adaptively changing the data transmission rate between the wireless base station and the wireless terminal according to the communication environment. That is, in the conventional method, the downlink data transmission from the wireless base station to the wireless terminal is
It has been performed using competitive access control based on CSMA / CA and multirate control that determines a data transmission rate according to a communication environment with a wireless terminal under its control.

[0021]

However, in the conventional multi-rate control, a high-speed communication data frame addressed to a wireless terminal in a favorable environment and a low-speed communication data frame addressed to a wireless terminal in a poor environment are This is done using a single data transmission queue. Therefore, when the number of wireless terminals that receive data using the low rate and the amount of the data increase, the wireless terminal that receives data using the high rate uses a throughput and a throughput that match the data transmission rate. There was a problem that performance such as delay time for data reception could not be obtained.

FIG. 11 is a diagram showing problems in data transmission using the conventional multi-rate control. The wireless access control shown in FIG. 11 uses CSMA / CA in the IEEE 802.11 system. The radio base station 100 transmits data frames of equal size to the subordinate radio terminals 200, 201, 202.

In FIG. 11, the wireless terminals 200, 20
The data frame addressed to 1 is 6 Mbit / s, and the wireless terminal 2
A data frame addressed to 02 uses a transmission rate of 24 Mbit / s. Therefore, the wireless terminal 200 of FIG.
The data frame transmission time for the wireless terminal 201 is four times as long as the data frame transmission time for the wireless terminal 202.

Since the wireless base station 100 has a single data transmission queue, the data frames addressed to the wireless terminals under its control are transmitted in the order stored in the queue. Therefore, like the wireless terminals 200 and 201, 6 Mbit / s
As the number of wireless terminals existing in a poor communication environment where communication is possible only increases, 24
A wireless terminal in a favorable environment capable of communicating at Mbit / s cannot obtain the performance commensurate with its high transmission rate.

In view of the above situation, the present invention provides a wireless base station with a plurality of transmission queues having different data transmission rates, adds priority control to multirate control, and transmits data transmitted at a high rate. By transmitting a frame with priority over a data frame transmitted using a low-speed rate, it is possible to realize high performance of a wireless terminal that receives at a high-speed rate and high performance of the entire wireless LAN system. With the goal.

[0026]

According to the present invention, the above problem is solved by the means described in the claims. That is, the invention according to claim 1 is a wireless base station device for relaying data between a wired network and a wireless network, wherein a transmission rate of a data frame transmitted to a wireless terminal under the control is:

In a multi-rate compatible wireless base station device which selects from a plurality of transmission rates according to the communication environment of a wireless medium and then performs wireless packet communication with the wireless terminal, data transmission between the wireless terminals under the control of the multi-rate is possible. A means for creating a transmission rate management table for managing the data transmission rate when transmitting and receiving, for each wireless terminal,

Transmission rate-specific transmission queues for storing the data frames addressed to the subordinate wireless terminals by a plurality of different data transmission rates, and means for setting priorities corresponding to the number of opportunities for data transmission. And a means for creating a transmission rate-based priority management table for managing a plurality of data transmission rates and priorities assigned to the data transmission rate-based queues. .

The invention according to claim 1 comprises a wireless base station for relaying data between a wired network and a wireless network, and a wireless terminal having a subordinate relationship with the wireless base station for wireless packet communication with the wireless base station. It is a multi-rate compatible wireless base station device.

The radio base station apparatus may perform carrier sense prior to data transmission, and after confirming that other radio terminals and radio base stations are not transmitting data, may transmit data frames. The wireless base station device,
It has multiple data transmission rates for transmitting data frames. The wireless base station device has means for selecting the transmission rate of the data frame to be transmitted according to the communication environment of the wireless medium.

If the radio base station apparatus fails to continuously transmit data frames to a specific receiving station,
It may have means for reducing the data transmission rate of the data transmitting station. The wireless base station device succeeds in continuously transmitting data frames to a specific receiving station, and the currently used data transmission rate is the highest data transmission rate among the available data transmission rates. If not, it may have means for increasing the data transmission rate of the data transmitting station.

The radio base station apparatus is a multirate compatible radio base station apparatus having a multirate function, in which data frame transmission is performed at a plurality of transmission rates. The priority corresponds to a large number of opportunities to transmit data, and data belonging to a higher priority can perform data communication with lower delay and higher speed than data belonging to a lower priority.

The radio base station apparatus determines the data transmission rate at the time of transmitting / receiving data to / from the subordinate radio terminals.
A transmission rate management table for managing each wireless terminal, a transmission rate-specific transmission queue for storing a data frame arriving at the wireless base station and addressed to the wireless terminal by a plurality of different data transmission rates, and a plurality of data transmissions And a priority management table for each transmission rate for managing the priority assigned to the queue for each rate and data transmission rate.

The invention of claim 1 is different from the prior art in that
The data transmission rate when sending and receiving data to and from the subordinate wireless terminals is managed by the transmission rate management table for each wireless terminal, in order to store the data frames addressed to the subordinate wireless terminals by data transmission rate. Different from the point that a plurality of transmission rate-specific transmission queues are prepared, and the priority is assigned to the data transmission rate-specific queues by the transmission rate-specific priority management table.

According to a second aspect of the present invention, there is provided a wireless base station device for relaying data between a wired network and a wireless network, wherein the transmission rate of a data frame to be transmitted to a wireless terminal under its control is one of a plurality of transmission rates. In the multi-rate compatible wireless base station device that performs wireless packet communication with the wireless terminal after selecting according to the communication environment of the wireless medium from

A means for creating a transmission rate management table for managing the data transmission rate at the time of transmitting / receiving data to / from a subordinate wireless terminal, and data arriving at the subordinate wireless terminal In this case, statistical data acquisition means for calculating statistics of the data for each subordinate wireless terminal, and transmission by transmission rate for storing a data frame addressed to the subordinate wireless terminal for each of a plurality of different data transmission rates With a queue

Each data transmission is performed using the number of wireless terminals belonging to each transmission rate obtained from the transmission rate management table and the data amount per fixed time Ts addressed to each wireless terminal obtained from the statistical data acquisition means. Rate and data transmission means for setting priorities corresponding to the number of opportunities to transmit data, which are assigned to queues by rate, and managing the priority assigned to a plurality of data transmission rates and data transmission rate queues Means for creating a priority management table for each transmission rate, and a multi-rate compatible wireless base station device.

The invention according to claim 2 comprises a wireless base station for relaying data between a wired network and a wireless network, and a wireless terminal having a subordinate relationship with the wireless base station for wireless packet communication with the wireless base station. It is a multi-rate compatible wireless base station device.

The radio base station apparatus may carry out carrier sensing prior to data transmission, and after confirming that other radio terminals and radio base stations are not transmitting data, may transmit data frames. The wireless base station device,
It has multiple data transmission rates for transmitting data frames. The wireless base station device has means for selecting the transmission rate of the data frame to be transmitted according to the communication environment of the wireless medium.

When the wireless base station device fails to continuously transmit data frames to a specific receiving station,
It may have means for reducing the data transmission rate of the data transmitting station. The wireless base station device has succeeded in continuously transmitting data frames to a specific receiving station,

If the currently used data transmission rate is not the highest available data transmission rate, a means for increasing the data transmission rate of the data transmitting station may be provided.

The radio base station apparatus is a multirate compatible radio base station apparatus having a multirate function, in which data frame transmission is performed at a plurality of transmission rates. The priority corresponds to a large number of opportunities to transmit data, and data belonging to a higher priority can perform data communication with lower delay and higher speed than data belonging to a lower priority.

The radio base station apparatus determines the data transmission rate at the time of transmitting and receiving data to and from the radio terminals under its control.
A transmission rate management table for managing each wireless terminal, a statistical data acquisition unit that calculates statistics of the data when the data arrives at the wireless terminals under the control, and the wireless base. A transmission queue for each transmission rate for storing data frames that have arrived at the station and are addressed to the wireless terminal by a plurality of different data transmission rates,

Each data transmission rate is calculated by using the number of wireless terminals belonging to each transmission rate obtained from the transmission rate management table and the data amount per fixed time Ta for each wireless terminal obtained from the statistical data acquisition means. And a means for determining the priority assigned to the data transmission rate queue, and a transmission rate priority management table for managing the plurality of data transmission rates and the priorities assigned to the data transmission rate queue.

The invention described in claim 2 is different from the prior art in that the data transmission rate at the time of transmitting / receiving data to / from a subordinate radio terminal is determined by using a transmission rate management table for each radio terminal. The point that it manages, the point that a transmission queue for each transmission rate for storing the data frame addressed to the wireless terminal under the control is stored for each data transmission rate,

The statistics of the amount of data addressed to the wireless terminals are calculated by the statistical data acquisition means, the number of wireless terminals belonging to each transmission rate is calculated, and the number of wireless terminals belonging to each transmission rate and the data of each wireless terminal are calculated. It has a means to determine the priority assigned to each data transmission rate and the queue for each data transmission rate from the amount of communication, and the priority is assigned to the queue for each data transmission rate by the transmission rate priority management table. Is different.

The invention according to claim 3 has a variable corresponding to each wireless terminal under its control, and when calculating the arrival rate for each wireless terminal, the amount of data arriving in Ta at each time interval Ta is calculated. 3. The statistical data acquisition means according to claim 2, further comprising a counter having means for calculating and dividing the amount of the data by the Ta, that is, an average arrival rate within the time interval Ta. The multi-rate compatible wireless base station device according to claim 2.

According to the invention described in claim 3, in the multi-rate compatible radio base station device according to claim 2, a counter is provided inside the statistical data acquisition means, and the counter corresponds to each wireless terminal under the counter. In calculating the arrival rate for each wireless terminal having a variable, the time interval T
A unit for calculating the amount of data arriving in Ta for each a and dividing the amount of the data by the Ta, that is, the average arrival rate within the time interval Ta is provided.

[0049]

1 is a diagram showing a first example of an embodiment of the present invention. This example shows a configuration of a radio base station corresponding to the invention described in claim 1. In the figure, a solid arrow means a data flow, and a broken arrow means a control flow. The radio base station 100 includes a scheduling unit 110, a relay processing unit 120, and an access control unit 1.
30, and lower layer processing means 14 for performing modulation, etc.
0, reception processing means 150.

Although the relay processing means 120 is not included in the data link layer in this figure, the relay processing means 120 may be included in the data link layer.
This also applies to other drawings described below.

The subject of the present invention is the part of the scheduling means 110. Scheduling means 110
Is a transmission rate queue 111 for storing a data frame for each data transmission rate, and a transmission rate for managing the data transmission rate when transmitting and receiving data to and from the wireless terminals under the control. Management table 112,
It has a transmission rate-based priority management table 113 which is a correspondence table between transmission rates and priorities.

In the scheduling means 110 according to the first aspect of the invention, the transmission rate management table 112 is appropriately updated based on the information indicating whether or not the data transmission reported by the receiving means 150 has succeeded immediately after the data frame transmission. To do. The receiving means 150 determines whether or not the data transmission has succeeded, depending on whether or not an acknowledgment frame (ACK frame) for the transmitted data is received.

Further, the transmission rate-based priority management table 113 is appropriately updated from the transmission rate management table 112, and based on the information obtained from the updated transmission-rate-based priority management table 113, each transmission rate-based queue is stored. The assigned priority is determined.

FIG. 2 is a flow chart for explaining the control of the invention described in claim 1. The process described in FIG. 2 is a process until the scheduling unit 110 in the radio base station 100 shown in FIG. 1 passes the data passed from the relay processing unit 120 to the access control unit 130. When the relay data arrives (step S001), the scheduling means 110 proceeds to step S002 and reads the destination terminal described in the header part of the relay data.

Next, in step S003, the transmission rate management table 112 is used to check the transmission rate used when transmitting data to the destination terminal. When the destination terminal of the relay data that has arrived is listed in the transmission rate management table 112, the transmission rate corresponding to the destination terminal of the relay data is acquired, and the data is sent to an appropriate queue in the transmission rate queue 111. Insert (step S004), step S00
Proceed to 7.

When the destination terminal of the relay data is not listed in the transmission rate management table 112, it is determined that the fastest transmission rate among the available data transmission rates is used, and the transmission corresponding to the transmission rate is performed. Queue by rate 1
Data is inserted into 11 (step S005).

Next, in step S006, the correspondence between the destination terminal and the data rate used for data transmission is newly added to the transmission rate management table 112. Next, in step S007, it is determined whether or not there is data in the transmission rate queue. If the data does not exist, the process returns to step S001 and it is determined again whether the relay data arrives. If the data is in the queue,
In step S008, data transmission processing is performed.

It should be noted that each transmission rate queue 111 is assigned in advance a priority corresponding to the transmission rate by the transmission rate priority management table 113. At the time of data transmission processing, the selection of queues for each transmission rate is performed according to the priority.

Next, in step S009, after transmitting the data frame, it is determined whether or not there is a change in the transmission rate used for the data transmission. If there is no change, the process returns to step S001 and relay data arrives again. It is determined whether or not to make a decision, and if there is a change, step S01.
In step 0, the correspondence between the destination terminal and the new transmission rate described in the transmission rate management table 112 is changed.

FIG. 3 is a diagram showing a second example of the embodiment of the present invention, and shows the configuration of a radio base station corresponding to claim 2. In the figure, a solid arrow means a data flow, and a broken arrow means a control flow. Radio base station 10
0 is scheduling means 110 and relay processing means 12
0, access control means 130, lower layer processing means 140 for performing modulation and the like, and reception processing means 150.

The subject of the present invention is the part of the scheduling means 110. Scheduling means 110
Is a transmission rate queue 111 for storing a data frame for each data transmission rate, and a transmission rate for managing the data transmission rate when transmitting and receiving data to and from the wireless terminals under the control. Management table 112,

It has a priority management table 113 for each transmission rate, which is a correspondence table between transmission rates and priorities, and a statistical data acquisition means 114 for obtaining statistics of the amount of data addressed to each wireless terminal.

In the scheduling means 110 according to the second aspect of the invention, the transmission rate management table 112 is appropriately updated based on the information indicating whether or not the data transmission reported by the receiving means 150 has succeeded immediately after the data frame is transmitted. .
The receiving means 150 determines whether or not the data transmission has succeeded, depending on whether or not an acknowledgment frame (ACK frame) for the transmitted data is received.

On the other hand, the statistical data acquisition means 114 appropriately updates the statistical value of the data amount addressed to each wireless terminal when the relay data arrives. In addition, the transmission rate management table 112 and the statistical data acquisition unit 114 allow the transmission rate priority management table 1 as appropriate.
13 is updated, and the priority assigned to each transmission rate queue is determined based on the information obtained from the updated transmission rate priority management table 113.

FIG. 4 shows a radio base station 10 according to the invention of claim 2.
0 shows a first example of means for creating the transmission rate priority management table 113 from the transmission rate management table 112 and the statistical data acquisition means 114. In the example of FIG. 4, the transmission rate management table 112 and the statistical data acquisition unit 1
From 14, the number of wireless terminals performing data communication and the total amount of data per fixed time are calculated for each transmission rate.

After that, when assigning priorities to the respective transmission rates, the priorities are assigned so that the total amount of data per constant time in each priority becomes equal.

That is, in FIG. 4, the transmission rate is 6 Mbi.
The number of wireless terminals belonging to t / s and 12 Mbit / s is 10, respectively, and the number of wireless terminals belonging to 18 Mbit / s and 36 Mbit / s is 20, respectively, and the transmission rate is 6 Mbit / s and 12 Mbit / s. The total amount of data transmitted at a fixed time is 1 Mbit / s, and the total amount of data transmitted at a transmission rate of 18 Mbit / s and 36 Mbit / s is 2 Mbit / s.
t / s.

Therefore, the transmission rate is 6 Mbit / s, 1
Priority 3 is assigned to 2 Mbit / s, priority 2 is assigned to 18 Mbit / s, and priority 1 is assigned to 36 Mbit / s. In FIG. 4, the total amount of data in each priority per constant time is 2 Mbit / s.

FIG. 5 shows a radio base station 10 according to the invention of claim 2.
10 is a diagram showing a second example of means for creating the transmission rate priority management table 113 from the transmission rate management table 112 and the statistical data acquisition means 114 in FIG. In the example of FIG. 5, as in the case of FIG. 4, the transmission rate management table 112 and the statistical data acquisition unit 114 are used to determine, for each transmission rate, the number of wireless terminals performing data communication using the transmission rate and the total number of wireless terminals per fixed time. Calculate the amount of data.

In the example of FIG. 5, the priority is assigned according to the total amount of data transmitted using each transmission rate per fixed time and the magnitude of the transmission rate. In the example of FIG. 5, the transmission rates are 6 Mbit / s and 12 Mbit / s.
The number of wireless terminals belonging to s, 18 Mbit / s, and 36 Mbit / s is 20, and the total amount of data per fixed time is 2 Mbit.

At this time, the maximum transmission rate is 36 Mbit.
Since it is / s, the highest priority 1 is assigned to 36 Mbit / s, and the priority of other transmission rates is determined based on the total data amount 2 Mbit per fixed time at this transmission rate.

In the example of FIG. 5, the transmission rate is 18 Mbit /
Since s is the next highest transmission rate after 36 Mbit / s, priority 2 is assigned. In the example of FIG. 5, the transmission rate of 18 Mbit / s assigned the priority 2 is the highest transmission rate of 36 Mbit assigned the priority 1.
Since the transmission rate is half that of / s, the priority 2 is allowed to have a data amount twice the priority 1, that is, 4 Mbits of data transmission.

The total amount of data transmitted at a transmission rate of 18 Mbit / s per constant time is 2 Mbit.
Highest transmission rate of 12 Mbit after 18 Mbit / s
The total amount of data transmitted at 1 / s is also 2M
Since it is a bit, the priority 2 is assigned to the transmission rate of 12 Mbit / s.

Next, the priority 3 is assigned to the transmission rate 6 Mbit / s. In the example of FIG. 5, when the total amount of data transmitted at the transmission rate of 18 Mbit / s is 4 Mbit or more, the priority is 2
The transmission rate to which is assigned is only 18 Mbit / s, and the priority 3 is assigned to 12 Mbit / s.

FIG. 6 is a flow chart for explaining the control of the invention described in claim 2. The processing illustrated in FIG. 6 is processing until the scheduling unit 110 in the wireless base station 100 illustrated in FIG. 2 passes the data received from the relay processing unit 120 to the access control unit. When the relay data arrives (step Sl01), the scheduling means 110 proceeds to step Sl02 to read the destination terminal described in the header part of the relay data.

Next, in step S 103, the transmission rate management table 112 is used to check the transmission rate used when transmitting data to the destination terminal. When the destination terminal of the relay data that has arrived is listed in the transmission rate management table 112, the transmission rate corresponding to the destination terminal of the relay data is acquired, and the data is sent to an appropriate queue in the transmission rate queue 111. Insert (step S104).

Next, in step S105, the statistical data acquisition means 114 updates the statistical data addressed to the wireless terminal, and by updating this statistical data, each transmission rate and priority listed in the transmission rate-based priority management table 113 is prioritized. It is determined whether there is a change in the degree correspondence (step Sl0).
6). If there is a change in the transmission rate-based priority management table 113, the process proceeds to step Sl07, the transmission rate-based priority management table is changed, and the process proceeds to step Sl10.

If there is no change in the transmission rate-based priority management table 113, the process proceeds to step S110. Also step S
In the determination in 103, if the destination terminal of the relay data is not listed in the transmission rate management table 112,
It is determined that the fastest transmission rate of the available data transmission rates is used, and the data is inserted into the transmission rate queue 111 corresponding to the transmission rate (step S).
108). Next, in step S109, the correspondence between the destination terminal and the data rate used for data transmission is newly added to the transmission rate management table 112.

Next, in step S110, it is determined whether or not there is data in the transmission rate queue. If the data does not exist, the process returns to step S001 to determine again whether the relay data arrives. If the data exists in the queue, the process proceeds to step S111, and the data transmission process is performed.

It should be noted that each transmission rate queue 111 is assigned in advance a priority corresponding to the transmission rate by the transmission rate priority management table 113. At the time of data transmission processing, the selection of queues for each transmission rate is performed according to the priority.

Next, in step S112, after transmitting the data frame, it is judged whether or not there is a change in the transmission rate used for the data transmission. If there is no change, the process returns to step S101 and relay data arrives again. It is determined whether or not to make a decision, and if there is a change, step S11.
3, the correspondence between the destination terminal and the new transmission rate described in the transmission rate management table 112 is changed.

Next, in step S014, it is determined whether or not the transmission rate-based priority management table has been changed by updating the transmission management table 112 in step S113.
If there is no change in the transmission rate-based priority management table, the process returns to step S101 to determine again whether relay data arrives, and if there is a change, step S115.
Then, the transmission rate-based priority management table is updated.

FIG. 7 is a diagram showing a third example of the embodiment of the present invention, and shows the configuration of a radio base station corresponding to claim 3. In FIG. In the invention according to claim 3, in addition to the configuration of FIG. 3, the wireless base station has a counter 115 for collecting statistics at the time of data transmission to each wireless terminal in the statistical data acquisition means 114, and a scheduling means 110. It has a timer 116 inside.

The counter 115 is provided with variables corresponding to the number of wireless terminals under its control, and holds the result of the average transmission rate of the data addressed to each wireless terminal that has arrived at the wireless base station at a constant time interval Ta. It Further, the timer 116 is
The scheduling means 110 times out at regular time intervals Ta, and the scheduling means 110 uses this as an opportunity to calculate statistical data.

FIG. 8 is a flowchart showing the control of the third example of the embodiment of the present invention. The scheduling means 110 activates the timer 116 in step S201, proceeds to step S202, and determines whether or not relay data has arrived. When the relay data arrives, the process proceeds to step S203, and the destination terminal described in the header part of the relay data is read. Next, in step S204, the transmission rate management table 112 is used to check the transmission rate used when transmitting data to the destination terminal.

When the destination terminal of the relay data that has arrived is listed in the transmission rate management table 112, the transmission rate corresponding to the destination terminal of the relay data is acquired, and an appropriate queue in the transmission rate queue 111 is acquired. Data is inserted into (step S205).

If the destination terminal of the relay data that has arrived is not listed in the transmission rate management table 112, it is determined that the fastest transmission rate among the available data transmission rates will be used, and the corresponding transmission rate is supported. The data is inserted into the transmission rate queue 111 (step S20).
6).

Next, in step S207, the correspondence between the destination terminal and the data rate used for data transmission is newly added to the transmission rate management table 112. Next, in step S208, it is determined whether or not there is data in the transmission rate queue.

If data exists, step S00.
In step 9, the data transmission process is performed. Each transmission rate queue 111 has a transmission rate priority management table 1 in advance.
13 assigns priorities corresponding to the transmission rates.

In the data transmission process, the queue for each transmission rate is selected according to the priority. If there is no data in the transmission rate queue, the process proceeds to step S210. In step S210, it is determined whether or not the timer 116 started in step S201 has timed out. If the timer 116 has not timed out, the process proceeds to step S211 to use the data frame after transmitting the data frame. It is determined whether or not the transmission rate to be changed is changed.

If there is no change in the transmission rate, the process returns to step S202, and it is determined whether or not the relay data has arrived. If the transmission rate is changed, step S21
2, the transmission rate management table is updated, and step S20
Return to 2.

Further, in the judgment of step S210,
If the timer 116 times out, step S2
In step 13, after transmitting the data frame, it is determined whether or not there is a change in the transmission rate used when transmitting the data. If there is no change in the transmission rate to be used, the process proceeds to step S215, and if there is a change in the transmission rate, the process proceeds to step S214 and the transmission rate management table 112.
After updating, the process proceeds to step S215.

In step S215, the radio base station 100
The average transmission rate of data addressed to each wireless terminal arriving at is calculated, and the process proceeds to step S216. The transmission rate priority management table 113 is updated from the statistical information analysis result of step Sl15 and the transmission rate management table 112 (step S
216). Then, it returns to step S201 and repeats the above control.

[0094]

Since the present invention has the structure as described above, it has the following advantages.

That is, according to the first aspect of the invention, the radio base station is provided with a plurality of transmission queues for each data transmission rate, and priority control is added to the multi-rate control.
It is possible to preferentially transmit a data frame using a high rate over a data frame transmitted using a low rate.

As a result, it becomes possible to set the number of transmission opportunities depending on whether the transmission rate used during data transmission is high or low, and a wireless terminal which receives data using a high transmission rate has higher performance. Can be obtained. As a result, high performance of the entire wireless LAN system can be realized.

According to the second aspect of the invention, in addition to the above effects, the number of wireless terminals that receive data transmitted from the wireless base station using the same transmission rate and the amount of data to be received are included in the data. It is possible to calculate for each transmission rate, and from the result, assign a plurality of data transmission rates and priorities to the queues for each data transmission rate.

As a result, the priority can be assigned to each transmission rate flexibly according to the time change such as the increase or decrease of the number of wireless terminals under its control and the increase or decrease of the data amount addressed to the wireless terminals. As a result, it is possible to achieve high performance of the entire wireless LAN system.

According to the invention of claim 3, in addition to the above effect, when the wireless base station obtains statistics of data addressed to the wireless terminals under its control for each destination wireless terminal, the average data arrival rate for every fixed time is used. Therefore, the calculation can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing a first example of an embodiment of the present invention.

FIG. 2 is a diagram showing control in a first example of an embodiment of the present invention.

FIG. 3 is a diagram showing a second example of an exemplary embodiment of the present invention.

FIG. 4 is a radio base station of the invention according to claim 2,
It is a figure which shows the 1st example of the means for producing the transmission rate management table from a transmission rate management table.

FIG. 5 is a radio base station of the invention according to claim 2,
It is a figure which shows the 2nd example of the means for creating the transmission rate management table from a transmission rate management table.

FIG. 6 is a diagram showing control of a second example of the embodiment of the present invention.

FIG. 7 is a diagram showing a third example of an exemplary embodiment of the present invention.

FIG. 8 is a diagram showing control of a third example of the embodiment of the present invention.

FIG. 9 is a diagram showing an example of conventional multi-rate control during data transmission.

FIG. 10 is a diagram showing conventional priority control during data transmission.

FIG. 11 is a diagram showing an example of problems in data transmission using conventional multi-rate control.

[Explanation of symbols]

100 wireless base stations 110 Scheduling means 111 Transmission rate queue 112 Transmission rate management table 113 Priority management table for each transmission rate 114 Statistical data acquisition means 115 counter 116 timer 120 relay processing means 130 Access control means 140 Lower Layer Transmission Means 150 Reception processing means 201-202 wireless terminal Dl to D9 data frames R1, R2, R3 Transmission rate (R1> R2> R3) A ACK frame

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04L 29/08 H04B 7/26 109A H04Q 7/38 H04L 13/00 307C (72) Inventor Masataka Iizuka Tokyo Nihon Telegraph and Telephone Corporation, 3-1, Otemachi, Chiyoda-ku (72) Inventor Masahiro Morikura 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation F-term (reference) 5K028 AA11 BB04 EE12 KK32 LL02 LL15 TT05 5K033 AA01 BA15 CA08 CB17 DA01 DA19 DB13 DB17 EA06 5K034 AA01 DD02 EE03 MM08 MM21 5K067 AA13 BB02 BB21 DD11 EE72 GG04

Claims (3)

[Claims] 1. A wireless base station device for relaying data between a wired network and a wireless network, wherein the transmission rate of data frames to be transmitted to a wireless terminal under the control of the wireless medium communication environment is selected from a plurality of transmission rates. In the multi-rate compatible wireless base station device that performs wireless packet communication with the wireless terminal after selecting according to, manages the data transmission rate when transmitting and receiving data to and from the wireless terminals under its control. Means for creating a transmission rate management table, a transmission rate-specific transmission queue for storing data frames that have arrived and are destined for wireless terminals under different data transmission rates, and a large number of opportunities to transmit data. A method for setting the priority corresponding to the above, and managing the priority assigned to multiple data transmission rates and data transmission rate queues Multi-rate wireless base station apparatus characterized by comprising means for creating a transmission rate per priority management table of order, the. 2. A wireless base station device for relaying data between a wired network and a wireless network, wherein the transmission rate of a data frame to be transmitted to a wireless terminal thereunder is selected from a plurality of transmission rates, and a wireless medium communication environment is provided. In the multi-rate compatible wireless base station device that performs wireless packet communication with the wireless terminal after selecting according to, manages the data transmission rate when transmitting and receiving data to and from the wireless terminals under its control. Means for creating a transmission rate management table for obtaining the data, statistical data acquisition means for calculating the statistics of the data for each subordinate wireless terminal when the data arrives at the subordinate wireless terminal, and Transmission queue for each transmission rate for storing a data frame addressed to a wireless terminal for each of a plurality of different data transmission rates, and transmission obtained from the transmission rate management table Data to be assigned to each data transmission rate and a queue for each data transmission rate, using the number of wireless terminals belonging to each wireless terminal and the amount of data per fixed time Ts addressed to each wireless terminal obtained from the statistical data acquisition unit. Means for setting the priority corresponding to the number of opportunities to send data, and means for creating the priority management table for each transmission rate for managing the priority assigned to a plurality of data transmission rates and the queues for each data transmission rate And a multirate-compatible wireless base station device comprising: 3. A variable corresponding to each wireless terminal under the control, and when calculating an arrival rate for each wireless terminal, calculates the amount of data that has arrived within Ta at each time interval Ta,
The statistical data acquisition means according to claim 2, wherein a counter having a means for calculating a value obtained by dividing the amount of the data by the Ta, that is, an average arrival rate within the time interval Ta is provided inside the statistical data acquisition means. Item 3. A multirate compatible wireless base station device according to Item 2.