The present invention relates to an access point, an access point control device and a wireless LAN system.
In place of a background art method for setting and installing access points (hereinafter referred to as APs) individually, batch processing of AP automatic setting, fault management, statistical information collection, etc. by an AP control device connected to a plurality of APs has been discussed. These discussions have brought advancement of a scheme of standardization among international standardization working groups such as the IETF (Internet Engineering Task Force) and the IEEE 802.11 working group.
In such architecture, IETF draft draft-ohara-capwap-lwapp-00.txt [Light Weight Access Point Protocol] “light weight access protocol” (hereinafter referred to as LWAPP) has been proposed by the CAPWAP (Control and Provisioning of Wireless Access Points) working group of the IETF. In the LWAPP, the AP control device 83 performs automatic setting of setting information, fault management, collection of statistical information and setting of encryption key information on the AP 82.
This band control device 105 includes a congestion detection unit 106 for detecting the congestion of each of the plurality of LANs by use of an inputted packet signal 101, and a traffic control unit 107 for controlling the traffic volume of packet communication performed through the backbone network by each terminal connected to a LAN under congestion. This band control device 105 is operated only when there is congestion in a wireless LAN circuit, so that one band control device 105 can perform traffic control on a plurality of LANs.
That is, when the band control device 105 accommodating a plurality of LANs detects traffic of a certain LAN exceeding a predetermined threshold, the band control device 105 controls the traffic volume of the certain LAN. According to this method, the traffic volume is detected every LAN, so that the throughput of the system as a whole can be kept high while congestion of each
Problem that the Invention is to Solve
In the aforementioned background-art band control device 105 and traffic controlling method, it is however conceived that the band is kept for some terminals not good in wireless radio wave condition on the assumption that congestion caused by a certain wireless LAN terminal (hereinafter referred to as terminal simply) is detected to thereby control the traffic volume of the certain wireless LAN in the case where the LANs are wireless LANs provided by the IEEE 802.11.
On the other hand, according to the LWAPP, batch processing of automatic setting of the AP 82, fault management, statistic information collection, etc. can be performed by the AP control device 83. Some wireless section QoS controls such as EDCA (Enhanced Distributed Channel Access), HCCA (HCF Controlled Channel Access) etc. between the AP 82 and the terminal 81 have been discussed by the IEEE 802.11e TGe (task group e).
When there is a terminal not good in radio wave condition, frames are also transmitted to the terminal not good in radio wave condition in the same manner as frames are transmitted to a terminal good in radio wave condition. For this reason, there is a problem that the throughput of the system as a whole is lowered.
Band control and priority control are not provided in the LWAPP proposed by the CAPWAP. For this reason, also in the configuration where congestion occurs in the AP control device 83, packets to be transmitted to a terminal good in radio wave condition are discarded regardless of presence of a terminal not good in radio wave condition. As a result, there is a problem that the throughput of the system as a whole is lowered.
For example, assume that there is a terminal MT1 (116) not good in radio wave condition. In this case, even when the AP control device 83 transmits 100 packets to the terminal MT1 (116), there may be a case where retransmission takes place repetitively between the AP1 (113) and the terminal MT1 (116) to thereby result in discarding of 80 packets. As the number of times of retransmission increases, an empty buffer of the AP1 (113) is decreased, so that the AP1 (113) transmits a pause frame to the AP control device 83. Thus, the AP control device 83 causes congestion and discards frames addressed to the terminal MT2 (115) with a good radio wave condition, as well as frames addressed to the MT1 (16).
On the other hand, also in the configuration where congestion occurs in the AP1 (113), packets addressed to a terminal good in radio wave condition are likewise discarded regardless of presence of a terminal not good in radio wave condition, so that there is a problem that the throughput of the system as a whole is lowered.
An object of the invention is to provide an access point, an access point control device and a wireless LAN system which are in a network system including the access point control device connected to a communication network, the access point controlled by the access point control device, and wireless terminals performing wireless communication with the access point and which are improved in the throughput of the network system as a whole in the case where there is a wireless terminal not good in radio wave condition in the network system.
Means for Solving the Problem
The access point control device according to the invention is an access point control device for connecting access points to a communication network, each access point accommodating terminals, the access point control device including: a communication unit which transmits/receives Ethernet frames to/from the access points and the communication network; a packet storage unit which stores packets transmitted/received by the communication unit; and a transmission control unit which decides whether to store the received packets in the packet storage unit or not and which controls the transmission/reception volume in accordance with the radio wave condition of each of the terminals notified by the access points to select packets stored in the packet storage unit and transmit the selected packets to the communication unit.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The access point according to the invention includes: a wireless communication unit which transmits/receives packets according to the IEEE 802.11 standard to/from a plurality of terminals; a wired communication unit which transmits/receives Ethernet frames to/from an access point control device; a packet storage unit which stores packets in accordance with each terminal; a wireless transmission control unit which selects packets stored in the packet storage unit to transmit the selected packets to the wireless communication unit and which generates information indicating the radio wave condition of each of the terminals when the number of times of retransmission to the terminal is larger than a predetermined threshold; and a radio wave condition notification unit which generates a packet corresponding to the information indicating the radio wave condition of the terminal notified by the wireless transmission control unit and transfers the generated packet to the wired communication unit.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The wireless LAN system according to the invention includes: the aforementioned access point control device; and the aforementioned access points for performing wired communication with the access point control device.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The access point control device according to the invention is an access point control device for connecting access points to a communication network through a layer 2 network, each access point accommodating a plurality of terminals, the access point control device including: a communication unit which transmits/receives Ethernet frames to/from the layer 2 network and the communication network; a packet storage unit which stores packets transmitted/received by the communication unit; and a transmission control unit which decides whether to store the received packets in the packet storage unit or not and which controls the transmission/reception volume in accordance with the radio wave condition of each of the terminals notified by the access points to select packets stored in the packet storage unit and transmit the selected packets to the communication unit.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The access point according to the invention includes: a wireless communication unit which transmits/receives packets according to the IEEE 802.11 standard to/from a plurality of terminals; a wired communication unit which transmits/receives Ethernet frames to/from an access point control device through a layer 2 network; a packet storage unit which stores packets; a wireless transmission control unit which selects packets stored in the packet storage unit to transmit the selected packets to the wireless communication unit and which generates information indicating the radio wave condition of each of the terminals when the number of times of retransmission to the terminal is larger than a predetermined threshold; and a radio wave condition notification unit which generates a packet corresponding to the information indicating the radio wave condition of the terminal notified by the wireless transmission control unit and transfers the generated packet to the wired communication unit.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The wireless LAN system according to the invention includes: the aforementioned access point control device; and the aforementioned access points for performing wired communication with the access point control device through the layer 2 network.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The access point control device according to the invention is an access point control device for connecting access points to a communication network through a layer 2 network, each access point accommodating a plurality of terminals, the access point control device including: a communication unit which transmits/receives Ethernet frames to/from the layer 2 network and the communication network; a packet storage unit which stores packets transmitted/received by the communication unit; and a transmission control unit which decides whether to store the received packets in the packet storage unit or not and which controls the transmission/reception volume in accordance with the radio wave condition of each of the access points notified by the access points to select packets stored in the packet storage unit and transmit the selected packets to the communication unit.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each access point so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The access point according to the invention includes: a wireless communication unit which transmits/receives packets according to the IEEE 802.11 standard to/from a plurality of terminals; a wired communication unit which transmits/receives Ethernet frames to/from an access point control device through a layer 2 network; a packet storage unit which stores packets; a wireless transmission control unit which selects packets stored in the packet storage unit to transmit the selected packets to the wireless communication unit and which generates information indicating the radio wave condition of the access point when the number of times of retransmission to each of the terminals is larger than a predetermined threshold; and a radio wave condition notification unit which generates a packet corresponding to the information indicating the radio wave condition of the access point notified by the wireless transmission control unit and transfers the generated packet to the wired communication unit.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each access point so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
The wireless LAN system according to the invention includes: the aforementioned access point control device; and the aforementioned access points for performing wired communication with the access point control device through the layer 2 network.
According to the aforementioned configuration, the transmission/reception volume is controlled in accordance with the radio wave condition of each access point so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
According to the invention, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal or each access point so that even in the case where there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority. Thus, the throughput of the network system as a whole can be improved.
Transmission to the terminal good in radio wave condition is performed in place of transmission to the terminal not good in radio wave condition so that the throughput of the network system as a whole can be improved.
[
[
[
[
[
[
[
[
[
[
[
In order to explain a first embodiment of the invention,
In
In this case, the wireless transmission control portion 33 performs retransmission control when communication is performed in an infrastructure mode and DCF and an ACK of a transmitted down frame cannot be received from a destination terminal. When the number of times of retransmission is larger than a predetermined threshold, the wireless transmission control portion 33 notifies the radio wave condition notification portion 34 of the radio wave condition of the terminal.
In this manner, according to this embodiment, down frames addressed to the MT2 (terminal 15) performing communication through the AP1 (13) can be transmitted well (steps S405 and S406) without being disturbed by down frames addressed to the MT1 (terminal 16). Thus, the throughput of the system as a whole can be improved, compared with the case where the down frames addressed to the MT1 (terminal 16) are transmitted.
Although the unicasting UDP has been described in the paragraph (A) by way of example, a similar effect can be obtained when TCP frames are used. Since flow control is performed in a TCP layer, it can be conceived that TCP has a smaller effect than UDP frames.
In the case where flow control etc. is performed between the AP1 (13) and the AP control device 12 (buffer overflow is not caused in the AP1 (13)) in the paragraph (K), the same effect can be obtained if discarding is performed only when the queue of the AP control device 12 is congested in a fixed period of time.
In addition, in the case where the packet storage portion 25 of the AP control device 12 is equipped with a mechanism having a queue for each terminal and performing priority control on the queue, a similar effect can be also obtained when transmission priority of packets stored in the queue addressed to the MT1 (terminal 16) is lowered in the fixed period of time.
In order to explain a second embodiment of the invention,
In this manner, according to this embodiment, down frames (steps S605 and S606) addressed to the MT3 (terminal 19) performing communication through the AP2 (17) can be transmitted well without being disturbed by down frames addressed to the MT1 (terminal 16). Thus, the throughput of the system as a whole can be improved, compared with the case where the down frames addressed to the MT1 (terminal 16) are transmitted.
Although the unicasting UDP has been described in the paragraph (A) by way of example, a similar effect can be obtained when TCP frames are used. Since flow control is performed in a TCP layer, it can be conceived that TCP has a smaller effect than UDP frames.
When flow control etc. is performed between the AP1 (13) and the AP control device 12 in the paragraph (K), the same effect can be obtained if discarding is performed only when the queue of the AP control device 12 is congested in a fixed period of time.
In addition, in the case where the packet storage portion 25 of the AP control device 12 is equipped with a mechanism having a queue for each terminal and performing priority control on the queue, a similar effect can be also obtained when transmission priority of packets stored in the queue addressed to the MT1 (terminal 16) is lowered in the fixed period of time.
Next, Embodiment 3 will be described. The system configuration of Embodiment 3 is the same as that of Embodiment 2 shown in
In this embodiment, as shown in
In this embodiment, as shown in
In this case, the wireless transmission control portion 33 performs retransmission control when communication is performed in an infrastructure mode and DCF and an ACK of a transmitted down frame cannot be received from a destination terminal. When the number of times of retransmission is larger than a predetermined threshold, the wireless transmission control portion 33 notifies the radio wave condition notification portion 34 of the radio wave condition of the AP 13.
In this manner, according to this embodiment, down frames addressed to the MT3 (terminal 19) performing communication through the AP2 (17) can be transmitted well without being disturbed by down frames addressed to the AP1 (13). Thus, the throughput of the system as a whole can be improved, compared with the case where the down frames addressed to the AP1 (16) are transmitted.
Although the paragraphs (C) and (D) have given description to the case where the communication condition of the MT1 (terminal 16) is deteriorated, the radio wave condition of the AP1 (13) as a whole is managed not in accordance with the number of times of retransmission to each terminal from the AP1 (13) but in accordance with the total number of times of retransmission to the MT1 (terminal 16) and the MT2 (terminal 15) from the AP1 (13).
In addition, in the case where the packet storage portion 25 of the AP control device 12 is equipped with a mechanism having a queue for each AP and performing priority control on the queue in the paragraph (K), a similar effect can be also obtained when transmission priority of packets stored in the queue addressed to the AP1 (13) is lowered in the fixed period of time.
By use of the access point, the access point control device and the wireless LAN system according to the invention, the transmission/reception volume is controlled in accordance with the radio wave condition of each terminal or each access point. Thus, even when there is a terminal not good in radio wave condition, communication with a terminal good in radio wave condition can be performed by priority so that there is an effect that the throughput of the network system as a whole can be improved. Thus, the access point, the access point control device and the wireless LAN system according to the invention are useful as a network throughput improving technique.
Number | Date | Country | Kind |
---|---|---|---|
2004-299847 | Oct 2004 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP05/14948 | 8/16/2005 | WO | 12/27/2006 |