CN101150469A - A packet dispatching method based on avoidance mechanism in WLAN - Google Patents
A packet dispatching method based on avoidance mechanism in WLAN Download PDFInfo
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Abstract
The invention discloses a group scheduling method adopted in the wireless LAN based on a back-off system. The group scheduling method includes a first competition back-off phase and a second competition back-off phase which are respectively provided with a corresponding competition window. The competition window for the first competition back-off phase has a broader range (1023 as the maximum value) while the competition window for the second competition back-off phase has a smaller range (255 as the maximum value). The nodes cannot visit the channels unless the data groups complete the two back-off phases in order. The group scheduling algorithm for the invention is characterized in that when the two nodes in the network are connected by using RTS/CTS frames, other nodes in the network detect the CTS frame. At the same time, the back-off timers which are not zero in the nodes during the first competition phase continue to back off. The invention includes two back-off phases, while the transmission of data groups and competition back-off are carried out simultaneously. Therefore, the utilization ratio of channels in the highly loaded network system can be greatly increased.
Description
Technical field
The present invention relates in WLAN (wireless local area network) (IEEE 802.11) system based on the packet scheduling algorithm of avoidance mechanism, belong to medium access control (MAC) the layer technical field in the wireless local area network (WLAN) system.
Background technology
Wireless communication means more and more is subject to people's attention in Modern Communication System.Compare with wired network system, the available channel width of wireless network is very narrow, use wireless channel by competition between wireless network node, the csma that has collision detection (CSMA/CA) mechanism in the wireless local area network (WLAN) system in the MAC layer can be with solving internodal race problem, so it is also used by the MAC layer of other system such as wireless self-organization network, wireless sensor network.This mechanism has exposed the low shortcoming of channel utilization in the high-load network system.
At present, improve the scheme of throughput performance of WLAN performance, mainly contain and improve medium access protocol, change competition window regulation mechanism, management information bank (MIB) parameter optimization etc.
In improving medium access protocol, frame burst method allows radio node (WS) to send N frame continuously after obtaining the medium access, and therefore sending a plurality of Frames only need distributed frame interval (DIFS) and a back off time.Its subject matter is that radio node (WS) will be monopolized medium, causes other radio node (WS) hunger phenomenon to occur.Acknowledgement frame (ACK) method that strengthens is by removing the ACK frame fully, using forward error correction (FEC) or only send an ACK frame behind one group of Frame of transmission and raise the efficiency.The method of removing the ACK frame fully can only be used for the low-down environment of error rate; The purpose of FEC method is to reduce and retransmits the time delay of bringing, because the FEC of Frame coding has been introduced extra expense, it can not improve throughput, and its complexity is higher.In the method that changes the competition window regulation mechanism, a famous method that improves throughput performance is to reduce to keep out of the way the shared time of state, as reduces initial contention window size, yet this will cause capacity to descend because of collision probability increases.In management information bank (MIB) parameter optimization method, attribute by a plurality of available Simple Network Management Protocols (SNMP) protocol update, allow an external management agency to determine the state of radio node (WS), and can carry out concrete parameter setting, performance measurement and coordination it; This fragmentation threshold method wherein in bigger bit error rate (BER) channel, adopts short transmitted in packets, its consideration be channel conditions and the relation that adopts which kind of packet.
Summary of the invention
The present invention is directed to the low shortcoming of channel utilization of the CSMA/CA mechanism existence of MAC layer in the existing wireless local area network (WLAN) system, grouping scheduling method based on avoidance mechanism is provided in the high WLAN (wireless local area network) of a kind of throughput, channel utilization that can improve system in the network of high capacity, the complexity of this method is low, compatible good with standard.
Grouping scheduling method based on avoidance mechanism in the WLAN (wireless local area network) of the present invention is:
Network node adopts based on the anti-channel of asking of the access way of the request transmission/clear to send (RTS/CTS) in WLAN (wireless local area network) medium access control (MAC) layer, backoff procedure before the node visit channel is divided into the stage is kept out of the way in first competition and second competition is kept out of the way two of stages and kept out of the way the stage, it is 0--1023 that the window value scope in stage is kept out of the way in first competition, it is 0-255 that the window value scope in stage is kept out of the way in second competition, after packet was finished two competitions in order and kept out of the way the stage, node could access channel; Network system brings into operation and during channel idle, all nodes are all kept out of the way the stage since first competition and are kept out of the way, the competition window that is used for random back produces at random by even distribution, window value is at random, finishing node that first competition keeps out of the way the stage will enter second competition and keep out of the way the stage, at first finish second competition and keep out of the way the node visit channel in stage, in the wall scroll transmission range, two nodes that data transfer task is arranged are in the transmission data, other is not finished the node that first competition keeps out of the way phase process and keeps out of the way continuing, if first competed the timer of keeping out of the way of keeping out of the way the stage and be kept to 0 then the value of resting on is 0 state before data packet transmission finishes; Second competition is kept out of the way the stage and only could begin after the free time at data channel, through first compete keep out of the way the filtration in stage after, will have only part of nodes to enter second at every turn and compete and keep out of the way the stage.Reduced internodal collision probability like this.To keep out of the way the node number in stage less owing to enter second competition, so this stage is kept out of the way the needs that the less span of window just can satisfy backoff procedure.
The concrete steps of packet scheduling algorithm of the present invention are:
If a competition node has packet etc. to be sent, it is kept out of the way the stage since first competition and uses backoff counter (BC1) to be at war with to keep out of the way, unless BC1 is a nonzero value, otherwise BC1 will be from [0, CW1] select a value at random by even distribution in the scope, wherein CW1 is that the competition window in stage is kept out of the way in first competition, and its maximum is 1023.After channel idle, BC1 is every to subtract 1 through a time slot; And when this node received clear to send CTS frame, if when detecting this node and not being the point of destination of this CTS frame, the BC1 of this node will whenever successively decrease 1 through a time slot, and the transmission that realizes data is carried out with keeping out of the way simultaneously.After the distributed time interval DIFS of channel idle, be not decremented to 0 BC1 continue to successively decrease (BC1 be kept to 0 i.e. first competition keep out of the way the stage keep out of the way finish), first competition is kept out of the way second competition that enters that the stage keeps out of the way end and is kept out of the way the stage.Second competition is kept out of the way the value of the backoff counter (BC2) in stage and select generation at random from [0, CW2], and wherein CW2 is that the competition window in stage is kept out of the way in second competition, and its maximum is 255.BC2 is every to successively decrease 1 through a time slot, at first reduces to 0 node and begins access channel.In case a node successfully sends packet, it will return first competition and keep out of the way stage contention access channel again.
Actual channel collision occurs in second competition to be kept out of the way the stage, and when this stage bumped, CW1 and CW2 were the exponent increases with 2, up to reaching their maximums separately.The collision node will rest on second competition to be kept out of the way the stage, continues to use and keeps out of the way timer BC2 competitive channel.CW1 is value in the scope of [CWmin1, CWmax1], and CW2 is value in the scope of [CWmin2, CWmax2].After success rate of data packet transmission sends, competition window will return their minimum value.
Present invention includes two competitions and keep out of the way the transmission of stage and packet and competition and keep out of the way simultaneously and carry out, in the network system of high capacity, channel utilization is improved significantly like this, has kept well compatible with standard, is easy to realize.When offered load heavier (interstitial content is more), algorithm of the present invention has improved systematic function.
Description of drawings
Fig. 1 is the conceptual schema based on the packet scheduling algorithm of avoidance mechanism.
The saturation throughput comparison diagram of (IEEE 802.11) system of WLAN (wireless local area network) when Fig. 2 is 512 bytes for packet and packet scheduling algorithm of the present invention.
The saturation throughput comparison diagram of (IEEE 802.11) system of WLAN (wireless local area network) when Fig. 3 is 1024 bytes for packet and packet scheduling algorithm of the present invention.
Embodiment
Packet scheduling algorithm of the present invention as shown in Figure 1, node will be kept out of the way the stage through two competitions before access channel, wherein first competition is kept out of the way the stage and can be continued to keep out of the way when other transmitting data between nodes.After packet was finished two competitions in order and kept out of the way the stage, node could access channel.The transmission of packet and competition are kept out of the way simultaneously and are carried out.At first whether network node detection data channel is idle, if channel busy, when node receives CTS frame (point of destination is not this node), begin to keep out of the way the timing of keeping out of the way of timer BC1, if before the data packet transmission process finishes, BC1 is kept to 0, and then the BC1 value of remaining on is 0 state, behind the distributed time interval DIFS of wait channel idle, BC2 begins to keep out of the way the timing of successively decreasing, BC2 is earlier that 0 node begins access channel, if before DTD, BC1 also is not decremented to 0, then behind the distributed time interval DIFS of channel idle, BC1 then keeps out of the way timing, if BC1 is kept to 0 in channel clear, then BC2 begins to keep out of the way timing.
Packet scheduling algorithm characteristics of the present invention are to use RTS/CTS (request tosend/clear to send) when frame connects when two nodes in the network, other node in the network listens to the CTS frame, and first competitive stage keeps out of the way non-vanishing the keeping out of the way continuing of timer in this moment these nodes.
Fig. 2 and Fig. 3 have compared algorithm of the present invention at different pieces of information grouping size and IEEE 802.11 standard agreements increase the change in throughput situation with interstitial content.Fig. 2 has provided the saturation throughput comparison diagram of WLAN (wireless local area network) (IEEE 802.11) system and packet scheduling algorithm of the present invention when packet is 512 bytes.Fig. 3 has provided the saturation throughput comparison diagram of WLAN (wireless local area network) (IEEE 802.11) system and packet scheduling algorithm of the present invention when packet is 1024 bytes.CW1 is value in the scope of [CWmin1, CWmax1], and CW2 is value in the scope of [CWmin2, CWmax2].After success rate of data packet transmission sends, competition window will return their minimum value.
By more as can be seen in the network system of high capacity, adopt method channel utilization of the present invention to be improved significantly.
Claims (1)
- In the WLAN (wireless local area network) based on the grouping scheduling method of avoidance mechanism, it is characterized in that:Network node adopts the access way access channel based on the request transmission/clear to send in the wireless local network media accessing control layer, backoff procedure before the node visit channel is divided into the stage is kept out of the way in first competition and second competition is kept out of the way two of stages and kept out of the way the stage, it is 0--1023 that the window value scope in stage is kept out of the way in first competition, it is 0-255 that the window value scope in stage is kept out of the way in second competition, after packet was finished two competitions in order and kept out of the way the stage, node could access channel; Network system brings into operation and during channel idle, all nodes are all kept out of the way the stage since first competition and are kept out of the way, the competition window that is used for random back produces at random by even distribution, window value is at random, finishing node that first competition keeps out of the way the stage will enter second competition and keep out of the way the stage, at first finish second competition and keep out of the way the node visit channel in stage, in the wall scroll transmission range, two nodes that data transfer task is arranged are in the transmission data, other is not finished the node that first competition keeps out of the way phase process and keeps out of the way continuing, if first competed the timer of keeping out of the way of keeping out of the way the stage and be kept to 0 then the value of resting on is 0 state before data packet transmission finishes; Second competition is kept out of the way the stage and only could begin after the free time at data channel, through first compete keep out of the way the filtration in stage after, will have only part of nodes to enter second at every turn and compete and keep out of the way the stage.
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Cited By (13)
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| CN101715241B (en) * | 2008-12-10 | 2012-04-18 | 北京新岸线无线技术有限公司 | Method and device for medium access control of distributed wireless local area network |
| CN102892206A (en) * | 2011-07-20 | 2013-01-23 | 上海交通大学 | Single-antenna MAC(multi-access computer) transmission method based on network characteristic in cognitive wireless sensor network |
| WO2014110806A1 (en) * | 2013-01-18 | 2014-07-24 | Broadcom Corporation | Channel reservation and synchronous transmission |
| CN104221303A (en) * | 2012-04-13 | 2014-12-17 | 高通股份有限公司 | Scheduling algorithms for ieee 802.11 multi-user (mu) multiple-input multiple-output (mimo) communication systems |
| CN104703288A (en) * | 2013-12-05 | 2015-06-10 | 上海无线通信研究中心 | Transmission method based on quasi-random back-off strategy in wireless distributed network |
| CN105122924A (en) * | 2013-04-03 | 2015-12-02 | 高通股份有限公司 | Systems and methods for collision management in a neighborhood aware network |
| CN105681277A (en) * | 2015-12-28 | 2016-06-15 | 中国科学院计算技术研究所 | Media access control method and system of nodes in full duplex wireless local area network |
| WO2017167165A1 (en) * | 2016-04-01 | 2017-10-05 | 索尼公司 | Electronic device, information processing apparatus, and information processing method |
| CN107535002A (en) * | 2015-01-07 | 2018-01-02 | 奥兰治 | System for transmitting packet according to multiple access protocol |
| CN107666489A (en) * | 2017-10-17 | 2018-02-06 | 西安电子科技大学 | A kind of method of media access control protocol based on two benches competition in full duplex radio network |
| CN107926060A (en) * | 2015-07-06 | 2018-04-17 | 瑞典爱立信有限公司 | For performing the transmission node transmitted in radio channel within a wireless communication network to the data of at least one receiving node and method therein |
| WO2018171713A1 (en) * | 2017-03-24 | 2018-09-27 | Mediatek Inc. | Two-phase backoff for access procedure in wireless communication systems |
| CN108934081A (en) * | 2018-06-15 | 2018-12-04 | 扬州大学 | A kind of wireless vehicle mounted network channel cut-in method |
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- 2007-10-24 CN CNA2007101132582A patent/CN101150469A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101715241B (en) * | 2008-12-10 | 2012-04-18 | 北京新岸线无线技术有限公司 | Method and device for medium access control of distributed wireless local area network |
| CN102892206A (en) * | 2011-07-20 | 2013-01-23 | 上海交通大学 | Single-antenna MAC(multi-access computer) transmission method based on network characteristic in cognitive wireless sensor network |
| CN102892206B (en) * | 2011-07-20 | 2014-12-31 | 上海交通大学 | Single-antenna MAC(multi-access computer) transmission method based on network characteristic in cognitive wireless sensor network |
| CN104221303B (en) * | 2012-04-13 | 2018-06-01 | 高通股份有限公司 | For the dispatching algorithm of 802.11 multi-users of IEEE (MU) multiple-input and multiple-output (MIMO) communication system |
| CN104221303A (en) * | 2012-04-13 | 2014-12-17 | 高通股份有限公司 | Scheduling algorithms for ieee 802.11 multi-user (mu) multiple-input multiple-output (mimo) communication systems |
| WO2014110806A1 (en) * | 2013-01-18 | 2014-07-24 | Broadcom Corporation | Channel reservation and synchronous transmission |
| CN105122924A (en) * | 2013-04-03 | 2015-12-02 | 高通股份有限公司 | Systems and methods for collision management in a neighborhood aware network |
| CN105122924B (en) * | 2013-04-03 | 2018-10-02 | 高通股份有限公司 | System and method for the conflict management in neighborhood aware network |
| CN104703288A (en) * | 2013-12-05 | 2015-06-10 | 上海无线通信研究中心 | Transmission method based on quasi-random back-off strategy in wireless distributed network |
| CN104703288B (en) * | 2013-12-05 | 2018-03-09 | 上海无线通信研究中心 | A kind of transmission method based on quasi- random back strategy in wireless distributed network |
| CN107535002A (en) * | 2015-01-07 | 2018-01-02 | 奥兰治 | System for transmitting packet according to multiple access protocol |
| CN107535002B (en) * | 2015-01-07 | 2021-09-14 | 奥兰治 | System for transmitting data packets according to a multiple access protocol |
| CN107926060A (en) * | 2015-07-06 | 2018-04-17 | 瑞典爱立信有限公司 | For performing the transmission node transmitted in radio channel within a wireless communication network to the data of at least one receiving node and method therein |
| CN105681277A (en) * | 2015-12-28 | 2016-06-15 | 中国科学院计算技术研究所 | Media access control method and system of nodes in full duplex wireless local area network |
| CN105681277B (en) * | 2015-12-28 | 2018-12-04 | 中国科学院计算技术研究所 | A kind of media access control method and system of full duplex radio local area network interior joint |
| RU2698430C1 (en) * | 2016-04-01 | 2019-08-26 | Сони Корпорейшн | Electronic device, information processing device and information processing method |
| CN108476529A (en) * | 2016-04-01 | 2018-08-31 | 索尼公司 | Electronic device, information processing equipment and information processing method |
| WO2017167165A1 (en) * | 2016-04-01 | 2017-10-05 | 索尼公司 | Electronic device, information processing apparatus, and information processing method |
| US10887914B2 (en) | 2016-04-01 | 2021-01-05 | Sony Corporation | Electronic device, information processing apparatus, and information processing method |
| WO2018171713A1 (en) * | 2017-03-24 | 2018-09-27 | Mediatek Inc. | Two-phase backoff for access procedure in wireless communication systems |
| TWI674028B (en) * | 2017-03-24 | 2019-10-01 | 聯發科技股份有限公司 | T w o - p h a s e b a c k o f f m e t h o d a n d u s e r e q u i p m e n t f o r a c c e s s p r o c e d u r e i n w i r e l e s s c o m m u n i c a t i o n s y s t e m s |
| CN107666489A (en) * | 2017-10-17 | 2018-02-06 | 西安电子科技大学 | A kind of method of media access control protocol based on two benches competition in full duplex radio network |
| CN108934081A (en) * | 2018-06-15 | 2018-12-04 | 扬州大学 | A kind of wireless vehicle mounted network channel cut-in method |
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