CN104219025B - The self-adapted adjustment system and method for the descending polymerization frame lengths of AP and speed - Google Patents
The self-adapted adjustment system and method for the descending polymerization frame lengths of AP and speed Download PDFInfo
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Abstract
The invention discloses a kind of descending polymerization frame lengths of AP and the self-adapted adjustment system and method for speed, mainly solve in wireless network between AP and website, cause the speed of transmission frame and frame length to be unable to the problem of adaptive channel changes because channel quality frequently changes.Implementation step is：1) AP calculates the transmission rate of current aggregate frame and misses subframe rate and estimate effective throughput, to predict channel quality；2) AP predicts the variation tendency of channel according to two sections of mistake subframe rate sizes before and after bit code table；3) AP is adaptively adjusted the length and speed of aggregate frame, and the MIMO mode of operations of physical layer are selected according to BACK signal to noise ratio；4) AP analyzes the number of maximum continuous " 0 " in bit code table, judges whether current transmission collides, and adaptively enable RTS/CTS mechanism collision frees.The present invention has the advantages of reacting fast to channel variation, adaptability is good, the wireless network frequently changed available for channel quality.
Description
Technical field
The present invention relates to field of wireless communications networks, more particularly to one kind to pass through medium access control MAC layer and physical layer
The descending polymerization frame lengths of access point AP of cooperative achievement and the system and method for rate adaptation adjustment, for solving foundation structure
When the frequent change of channel quality between AP and receiving node causes the transmission rate of currently transmitted frame and gathers in type wireless network
Close frame frame length can not adaptive channel and the problem of cause excessive bust this, improve the transmission performance of network.
Background technology
The major technique that WLAN WLAN is used at present is the series of standard protocols of IEEE 802.11.From 1999
IEEE802.11 working groups propose IEEE 802.11a and IEEE802.11b standard and proposed 802.11g by 2003 in succession
Standard, its physical layer define different modulation and coded system, support multi-rate data transmission.Wherein, IEEE802.11b
Physical layer uses Direct-Spread frequency hopping DSSS technologies, is operated in 2.4GHz frequency ranges, and rate bandwidth reaches as high as 11Mbps, according to
The actual conditions of network environment can also use 1Mbps, 2Mbps and 5.5Mbps transmission rate.In order to improve the biography of WLAN
Defeated speed, IEEE802.11a physical layers use OFDM technology to substitute 802.11b DSSS technologies, are operated in 5.8GHz frequency ranges,
Flank speed can reach 54Mbps, can use 6Mbps, 9Mbps, 129Mbps, 189Mbps, 249Mbps, 369Mbps,
8 kinds of speed such as 489Mbps, 54Mbps are transmitted.By 2003,802.11 working groups proposed 802.11g standards, its work
In 2.4GHz frequency ranges, using orthogonal frequency division multiplex OFDM technology, 54Mbps transmission rate is equally held up to.
With the continuous improvement of physical layer transmission technology, IEEE have approved 802.11n high speed wireless access again within 2009
Standard.IEEE 802.11n employ several important technologies to increase the message transmission rate of oneself, including：MIMO multiple antennas skills
Art, physical layer channel merges and MAC layer techniques of frame aggregation.In addition, its core is MIMO and OFDM technology, 2.4GHz frequencies are operated in
Section and 5GHz frequency ranges, the use of speed during transmission with a width of 20MHZ is up to 300Mbps, when using by two 20MHZ's
Combining channel into a 40MHZ bandwidth channel when, transmission speed reaches as high as 600Mbps.
With technology development and update, the agreements of IEEE 802.11 in terms of high-speed multimedia mobile service should
With quite ripe.However, the development of current WLAN nevertheless suffers from all many challenges.Such as how to the greatest extent may be used
Wireless network resource utilization rate can be improved, the antijamming capability of network how is improved under complex environment, how in guaranteed qos
In the case of the high speed business etc. for supporting mobility in real time is provided.Although new standard has had very big in speed
Improve, but be not meant to higher link throughput and service quality at a high speed.Due to signal fadeout in wireless network environment,
The influence of node motion and bursty interference, quality of wireless channel quickly can frequently change, the data transfer on wireless channel
The performance of speed and whole network all needs to change therewith.Therefore still need in transmitting procedure interior joint and estimate in real time
With the change of prediction channel quality, and its message transmission rate is adaptively adjusted.Rate adaptation problem is to improving wireless money
Source utilization rate, and the performance of whole network have important influence.
In order to improve the throughput of network, domestic extrinsic forecast channel quality, and adaptive its transmission rate side of adjustment
Face, i.e., many researchs are carried out to rate adaptation algorithm.Wherein, main technical scheme has following three kinds：
1. the method successfully with frequency of failure adjustment speed is continuously transmitted based on statistics.In this approach, node not area
Framing miss-reason, no matter the loss of frame is due to signal fadeout, change causes, and is also due to that bursty interference causes collision to cause,
It is due to unsuccessfully that channel quality deterioration causes all to think current transmission without exception.In transmitting procedure, node M AC layers pass through the company of statistics
Resume the quality sent and channel quality is successfully estimated with the frequency of failure.I.e. when the continuous Successful transmissions n times of node, then it is assumed that current letter
Road quality is good, higher rate can be supported to transmit, therefore improves node-node transmission speed, and if is transmitted immediately after raising speed
Fail, then node returns to original low rate and is transmitted；When node continuously transmits unsuccessfully M times, then it is assumed that current letter
Road deterioration, it is impossible to support high rate data transmission, therefore node reduces transmission rate.Such method needs the biography based on multiple frames
Defeated result carries out the estimation of channel quality, it is impossible to which the change to channel conditions, which is made, timely to be adjusted and react, and causes major part
Speed used in transmission is less than the maximum rate that actual channel can be supported.
2. the method based on measurement physical layer signal to noise ratio or received signal strength adjustment speed.In this approach, node
Estimate channel quality status by measuring physical layer snr of received signal SNR or received signal strength RSSI.When measuring
When SNR or RSSI exceedes a certain thresholding, then it is assumed that present channel quality is good, higher rate can be supported to transmit, therefore node
Improve transmission rate；When measuring SNR or RSSI and being less than a certain thresholding, then it is assumed that present channel quality deteriorates, it is impossible to supports
High rate data transmission, therefore reduce message transmission rate.Or according between the SNR or RSSI and transmission rate for estimating to obtain in advance
Mapping table, table look-at obtain adapt to current channel condition message transmission rate.Such method is wireless reality
In network environment, due to the influence of the fast-fading of signal, node motion and bursty interference, quality of wireless channel can Rapid Frequency
Numerous change, the optimal transmission rate of channel and between SNR or RSSI and in the absence of mutual corresponding relation.
3. the method for adjusting speed by estimating the FER in statistical window.In this approach, node is solid at one
In the transmission time window for determining size or size adaptation change, continuously send data frame and carry out channel quality detection, lead to
Cross and count the ACK received in the detection cycle, number of retransmissions and number of giving out a contract for a project estimates FER, so as to predict channel quality
Situation.When FER is less than a certain thresholding, then it is assumed that present channel quality is good, higher rate can be supported to transmit, therefore
Node improves transmission rate；When FER is more than a certain thresholding, then it is assumed that present channel quality deteriorates, it is impossible to supports high-speed
Transmission, therefore reduce message transmission rate.Such method is needed according to the transmission situation in a longer statistical window come pre-
Channel is surveyed, and is all carried out data transmission in same transmission window using identical speed, therefore to the mutation of channel quality
It is insensitive.
These above-mentioned methods are due to can not accurately estimate channel, so as to cause the transmission rate of estimation and non-optimal transmission
Speed, influence the raising of network throughput.
The content of the invention
It is an object of the invention to for above-mentioned prior art problem, on the basis of existing IEEE802.11n agreements,
A kind of descending polymerization frame lengths of AP and the self-adapting regulation method of speed are proposed, to improve network throughput.
The technical proposal of the invention is realized in this way：
One, term explanations
MAC：Media access contorl；
PHY：Physical layer；
MCS：Modulation and coding strategy；
AP：Access point；
STA：Website；
MIMO：Multiple input and multiple output；
RSSI：Received signal strength indicator；
SNR：Received signal to noise ratio；
ADDBA：Establish block and receive the management frame for confirming frame mechanism；
LQE：Link quality estimation；
SFER：Subframe rate by mistake；
Bitmap：Sub-frame transmission situation confirmation form；
Data frame DATA：Carry the link layer protocol unit of user data service content；
Control frame：Carrier signaling information, for realizing the medium access control layer protocol element of the tasks such as control management；
RTS/CTS/ACK：Three kinds of control frames for being used to realize 802.11 wireless network Media access contorl Handshake Protocols, point
Do not correspond to send claim frame RTS, send permission CTS and receive acknowledgement frame ACK.
A-RTS：It is adaptive to send claim frame；
BACK：Block receives acknowledgement frame, for confirming to multiframe；
AMPDU：The Medium Access Control Protocol data cell of polymerization；
FAMPDU：The Medium Access Control Protocol data cell of first polymerization；
NAV timers：Network allocation vector timer；
Sending node：Send the wireless device of frame；
Receiving node：The wireless device of receiving frame；
Communication or session：Frame transmitting-receiving between sending node and destination node.
Two, system architectures
A kind of self-adapted adjustment system of the descending polymerization frame length of AP and speed, including：
Media access contorl MAC layer distribution access-in management unit (1), physical channel administrative unit (2), medium access control
Mac layer frame extraction unit (3) processed, the unit that depolymerizes (4), receiver (5), physical layer frame form unit (6), frame aggregation unit
(7), emitter (8) and radio frequency front-end unit (9), it is characterised in that：Also include being used to adjust transmission rate and polymerization frame length
Adjustment unit (10), the input of the adjustment unit (10) and the output of Media access contorl mac layer frame extraction unit (3) connect
Connect, its output is connected with the input of Media access contorl MAC layer distribution access-in management unit (1) and frame aggregation unit (7).
Wherein described adjustment unit (10) includes：
Frame receive information management module (101), for being identified simultaneously from Media access contorl mac layer frame extraction unit (3)
Extract bit code table Bitmap, record current block receives acknowledgement frame BACK receiving power and previous aggregate frame AMPDU
Transmission rate；
Subframe rate estimation module (102) by mistake, for obtaining bit code table Bitmap from frame receive information management module (101)
And calculate overall subframe rate SFER, the mistake subframe rate SFER1 of front half section and the mistake subframe rate of second half section by mistake of the bit code table
SFER2；
Noise ratio measurement module (103), acknowledgement frame is received for obtaining block from frame receive information management module (101)
BACK, and calculate its signal to noise ratio；
Effective throughput estimation module (104), for the aggregate frame obtained using frame receive information management module (101)
AMPDU transmission rate, and the mistake subframe rate SFER that subframe rate estimation module (102) obtains by mistake, once transmission is poly- before calculating
Close frame AMPDU effective throughput；
Bit code table Bitmap analysis modules (105), for the distribution according to " 0 " and " 1 " in bit code table Bitmap, sentence
The variation tendency of disconnected present channel, and calculate the number of maximum continuous " 0 " in current bit code table Bitmap；
It polymerize frame length and confirms module (106), for obtains present channel from bit code table Bitmap analysis modules (105)
The aggregate frame AMPDU to be sent such as situation and variation tendency, adaptive adjustment the degree of polymerization；
Transmission rate determining module (107), for from noise ratio measurement module (103) and effective throughput estimation module
(104) current channel conditions are obtained and block receives acknowledgement frame BACK signal to noise ratio, are adaptively adjusted the polymerization sent next time
Frame AMPDU transmission rate and multiple-input, multiple-output MIMO mode of operations；
Collision detection and processing module (108), for obtaining maximum according to from bit code table Bitmap analysis modules (105)
The continuously number of " 0 ", judge whether previous aggregate frame AMPDU is collided, and after it is determined that colliding, enables RTS/
CTS handshake mechanisms carry out channel booking, and wherein RTS/CTS represents to send claim frame and send to allow frame；
Frame sends information management module (109), for the aggregate frame AMPDU for obtaining transmission rate determining module (107)
Transmission rate and multiple-input, multiple-output MIMO mode of operations are sent to Media access contorl MAC layer distribution access-in management unit (1), will
Polymerization frame length confirms that the degree of polymerization that module (106) obtains is sent to frame aggregation unit (7), and when collision detection and processing mould
When block (108) judges that needs enable adaptive RTS/CTS, Media access contorl MAC layer distribution access-in management unit (1) is notified
RTS/CTS channel bookings are first carried out before aggregate frame AMPDU is sent, wherein RTS/CTS represents to send claim frame and send to permit
Perhaps frame.
Three, implementation methods
A kind of access point AP is descending to polymerize frame length and the self-adapting regulation method of speed, comprises the following steps：
(1) access point AP sends the claim frame established block and receive confirmation frame mechanism ADDBA to receiving node first；
(2) after receiving node receives the ADDBA claim frames, response frame is returned to access point AP, access point AP receives this
After response frame, both sides establish aggregate frame transmission mechanism；
(3) access point AP, which first sends claim frame and receives request, allows frame, i.e., prevents first using RTS/CTS handshake mechanisms
Individual aggregate frame AMPDU collides in transmission；Retransmit the first aggregate frame AMPDU using minimum polymerization length；
(4) access point AP sends aggregate frame request acknowledgement frame BlockACK Request to receiving node, and request receives section
Point confirms to aggregate frame AMPDU；
(5) receiving node generates bit code table Bitmap, so as to group according to the aggregate frame AMPDU received transmission situation
Dress up block and receive acknowledgement frame BACK, and send the block to access point AP and receive acknowledgement frame；
(6) access point AP judges whether to collide according to reception condition：If access point AP does not receive block and received really
The number of bit code table Bitmap maximum continuous " 0 " in the frame BACK or block received reception acknowledgement frame BACK is recognized more than 8, then table
Show and collide, perform step (7)；Otherwise, do not collide, perform step (8)；
(7) access point AP enables adaptive RTS/CTS mechanism, and keeps transmission rate and polymerization frame length constant, to
Receiving node sends next aggregate frame AMPDU, return to step (4)；Wherein RTS/CTS represents to send claim frame and send to allow
Frame；
(8) access point AP receives acknowledgement frame BACK signal-to-noise ratio computation current throughput according to the block received, and combines
Block receives the bit code table Bitmap in acknowledgement frame BACK, predicts present channel quality and variation tendency；
(9) handling capacity and channel quality prediction information that access point AP obtains according to step (8), is adaptively adjusted next
Individual aggregate frame AMPDU transmission rate and polymerization frame length；
(10) transmission rate and polymerization frame length that access point AP obtains according to step (9) send next to receiving node
Aggregate frame AMPDU, return to step (4).
The invention has the advantages that：
1) channel utilization that the present invention eats dishes without rice or wine in the time from raising AP channels, according to channel quality quality and change
The prediction of trend, the transmission rate and polymerization frame length of adaptive adjustment aggregate frame, with the change of adaptive channel quality, is avoided
Excessive packet loss and re-transmission.
2) present invention is sent out by the transmission rate and polymerization frame length of adaptive adjustment aggregate frame when reducing low speed transmissions
Eating dishes without rice or wine the time for data frame occupancy is sent, AP is sent more data, so as to improve downlink throughput capacity.
Brief description of the drawings
Fig. 1 is the principle schematic of the present invention；
Fig. 2 is the system architecture diagram of the present invention；
Fig. 3 is adjustment unit structure chart in present system；
The method that Fig. 4 is the present invention realizes general flow chart；
Fig. 5 is the sub-process figure that first AMPDU aggregate frames are sent in the inventive method；
Fig. 6 is the sub-process figure that the inventive method medium-rate adaptively adjusts；
Fig. 7 is the sub-process figure that polymerization frame length adaptively adjusts in the inventive method.
Embodiment
For the object of the invention, technical scheme and advantage is more clearly understood, the present invention is carried out with reference to the accompanying drawings
It is further to describe in detail.
Reference picture 1, the technology of the present invention principle are as follows：
When AP sends data to website, its link circuit condition between website is unknown, so AP is before data are sent, it is sharp
With needing to establish BACK mechanism between AP and website, chain is carried out by sending ADDBA claim frames and receiving ADDBA response frames first
Road quality detection, while subsequent frame transmission is influenceed in order to avoid the first LOF, AP uses RTS/CTS when sending the first frame
Handshake mechanism.
After AP sends AMPDU frames to website, confirmed using BACK claim frames requesting site.AP in physical layer by measuring
The receiving power of the BACK acknowledgement frames of website feedback, and the BACK acknowledgement frames of feedback are analyzed in MAC layer, and by estimating
Calculate and transmit the effective throughput for missing subframe rate and current transmission to predict the change of channel quality and channel between AP and website
Change trend；Then AP sends AMPDU aggregate frames according to the prediction to present channel quality quality, adaptive adjustment AP to website
Transmission rate, and determine that physical layer sends AMPDU aggregate frames according to the signal to noise ratio of the reception BACK acknowledgement frames measured
MIMO mode of operations；Last AP, which combines, to be sent out to website the quality of channel quality and the prediction of variation tendency, adaptive adjustment
Send the polymerization length of AMPDU aggregate frames, the i.e. degree of polymerization.
Reference picture 2, system of the invention include：MAC layer distribution access-in management unit 1, physical channel administrative unit 2,
Mac layer frame extraction unit 3, the unit 4 that depolymerizes, receiver 5, physical layer frame form unit 6, frame aggregation unit 7, emitter 8, penetrated
Frequency front end unit 9 and adjustment unit 10.Wherein：
MAC layer distribution access-in management unit 1, physical layer frame form unit 6, frame aggregation unit 7, emitter 8 and radio frequency
The unidirectional connection successively of front end unit 9, collectively forms data transmitting channel；Radio frequency front-end unit 9, receiver 5, the unit 4 that depolymerizes,
Mac layer frame extraction unit 3 is unidirectionally connected successively with MAC layer distribution access-in management unit 1, collectively forms data receiving channel.
Radio frequency front-end unit 9 is bi-directionally connected with physical channel administrative unit 2 and transmits control and notification message；Physical channel administrative unit 2
Unidirectionally it is connected with MAC layer distribution access-in management unit 1, channel status is notified to it；MAC layer distribution access-in management unit 1
Be bi-directionally connected with adjustment unit 10, the frame for simultaneous polymerization frame deliver letters breath and send aggregate frame transmission rate and polymerization
Spend information；Mac layer frame extraction unit 3 is unidirectionally connected with adjustment unit 10, for transmitting the Bitmap letters received in BACK frames
Breath；Adjustment unit 10 is unidirectionally connected with physical layer frame polymerized unit 7, for sending AMPDU aggregate frames to the transmission of frame aggregation module
Frame length information；Radio frequency front-end unit 9 is bi-directionally connected for receiving and sending wireless signal with antenna.
After the AMPDU aggregate frames of first shortest length of transmission of MAC layer distribution access-in management unit 1, website receives
Machine 5 receives the AP AMPDU frames sent, and submits to physical layer and depolymerize unit 4, after the unit 4 that depolymerizes will depolymerize
Subframe once submit to mac layer frame extraction unit 3, mac layer frame extraction unit 3 will carry out CRC check to each subframe, so as to
Determine the subframe whether transmission success, and transmission situation each subframe and corresponding sequence number are sent to MAC layer distribution
Formula access-in management unit 1；MAC layer distribution access-in management unit 1 generates according to the transmission situation and sequence number of corresponding subframe
Bitmap, and BACK frames are assembled, unit 6 and emitter 8 are formed to AP feedback acknowledgment information by physical layer frame.Equally, AP connects
Receipts machine 5 receives the BACK frames that website is sent, and is sent to mac layer frame extraction unit 3；The basis of mac layer frame extraction unit 3
Bitmap information in the BACK received, estimation transmission AMPDU mistake subframe rate and effective throughput, and send it to
Adjustment unit 10；Adjustment unit 10 is worked as according to the effective throughput prediction of the mistake subframe rate and current transmission of Bitmap rear and front ends
The quality and variation tendency of preceding channel, and accordingly adaptive adjustment send next AMPDU aggregate frames transmission rate and
Frame length information, rate information is sent to MAC layer distribution access-in management unit 1, frame length information is sent to physical layer frame and gathered
Close unit 7；Extracted again by MAC layer distribution access-in management unit 1 from queue and be sent to the packet of purpose website, and add frame
Header, unit 6 is formed by physical layer frame and frame aggregation unit 7 carries out physical layer frame polymerization and encapsulation, finally from emitter 8
It is sent to website.
Reference picture 3, adjustment unit 10 of the present invention include：Frame receive information management module 101, by mistake subframe rate estimation
Module 102, noise ratio measurement module 103, effective throughput estimation module 104, Bitmap analysis modules 105, AMPDU aggregate frames
Long determining module 106, AMPDU transmission rates determining module 107, collision detection and processing module 108 and frame send information management
Module 109.Wherein：
Frame receive information management module 101, respectively with missing subframe rate estimation module 102, noise ratio measurement module 103 and having
Effect handling capacity estimation module 104 unidirectionally connects, for transmitting Bitmap information in the MAC received and the BACK received
Signal to noise ratio；
Subframe rate estimation module 102 by mistake, it is unidirectionally connected with effective throughput estimation module 104, for effectively handling up
Measure estimation module transmission and miss subframe rate information, so as to estimate the effective throughput of transmission AMPDU frames；Estimate mould with mistiming subframe rate
Block 102 and Bitmap analysis modules 105 are bi-directionally connected, for the mistake subframe rate information prediction channel according to two sections before and after Bitmap
Variation tendency；
AMPDU polymerization frame lengths determining module 106, it is unidirectionally connected with Bitmap analysis modules 105, is analyzed according to Bitmap
The mistake subframe rate information prediction channel variation trend that module 105 obtains, it is determined that transmitting the frame length letter of next AMPDU aggregate frames
Breath；
Collision detection and processing module 108, it is unidirectionally connected with Bitmap analysis modules 105, according to maximum in Bitmap
Continuously the number of " 0 " judges whether current transmission collides, and the progress of RTS/CTS handshake mechanisms is enabled when colliding
Channel booking；
Noise ratio measurement module 103 and effective throughput estimation module 104 respectively with AMPDU transmission rate determining modules
107 unidirectional connections, AMPDU transmission rates determining module 107 receives according to the effective throughput information and BACK of current transmission to be believed
Make an uproar than the quality of information prediction channel quality, and determine to transmit next AMPDU transmission rate and physical layer MIMO Working moulds
Formula；
AMPDU polymerization frame lengths determining module 106, AMPDU transmission rates determining module 107, collision detection and processing module
108, it sends information management module 109 with frame respectively and is unidirectionally connected, and sending information management module 109 by frame will be next
Frame length information, transmission rate and the MIMO operating mode informations of AMPDU aggregate frames, and whether enable RTS/CTS handshake mechanisms
Information, it is sent respectively to the formation of MAC layer respective frame and polymerized unit.
Reference picture 4, the implementation method of the descending adaptive adjustment for polymerizeing frame length and speed of AP of the present invention, including following step
Suddenly：
Step 1：When being sent to the frame number of receiving node in AP MAC layer queue more than BACK threshold values, AP is first
ADDBA claim frames first are sent to receiving terminal, prepare to establish BACK mechanism with receiving end.
Step 2：After receiving node receives ADDBA claim frames, ADDBA response frames are returned to AP, AP establishes with receiving end
BlockACK mechanism.
Step 3：AP sends first AMPDU aggregate frame to website, and is sending aggregate frame request acknowledgement frame afterwards
BlockACK Request, request receiving node confirm to aggregate frame AMPDU.
Reference picture 5, this step are implemented as follows：
(3a) AP measurement receiving nodes return to the received signal to noise ratio SNR of ADDBA response framesADDBA, and determined according to signal to noise ratio
The transmission rate R of one adaptation present channel qualityA, and first AMPDU is calculated with RATransmission time T=S/R during transmissionA,
Wherein S represents aggregate frame AMPDU byte count sizes；
(3b) in order to prevent the transmission of first AMPDU data frame from colliding, AP sends RTS frames and carries out channel booking,
Wherein RTS frames subscription time Duration fields DurRTSFor：
DurRTS=4SIFS+CTStime+T+BAreqtime+BAtime,
Wherein SIFS represents short frame period, CTStimeThe time that transmission CTS needs is represented, T represents first AMPDU of transmission
The time needed, BAreqtimeRepresent the time that transmission BACK claim frames need, BAtimeRepresent what transmission BACK response frames needed
Time；
(3c) receiving node sets the subscription time Duration fields Dur of CTS frame channelsCTS, and send the CTS to AP
Frame, wherein
DurCTS=3SIFS+T+BAreqtime+BAtime,
SIFS represents short frame period in formula, and T represents to transmit the time that first AMPDU needs, BAreqtimeRepresent transmission
The time that BACK claim frames need, BAtimeRepresent the time that transmission BACK response frames need；
After (3d) AP receives the CTS frames of receiving node transmission, its signal to noise ratio snr is measuredCTS, and determine to work as according to signal to noise ratio
The transmission rate R of preceding channel qualityC；
(3e) AP is according to the transmission rate R for measuring signal-to-noise ratio (SNR) estimation twiceAAnd RC, it is determined that first AMPDU's of transmission is final
Transmission rate：R=max (RA, RC)。
Step 4：After receiving node receives first AMPDU and BACK claim frame, given birth to according to the transmission situation of each subframe
Into Bitmap, receiving node is filled according to the Bitmap to block acknowledgement frame BACK, and populated BACK is sent into AP；
Step 5：AP judges whether current transmission sends collision according to reception condition：
If AP has had correctly received BACK, and it is filled the number of continuous " 0 " in bitmap Bitmap and is no more than 8, illustrates to work as
Before be transmitted without colliding, perform step 6；
If AP has had correctly received BACK, and it fills the number of continuous " 0 " in bitmap Bitmap more than 8, illustrates current
Transmission collides, then AP enables adaptive RTS/CTS mechanism, and keeps transmission rate and polymerization frame length constant, hair
Send next AMPDU；
If AP receives BACK twice in succession, and it is filled the number of continuous " 0 " in bitmap Bitmap and all surpassed twice at this
Cross 8, then it is assumed that such a situation is due to that channel quality deterioration causes, and AP reduces transmission rate and simultaneously reduces polymerization length；
If AP is not received by BACK, illustrate that current transmission is collided, then AP keeps transmission rate and polymerization frame length
Degree is constant, and before next AMPDU is sent, enables adaptive RTS/CTS mechanism, i.e., before next AMPDU is sent
RTS/CTS handshake mechanisms are enabled first carries out channel booking.
Step 6：AP predicts present channel quality according to the BACK received, and adaptively adjust transmission rate and
MIMO mode of operations.
Reference picture 6, this step is implemented as follows：
(6a) estimates the effective throughput G under present rate first after AP receives the BACK of receiving node feedbackrAnd have
Imitate handling capacity sliding average
Wherein, P represents aggregate frame AMPDU byte-sized, and SFER represents whole BACK mistake subframe rate, and T represents other
Overhead time, R represent transmission AMPDU speed；Represent the effective throughput sliding average of an aggregate frame, α tables
Show smoothing factor and α=0.25；
(6b) AP is according to GrWithRelation, be divided into following three kinds of situations and transmission rate be adjusted：
Situation one：WhenWhen, show that present channel quality is good, transmission rates of the AP in previous AMPDU
On the basis of improve a speed grade；
Situation two：WhenWhen, show that present channel quality deteriorates, transmission rates of the AP in previous AMPDU
On the basis of reduce a speed grade；
Situation three：Work as GrWhen being unsatisfactory for both the above condition, show that present channel quality is stable, AP is in previous AMPDU
Transmission rate on the basis of keep speed grade it is constant；
Wherein, Δ represents the standard deviation of effective throughput, and has
(6c) AP measures BACK received signal to noise ratio SNR, so that it is determined that physical layer MIMO mode of operation：
When the signal to noise ratio snr for receiving BACK is more than 16dB, then AP prioritizing selections multiplexer mode；
When the signal to noise ratio snr for receiving BACK is less than 13dB, then AP prioritizing selections diversity mode；
When the signal to noise ratio snr for receiving BACK meets 13dB≤SNR≤16dB, then AP keeps MIMO mode of operations not
Become.
Step 7：AP calculates the mistake subframe rate SFER of Bitmap first halfs in BACK1With the mistake subframe rate of latter half
SFER2, obtain its difference SFER1-SFER2, then with uniform miss-threshold ELthresholdIt is compared, so as to predict channel matter
Variation tendency is measured, and adaptively adjusts aggregate frame frame length.
Reference picture 7, this step are implemented as follows：
(7a) is if effective throughput meets under present rateAccording to two sections before and after Bitmap of mistake
Frame per second and uniform miss-threshold ELthresholdRelation, be divided into following 3 kinds of situations again：
Situation one：If SFER1-SFER2＞ ELthreshold, show that present channel quality is good and improves, in order to believe
In the case that road quality is good, data as much as possible are transmitted, then AP increases frame aggregation degree, and this example takes ELthreshold=0.2；
Situation two：If SFER1-SFER2＜ ELthreshold, show that present channel quality is good but deteriorates, in order to prevent
Long aggregate frame meets with the channel condition of difference and causes tail bust this, then AP reduces frame aggregation length；
Situation three：If | SFER1-SFER2|≤ELthreshold, illustrate present channel quality well and stably, AP improve frame and gathered
Close length；
(7b) is if effective throughput meets under present rateIllustrate that present channel quality is very poor, be
Reduce and eated dishes without rice or wine the time using low speed transmissions, improve sensitivity of the algorithm to channel variation, AP reduces frame aggregation degree.
(7c) is if effective throughput meets under present rateIllustrate current letter
Road situation is maintained at stable state, and AP keeps transmission rate constant, only increase polymerization length；
(7d) judges that present channel is in the stable state described by step (7c) when AP receives BACK continuous 10 times,
Then AP improves a speed grade on the basis of original transmission rate grade, sends aggregate frame AMPDU and carries out channel quality detection.
Step 8：AP polymerize and sent down according to transmission rate determined above, MIMO mode of operations and polymerization frame length
One aggregate frame AMPDU, and aggregate frame request acknowledgement frame BlockACK Request are being sent afterwards, request receiving node is to poly-
Frame AMPDU is closed to be confirmed.
Above description is only the specific example of the present invention, is not construed as limiting the invention.Clearly for ability
, all may be without departing substantially from the principle of the invention, the situation of structure after present invention and principle is understood for the professional in domain
Under, the various modifications and variations in form and details are carried out, but these modifications and variations based on inventive concept are still at this
Within the claims of invention.
Claims (2)
1. the self-adapted adjustment system of a kind of descending polymerization frame length of access point AP and speed, including：Media access contorl MAC layer
Distributed access-in management unit (1), physical channel administrative unit (2), Media access contorl mac layer frame extraction unit (3), depolymerization
Close unit (4), receiver (5), physical layer frame and form unit (6), frame aggregation unit (7), emitter (8) and radio frequency front-end unit
(9), it is characterised in that：Also include being used to adjust transmission rate and polymerize the adjustment unit (10) of frame length, the adjustment unit
(10) input is connected with the output of Media access contorl mac layer frame extraction unit (3), and it is exported and Media access contorl MAC
The distributed access-in management unit (1) of layer connects with the input of frame aggregation unit (7)；
Described adjustment unit (10) includes：
Frame receive information management module (101), for identifying and extracting from Media access contorl mac layer frame extraction unit (3)
Bit code table Bitmap, record current block receive acknowledgement frame BACK receiving power and previous aggregate frame AMPDU transmission
Speed；
By mistake subframe rate estimation module (102), by from frame receive information management module (101) obtain bit code table Bitmap and based on
Calculate overall subframe rate SFER, the mistake subframe rate SFER1 of front half section and the mistake subframe rate of second half section by mistake of the bit code table
SFER2；
Noise ratio measurement module (103), acknowledgement frame BACK is received for obtaining block from frame receive information management module (101), and
Calculate its signal to noise ratio；
Effective throughput estimation module (104), for the aggregate frame AMPDU obtained using frame receive information management module (101)
Transmission rate, and subframe rate estimation module (102) obtained mistake subframe rate SFER by mistake, a transmission convergence frame before calculating
AMPDU effective throughput；
Bit code table Bitmap analysis modules (105), for the distribution according to " 0 " and " 1 " in bit code table Bitmap, judge to work as
The variation tendency of preceding channel, and calculate the number of maximum continuous " 0 " in current bit code table Bitmap；
It polymerize frame length and confirms module (106), for obtains the shape of present channel from bit code table Bitmap analysis modules (105)
The aggregate frame AMPDU to be sent such as condition and variation tendency, the adaptive adjustment degree of polymerization；
Transmission rate determining module (107), for obtaining block reception acknowledgement frame BACK noise from noise ratio measurement module (103)
Than being adaptively adjusted multiple-input, multiple-output MIMO mode of operations, present channel shape being obtained from effective throughput estimation module (104)
Condition, it is adaptively adjusted the aggregate frame AMPDU sent next time transmission rate；
Collision detection and processing module (108), for maximum continuous according to being obtained from bit code table Bitmap analysis modules (105)
The number of " 0 ", judge whether previous aggregate frame AMPDU is collided, after it is determined that colliding, enable RTS/CTS and hold
Mobile phone system carries out channel booking, and wherein RTS/CTS represents to send claim frame and send to allow frame；
Frame sends information management module (109), for the aggregate frame AMPDU transmission for obtaining transmission rate determining module (107)
Speed and multiple-input, multiple-output MIMO mode of operations are sent to Media access contorl MAC layer distribution access-in management unit (1), will polymerize
Frame length confirms that the degree of polymerization that module (106) obtains is sent to frame aggregation unit (7), and when collision detection and processing module
(108) when judging that needs enable adaptive RTS/CTS, notice Media access contorl MAC layer distribution access-in management unit (1) exists
RTS/CTS channel bookings are first carried out before sending aggregate frame AMPDU, wherein RTS/CTS represents to send claim frame and send to allow
Frame.
2. a kind of access point AP is descending to polymerize frame length and the self-adapting regulation method of speed, comprise the following steps：
1) access point AP sends the claim frame established block and receive confirmation frame mechanism ADDBA to receiving node first；
2) after receiving node receives the ADDBA claim frames, response frame is returned to access point AP, access point AP receives the response frame
Afterwards, both sides establish aggregate frame transmission mechanism；
3) access point AP, which first sends claim frame and receives request, allows frame, i.e., prevents that first is gathered using RTS/CTS handshake mechanisms
Frame AMPDU is closed to collide in transmission；Retransmit the first aggregate frame AMPDU using minimum polymerization length；
4) access point AP sends aggregate frame request acknowledgement frame BlockACK Request to receiving node, and request receiving node is to poly-
Frame AMPDU is closed to be confirmed；
5) receiving node is according to the aggregate frame AMPDU received transmission situation, generation bit code table Bitmap, blocking so as to assemble
Acknowledgement frame BACK is received, and sends the block to access point AP and receives acknowledgement frame；
6) access point AP judges whether to collide according to reception condition：If access point AP does not receive block and receives acknowledgement frame
BACK or the block received receive bit code table Bitmap in acknowledgement frame BACK maximum continuous " 0 " number more than 8, then it represents that hair
Raw collision, performs step 7)；Otherwise, do not collide, perform step 8)；
7) access point AP enables adaptive RTS/CTS mechanism, and keeps transmission rate and polymerization frame length constant, is saved to receiving
Point sends next aggregate frame AMPDU, return to step 4), wherein RTS/CTS represents to send claim frame and send to allow frame；
8) information that access point AP is received according to the block received in acknowledgement frame BACK calculates current throughput, and combined block receives
Bit code table Bitmap in acknowledgement frame BACK, predict present channel quality and variation tendency；According to the BACK received letter
Make an uproar and compare, selecting mimo system is worked with diversity mode or with multiplex mode；
9) handling capacity and channel quality prediction information that access point AP obtains according to step 8), are adaptively adjusted next polymerization
Frame AMPDU transmission rate and polymerization frame length；
10) transmission rate and polymerization frame length that access point AP obtains according to step 9) send next aggregate frame to receiving node
AMPDU, return to step 4).
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