CN102868507B - Based on the segmentation ARQ method of transmission reliability - Google Patents

Abstract

The invention provides a kind of segmentation ARQ method based on transmission reliability, comprise: one, pre-set step: the single-hop transmission success rate that in network, each intermediate node requires according to user, segmentation ARQ threshold value is set neatly in conjunction with the hardware of the reality of self and environmental condition; Two, segmentation ARQ determining step: in data transmission procedure, in network, in data flow, each is jumped intermediate node and periodically reads RSSI value, when the RSSI value that this section point reads is less than the local threshold value preset, open the segmentation ARQ of link between this node and next-hop node, otherwise, close the segmentation ARQ of link between this node and next-hop node.The present invention uses the physical quantity RSSI of signal power when physical layer characterizing receipt message on link to assess channel quality, carries out monitoring reliability.Because RSSI value directly can be read by hardware, so can not produce extra consumption, with trying one's best, few cost meets the reliability requirement of user to data.

Description

Based on the segmentation ARQ method of transmission reliability

Technical field

The present invention relates to radio network technique, especially relate to HARQ (Automatic Repeat request, ARQ) technology.

Background technology

Under wireless multi-hop network applied environment, the channel quality between radio node is different, and is time dependent.This brings challenge to the data reliability in radio communication.ARQ is widely used in improving data transmission credibility.Automatic retransmission mechanism (End to End end to end, E2E), data-bag lost ratio hop-by-hop is accumulated, make the final transmission success rate of packet far below the situation of single-hop channel, jumping figure is more, and final arrival rate is lower, as shown in Figure 1, and retransmit at every turn and all from source node, will also bring great data delay.The automatic retransmission mechanism (Hop by Hop, HBH) of point-to-point, node hop-by-hop carries out confirming and retransmits, and but introduces more data traffic volume, all brings serious challenge to channel loading, node energy consumption.Traditional ARQ mechanism, from stopping-waiting (Stop-Wait), rollback N (Go back N), select to retransmit (Selective ACK) to hybrid ARQ (Hybrid ARQ, HARQ), the efficiency how improving ARQ itself is paid close attention to.Cross-layer (Cross Layer) ARQ occurred afterwards, (Channel Aware) ARQ, self adaptation (Adaptive) ARQ etc. of channel-aware, emphasis is by the perception to channel situation, the length, re-transmission time etc. of self-adaptative adjustment packet.

Existing ARQ method does not all process following important problem preferably above:

(1) energy consumption.Under quite a few wireless network environment, equipment is by battery powered, and its energy ezpenditure determines equipment task time and life cycle, is a very important factor.

(2) time delay.For a lot of wireless network, as environment measuring network, security control network etc., time delay is a very crucial factor.

(3) reliability.Data transmission credibility is controlled in a zone of reasonableness.Generally, reliability value is higher, continues to improve the cost paid needed for one percentage point larger.And user is to the demand of data transmission credibility, need not be 100% reliable, but higher, a suitable value.

Along with the continuous popularization that wireless network is applied in various field, especially emergent self-organizing network (Ad hoc Network), wireless senser (Wireless Sensor Network) network, device-to-device (Machine to Machine, m2m) communication waits the sustainable development of application, need to propose a kind of ARQ method, can fully adaptive channel quality change over time and space, meet time delay and the reliability requirement of user, and there is lower energy ezpenditure, the basis meeting communication requirement extends operating time and the network lifetime of radio node.

Summary of the invention

Technical problem to be solved by this invention is, provides a kind of energy-conservation ARQ method of block switch formula based on transmission reliability.

The present invention for solving the problems of the technologies described above is, based on the segmentation ARQ method of transmission reliability, comprises the following steps:

One, step is pre-seted: in network, each intermediate node pre-sets segmentation ARQ threshold value RSSI according to user for the requirement of single-hop transmission success rate _thh, segmentation ARQ threshold value RSSI _thhdetermination mode be:

$P_{\mathrm{SUCCESS}}=\underset{\mathrm{\Δ}\→0}{\lim }\frac{1}{\sqrt{2\mathrm{\π}}}{\∫}_{(\mathrm{\γ}-{\mathrm{RSSI}}_{\mathrm{thh}}+45+\mathrm{\Δ})/\mathrm{\σ}}^{\∞}\exp (-\frac{x^2}{2})\mathrm{dx}$

Wherein, P _sUCCESSfor the single-hop transmission success rate that user requires; γ is hardware acceptance sensitivity; σ is ambient noise value; RSSI _thhfor segmentation ARQ threshold value; Δ represents the time that receives data packets uses;

Two, segmentation ARQ determining step: in data transmission procedure, each jumping intermediate node of data flow in network, each intermediate node periodically reads RSSI value, and the RSSI value read when this section point is less than the local threshold value RSSI preset _thhtime, arranging this node with next-hop node is segmentation ARQ node, opens the segmentation ARQ of link between this node and next-hop node, otherwise, arranging this node with next-hop node is common intermediate node, closes the segmentation ARQ of link between this node and next-hop node.

The present invention uses physical quantity RSSI (Received SignalStrength Indication, the signal strength signal intensity instruction of reception) the assessment channel quality of signal power when physical layer characterizing receipt message on link, carries out monitoring reliability.Because RSSI value directly can be read by hardware, so extra consumption can not be produced.The single-hop transmission success rate that each intermediate node requires according to user, arranges segmentation ARQ threshold value RSSI neatly in conjunction with the hardware of the reality of self and environmental condition _thh, with trying one's best, few cost meets the reliability requirement of user to data.

Further, in order to ensure the overall transfer success rate of transmission system, the transfer of data arranged between source node to destination node is end-to-end ARQ.

The invention has the beneficial effects as follows, under the wireless multi-hop network environment of channel quality dynamic change, with trying one's best, few cost meets the reliability requirement of user to data, and ensures lower data delay and energy ezpenditure.

Accompanying drawing explanation

Fig. 1. the reliability schematic diagram in wireless multi-hop transmission;

Fig. 2. based on the energy-conservation ARQ schematic diagram of block switch formula of transmission reliability;

Fig. 3. based on the frame format of the energy-conservation ARQ of block switch formula of transmission reliability;

Fig. 4. segmentation ARQ node state transition diagram; Solid line represents transmission, initiatively enters arrow institute refers to state; Dotted line represents reception, is additionally related to multi-functional passive entry arrow institute refers to state.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing and embodiment, the present invention is described in further detail.

(1) reading of RSSI value.RSSI is the physical quantity of signal power when characterizing receipt message on link, can assess channel quality by RSSI value.On hardware, the RF module of main flow node is integrated with the internal register depositing RSSI value usually, according to IEEE802.15.4 standard, sender node is sending the request of data frame (DataRequest) or signaling (Beacon) that will inevitably to receive before packet from receiving terminal, get its (n-1)th byte (n is frame length) and be RSSI value, the channel quality of current ink can be calculated accordingly, and directly read RSSI value, so extra consumption can not be produced due to hardware supports.

(2) threshold value RSSI _thhdetermination.Threshold value weighs channel quality quality RSSI critical value, and when RSSI value is greater than threshold value, the probability that packet receiving end successfully receives is high, otherwise the probability that packet cannot arrive receiving terminal is high.Suppose that transmitting terminal receives request and ignores with the processing time between response request, then the probability P that successfully receives of packet receiving end _sUCCESSfor:

$P_{\mathrm{SUCCESS}}=\underset{\mathrm{\Δ}\→0}{\lim }\frac{1}{\sqrt{2\mathrm{\π}}}{\∫}_{(\mathrm{\γ}-{\mathrm{RSSI}}_{\mathrm{thh}}+45+\mathrm{\Δ})/\mathrm{\σ}}^{\∞}\exp (-\frac{x^2}{2})\mathrm{dx}$

Wherein, γ is hardware acceptance sensitivity, is determined by selected hardware; σ is ambient noise value, relevant to surrounding environment; RSSI is the signal strength signal intensity on link; Δ represents the time that receives data packets uses.Otherwise, when determining the probability P of the successful reception that user needs _sUCCESS, just can extrapolate the minimum RSSI value of meeting consumers' demand, be segmentation ARQ threshold value RSSI _thh.

For the zigbee platform of TI company, the receiving sensitivity γ=-94dBm of zigbee platform, for typical WSN environment, σ can value be 3dB.According to the requirement of user for single-hop transmission success rate, threshold value RSSI can be solved _thh.

(3) realization of the energy-conservation ARQ of block switch formula: a kind of wireless multi-hop transmission path, is made up of the radio node of some homogeneities.This wireless path can be the fixed route that static routing is formed, and also can be the dynamic routing formed according to network condition.Radio node comprises a source node, a destination node and several intermediate nodes, and intermediate node is responsible for the data that trunk source node issues destination node.

As shown in Figure 2, channel quality, according to the situation of real time channel quality, is judged to be that poor (RSSI value of reading is less than threshold value RSSI by the present invention _thh) Node be segmentation ARQ node.First, end-to-end ARQ is implemented between source node to destination node, can select to stop-wait (Stop-Wait), rollback N (Go back N), select to retransmit (Selective ACK) and hybrid ARQ (Hybrid ARQ, HARQ) any one in, but for making description more clear, embodiment choice for use the most simply stops-waits ARQ and is described.Secondly, in data transmission procedure, be as the criterion with data flow on all the nodes, real-time judgment is carried out to each hop channel quality, when any intermediate node judges channel quality as difference, this intermediate node and next-hop node will be converted into segmentation ARQ node, open the segmentation ARQ in this hop link.After a period of time, this node re-starts periodically channel quality and judges, if as well (RSSI value of reading is more than or equal to threshold value RSSI _thh), this node and next-hop node will be converted into common intermediate node, close the segmentation ARQ in this hop link.

(4) frame format is resolved: as shown in Figure 3, any frame data are determined by destination address, source address, Syn/Ack Number tri-field uniquenesss.Determine when wherein Syn/Ack Number is sent by source node.

Segmentation ARQ flag bit in frame represents the segmentation ARQ on off state of this hop link, when the segmentation ARQ on a certain section of link opens, segmentation ARQ flag bit assignment in frame is 1, represents that this frame is segmentation ARQ Frame, requires that next-hop node is replied segmentation Ack at once and carried out confirmation of receipt.Otherwise, then for closing.

Syn/Ack flag bit in frame represents data or acknowledgement state, when this position is 0, represents that this frame is Frame (Syn); When this position is 1, represent that this frame is acknowledgement frame (Ack).Such as when segmentation ARQ flag bit and Syn/Ack flag bit are all set to 1, represent that this frame is segmentation ARQ acknowledgement frame.

Timer field in frame is determined by source node, confirms, then retransmit if do not receive Ack after source node sends the time of this frame Timer.And often through a segmentation ARQ, the Timer value in frame will be reduced to 1/2nd of original value.

Data in frame is upper layer data.

Embodiment

Figure 2 shows that network topology, for a data transmission procedure:

Step (1) implements end-to-end ARQ on end-to-end system, in order to ensure the overall transfer success rate of transmission system.At source node s ₁the frame that place's buffer memory sends, and start timer, when receiving acknowledgement frame (Ack) of this Frame in Timer value, judge this time to send successfully, enter process of transmitting next time; When not receiving acknowledgement frame in Timer time value, then judging last data transmission fails, resending this Frame.

Step (2) is as Frame arrival node s ₃time, through judging s ₃to next-hop node s ₄channel quality for poor, then node s ₃and s ₄be converted into segmentation ARQ node, this hop link is opened segmentation ARQ, node s ₃be 1 by the segmentation ARQ mark position in this frame.As shown in Figure 4, node s ₃to s ₄send Frame, enter transmission " Send " state, this Frame of buffer memory by idle " Idle " state, and to node s ₄forward this Frame.Start a time is the timer of 100ms simultaneously, when receiving segmentation acknowledgement frame (Ack) of this Frame in 100ms, judging this time to send successfully, deleting corresponding data frame in cache table, enter " Idle " state by " Send " state; When not receiving segmentation acknowledgement frame (Ack) in 100ms, then judge that this jumps data transmission fails, resend this Frame.

Step (3) is as Frame arrival node s ₄time, node s ₄" Recieve " state is entered by " Idle " state.Node s ₄be 0 by the segmentation ARQ mark position in Frame, the numerical value of Timer be set to 1/2nd of original value, and buffer memory this time Frame.Continue to node s ₅forwarding data frame, starts the timer of a Timer value simultaneously.

Step (4) is as Frame arrival node s ₆and s ₇time, repeat step (2) and step (3).

Step (5) is as Frame arrival destination node s ₈, node s ₈will to source node s ₁reply acknowledgement frame (Ack).

Step (6) is as acknowledgement frame arrival node s ₄time, node s ₄enter " Idle " state by " Recieve " state, delete Frame corresponding in cache table simultaneously.

Step (7) acknowledgement frame arrives node s ₁, node s ₁delete Frame corresponding in cache table, complete this transmitting procedure.

The method combines the advantage of end-to-end (E2E) autonomous retransmission and hop-by-hop (HBH) automatic retransmission mechanism, and end-to-end system is implemented end-to-end (E2E) ARQ, in order to ensure the transmission success rate of entire system; Improve the situation causing end-to-end (E2E) transmission success rate significantly to reduce because the defeated success rate of certain jump set is too low with the method for dynamic switch segmentation ARQ, and then reduce by the number of retransmissions of source node to destination node.While meeting the reliability requirement of user, for the short slab of transmission system, by improving the transmission success rate of data in poor channel, reducing end-to-end (E2E) number of retransmissions, thus reaching reduction Time Delay of Systems, reduce the object of system energy consumption.

Claims (4)

1., based on the segmentation ARQ method of transmission reliability, it is characterized in that, comprise the following steps:

1) step is pre-seted: in network, each intermediate node pre-sets segmentation ARQ threshold value RSSI according to user for the requirement of single-hop transmission success rate _thh, segmentation ARQ threshold value RSSI _thhdetermination mode be:

$P_{\mathrm{SUCCESS}}=\underset{\mathrm{\Δ}\→0}{\lim }\frac{1}{\sqrt{2\mathrm{\π}}}{\∫}_{(\mathrm{\γ}-{\mathrm{RSSI}}_{\mathrm{thh}}+45+\mathrm{\Δ})/\mathrm{\σ}}^{\∞}\exp (-\frac{x^2}{2})\mathrm{dx}$

Wherein, P _sUCCESSfor the single-hop transmission success rate that user requires; γ is hardware acceptance sensitivity; σ is ambient noise value; RSSI _thhfor segmentation ARQ threshold value; Δ represents the time that receives data packets uses;

2) segmentation ARQ determining step: in data transmission procedure, each in network data flow jumps the RSSI value that intermediate node periodically reads physical layer, and the RSSI value read when this section point is less than the local threshold value RSSI preset _thhtime, arranging this node with next-hop node is segmentation ARQ node, opens the segmentation ARQ of link between this node and next-hop node, otherwise, arranging this node with next-hop node is common intermediate node, closes the segmentation ARQ of link between this node and next-hop node.

2., as claimed in claim 1 based on the segmentation ARQ method of transmission reliability, it is characterized in that, in data transmission procedure, the transfer of data between source node to destination node is end-to-end ARQ.

3. as claimed in claim 2 based on the segmentation ARQ method of transmission reliability, it is characterized in that, described end-to-end ARQ adopts and stops-wait, rollback N, selects to retransmit or hybrid ARQ mode.

4. as claimed in claim 1 based on the segmentation ARQ method of transmission reliability, it is characterized in that, the flag bit of the Frame of transmission data comprises segmentation ARQ flag bit and Syn/Ack flag bit;

Segmentation ARQ flag bit is for representing the segmentation ARQ on off state of this hop link; When segmentation ARQ flag bit is 1, represent that the segmentation ARQ in this hop link opens; When segmentation ARQ flag bit is 0, represent that the segmentation ARQ in this hop link closes;

Syn/Ack flag bit is for representing that the state of current data is data or confirmation; When Syn/Ack flag bit is 1, represent that this frame is acknowledgement frame; When Syn/Ack flag bit is 0, represent that this frame is Frame.