CN104320217A - Link quality estimator with signal-to-noise ratio, chain quality index and packet receiving rate fused - Google Patents

Link quality estimator with signal-to-noise ratio, chain quality index and packet receiving rate fused Download PDF

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CN104320217A
CN104320217A CN201410597267.3A CN201410597267A CN104320217A CN 104320217 A CN104320217 A CN 104320217A CN 201410597267 A CN201410597267 A CN 201410597267A CN 104320217 A CN104320217 A CN 104320217A
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packet
node
lqi
snr
prr
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CN104320217B (en
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鲁琛
杨祥龙
葛丁飞
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Zhejiang Lover Health Science and Technology Development Co Ltd
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Zhejiang Lover Health Science and Technology Development Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
    • H04W40/248—Connectivity information update
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Environmental & Geological Engineering (AREA)
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Abstract

The invention discloses a link quality estimator with the signal-to-noise ratio, the chain quality index and the packet receiving rate fused, and belongs to the technical field of wireless sensing networks. A link quality estimator applying a collection tree protocol has the following defects that the great influence, on the packet receiving rate, of the packet length is not considered; statistics of a great number of data packets is needed to estimate the link quality; further improvement of the energy efficiency is needed. To overcome the defects, the link quality estimator with the signal-to-noise ratio, the chain quality index and the packet receiving rate fused is designed, and the link quality estimator includes link quality expression fitting, packet design and updating of items of neighbor tables. The link quality estimator has the advantages that high-resolution link quality estimation can be conducted just by conducting statistics on a small amount of packets (less than 10), the totally-same length is adopted for all the packets, the link quality estimating can reach quick change of the link quality, and the estimator is high in energy efficiency.

Description

Merge the link quality valuator of signal to noise ratio, link-quality exponential sum packet reception rate
Technical field
The present invention relates to a kind of link quality valuator merging signal to noise ratio, link-quality exponential sum packet reception rate, belong to technology of wireless sensing network field.
Background technology
Due to wireless signal transmission and accept power limited, must estimate link-quality in radio sensing network, therefore link quality valuator is the indispensable part of radio sensing network, directly affects the energy efficiency of the whether accurate and communication protocol of Route Selection.
At present, gathering tree protocol (hereinafter referred to as CTP) is agreement conventional in research both at home and abroad, in collection tree protocol, send between node or receive packet and route beacon package, agreement is made up of following three parts: 1. routing engine is responsible for sending route beacon, upgrades route, is prevented route loop and prevent from repeating to send; 2. forward and send engine be responsible for the transmission of packet and prevent from repeating to send by transmit queue and transmission buffer memory; 3. link quality valuator is added up packet and route beacon and is resolved, thus upgrades the two-way expected transmission times (hereinafter referred to as ETX) between neighbor node.
Containing following 4: ll_addr (this records this neighbor node address), inquality (this records the value after this neighbor node to the packet reception rate normalization of the link of this node), outquality (value after this minute book node to the packet reception rate normalization of the link of neighbor node), etx (this minute book node is to the two-way ETX value of neighbor node link) in each entry of the neighbor table of CTP.Link quality valuator upgrades corresponding neighbor table entries in following several situation: 1. node is after receiving neighbor node broadcast beacon, record the number of the route beacon received, and calculate unreceived beacon number by the beacon sequence number received, when the route beacon number received is increased to some, just calculate the PRR of (windowed time is the natural number of 5-10) in route beacon reception window, get also normalization reciprocal, then the method for exponentially weighted moving average (EWMA) (hereinafter referred to as EWMA) is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this, 2. after node receives the route beacon of neighbor node broadcast, just according to the outquality item of this neighbor node recorded in this node contained in this route beacon to this node of inquality value renewal neighbor table of the one way link of this neighbor node, 3. after node often sends a packet, the response whether receiving destination node is recorded, and the number of unreceived packet is calculated by the sequence number of the packet received, when the packet number received is increased to some, just calculate the receives data packets rate of (windowed time is the natural number of 5-10) in receives data packets window, get also normalization reciprocal, then adopt the method for EWMA to obtain etx' with the former etx that records in neighbor table entries, upgrade the etx item of neighbor table entries with this.Like this, gathering tree protocol by adding up transmission or reception route beacon, packet, just can complete the real-time estimation of link-quality.
But, there is following shortcoming in the link quality valuator gathering tree protocol: 1. gathers in the link quality valuator of tree protocol, be used for add up acceptance rate (hereinafter referred to as PRR) packet, the length of route beacon or new response packet is all different, the effect length that the acceptance rate of bag is wrapped is very large, when other environment are all identical, the bag that the acceptance rate of the bag that length is large is little far below length, therefore, the link quality valuator of CTP also exists problem by the method for the reception condition of statistics route beacon package and then the link quality parameter of renewal measurement packet, 2. the link quality valuator gathering tree protocol adopts the most original method acquisition PRR added up packet and route beacon package, and then calculate ETX, therefore, when add up packet and route beacon package less time, this method exists estimates that the too low shortcoming of the accuracy of PRR is (as added up 10 bags, then whether 1 bag adds up error statistics being caused to 10%), and when add up packet and route beacon package more time, this method exists estimates the speed of PRR excessively slow (because needing to add up a large amount of bags), and then cause link quality valuator cannot follow the tracks of the fast-changing shortcoming of link-quality, this is a problem of facing a difficult choice, 3. the link quality valuator of tree protocol is gathered owing to not considering to affect this quality factor of link, as link-quality index (hereinafter referred to as LQI) and signal to noise ratio (hereinafter referred to as SNR) etc., therefore the accuracy of its link quality estimation leaves a question open, and this will affect the efficiency of link quality valuator undoubtedly.
Summary of the invention
In order to the shortcoming that the link quality valuator overcoming aforesaid collection tree protocol exists, the invention provides a kind of link quality valuator merging signal to noise ratio, link-quality exponential sum packet reception rate, it comprises:
(1) the matching of the expression formula of link-quality: the expression formula estimating link-quality by carrying out link-quality field experiment matching;
(2) the design of wrapping: redesign node and send or receive 3 kinds of bags, i.e. packet, new response packet and route beacon package.Design the form of new response packet.It is allowed " to carry " information of link between destination node to response packet sending node, like this, when node receives route beacon or the response packet of transmission of neighbor node broadcast, just can according to the corresponding field in information updating self neighbor table contained by this route beacon.For utilizing the conclusion of the expression formula that matching obtains (1) better, the length of all packets, route beacon or new response packet is fixed as 35 bytes;
(3) neighbor table discal patch object upgrades: when SNR, LQI information of the number of the bag that node obtains the reception number of (windowed time is the natural number of 5-10) packet, route beacon or new response packet in current receive window, transmitter sends and the bag that receives, just these information can be brought into the expression formula of the estimation link-quality of matching (1), thus predict the PRR of respective link in a period of time in the future, and then can upgrade the inquality item of the link quality valuator neighbor table respective entries of collection tree protocol or etx item.
It should be noted that, length due to bag can affect the acceptance rate of bag, therefore, (1) the prerequisite that is suitable for of the expression formula that obtains of middle matching is that the length of bag is identical, in order to utilize the conclusion of the expression formula that matching obtains (1) better, the length of all packets, route beacon or new response packet is fixed as 35 bytes.
(1) the matching of the expression formula of link-quality
By 10 node deployments at experimental field, between node, form wireless link between two, totally 90 wireless links.For i-th link, transmit the packet that 60 total lengths are 35 bytes, the time interval between packet is 50ms, the accumulated value SNR of the SNR of front 10 packets of receiver statistics totali, LQI accumulated value LQI totaliwith the number m received in front 10 packets, by formula PRR ' i=m/10 calculates PRR ' i, by formula S NR avgi=PRR ' isNR totali/ m calculates SNR avgi, by formula LQI avgi=PRR ' ilQI totali/ m calculates LQI avgi.Add up the PRR of ensuing 50 packets again i, the data composition modeling collection that such 60 bags obtain.
The acquisition methods of SNR is as follows: received signal strength index when receiver take 30ms as cycle timing sampling channel idle, sample value as a noise floor upgrades the entry in noise floor table, by the mean value calculation now noise floor of 8 entries after every 8 samplings, with after old noise floor data weighted average as new noise floor, the signal to noise ratio of the packet received deducts up-to-date noise floor by the value in the rssi territory of this packet and obtains, and the LQI then direct lqi territory from packet obtains.
Will remove the data point that PRR equals 1 during the expression formula of matching link-quality, the data utilizing modeling to concentrate PRR not reach 1 carry out matching to the expression formula of following link-quality:
PRR i＝A·SNR Avgi+B·LQI Avgi I
The parameter of expression formula can be obtained:
A = ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p LQI Avgi 2 ) - ( Σ i = 1 p LQI Avgi · PRR i ) ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi 2 ) - ( Σ i = 1 p LQI Avgi · SNR Avgi ) 2 - - - II
B = ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p LQI Avgi 2 · SNR Avgi ) - ( Σ i = 1 p LQI Avgi · PRR i ) ( Σ i = 1 p SN R Avgi 2 ) ( Σ i = 1 p LOI Avgi · SNR Avgi ) 2 - ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi 2 ) - - - III
And then the concrete form of expression formula I of link-quality can be determined:
PRR i＝A·PRR'·SNR total/m+B·PRR′ i·LQI total/m IV
(2) the design of wrapping
Merge in the link quality valuator of signal to noise ratio, link-quality exponential sum packet reception rate, each node sends or receives 3 kinds of bags: packet, new response packet and route beacon package.
New response is made up of packet header (length is 10 bytes), response sequence territory (length is 1 byte), unidirectional etx (length the is 2 bytes) territory needing to return the neighbor node of response, filling (length is 13 bytes) territory, metadata (length is 10 bytes) territory.Packet is by packet header (length is 10 bytes), option (option, length is 1 byte) territory, time-to-live (THL, Time Have Lived, length is 1 byte) territory, expected transmission times (represents the ETX value of the node sending this packet, length is 2 bytes) territory, source address (origin, length is 2 bytes) territory, source node sequence number (originSeqNo, length is 1 byte) territory, type (represents the type of this packet in application layer, length is 1 byte) territory, (length is 4 bytes to data, packet particular content) territory, fill (length is 5 bytes) territory, metadata (length is 10 bytes) territory forms.Route beacon is by packet header (length is 10 words), beacon packet header (length is 2 bytes) territory, beacon payload (length is 3 bytes) territory, bag tail (length is 10 bytes) territory and metadata (length is 10 bytes) territory composition, wherein the fill rule in bag tail territory is as follows: if the entry number 1. not writing the neighbor table of a route beacon handbag tail is less than 6, then by the ll_addr in these entries, inquality fills out the bag tail (relevant " description " of each neighbor table entries accounts for 2 bytes in bag tail) at this route beacon entirely, remaining word is saved 0x00 and is taken, if the entry number 2. not writing a route beacon handbag tail is greater than 6, then first 5 are filled in by method 1., continue to judge by method 1. and fill in remaining entry in next route beacon.Like this, the length of all bags is all 35 bytes.
(3) neighbor table discal patch object upgrades:
This node or neighbor node in following several situation to neighbor table in respective entries upgrade:
1. neighbor node broadcast beacon, this node receives and records the number of the route beacon received afterwards and added up by SNR and LQI received, calculated that receive with number that is unreceived route beacon by the sequence number of the route beacon received simultaneously, when the route beacon number received is increased to some, just by the SNR accumulated value SNR of (windowed time is the natural number of 5-10) in bag receive window total, LQI accumulated value LQI total, the number m of the route beacon received, in current route beacon reception window, the route beacon reception rate PRR' of (windowed time is the natural number of 5-10) brings formula IV into, calculate the PRR of a period of time in the future, get the unidirectional link quality parameter of normalization reciprocal as record, then the method for EWMA is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this,
2. time this section point receives the route beacon of neighbor node broadcast, just according to the outquality item of this neighbor node entry in this node contained in this route beacon to the neighbor table of this node of inquality value renewal of the one way link of this neighbor node;
3. forbid that in former collection tree protocol, each node automatically sends the function of response packet after receiving packet, reply with new response packet, to record this response packet in the response sequence territory of new response packet be this node to " which the " response packet needing the neighbor node returning response to return, and the needs of new response packet return the unidirectional etx value of neighbor node to this link of this node that record in the unidirectional etx territory of the neighbor node of response needs to return response.Receiving or sending in the process of packet and new response packet, in following several situation to neighbor table entries in inquality, outquality and etx item of recording upgrade: after this node of i. receives new response packet at every turn, the unidirectional etx territory of the neighbor node needing to return response is recorded as etx', upgrades the outquality in the neighbor table of this node in this neighbor node entry with this.The number of this node to the new response packet receiving destination node is carried out cumulative and is calculated by the sequence number in new response packet that receive with number that is unreceived new response packet, and SNR and LQI receiving new response packet is added up, when the response sequence number of the new response packet received increases some, just by the SNR accumulated value SNR of (windowed time is the natural number of 5-10) in new response packet receive window total, LQI accumulated value LQI total, the number m of the new response packet received, in current route beacon reception window, the new response packet acceptance rate PRR' of (windowed time is the natural number of 5-10) brings formula IV into, calculate the PRR of a period of time in the future, get the unidirectional link quality parameter of normalization reciprocal as record, then the method for EWMA is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this.Ii. the number of packet that receives of neighbor node record SNR and LQI of the packet each received add up, when the sequence number receiving packet increases some, the accumulated value SNR of the SNR of the packet just (windowed time is the natural number of 5-10) in new response packet receive window received total, LQI accumulated value LQI totalwith the number m of the packet received, in current data packet receive window, the receives data packets rate PRR' of (windowed time is the natural number of 5-10) brings formula IV into, calculate the PRR of a period of time in the future, then the unidirectional link quality parameter of rear normalization reciprocal as record is got, the method of EWMA is adopted to obtain inquality' with the former inquality recorded in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this.
Beneficial effect of the present invention:
(1) link quality valuator of the present invention is by merging the design of SNR, LQI and PRR, the problem of facing a difficult choice that the link quality valuator solving collection tree protocol faces, only need add up a small amount of (being less than 10) packet, route beacon or new response packet, the very high link quality estimation of resolution (PRR) can be carried out;
(2) gather in the link quality valuator of tree protocol, be used for adding up the packet of acceptance rate, the length difference of route beacon, the effect length that the acceptance rate of bag is wrapped is very large, when other environment are all identical, the bag that the acceptance rate of the bag that length is large is little far below length, therefore, the method that the link quality valuator of CTP carrys out the link-quality of more new data packets by the reception condition of statistics route beacon package also exists problem, the length of packet, route beacon and new response packet that the present invention is used is all 35 bytes, therefore overcomes this problem completely;
(3) the link quality valuator of the comparison of efficiency: CTP is different with the difference mainly comprehensive information of the link quality valuator of fusion signal to noise ratio, link-quality exponential sum packet reception rate different with the opportunity upgraded link quality parameter, but both adopt cross layer design, and it is very similar, for comparing the performance of the two, by gather the link quality valuator of tree protocol replace with merge signal to noise ratio, link-quality exponential sum packet reception rate link quality valuator and corresponding amendment is made to the assembly of former agreement, finally form SNR-LQI-PRR and gather tree protocol.Meanwhile, in order to calculate the transmission consumption of the average each packet of all nodes, need add up the number of beacon and Packet Generation, the implementation method in program is write BeaconPlus-DataRetriesCounterP module and completes corresponding binding.
Accompanying drawing explanation
Fig. 1 is that this node sends packet and route beacon schematic diagram with neighbor node;
Fig. 2 is the receives data packets rate figure of the node adopting CTP;
Fig. 3 be adopt SNR LQI PRR gather the receives data packets rate figure of node of tree protocol;
Fig. 4 be CTP and SNR LQI PRR gather tree protocol average each packet transmission consume comparison diagram.
Embodiment
In order to the shortcoming that the link quality valuator overcoming aforesaid collection tree protocol exists, the present invention devises a kind of link quality valuator merging signal to noise ratio, link-quality exponential sum packet reception rate, comprises following content:
(1) the matching of the expression formula of link-quality: the expression formula estimating link-quality by carrying out link-quality field experiment matching;
(2) the design of wrapping: redesign node and send or receive 3 kinds of bags, i.e. packet, new response packet and route beacon package.Design the form of new response packet.It is allowed " to carry " information of link between destination node to response packet sending node, like this, when node receives route beacon or the response packet of transmission of neighbor node broadcast, just can according to the corresponding field in information updating self neighbor table contained by this route beacon.The length of bag can affect the acceptance rate of bag, therefore, (1) the prerequisite that is suitable for of the expression formula that obtains of middle matching is that the length of bag is identical, the greatest differences of acceptance rate is caused in order to avoid factor data packet length difference, and utilize the conclusion of the expression formula that matching obtains (1) better, the length of all packets, route beacon or new response packet is fixed as 35 bytes;
(3) neighbor table discal patch object upgrades: when SNR, LQI information of the number of the bag that node obtains the reception number of (windowed time is the natural number of 5-10) packet, route beacon or new response packet in current receive window, transmitter sends and the bag that receives, just these information can be brought into the expression formula of the estimation link-quality of matching (1), thus predict the PRR of respective link in a period of time in the future, and then can upgrade the inquality item of the link evaluator neighbor table respective entries of collection tree protocol or etx item.
The matching of the expression formula of above-mentioned (1) link-quality is specific as follows:
By 10 TelosB (Crossbow Technology, California, USA) node deployment is at experimental field, software adopts TinyOS-2.1.0 operating system, program nesC language compilation, and MAC layer adopts the channel access algorithm of CSMA-CA, the form of packet meets the standard of IEEE802.15.4, wireless channel is elected as on the 26th channel of this standard, and to avoid the impact of the signals such as Wifi, all node CC2420 chip power outputs are set to 0dBm.Form wireless link between two between node, therefore one have 90 wireless links.For i-th link, transmit the packet that 60 total lengths are 35 bytes, the time interval between packet is 50ms, the accumulated value SNR of the SNR of front 10 packets of receiver statistics totali, LQI accumulated value LQI totaliwith the number m received in front 10 packets, by formula PRR ' i=m/10 calculates PRR ' i, by formula S NR avgi=PRR ' isNR totali/ m calculates SNR avgi, by formula LQI avgi=PRR ' ilQI totali/ m calculates LQI avgi.Add up the PRR of ensuing 50 packets again i, the data composition modeling collection that such 60 bags obtain.
The acquisition methods of SNR is as follows: the received signal strength index (hereinafter referred to as RSSI) when receiver take 30ms as cycle timing sampling channel idle, sample value as a noise floor upgrades the entry in noise floor table, by the mean value calculation now noise floor of 8 entries after every 8 samplings, with after old noise floor data weighted average as new noise floor, the signal to noise ratio of the packet received deducts up-to-date noise floor by the value in the rssi territory of this packet and obtains, and the LQI then direct lqi territory from packet obtains.
Synchronously increase with LQI and SNR, PRR also can increase, under normal circumstances, as SNR>13 or LQI>90, PRR just reaches 1, now, SNR and LQI continues to increase, PRR is still 1 (saturation value), so will remove the data point that PRR equals 1 during the expression formula of matching link-quality, the data utilizing modeling to concentrate PRR not reach 1 carry out matching to the expression formula of following link-quality:
PRR i＝A·SNR Avgi+B·ＬQI Avgi I
The parameter of expression formula can be obtained:
A = ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p LQI Avgi 2 ) - ( Σ i = 1 p LQI Avgi · PRR i ) ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi 2 ) - ( Σ i = 1 p LQI Avgi · SNR Avgi ) 2 - - - II
B = ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p LQI Avgi 2 · SNR Avgi ) - ( Σ i = 1 p LQI Avgi · PRR i ) ( Σ i = 1 p SN R Avgi 2 ) ( Σ i = 1 p LOI Avgi · SNR Avgi ) 2 - ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi 2 ) - - - III
And then the concrete form of expression formula I of link-quality can be determined:
PRR i＝A·PRR'·SNR total/m+B·PRR′ i·LQI total/m IV
Above-mentioned design of (2) wrapping specific as follows: the link quality valuator merging SNR, LQI and PRR with gather in the link quality valuator of tree protocol, each node sends or receives 3 kinds of bags: packet, new response packet and route beacon package.
New response is made up of packet header (length is 10 bytes), response sequence territory (length is 1 byte), unidirectional etx (length the is 2 bytes) territory needing to return the neighbor node of response, filling (length is 13 bytes) territory, metadata (length is 10 bytes) territory.Packet is by packet header (length is 10 bytes), option (option, length is 1 byte) territory, time-to-live (THL, Time Have Lived, length is 1 byte) territory, expected transmission times (represents the ETX value of the node sending this packet, length is 2 bytes) territory, source address (origin, length is 2 bytes) territory, source node sequence number (originSeqNo, length is 1 byte) territory, type (represents the type of this packet in application layer, length is 1 byte) territory, (length is 4 bytes to data, packet particular content) territory, fill (length is 5 bytes) territory, metadata (length is 10 bytes) territory forms.Route beacon is by packet header (length is 10 words), beacon packet header (length is 2 bytes) territory, beacon payload (length is 3 bytes) territory, bag tail (length is 10 bytes) territory and metadata (length is 10 bytes) territory composition, wherein the fill rule in bag tail territory is as follows: if the entry number 1. not writing the neighbor table of a route beacon handbag tail is less than 6, then by the ll_addr in these entries, inquality fills out the bag tail (relevant " description " of each neighbor table entries accounts for 2 bytes in bag tail) at this route beacon entirely, remaining word is saved 0x00 and is taken, if the entry number 2. not writing a route beacon handbag tail is greater than 6, then first 5 are filled in by method 1., continue to judge by method 1. and fill in remaining entry in next route beacon.Like this, the length of all bags is all 35 bytes.
It should be noted that, the link quality valuator merging SNR, LQI and PRR prohibits each node in former CTP after receiving packet, automatically replies the function of response packet, define new response packet, two territories are newly increased in the new response packet that each node returns, first is response sequence territory, recording this response packet in this territory is that this node is to " which the is individual " response packet needing the neighbor node returning response to return, second is the unidirectional etx territory of the neighbor node needing to return response, and record needs to return the unidirectional etx value of neighbor node to this node of response.
With this node as a reference, send packet and route beacon and neighbor table as shown in Figure 1 with neighbor node, this node or neighbor node in following several situation to neighbor table in respective entries upgrade:
1. neighbor node broadcast beacon, this node receives and records the number of the route beacon received afterwards and added up by SNR and LQI received, calculated that receive with number that is unreceived route beacon by the sequence number of the route beacon received simultaneously, when the route beacon number received is increased to some, just by the SNR accumulated value SNR of (windowed time is the natural number of 5-10) in bag receive window total, LQI accumulated value LQI total, the number m of the route beacon received, in current route beacon reception window, the route beacon reception rate PRR' of (windowed time is the natural number of 5-10) brings formula IV into, calculate the PRR of a period of time in the future, get the unidirectional link quality parameter of normalization reciprocal as record, then the method for EWMA is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this,
2. time this section point receives the route beacon of neighbor node broadcast, just according to the outquality item of this neighbor node entry in this node contained in this route beacon to the neighbor table of this node of inquality value renewal of the one way link of this neighbor node;
3. forbid that in former collection tree protocol, each node automatically sends the function of response packet after receiving packet, reply with new response packet, to record this response packet in the response sequence territory of new response packet be this node to " which the " response packet needing the neighbor node returning response to return, and the needs of new response packet return the unidirectional etx value of neighbor node to this link of this node that record in the unidirectional etx territory of the neighbor node of response needs to return response.Receiving or sending in the process of packet and new response packet, in following several situation to neighbor table entries in inquality, outquality and etx item of recording upgrade: after this node of i. receives new response packet at every turn, the unidirectional etx territory of the neighbor node needing to return response is recorded as etx', upgrades the outquality in the neighbor table of this node in this neighbor node entry with this.The number of this node to the new response packet receiving destination node is carried out cumulative and is calculated by the sequence number in new response packet that receive with number that is unreceived new response packet, and SNR and LQI receiving new response packet is added up, when the response sequence number of the new response packet received increases some, just by the SNR accumulated value SNR of (windowed time is the natural number of 5-10) in new response packet receive window total, LQI accumulated value LQI total, the number m of the new response packet received, in current route beacon reception window, the new response packet acceptance rate PRR' of (windowed time is the natural number of 5-10) brings formula IV into, calculate the PRR of a period of time in the future, get the unidirectional link quality parameter of normalization reciprocal as record, then the method for EWMA is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this.Ii. the number of packet that receives of neighbor node record SNR and LQI of the packet each received add up, when the sequence number receiving packet increases some, the accumulated value SNR of the SNR of the packet just (windowed time is the natural number of 5-10) in new response packet receive window received total, LQI accumulated value LQI totalwith the number m of the packet received, in current data packet receive window, the receives data packets rate PRR' of (windowed time is the natural number of 5-10) brings formula IV into, calculate the PRR of a period of time in the future, then the unidirectional link quality parameter of rear normalization reciprocal as record is got, the method of EWMA is adopted to obtain inquality' with the former inquality recorded in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this.
In 1. or 3. situation, if do not receive any route beacon or response packet in window phase, then need not carry out subsequent calculations, directly unidirectional link quality parameter is set to maximum (255).
By 23 TelosB (Crossbow Technology, California, USA) node deployment is at orchard experimental field, be highly 2.5 meters, the spacing of adjacent node 35 meters, test before test shows, and jitter, can be used to the performance checking link quality valuator, keep all node circuit board planes vertical with ground level in process of the test, all node softwares adopt TinyOS-2.1.0 operating system, program nesC language compilation, MAC layer adopts the channel access algorithm of CSMA-CA, the form of packet meets the standard of IEEE802.15.4, wireless channel is elected as on the 26th channel of this standard, to avoid the impact of the signals such as Wifi, all node CC2420 chip power outputs are set to 0dBm.In program, this link quality valuator forms new module SNR-LQI-PRRM, run SNR-LQI-PRR respectively and gather tree protocol and complete CTP, each agreement runs 24 hours, one of them node is as root node, for collecting data, other each node every 1 minute virtual 1 data send to root node, the number of the packet that each nodes records sent oneself and route beacon, the receives data packets rate in every 1 hour of each node is added up by root node, total number of the packet oneself sent within the whole service time by each node statistics and total number of route beacon, be stored in the flash of node, read out after experiment terminates and add up.
Complete CTP and SNR-LQI-PRR is adopted to gather the receives data packets rate of tree protocol node over time as shown in Figures 2 and 3, the PRR maximum of 22 TelosB nodes is general all close to 100%, but there is fluctuation during mean value, in 24 hours, the node data packet reception rate mean value adopting SNR-LQI-PRR to gather tree protocol is 74.7%, higher than adopting 61.9% of CTP agreement, as can be seen here, compared with gathering the link quality valuator of tree protocol, merge signal to noise ratio, the link quality valuator of link-quality exponential sum packet reception rate is better than the link quality valuator of CTP agreement really.
As shown in Figure 4, in whole test, adopt the average every transmission success packet of all nodes of CTP agreement need send 5.32 packets factors such as (comprise multi-hop transmission) not receiving, route consumed by beacons 0.14, it is then 4.45 and 0.20 respectively that SNR-LQI-PRR gathers tree protocol, and the packet ratio of transmission former reduces 16.4%.In general, the transmission consumption rate of the average each packet of the latter the former few 0.81, decrease 14.8%.
As can be seen here, the efficiency of link quality valuator of the present invention is apparently higher than the link quality valuator of CTP.

Claims (8)

1. merge a link quality valuator for signal to noise ratio, link-quality exponential sum packet reception rate, it is characterized in that, it comprises: the matching of the expression formula of link-quality, the design of bag, and neighbor table discal patch object upgrades;
(1) the matching of the expression formula of link-quality: form 90 wireless links between two between 10 nodes, for wherein i-th link, transmit the packet that 60 total lengths are 35 bytes, the time interval between packet is 50ms; The accumulated value SNR of the signal to noise ratio snr of front 10 packets of receiver statistics totali, link-quality index LQI accumulated value LQI totaliwith the number m received in front 10 packets, by formula PRR ' i=m/10 calculates the receives data packets rate PRR ' of i-th link i, by formula S NR avgi=PRR ' isNR totali/ m calculates the average signal-to-noise ratio SNR of i-th link avgi, by formula LQI avgi=PRR ' ilQI totali/ m calculates the average link quality index LQI of i-th link avgi, then add up the PRR of ensuing 50 packets i, the data composition modeling collection that such 60 bags obtain;
Will remove the data point that receives data packets rate PRR equals 1 during the expression formula of matching link-quality, the data utilizing modeling to concentrate PRR not reach 1 carry out matching to the expression formula of following link-quality:
PRR i＝A·SNR Avgi+B·LQI Avgi I
Obtain the parameter of expression formula:
A = ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p LQI Avgi 2 ) - ( Σ i = 1 p LQI Avgi · PRR i ) ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi 2 ) - ( Σ i = 1 p LQI Avgi · SNR Avgi ) 2 - - - II
B = ( Σ i = 1 p SNR Avgi · PRR i ) ( Σ i = 1 p LQI Avgi · SNR Avgi ) - ( Σ i = 1 p LQI Avgi · PRR i ) ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi · SNR Avgi ) 2 - ( Σ i = 1 p SNR Avgi 2 ) ( Σ i = 1 p LQI Avgi 2 ) - - - III
And then determine the concrete form of expression formula I of link-quality:
PRR i＝A·PRR'·SNR total/m+B·PRR′ i·LQI total/m IV；
(2) the design of wrapping,
Each node sends or receives 3 kinds of bags: packet, new response packet and route beacon package;
(3) neighbor table discal patch object upgrades:
This node or neighbor node in following several situation to neighbor table in respective entries upgrade: when the route beacon number that 1. this node receives is added to some, the inquality item of neighbor table entries is upgraded; 2. when this section point receives route beacon, the outquality item of neighbor node entry is upgraded; 3. the renewal to neighbor table entries when the new response packet that receives of this node and packet are added to some.
2. link quality valuator according to claim 1, it is characterized in that, the acquisition methods of described signal to noise ratio snr is as follows: received signal strength index RSSI when receiver take 30ms as cycle timing sampling channel idle, sample value as a noise floor upgrades the entry in noise floor table, by the mean value calculation now noise floor of 8 entries after every 8 samplings, with after old noise floor data weighted average as new noise floor, the signal to noise ratio of the packet received deducts up-to-date noise floor by the value in the RSSI territory of this packet and obtains, the LQI then direct lqi territory from packet obtains.
3. link quality valuator according to claim 1, is characterized in that, in the design of (2) wrapping, described new response packet comprises: packet header, and length is 10 bytes; Response sequence territory, length is 1 byte; Need the unidirectional expected transmission times etx territory of the neighbor node returning response, length is 2 bytes; Region filling, length is 13 bytes; Metadata fields, length is 10 bytes.
4. link quality valuator according to claim 1, is characterized in that, in the design of (2) wrapping, described packet comprises: packet header, and length is 10 bytes; Option field, option, length is 1 byte; Time-to-live territory, THL, Time Have Lived, length is 1 byte; Expected transmission times territory, represent the ETX value of the node sending this packet, length is 2 bytes; Source address, origin, length is 2 bytes; Source node sequence number territory, originSeqNo, length is 1 byte; Type field, represents the type of this packet in application layer, and length is 1 byte; Data field, length is 4 bytes, packet particular content; Fill, length is 5 bytes; Metadata fields, length is 10 bytes.
5. link quality valuator according to claim 1, is characterized in that, in the design of (2) wrapping, described route beacon is by packet header, and length is 10 bytes; Beacon package header field, length is 2 bytes; Beacon payload territory, length is 3 bytes; Bag tail territory, length is 10 bytes; Metadata fields, length is 10 bytes; The fill rule in described bag tail territory is as follows: if the entry number 1. not writing the neighbor table of a route beacon handbag tail is less than 6, then ll_addr, the inquality in these entries is filled out full the bag tail at this route beacon, the associated description of each neighbor table entries accounts for 2 bytes in bag tail, and remaining word is saved 0x00 and taken; If the entry number 2. not writing a route beacon handbag tail is greater than 6, then first 5 are filled in by method 1., continue to judge by method 1. and fill in remaining entry in next route beacon; Like this, the length of all bags is all 35 bytes.
6. link quality valuator according to claim 1, is characterized in that, during (3) neighbor table discal patch object upgrades,
1. neighbor node broadcast beacon, this node receives and records the number of the route beacon received afterwards and added up by SNR and LQI received, calculated that receive with number that is unreceived route beacon by the sequence number of the route beacon received simultaneously, when the route beacon number received is increased to some, just by bag receive window, windowed time is the natural number of 5-10, SNR accumulated value SNR total, LQI accumulated value LQI total, the number m of the route beacon received, route beacon reception rate PRR' in current route beacon reception window brings formula IV into, calculate the PRR of a period of time in the future, get the unidirectional link quality parameter of normalization reciprocal as record, then the method for exponentially weighted moving average (EWMA) EWMA is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this.
7. link quality valuator according to claim 1, is characterized in that, during (3) neighbor table discal patch object upgrades,
2. time this section point receives the route beacon of neighbor node broadcast, just according to the outquality item of this neighbor node entry in this node contained in this route beacon to the neighbor table of this node of inquality value renewal of the one way link of this neighbor node.
8. link quality valuator according to claim 1, is characterized in that, during (3) neighbor table discal patch object upgrades,
3. forbid that in former collection tree protocol, each node automatically sends the function of response packet after receiving packet, reply with new response packet, record in the response sequence territory of new response packet this response packet be this node to which response packet needing the neighbor node returning response to return, the needs of new response packet return the unidirectional etx value of neighbor node to this link of this node that record in the unidirectional etx territory of the neighbor node of response needs to return response, receiving or sending in the process of packet and new response packet, in following several situation to neighbor table entries in inquality, outquality and etx item of recording upgrade: after this node of i. receives new response packet at every turn, the unidirectional etx territory of the neighbor node needing to return response is recorded as etx', upgrades the outquality in the neighbor table of this node in this neighbor node entry with this, the number of this node to the new response packet receiving destination node is carried out cumulative and is calculated by the sequence number in new response packet that receive with number that is unreceived new response packet, and SNR and LQI receiving new response packet is added up, when the response sequence number of the new response packet received increases some, just by the SNR accumulated value SNR in new response packet receive window total, LQI accumulated value LQI total, the number m of the new response packet received, new response packet acceptance rate PRR' in current route beacon reception window brings formula IV into, calculate the PRR of a period of time in the future, get the unidirectional link quality parameter of normalization reciprocal as record, then the method for EWMA is adopted to obtain inquality' with the former inquality that records in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this, ii. the number of packet that receives of neighbor node record SNR and LQI of the packet each received add up, when the sequence number receiving packet increases some, the accumulated value SNR of the SNR of packet just will received in new response packet receive window total, LQI accumulated value LQI totalwith the number m of the packet received, receives data packets rate PRR' in current data packet receive window brings formula IV into, calculate the PRR of a period of time in the future, then the unidirectional link quality parameter of rear normalization reciprocal as record is got, the method of EWMA is adopted to obtain inquality' with the former inquality recorded in neighbor table entries, the inquality item of neighbor table entries is upgraded with this, inquality and outquality according to this neighbor table entries calculates etx, the method of EWMA is adopted to obtain etx' with the former etx of neighbor table entries, the etx item of neighbor table entries is upgraded with this.
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