CN107172715B - Differentiated Services implementation method in underground coal mine wireless multimedia sensor network - Google Patents
Differentiated Services implementation method in underground coal mine wireless multimedia sensor network Download PDFInfo
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- CN107172715B CN107172715B CN201710255237.8A CN201710255237A CN107172715B CN 107172715 B CN107172715 B CN 107172715B CN 201710255237 A CN201710255237 A CN 201710255237A CN 107172715 B CN107172715 B CN 107172715B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access, e.g. scheduled or random access
- H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
- H04W74/0808—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using carrier sensing, e.g. as in CSMA
- H04W74/0816—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using carrier sensing, e.g. as in CSMA carrier sensing with collision avoidance
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/27—Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/80—Responding to QoS
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access, e.g. scheduled or random access
- H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
- H04W74/0833—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using a random access procedure
- H04W74/0841—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using a random access procedure with collision treatment
- H04W74/085—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using a random access procedure with collision treatment collision avoidance
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks
Abstract
The present invention provides the Differentiated Services implementation methods in a kind of underground coal mine wireless multimedia sensor network.This method specifically includes that the setting environment monitoring node, voice node, video node in underground coal mine wireless multimedia sensor network, according to sensing data business, the voice service quality of service requirement different with video traffic, different competition windows is separately designed to sensing data business, voice service and video traffic；Environment monitoring node, voice node, video node are based respectively on various competition windows and transmit competitive strategy according to the business of setting, pass through the channel of wireless multimedia sensor network monitoring center transmitting data service to the ground.The present invention realizes the Differentiated Services of three kinds of business, to ensure the different QoS requirement of three kinds of business, the handling capacity of sensing data business and voice service can be increased by reducing the handling capacity of video traffic, reduce the time delay of sensing data business and voice service by increasing the time delay of video traffic.
Description
Technical field
The present invention relates to wireless multimedia sensor network technical field more particularly to a kind of underground coal mine radio multimediums
Differentiated Services implementation method in sensor network.
Background technique
Safety of Coal Mine Production has urgent demand to environmental monitoring, wireless voice communication and wireless video surveillance.WMSNs
(Wireless Multimedia Sensor Networks, wireless multimedia sensor network) is in conventional wireless sensor
The novel sensor network of the multimedia application such as audio, image, video is introduced on network foundation.WMSNs has efficient and convenient
Wireless access, flexible and changeable topological structure and relatively rich media-aware ability.Therefore, it can be constructed in underground coal mine
WMSNs ensures coal mine to further increase underground coal mine environmental monitoring, wireless voice communication and wireless video surveillance ability
Lower safety in production.
Underground coal mine WMSNs integrates environmental monitoring, wireless voice communication and wireless video surveillance.Environmental monitoring letter
The service traffics characteristic, sudden, real-time and severity level difference of breath, audio-frequency information and video information, to WMSNs QoS
The guarantee of (Quality of Service, service quality) requires also different.MAC (visit by Mdium Access Control, media
Ask control) agreement is in the floor portions of WMSNs protocol stack, and directly decide data message and control message to wireless channel
Access, largely affects the performance and service quality of business in WMSNs.It is, therefore, desirable to provide the MAC of Differentiated Services
Agreement is so that underground coal mine WMSNs supports the business of different QoS guarantee.
Existing WMSNs Differentiated Services MAC protocol, business are generally also divided into video traffic, non-real-time service and do the best
And it is business.Video traffic is arranged to high-priority service, possesses the smallest competition window and maximum duty ratio, is handling up
Performance in terms of amount and time delay is preferentially ensured.Non-real-time service is arranged to high medium priority business, possesses medium sized
Competition window and duty ratio, the performance in terms of handling capacity and time delay are only second to video traffic.Best-Effort service is arranged to
Low priority traffice possesses maximum competition window and the smallest duty ratio, and the performance in terms of handling capacity and time delay can not show a candle to
Video traffic and non-real-time service.
Currently, most of the MAC protocol that WMSNs is used is kept away based on time division multiple acess (TDMA) mechanism or based on conflict is had
Carrier Sense Multiple Access (CSMA/CA) mechanism exempted from.It is underground coal mine environment monitoring node collection carbon monoxide, methane, temperature, wet
The multiple types sensor such as degree, air pressure, wind speed, dust concentration and smokescope is integrated, general only in crucial monitoring region
Carry out a small amount of arrangement.Voice node is the portable mining explosion-proof type mobile phone of underground operators, generally in same monitoring
Only have the underground operators of part to carry in region.Video node is to be arranged in the mining explosion-proof type camera shooting of underground coal mine
Machine, general only to carry out video monitor to the common-denominator target in monitoring region, the quantity of arrangement is also fewer.
The quantity of environment monitoring node, voice node and video node is generally all fewer in underground coal mine WMSNs.In
The MAC protocol that CSMA/CA mechanism is applied in the less WMSNs of number of nodes, can make network have higher handling capacity and more
Low delay character.The existing MAC protocol using CSMA/CA mechanism is in the less WMSNs technical application of number of nodes, usually
It is preferential to guarantee video traffic and voice service, and it is poor to the service quality guarantee of sensing data business.
Summary of the invention
The embodiment of the invention provides the Differentiated Services realization sides in a kind of underground coal mine wireless multimedia sensor network
Method is protected with realizing the Differentiated Services to three kinds of environment monitoring node, voice communication node and video node different communication business
The QoS demand of tri- kinds of different communication business of underground coal mine WMSNs is hindered.
To achieve the goals above, this invention takes following technical solutions.
A kind of Differentiated Services implementation method in underground coal mine wireless multimedia sensor network, comprising:
Environment monitoring node, voice node, video node, institute are set in underground coal mine wireless multimedia sensor network
It states environment monitoring node and environmental monitoring data is acquired by sensor, form sensing data business, the voice node acquires language
Sound data form voice data traffic, and the video node acquires video data, form video data service；
According to the sensing data business, the voice service quality of service requirement different with video traffic, the sensing is given
Data service, voice service and video traffic separately design different competition windows；
The environment monitoring node, voice node, video node are based respectively on various competition windows according to the industry of setting
Business transmission competitive strategy, by the channel of wireless multimedia sensor network to the ground the data service of monitoring center transmission sensing,
Voice data traffic and video data service.
Further, described that environment monitoring node, voice are set in underground coal mine wireless multimedia sensor network
Node, video node, comprising:
The architecture of underground coal mine wireless multimedia sensor network is constructed, which includes in ground monitoring
The heart, wired fiber backbone network and the wireless multimedia sensor network for being deployed in underground coal mine, the radio multimedium of underground coal mine
Sensor network includes environment monitoring node, voice node, video node, leader cluster node and aggregation node, the leader cluster node
Wirelessly access is provided for environment monitoring node, voice node and video node, and will in a manner of single-hop or multi-hop relay
The multimedia messages collected are transferred to aggregation node, and the aggregation node is believed the multimedia collected by wired fiber backbone network
Breath is transferred to ground monitoring center.
Further, the service quality different with video traffic according to the sensing data business, voice service
It is required that separately designing different competition windows to the sensing data business, voice service and video traffic, comprising:
Minimum, medium and maximum competition window has been separately designed for sensing data business, voice service and video traffic,
The environment monitoring node selects the value of the smallest back off time counter, institute in the corresponding competition window of sensing data business
State the value that voice node selects medium back off time counter in the corresponding competition window of voice service, the video node
The value of maximum back off time counter is selected in the corresponding competition window of video traffic.
Further, the service quality different with video traffic according to the sensing data business, voice service
It is required that separately designing different competition windows to the sensing data business, voice service and video traffic, comprising:
Sensing data business, voice service and video traffic are respectively indicated with the i-th class business, distinguishes table with the i-th class node
Show environment monitoring node, voice node and video node, i=1,2,3, the i-th class node is sent and is moved back designed by the i-th class business
Keep away time counter are as follows:
Ti,backoff=Random (CWi)×aSlotTime CWi∈[Wi,0,Wi,max]
In formula, Ti,backoffFor the value of the i-th class business back off time counter, CWiFor the competition window of the i-th class business,
Random(CWi) it is the i-th class business in competition window [0, CWi) in the integer that randomly selects, aSlotTime is radio multimedium
The slot length of the channel of sensor network, Wi,0And Wi,maxThe respectively minimum competition window and maximum contention window of the i-th class business
Mouthful.
Further, the i-th class service competition window CW is designediAre as follows:
In formula, Wi,jFor competition window of the i-th class business when keeping out of the way series j-th, miIndicate the maximum of the i-th class business
Keep out of the way series, keeps out of the way series m when the i-th class business reaches maximumiWhen, the window of the i-th class business is maximum contention window, i.e.,liIndicate the maximum retransmission of the i-th class business, liValue be greater than maximum keep out of the way series miValue.
Further, the environment monitoring node, voice node, video node be based respectively on various competition windows by
Competitive strategy is transmitted according to the business of setting, passes through the channel of wireless multimedia sensor network monitoring center transmission sensing to the ground
Data service, voice data traffic and video data service, comprising:
Environment monitoring node, voice node and video node are sending sensing data business, voice service and video traffic
The channel of wireless multimedia sensor network is monitored before, when the channel for listening to wireless multimedia sensor network
When free time is longer than distributed interframe gap, the environment monitoring node, voice node and video node are respectively respectively competing
It strives in window and randomly selects a back off time counter；
When the back off time counter of the environment monitoring node is reduced to 0, the environment monitoring node passes through wireless
The channel of multimedia sensor network to leader cluster node transmission sensing data service, keep out of the way by the voice node and video node
Time counter pause counts, and the leader cluster node receives the sensing data business data packet sent from environment monitoring node
Afterwards, Xiang Suoyou node sends confirmation and receives response bag；
The environment monitoring node, voice node and video node receive the confirmation reception sent from leader cluster node and answer
After answering packet, restart the channel of monitoring wireless multimedia sensor network, when listening to wireless multimedia sensor network
When the free time of channel is longer than distributed interframe gap, the back off time counter of the voice node and video node is from upper
The value that secondary pause counts continues to start counting；
When the back off time counter of the voice node is reduced to 0, the voice node is passed by radio multimedium
The channel of sensor network is to leader cluster node transmitting voice service, and the back off time counter of the video node, which suspends, to be counted, institute
It states leader cluster node to receive after the sensing data business data packet that environment monitoring node is sent, Xiang Suoyou node sends confirmation
Receive response bag；
The environment monitoring node, voice node and video node receive the confirmation reception sent from leader cluster node and answer
After answering packet, restart the channel of monitoring wireless multimedia sensor network, when listening to wireless multimedia sensor network
When the free time of channel is longer than distributed interframe gap, the back off time counter of the video node suspended from last time to be counted
Value continue to start counting, when the back off time counter of the video node is reduced to 0, the video node passes through wireless
The channel of multimedia sensor network transmits video traffic to leader cluster node.
Further, the method further include:
Assuming that Ps,iIndicate the probability of the i-th class business Successful transmissions data packet in a time slot, E (Li) indicate the i-th class industry
The mean effective load of business transmission data packet, then sensing data business, voice service and video traffic transmit in a time slot
Payload SiIt can indicate are as follows:
Si=Ps,iE(Li)
In formula, E (Li) depend on sensing data business, the size of voice service and video traffic data packet, Ps,iEqual to only
There is an i-th class node to send data packet, other nodes do not send the sum of the probability of data packet, i.e.,
The average duration T of i-th class business Successful transmissions data packets,iIt is expressed from the next:
Ts,i=TH+TE(Li)+SIFS+TACK+DIFS
In formula, THIndicate the duration of transmitting physical layer header file and MAC layer header file, TE(Li)Indicate the i-th class business
The average duration of data packet transmission, SIFS indicate to wait short interFrameGap duration, TACKIndicate continuing for transmission ACK
Time, DIFS indicate gap duration between waiting distributed frame；
The average duration T of channel conflictioncIt is expressed from the next
Tc=TH+TE(L*)+SIFS+TACK+DIFS
In formula, TE(L*)Indicate the average duration of longest data packet transmission in conflict.
Further, the method further include:
Sensing data business, voice service and video traffic MAC layer in underground coal mine wireless multimedia sensor network
Access delay to be data packet sent to success or reached maximum retransmission and be abandoned transmission from starting competitive channel
Time, the time of back off time counter experience backoff period when including WMSNs channel idle, when WMSNs channel busy keeps out of the way
Between counter frozen time, and send the time that data packet is unsuccessfully undergone；
I-th class business retransmits the probability P completing data packet and being successfully sent in jth timei,jIt indicates are as follows:
With stochastic variable XiIndicate that i-th class business is successfully transmitted in the case where not considering that back off time counter is frozen
Timeslot number experienced before data packet, then stochastic variable XiMathematic expectaion E (Xi) retransmitted to undergo every time with the i-th class business and be put down
Equal timeslot number and indicate have:
Stochastic variable BiIndicate the i-th class business frozen number of back off time counter in backoff procedure, then at random
Variable BiMathematic expectaion E (Bi) use E (Xi) and keep out of the way the product representation for being likely encountered freezing probability every time, it may be assumed that
With E (Ni) indicate the average time that the i-th class business data packet is retransmitted, then:
With stochastic variable ToWait the time competed next time after indicating transmission data packet collisions, then:
To=SIFS+TACK_TIMEOUT
Wherein, TACK—TIMEOUTIndicate the duration of ACK time-out；
With stochastic variable DiIndicate the i-th class business MAC layer access delay, then stochastic variable DiMathematic expectaion E (Di) indicate
Are as follows:
Wherein, E (Xi) δ be the i-th class Traffic Channel free time when back off time counter undergo backoff period used in the time,For the i-th class Traffic Channel busy back off time counter be frozen when
Between, E (Ni)(Tc+To) it is the time that the i-th class node sends that data packet is unsuccessfully undergone.
As can be seen from the technical scheme provided by the above-mentioned embodiment of the present invention, the present invention by for sensing data business,
Voice service and video traffic design different competition windows, realize the Differentiated Services of three kinds of business, to ensure three kinds of business not
Same QoS requirement.Establish the Markov chain model that three kinds of business keep out of the way sum of series back off time counter, and analysis area
The saturation throughput and the performance in terms of access delay of the QoS-MAC agreement of sub-service business.The simulation experiment result shows in low-load
Under state and under high load condition, the QoS-MAC agreement of the underground coal mine Differentiated Services proposed can be by reducing video industry
The handling capacity of business increases the handling capacity of sensing data business and voice service, is passed to reduce by increasing the time delay of video traffic
Feel the time delay of data service and voice service.
The additional aspect of the present invention and advantage will be set forth in part in the description, these will become from the following description
Obviously, or practice through the invention is recognized.
Detailed description of the invention
In order to illustrate the technical solution of the embodiments of the present invention more clearly, required use in being described below to embodiment
Attached drawing be briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for this
For the those of ordinary skill of field, without any creative labor, it can also be obtained according to these attached drawings other
Attached drawing.
Fig. 1 is a kind of underground coal mine WMSNs architecture structural schematic diagram provided in an embodiment of the present invention；
Fig. 2 is that a kind of design of QoS-MAC agreement of underground coal mine WMSNs Differentiated Services provided in an embodiment of the present invention is former
Manage schematic diagram；
Fig. 3 is a kind of two-dimensional discrete time Markov chain state transition diagram of i-th class business provided in an embodiment of the present invention.
Specific embodiment
Embodiments of the present invention are described below in detail, the example of the embodiment is shown in the accompanying drawings, wherein from beginning
Same or similar element or element with the same or similar functions are indicated to same or similar label eventually.Below by ginseng
The embodiment for examining attached drawing description is exemplary, and for explaining only the invention, and is not construed as limiting the claims.
Those skilled in the art of the present technique are appreciated that unless expressly stated, singular " one " used herein, " one
It is a ", " described " and "the" may also comprise plural form.It is to be further understood that being arranged used in specification of the invention
Diction " comprising " refer to that there are the feature, integer, step, operation, element and/or component, but it is not excluded that in the presence of or addition
Other one or more features, integer, step, operation, element, component and/or their group.It should be understood that when we claim member
Part is " connected " or when " coupled " to another element, it can be directly connected or coupled to other elements, or there may also be
Intermediary element.In addition, " connection " used herein or " coupling " may include being wirelessly connected or coupling.Wording used herein
"and/or" includes one or more associated any cells for listing item and all combinations.
Those skilled in the art of the present technique are appreciated that unless otherwise defined, all terms used herein (including technology art
Language and scientific term) there is meaning identical with the general understanding of those of ordinary skill in fields of the present invention.Should also
Understand, those terms such as defined in the general dictionary, which should be understood that, to be had and the meaning in the context of the prior art
The consistent meaning of justice, and unless defined as here, it will not be explained in an idealized or overly formal meaning.
In order to facilitate understanding of embodiments of the present invention, it is done by taking several specific embodiments as an example below in conjunction with attached drawing further
Explanation, and each embodiment does not constitute the restriction to the embodiment of the present invention.
Wireless multimedia sensor network has important value to realization underground coal mine multimedia monitoring.To ensure coal mine
Underground WMSNs sensing data business, the voice service requirement different to network service quality with video traffic, propose a kind of coal
The QoS-MAC agreement of WMSNs Differentiated Services under mine.
MAC protocol of the embodiment of the present invention based on CSMA/CA mechanism proposes a kind of underground coal mine WMSNs Differentiated Services
QoS-MAC agreement.The MAC protocol proposed passes through three kinds of differences for environment monitoring node, voice node and video node
Communication service designs different competition windows, realizes to three kinds of environment monitoring node, voice communication node and video node not
With the Differentiated Services of communication service, the QoS demand of tri- kinds of different communication business of underground coal mine WMSNs has been ensured.
There is very big difference in the underground coal mine WMSNs QoS of survice requirements of support and the existing WMSNs QoS of survice requirements of support
Not.The environmental parameter that underground coal mine environmental monitoring wireless sensor node is monitored is sensing data business, and business is passed to wireless
Defeated bandwidth demand is generally lower.But sensing data business is directly related to safety of coal mines, it is very high to propagation delay time requirement,
It needs to be arranged to high-priority service.Voice communication is real-time between guarantee ground monitoring center and underground operators
Property, voice service is generally set to high medium priority business.Underground coal mine video traffic is mostly derived from the view to underground work situation
Frequency monitors, and there are a fixed response times will not usually have an impact to coal mine downhole safety for video traffic.Underground coal mine video industry
Business is using video frame as unit of transfer, and data volume is relatively large, but video traffic need to only be set as low priority.As it can be seen that ensure coal
WMSNs provides QoS for different business and ensures under mine, need to be based on underground coal mine WMSNs sensing data business, voice service and view
The importance of frequency business, occurrence frequency, one-way or bi-directional transmission traffic characteristics, summarize underground coal mine WMSNs business
Basic model.
Underground coal mine WMSNs architecture as shown in Figure 1, architecture mainly by ground monitoring central part, wired optical fiber
Backbone network is formed with 3 layer architecture such as WMSNs of underground coal mine is deployed in.Underground coal mine WMSNs include environment monitoring node,
Voice node, video node, leader cluster node and aggregation node.Leader cluster node is environment monitoring node, voice node and video section
Point provides wirelessly access, and the multimedia messages collected are transferred to aggregation node in a manner of single-hop or multi-hop relay.
The multimedia messages collected are transferred to ground monitoring center by wired fiber backbone network by aggregation node.In this way,
The important environmental parameter of underground coal mine can be monitored in real time in ground monitoring center, and underground operators real-time speech communicating, and
Video monitoring is carried out to underground work situation.
Sensing data business
Sensing data business is generated by the environment monitoring node for being deployed in underground coal mine, is the basic of underground coal mine WMSNs
Business.Each environment monitoring node integrates a plurality of types of sensors, can acquire a plurality of types of environmental monitoring datas simultaneously.Ring
Border monitoring node is arranged and is encapsulated to the various environmental monitoring datas of acquisition, is formed sensing data business, is then passed through
WMSNs uploads to ground monitoring center.
The transmission direction of sensing data business is from underground coal mine monitoring center one-way transmission to the ground.Sensing data business
Portfolio and the quantity of environment monitoring node, the number of single environment monitoring node integrated sensor and sensor acquire ring
The frequency of border monitoring data is related.Underground coal mine generally requires monitoring carbon monoxide, methane, temperature, humidity, air pressure, wind speed, powder
The important environmental parameters of 8 seed type such as dust concentration and smokescope.If the frequency of every kind of sensor acquisition environmental monitoring data is
1s is primary, and the size of each environmental monitoring data is 512bits, then the data rate of every kind of sensor is about 0.5Kbps, in this way
The data rate for the sensing data business that the environment monitoring node of one integrated 8 seed type sensor generates is about 4Kbps.Coal mine
The next WMSNs of well generally arranges 2~6 environment monitoring nodes, the data rate of sensing data business be about 8Kbps~
24Kbps.As it can be seen that the bandwidth demand of underground coal mine WMSNs sensing data business is lower.But to ensure ground monitoring center energy
The environmental information of enough real-time monitoring underground coal mines, sensing data business are higher to the requirement of real-time of transmission.
Voice service
Voice service be mainly between voice node and ground monitoring center in underground coal mine WMSNs voice scheduling communicate
The business of generation.It is shorter that underground coal mine voice scheduling communicates the general single duration of call, but voice scheduling communication have frequency compared with
High, sudden stronger feature.Nyquist theorem provides that the sample frequency of voice is 8000 times per second, every time 8 bit, therefore
The baseband bandwidth of voice communication is 64Kbps.For the efficiency of transmission and reliability for improving voice communication, G.711 audio volume can be used
Code mode compresses voice communication bandwidth, and compressed transmission bandwidth is 90.4Kbps.The next WMSNs voice of coal mine
The quantity of node is generally 1~3, and the data rate of voice service is about 90.4Kbps~271.2Kbps.To guarantee call sound
The identifiability of sound, time delay is usually no more than 150ms end to end for voice communication.Therefore, to underground coal mine WMSNs voice service
Propagation delay time is required no more than 150ms end to end.
Video traffic
Video traffic is generated by the video surveillance nodes in underground coal mine WMSNs.The video letter of video surveillance nodes acquisition
Breath uploads to ground monitoring center by WMSNs, provides underground work intuitive video information for ground monitoring center.Video prison
The control instruction that can receive ground monitoring center depending on node adjusts monitoring visual angle according to control instruction, meets ground monitoring center
Observation demand.
For video traffic using video frame as unit of transfer, data volume is relatively large, the video of specific transmission rate and use
Compression standard is related.H.264 for video compression standard by ITU-T and ISO/IEC joint development, compression efficiency is higher, and to channel
Time delay has stronger adaptability.Meanwhile H.264 video compression standard strengthens the processing to error code and packet loss, improves and understands
The error resilience of code device, is very suitable for underground coal mine video monitoring.H.264 the compression speed of video compression standard is
32Kbps~2Mbps.The next WMSNs of coal mine generally arranges 1~3 video node, and the data rate of video traffic is about
32Kbps~6Mbps.
Compared with sensing data business and voice service, requirement of the underground coal mine WMSNs video traffic to real-time is opposite
It is lower.The reason is that video traffic, which is mainly to aid in ground monitoring center, intuitively understands coal mine operation situation, not directly
It is related to coal mine operation Environmental security parameter.To guarantee downhole video image quality, video traffic is to the steady of network transmission
Qualitative requirement with higher.
Table 1 from service condition, bandwidth demand, real-time, directionality etc. to underground coal mine WMSNs business the characteristics of into
Conclusion is gone.
The characteristics of 1 underground coal mine WMSNs business of table
The algorithm description of the QoS-MAC agreement of WMSNs Differentiated Services
It can be seen that underground coal mine sensing data industry from the analysis above to underground coal mine WMSNs multimedia service demand
There are different discharge characteristics and the QoS requirements of support for business, voice service and video traffic.It is proposed to this end that a kind of underground coal mine
The QoS-MAC agreement of WMSNs Differentiated Services.The QoS-MAC agreement of proposed Differentiated Services is by for sensing data business, voice
Business and video traffic design different competition windows, rationally keep out of the way, and realize the Differentiated Services of three kinds of business, have ensured difference
The QoS demand of business.The characteristics of according to 1 underground coal mine WMSNs business of table, by sensing data business, voice service and video industry
The priority of business is respectively set to advanced, intermediate and rudimentary.
Fig. 2 illustrates the design principle schematic diagram of the QoS-MAC agreement of proposed underground coal mine WMSNs Differentiated Services.
In Fig. 2, environment monitoring node, voice node and video node are sending sensing data business, voice service and video traffic
WMSNs channel is monitored before.When underground coal mine WMSNs idle time of channel is longer than DIFS (Distributed
Inter-frame Spacing, distributed interframe gap) when, environment monitoring node, voice node and video node are respectively each
A back off time counter is randomly selected from competition window.It, should when the back off time counter of some node is reduced to 0
Node begins to send data packet.For the different priorities of sensing data business, voice service and video traffic, to sense number
Minimum, medium and maximum competition window has been separately designed according to business, voice service and video traffic.Environmental monitoring section in this way
The value for the back off time counter that point, voice node and video node randomly select in competition window also just respectively it is minimum, in
Deng and it is maximum.Since sensing data business back off time counter is usually minimum, so the back off time meter of environment monitoring node
Number device is generally reduced to 0 at first, that is, is initially completed backoff procedure, and starts to send data packet, such as first competition phase in Fig. 2
Shown in vertical line afterwards.Voice node and the back off time counter of video node suspend counting, delay access WMSNs simultaneously at this time
Channel.Leader cluster node is properly received the sensing data business data packet sent from environment monitoring node, waits a short interframe
Interval (SIFS) time is converted into transmission state from reception state, and sends confirmation to all nodes and receive response bag (ACK), accuses
Know that all node leader cluster nodes are successfully received data packet.
All nodes of WMSNs receive after the ACK that leader cluster node is sent, and restart to monitor WMSNs channel.Work as letter
When road free time is longer than DIFS, the back off time counter of voice node and video node continues from the value that last time pause counts
It starts counting.Back off time of the voice node and video node to fail in last time competition in this way in competition next time is just shorter,
The case where competing always so as to avoid the low business of priority less than WMSNs channel.Due to the back off time meter of voice service
Number device is less than video traffic, so the back off time counter of voice node is first reduced to 0, i.e., secondly completes backoff procedure, and
Start to send data packet, as shown in the vertical line after second competition phase in Fig. 2.The back off time counter of video node at this time
Pause counts, delay access WMSNs channel, if environment monitoring node is also in contention access WMSNs channel, environmental monitoring
Node also suspends.Likewise, leader cluster node is properly received the Voice traffic data packet sent from voice node, one is waited
The SIFS time is converted into transmission state from reception state, and sends confirmation to all nodes and receive response bag (ACK), informs all
Node leader cluster node is successfully received data packet.
All nodes of WMSNs receive after the ACK that leader cluster node is sent, and restart to monitor WMSNs channel.When etc.
When idle time of channel is longer than DIFS, the back off time counter of video traffic from voice service compete in pause count
Value continues to start counting.When the back off time counter of video node is reduced to 0, that is, backoff procedure is finally completed, and start to send out
Data packet is sent, as shown in the vertical line after the third competition phase in Fig. 2.In above-mentioned environment monitoring node, voice node and video
During node sends data packet, the value of various businesses back off time counter and the size of competition window are directly affected
The performance of MAC protocol Differentiated Services.The back off time of the QoS-MAC agreement of underground coal mine WMSNs Differentiated Services is counted below
The parameter of device and competition window optimizes.
Assuming that sensing data business, voice service and video traffic are respectively indicated with i-th (i=1,2,3) class business, with
I (i=1,2,3) class node respectively indicates environment monitoring node, voice node and video node.I-th class is sent to the i-th class node
Back off time counter designed by business are as follows:
Ti,backoff=Random (CWi)×aSlotTime CWi∈[Wi,0,Wi,max] (1)
In formula, Ti,backoffFor the value of the i-th class business back off time counter, CWiFor the competition window of the i-th class business,
Random(CWi) it is the i-th class business in competition window [0, CWi) in the integer that randomly selects, aSlotTime is slot length,
Wi,0And Wi,maxThe respectively minimum competition window and maximum contention window of the i-th class business.It can be passed in equation 1 by choosing
Sense data service, the voice service competition window different with video traffic, to adjust the value of back off time counter to meet not
With the access demand of business.
Design the i-th class service competition window CWiAre as follows:
In formula, Wi,jFor competition window of the i-th class business when keeping out of the way series j-th, miIndicate the maximum of the i-th class business
Keep out of the way series, keeps out of the way series m when the i-th class business reaches maximumiWhen, the window of the i-th class business is maximum contention window, i.e.,liIndicate the maximum retransmission of the i-th class business.It is assumed that the i-th class business maximum retransmission li's
Value is greater than maximum and keeps out of the way series miValue.
By formula 2 it is found that the i-th class service competition window CWiValue and the business number, the minimum competition window that collide
Mouth Wi,0With maximum contention window Wi,maxIt is related.I-th class service competition window CWiInitial value be minimum competition window Wi,0.When i-th
When the i-th class business of class node transmission collides, the series of keeping out of the way of business adds 1, competition window CWiIncrease by 1 times.When the i-th class industry
When business reaches maximum and keeps out of the way series, the competition window CW of businessiRemain maximum contention window Wi,maxIt is constant, until completing i-th
The transmission of class business reaches maximum retransmission and no longer reattempts to transmission.
Since sensing data business is directly related to safety of coal mines, so the competition window of design sensing data business is always
Remain less than voice service and video traffic.Design the minimum competition window of voice service and the maximum contention of sensing data business
Window is identical, and the priority of voice service is kept to be only second to sensing data business.Design video traffic minimum competition window be
2 times of voice service minimum competition window, so that the priority of video traffic access WMSNs channel is minimum.Meanwhile designing sensing
The maximum of data service, voice service and video traffic keeps out of the way series miIt is all 2, i.e. environment monitoring node, voice node and view
After frequency node transmission data packet clashes, keeps out of the way and reach maximum contention window twice.In conclusion table 2 gives coal mine
The different minimum competition window W of three kinds of business of QoS-MAC agreement of lower WMSNs Differentiated Servicesi,0With maximum contention window Wi,max's
Design parameter.
The QoS-MAC agreement W of 2 WMSNs Differentiated Services of tablei,0And Wi,maxDesign parameter
As shown in table 2, in the QoS-MAC agreement of the underground coal mine WMSNs Differentiated Services proposed, sensor business,
The competition window of voice service and video traffic is sequentially increased, and the high business of User Priority possesses smaller competition window, is begun
The transmission priority of greater degree is kept eventually.
3.2 system model
Underground coal mine WMSNs environment monitoring node, voice node and video node therein only exist a kind of business, section
The competition of different business is not present in point.Sensing data business is periodic traffic, and voice service is bursts of traffic, video industry
Business is continuity business.When three kinds of business load flows are lower or do not have voice service within certain time, if use area
The QoS-MAC agreement of sub-service business distinguishes WMSNs QoS guarantee in multimedia services little.But it is high in three kinds of business load flows
Under saturation state, the QoS-MAC agreement of Differentiated Services is then particularly significant to WMSNs QoS guarantee in multimedia services.Assuming that in full
Quantity with environment monitoring node, voice node and video node under working condition is respectively n1、n2And n3, it is denoted as (n1,n2,
n3).When environment monitoring node, video node work are under stable saturation state, it is constant for sending the rhythm of data, and
Although the rhythm that voice node sends data happens suddenly at random, but the statistical probability that it happens suddenly at random in longer period of time
It is constant.It may be assumed that environment monitoring node, voice node and video node send the probability of data packet every time as difference in this way
Constant, be denoted as τi。
Assuming that underground coal mine WMSNs channel does not have concealed terminal and channel acquisition, packet loss is only because there are two or more than two
Node the same time slot send simultaneously data packet collide it is caused.When a certain environment monitoring node, voice node or view
When frequency node sends data packet in some time slot, if thering are other nodes to send number in same time slot in remaining all nodes
According to packet, then the collision of data packet can occur.So the i-th class node sends the probability P to collide when data packetc,iIt can indicate
Are as follows:
In formula, τiIndicate that the i-th class node sends the probability of data packet, niIndicate the quantity of the i-th class node.
The probability P of underground coal mine WMSNs channel busybDepending on the environment monitoring node of work, voice node and video section
The probability of the quantity of point and their transmission data packets, PbAt least one node of underground coal mine should be equal to and sending the general of data packet
Rate, so that
In formula, τiIndicate that the i-th class node sends the probability of data packet, niIndicate the quantity of the i-th class node.
It can be observed from fig. 2 that environment monitoring node, voice node and video node are sending sensing data business, voice
Before business and video traffic, need to complete respective backoff procedure.T at the time of in backoff procedure, it is assumed that the i-th class business
Keep out of the way sum of series back off time counter uses stochastic variable s (i, t) and b (i, t) to indicate respectively.So the i-th class business is kept out of the way
Sum of series back off time counter { s (i, t+1), b (i, t+1) } only and previous moment { s (i, t), b (i, t) } it is related, and with { s
(i, t-1), b (i, t-1) } it is unrelated.It thus can use two-dimensional discrete time Markov chain modeling sensing data business, voice
The backoff procedure of business and video traffic, and kept out of the way the state transition diagram of sum of series back off time counter as shown in Figure 3.
What needs to be explained here is that in the two-dimensional discrete time Markov chain of Fig. 3 the i-th class business, sensing data business, voice service
The probability P to collide when sending data packet with video trafficc,iDifference, sensing data business, voice service and video traffic
Competition window Wi,jAlso different.
Fig. 3 be the i-th class business two-dimensional discrete time Markov chain state transition diagram, from Fig. 3 the i-th class business two dimension from
What the backoff procedure that scattered time Markov chain can be seen that sensing data business, voice service and video traffic can be unified
It is described as keeping out of the way the state transition probability of sum of series back off time counter.Sensing data business, voice service and video traffic
The state transition probability for keeping out of the way sum of series back off time counter can be described by following 5 formula:
In formula, p i, j, k | and i, j, k+1 } indicate that the i-th class business is transferred to from state { s (i, t)=j, b (i, t)=k+1 }
The transition probability of state { s (i, t+1)=j, b (i, t+1)=k }.Formula (5) if the 1st formula indicate the i-th class business detect
Channel idle, then back off time counter subtracts 1 at the beginning of each time slot.If channel is idle always, back off time meter
Number device can be decremented to always 0.Formula (5) if the 2nd formula indicate the i-th class business detect that channel busy, the i-th class business are moved back
It keeps away sum of series back off time counter and is held at this state and do not change.When the i-th class business back off time counter is passed
When being kept to 0, start to send data packet.It is clashed when if sending data packet, the series of keeping out of the way of the i-th class business adds 1, such as formula
(5) shown in the 3rd formula.If being successfully transmitted data packet, keeping out of the way series becomes 0, as shown in the 4th formula of formula (5).Formula
(5) the 5th formula is indicated when the i-th class business reaches maximum retransmission, no matter sends whether data packet succeeds, lower a moment
0 will all be become by keeping out of the way grade, be clashed even if sending data packet, the i-th class node can also abandon current data packet and abandon sending out again
It send.
Since two-dimensional discrete time Markov chain is ergodicity, the Stationary Distribution of { s (i, t), b (i, t) } is exactly pole
Limit distribution, has:
For the Stationary Distribution of { s (i, t), b (i, t) }.Then have:
1st formula of formula (7) indicates bi,j,0It can be expressed as bi,0,0Collision j times probability when sending data packet.Formula
(7) the 2nd formula indicates all bi,j,kBack off time counter is decremented to 0 the sum of probability and is under channel idle condition
bi,j,0.3rd formula of formula (7) indicates that all of the i-th class business keep out of the way the stage and exhaust the general of all back off time Counter Values
The sum of rate is 1.
From formula (8) as can be seen that the i-th class node sends the probability τ of the i-th class business data packetiIt is sent out depending on the i-th class node
The probability P to collide when sending data packetc,i, the maximum retransmission l of the i-th class businessiAnd i-th class business keeping out of the way series
For 0 stage, back off time counter is decremented to 0 probability bi,0,0.Wherein bi,0,0It can be calculated by formula (7).
From the two-dimensional discrete time Markov chain of Fig. 3 the i-th class business can be seen that environment monitoring node, voice node and
Video node sends the probability τ of data packet respectively1、τ2And τ3, the i-th class node should be equal to each and keep out of the way stage back off time meter
Number device is decremented to the sum of 0 probability, it may be assumed that
In the QoS-MAC agreement avoidance mechanism of the underground coal mine WMSNs Differentiated Services proposed, sensing data business,
The maximum of voice service and video traffic keeps out of the way series miIt is all 2.Therefore, formula (9) can be unfolded are as follows:
Formula (3), (4), (8) and (10) constitutes a Nonlinear System of Equations, can parse this equation by numerical solution
The approximate solution of group obtains when environment monitoring node, voice node and video node working quantity being (n1,n2,n3) when, coal mine
The probability P of lower WMSNs channel busyb, the probability τ of the i-th class node transmission data packetiAnd it collides when sending data packet general
Rate pc,i。
The analysis of 3.3 saturation throughputs
Assuming that Ps,iIndicate the probability of the i-th class business Successful transmissions data packet in a time slot, E (Li) indicate the i-th class industry
The mean effective load of business transmission data packet, then sensing data business, voice service and video traffic transmit in a time slot
Payload SiIt can indicate are as follows:
Si=Ps,iE(Li) (11)
In formula, E (Li) depend on sensing data business, the size of voice service and video traffic data packet, Ps,iEqual to only
There is an i-th class node to send data packet, other nodes do not send the sum of the probability of data packet, i.e.,
The probability P for thering is business to be successfully transmitted data packet in one time slotsEqual to sensing data business, voice service and video
Business is successfully transmitted the sum of the probability of data packet in a time slot, i.e.,
The lasting average time T of one time slot can use idle time of channel, Successful transmissions packet time and channel
Conflict time and their probability indicate, i.e.,
In formula, δ indicates the duration of a non-slotted channel free time, 1-PbIndicate the probability of channel idle, Ts,iIndicate the
The average duration of i class business Successful transmissions data packet, TcIndicate the average duration of channel confliction, Pb-PsFor channel busy
But without the probability of Successful transmissions data packet, the i.e. probability of channel confliction.
The average duration T of i-th class business Successful transmissions data packets,iIt is expressed from the next
Ts,i=TH+TE(Li)+SIFS+TACK+DIFS (15)
In formula, THIndicate the duration of transmitting physical layer header file and MAC layer header file, TE(Li)Indicate the i-th class business
The average duration of data packet transmission, SIFS indicate to wait short interFrameGap duration, TACKIndicate continuing for transmission ACK
Time, DIFS indicate gap duration between waiting distributed frame.
The average duration T of channel conflictioncIt is expressed from the next
Tc=TH+TE(L*)+SIFS+TACK+DIFS (16)
In formula, TE(L*)Indicate the average duration of longest data packet transmission in conflict.
The normalization saturation throughput SN of sensing data business, voice service and video trafficiIt is it in a time slot
The payload S of transmissioniWith the ratio of a time slot average time T, i.e.,
The analysis of 3.4 access delays
The access delay of underground coal mine WMSNs sensing data business, voice service and video traffic MAC layer be data packet from
Start the time that competitive channel send to success or is reached maximum retransmission and be abandoned transmission, including WMSNs channel sky
Idle back off time counter undergoes the time of backoff period, back off time counter frozen time when WMSNs channel busy,
And send the time that data packet is unsuccessfully undergone.
I-th class business retransmits the probability P completing data packet and being successfully sent in jth timei,jIt can be expressed as
With stochastic variable XiIndicate that i-th class business is successfully transmitted in the case where not considering that back off time counter is frozen
Timeslot number experienced before data packet, then stochastic variable XiMathematic expectaion E (Xi) can be retransmitted and passed through every time with the i-th class business
Go through average timeslot number and indicate have:
Stochastic variable BiIndicate the i-th class business frozen number of back off time counter in backoff procedure, then at random
Variable BiMathematic expectaion E (Bi) E (X can be usedi) and keep out of the way the product representation for being likely encountered freezing probability every time, i.e.,
With E (Ni) indicate the average time that the i-th class business data packet is retransmitted, then
With stochastic variable ToThe time competed next time is waited after indicating transmission data packet collisions, then
To=SIFS+TACK_TIMEOUT (22)
Wherein, TACK—TIMEOUTIndicate the duration of ACK time-out.
With stochastic variable DiIndicate the i-th class business MAC layer access delay, then stochastic variable DiMathematic expectaion E (Di) can be with
It indicates are as follows:
Wherein, E (Xi) δ be the i-th class Traffic Channel free time when back off time counter undergo backoff period used in the time,For the i-th class Traffic Channel busy back off time counter be frozen time,
E(Ni)(Tc+To) it is the time that the i-th class node sends that data packet is unsuccessfully undergone.
Simulation model
For the performance of the QoS-MAC agreement of the underground coal mine WMSNs Differentiated Services of inspection institute's proposition, it is assumed that in coal mine
Random placement n on the working face of lower 300m × 300m1A environment monitoring node, n2A voice node, n3A video node and one
Leader cluster node.The service convergence of all multi-media nodes is sent to ground monitoring center to leader cluster node and by leader cluster node.
Assuming that by the sensing data business of subsurface environment monitoring node monitoring center one-way transmission to the ground, each node is every
The time interval of secondary transmission data packet is 1s, and the size of data packet is 512Bytes, bandwidth demand 4Kbps.Underground voice section
Point ground monitoring center between transmitted in both directions voice service, underground voice node is to the ground in monitoring center and ground monitoring
Time interval to underground voice node transmission data packet is all 0.02s, and the size of data packet is all 200Bytes, transmitted in both directions
Bandwidth demand be 160Kbps.Assuming that transmitting 10 frames video traffic each second, frame size is 128 × 120 pixels, each picture
Element needs 9bit.By the video traffic of downhole video node monitoring center one-way transmission to the ground, each node transmits number every time
Time interval according to packet is 0.1s, and the size of data packet is 17280Bytes, bandwidth demand 1382Kbps.It is mentioned to investigate
The performance of the QoS-MAC agreement of underground coal mine WMSNs Differentiated Services out, environment monitoring node n1, voice node n2With video section
Point n3Quantity be taken as two groups of (2,1,1) and (6,3,3), be respectively used to simulation low discharge load and High traffic loads.Table 3 is coal
The quantity of the description of WMSNs different business demand and the multi-media nodes disposed under mine.
The quantity of 3 underground coal mine WMSNs different business demand of table and the multi-media nodes of deployment
In the QoS-MAC protocol emulation of underground coal mine WMSNs Differentiated Services, it is assumed that the minimum competition of sensing data business
Window CW1,0It is 32.According to the minimum competition window and maximum contention window of sensing data business in the available backoff procedure of table 2
It mouthful is respectively 32 and 128, the minimum competition window and maximum contention window of voice service are respectively 128 and 512, video traffic
Minimum competition window and maximum contention window are respectively 256 and 1024.It is also supposed that subsurface environment monitors sensor section in emulation
The cache size of point, voice node and video node is 125Kbits, and transmission power is 5mw, and maximum retransmission is 4
Secondary, the transmission rate of physical layer is 5.5Mbps, and emulation experiment is continuously 30 minutes, as shown in table 4.It is proposed to investigate
The performance of the QoS-MAC agreement of underground coal mine WMSNs Differentiated Services is assisted also under same network condition using 802.11DCF
View is compared with the agreement proposed.The minimum competition window and maximum contention window of all business of 802.11DCF agreement
It is 32 and 1024.
The simulation parameter of the QoS-MAC agreement of 4 underground coal mine WMSNs of table
In conclusion the embodiment of the present invention is different by designing for sensing data business, voice service and video traffic
Competition window realizes the Differentiated Services of three kinds of business, to ensure the different QoS requirement of three kinds of business.Establish three kinds of business
Keep out of the way the Markov chain model of sum of series back off time counter, and the saturation for analyzing the QoS-MAC agreement of Differentiated Services is handled up
Performance in terms of amount and access delay.The simulation experiment result shows to be proposed in low load condition and under high load condition
The QoS-MAC agreement of underground coal mine Differentiated Services can by reduce video traffic handling capacity come increase sensing data business and
The handling capacity of voice service reduces the time delay of sensing data business and voice service by increasing the time delay of video traffic.
The embodiment of the present invention summarize the bandwidth of underground coal mine sensing data business, voice service and video traffic, time delay,
The characteristics such as directionality establish the business model of underground coal mine WMSNs communication requirement.The QoS-MAC of proposed Differentiated Services is assisted
View realizes service priority by designing sensing data business, voice service and video traffic different competition windows
Differentiated Services establish the Markov chain state transition diagram that three kinds of business keep out of the way sum of series back off time counter, utilize
The saturation throughput and the performance in terms of access delay of the Markov chain theoretical model analysis QoS-MAC agreement of Differentiated Services.
The simulation experiment result shows that the underground coal mine proposed in low load condition and under high load condition distinguishes clothes
The QoS-MAC agreement of business can increase handling up for sensing data business and voice service by reducing the handling capacity of video traffic
Amount reduces the time delay of sensing data business and voice service by increasing the time delay of video traffic.
Those of ordinary skill in the art will appreciate that: attached drawing is the schematic diagram of one embodiment, module in attached drawing or
Process is not necessarily implemented necessary to the present invention.
As seen through the above description of the embodiments, those skilled in the art can be understood that the present invention can
It realizes by means of software and necessary general hardware platform.Based on this understanding, technical solution of the present invention essence
On in other words the part that contributes to existing technology can be embodied in the form of software products, the computer software product
It can store in storage medium, such as ROM/RAM, magnetic disk, CD, including some instructions are used so that a computer equipment
(can be personal computer, server or the network equipment etc.) executes the certain of each embodiment or embodiment of the invention
Method described in part.
All the embodiments in this specification are described in a progressive manner, same and similar portion between each embodiment
Dividing may refer to each other, and each embodiment focuses on the differences from other embodiments.Especially for device or
For system embodiment, since it is substantially similar to the method embodiment, so describing fairly simple, related place is referring to method
The part of embodiment illustrates.Apparatus and system embodiment described above is only schematical, wherein the conduct
The unit of separate part description may or may not be physically separated, component shown as a unit can be or
Person may not be physical unit, it can and it is in one place, or may be distributed over multiple network units.It can root
According to actual need that some or all of the modules therein is selected to achieve the purpose of the solution of this embodiment.Ordinary skill
Personnel can understand and implement without creative efforts.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
In the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by anyone skilled in the art,
It should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with scope of protection of the claims
Subject to.
Claims (5)
1. the Differentiated Services implementation method in a kind of underground coal mine wireless multimedia sensor network characterized by comprising
Environment monitoring node, voice node, video node, the ring are set in underground coal mine wireless multimedia sensor network
Border monitoring node acquires environmental monitoring data by sensor, forms sensing data business, and the voice node acquires voice number
According to formation voice data traffic, the video node acquires video data, forms video data service；
According to the sensing data business, the voice service quality of service requirement different with video traffic, the sensing data is given
Business, voice service and video traffic separately design different competition windows；
The environment monitoring node, voice node, video node are based respectively on various competition windows and pass according to the business of setting
Defeated competitive strategy passes through the channel data service of monitoring center transmission sensing, voice to the ground of wireless multimedia sensor network
Data service and video data service；
The quality of service requirement different with video traffic according to the sensing data business, voice service give the biography
Sense data service, voice service and video traffic separately design different competition windows, comprising:
Minimum, medium and maximum competition window has been separately designed for sensing data business, voice service and video traffic, it is described
Environment monitoring node selects the value of the smallest back off time counter, institute's predicate in the corresponding competition window of sensing data business
Syllable point selects the value of medium back off time counter in the corresponding competition window of voice service, and the video node is regarding
The value of maximum back off time counter is selected in the corresponding competition window of frequency business；
The quality of service requirement different with video traffic according to the sensing data business, voice service give the biography
Sense data service, voice service and video traffic separately design different competition windows, comprising:
Sensing data business, voice service and video traffic are respectively indicated with the i-th class business, respectively indicates ring with the i-th class node
Border monitoring node, voice node and video node, i=1,2,3, when to keeping out of the way designed by the i-th class node the i-th class business of transmission
Between counter are as follows:
Ti,backoff=Random (CWi)×aSlotTime CWi∈[Wi,0,Wi,max]
In formula, Ti,backoffFor the value of the i-th class business back off time counter, CWiFor the competition window of the i-th class business,
Random(CWi) it is the i-th class business in competition window [0, CWi) in the integer that randomly selects, aSlotTime is radio multimedium
The slot length of the channel of sensor network, Wi,0And Wi,maxThe respectively minimum competition window and maximum contention window of the i-th class business
Mouthful；
Assuming that Ps,iIndicate the probability of the i-th class business Successful transmissions data packet in a time slot, E (Li) indicate that the i-th class business passes
The mean effective load of transmission of data packet, then what sensing data business, voice service and video traffic transmitted in a time slot has
Effect load SiIt can indicate are as follows:
Si=Ps,iE(Li)
In formula, E (Li) depend on sensing data business, the size of voice service and video traffic data packet, Ps,iEqual to only one
A i-th class node sends data packet, other nodes do not send the sum of the probability of data packet, i.e.,
The average duration T of i-th class business Successful transmissions data packets,iIt is expressed from the next:
Ts,i=TH+TE(Li)+SIFS+TACK+DIFS
In formula, THIndicate the duration of transmitting physical layer header file and MAC layer header file, TE(Li)Indicate the i-th class business datum
It wraps the average duration of transmission, SIFS indicates to wait short interFrameGap duration, TACKIndicate the duration of transmission ACK,
DIFS indicates gap duration between waiting distributed frame；
The average duration T of channel conflictioncIt is expressed from the next
Tc=TH+TE(L*)+SIFS+TACK+DIFS
In formula, TE(L*)Indicate the average duration of longest data packet transmission in conflict.
2. the method according to claim 1, wherein described in underground coal mine wireless multimedia sensor network
Middle setting environment monitoring node, voice node, video node, comprising:
The architecture of underground coal mine wireless multimedia sensor network is constructed, which includes ground monitoring center, has
Line fiber backbone network and the wireless multimedia sensor network for being deployed in underground coal mine, the wireless multimedia sensor of underground coal mine
Network includes environment monitoring node, voice node, video node, leader cluster node and aggregation node, and the leader cluster node is environment
Monitoring node, voice node and video node provide wirelessly access, and will be collected in a manner of single-hop or multi-hop relay
Multimedia messages are transferred to aggregation node, and the aggregation node is transmitted the multimedia messages collected by wired fiber backbone network
To ground monitoring center.
3. the method according to claim 1, wherein the i-th class service competition window CW of designiAre as follows:
In formula, Wi,jFor competition window of the i-th class business when keeping out of the way series j-th, miIndicate that the maximum of the i-th class business keeps out of the way grade
Number, keeps out of the way series m when the i-th class business reaches maximumiWhen, the window of the i-th class business is maximum contention window, i.e.,liIndicate the maximum retransmission of the i-th class business, liValue be greater than maximum keep out of the way series miValue.
4. method according to any one of claims 1 to 3, which is characterized in that the environment monitoring node, voice section
Point, video node are based respectively on various competition windows and transmit competitive strategy according to the business of setting, are passed by radio multimedium
The channel of sensor the network data service of monitoring center transmission sensing, voice data traffic and video data service to the ground, comprising:
Environment monitoring node, voice node and video node are before sending sensing data business, voice service and video traffic
The channel of wireless multimedia sensor network is monitored, when the free time for the channel for listening to wireless multimedia sensor network
When time is longer than distributed interframe gap, the environment monitoring node, voice node and video node are respectively in respective contention window
A back off time counter is randomly selected in mouthful；
When the back off time counter of the environment monitoring node is reduced to 0, the environment monitoring node passes through wireless more matchmakers
The channel of body sensor networks is to leader cluster node transmission sensing data service, the back off time of the voice node and video node
Counter pause counts, and the leader cluster node receives after the sensing data business data packet that environment monitoring node is sent,
Confirmation, which is sent, to all nodes receives response bag；
The environment monitoring node, voice node and video node receive the confirmation sent from leader cluster node and receive response bag
Afterwards, the channel for restarting monitoring wireless multimedia sensor network, when the channel for listening to wireless multimedia sensor network
Free time when being longer than distributed interframe gap, the back off time counter of the voice node and video node is temporary from last time
The value for stopping counting continues to start counting；
When the back off time counter of the voice node is reduced to 0, the voice node passes through wireless multimedia sensor
The channel of network is to leader cluster node transmitting voice service, and the back off time counter of the video node, which suspends, to be counted, the cluster
Head node receives after the sensing data business data packet that environment monitoring node is sent, and Xiang Suoyou node sends confirmation and receives
Response bag；
The environment monitoring node, voice node and video node receive the confirmation sent from leader cluster node and receive response bag
Afterwards, the channel for restarting monitoring wireless multimedia sensor network, when the channel for listening to wireless multimedia sensor network
Free time when being longer than distributed interframe gap, the value that the back off time counter of the video node is counted from last time pause
Continue to start counting, when the back off time counter of the video node is reduced to 0, the video node passes through wireless more matchmakers
The channel of body sensor networks transmits video traffic to leader cluster node.
5. the method according to claim 1, wherein the method further include:
Sensing data business, voice service and video traffic MAC layer in underground coal mine wireless multimedia sensor network connect
Entering time delay is the time that data packet send from beginning competitive channel to success or is reached maximum retransmission and be abandoned transmission,
The time of back off time counter experience backoff period when including WMSNs channel idle, back off time counts when WMSNs channel busy
The device frozen time, and send the time that data packet is unsuccessfully undergone；
I-th class business retransmits the probability P completing data packet and being successfully sent in jth timei,jIt indicates are as follows:
With stochastic variable XiIndicate that i-th class business is successfully transmitted data in the case where not considering that back off time counter is frozen
Preceding timeslot number experienced is wrapped, then stochastic variable XiMathematic expectaion E (Xi) with the i-th class business undergone mean time is retransmitted every time
Gap number and indicate, have:
Stochastic variable BiIndicate the i-th class business frozen number of back off time counter in backoff procedure, then stochastic variable Bi
Mathematic expectaion E (Bi) use E (Xi) and keep out of the way the product representation for being likely encountered freezing probability every time, it may be assumed that
With E (Ni) indicate the average time that the i-th class business data packet is retransmitted, then:
With stochastic variable ToWait the time competed next time after indicating transmission data packet collisions, then:
To=SIFS+TACK_TIMEOUT
Wherein, TACK—TIMEOUTIndicate the duration of ACK time-out；
With stochastic variable DiIndicate the i-th class business MAC layer access delay, then stochastic variable DiMathematic expectaion E (Di) indicate are as follows:
Wherein, E (Xi) δ be the i-th class Traffic Channel free time when back off time counter undergo backoff period used in the time,For the i-th class Traffic Channel busy back off time counter be frozen time,
E(Ni)(Tc+To) it is the time that the i-th class node sends that data packet is unsuccessfully undergone.
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