CN104967670B - A kind of method of the vehicle access network based on IEEE 802.11p - Google Patents
A kind of method of the vehicle access network based on IEEE 802.11p Download PDFInfo
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- H—ELECTRICITY
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- H—ELECTRICITY
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Abstract
The invention discloses a kind of method of the vehicle access network based on IEEE 802.11p, this method can adapt to requirement of the vehicular ad hoc network security application to time delay and acceptance rate.VeDA is based on 802.11p/DSRC, and vehicle is allowed to be linked into contention free period in shared channel.VeDA schemes support the security service (emergency safety message and routing safety message) of two kinds of different priorities and provide stringent the limit of time delay.DTIM frames are divided into contention free period and competition phase by VeDA, and two kinds of security messages make a reservation for access channel by VeDA Opportunities, and VDAOPs is multiple time slots of contention free period, and non-secure messages is that channel is accessed in a manner of competing in the competition phase.Simulation result shows that VeDA can effectively ensure the time delay and acceptance rate of security message, especially in the case of high traffic load, is better than the access scheme based on back off algorithm in terms of time delay and acceptance rate.
Description
Technical field
The present invention relates to the channel access methods in vehicular ad hoc network, belong to technical field of network communication.
Background technology
Vehicular ad hoc network technology (Vehicular Ad-hoc Network, abbreviation VANET).VANET is used exclusively for vapour
The self-organizing network of vehicle communication is the pith of intelligent transportation system composition.Federal Communications Committee 5.850~
The frequency range of the 75Mhz of 5.925GHz is dedicated for intelligent transportation system.By dedicated short-range communication (DSRC), this 75Mhz is special
Door for vehicle and vehicle (Vehicle-to-Vehicle, V2V) and vehicle and facility (Vehicle-to-Infrastructure,
V2I the communication between), therefore this 75Mhz is also designated as DSRC channels.It is small that IEEE working groups have specially set up IEEE 802.11p
Group carries out the research of DSRC, it is proposed that WAVE patterns.
The channel composition of 7 10MHz of DSRC channels.In addition the common 5MHz frequency spectrums of 5.850GHz to 5.855GHz are by as reservation
Frequency spectrum, for potential expansible application.Channel 178 is referred to as control channel (Control Channel, CCH), is mainly used for
Public safety communication is mainly used for propagating and safety-related message (such as WAVE short messages, WAVE serviced broadcasts).Ch 172、
174th, 176,180,182,184 are referred to as Traffic Channel (Service Channel.SCH), are mainly used to transmit WAVE short messages
With the data packet of personal business.Ch 172 and Ch 184 is by the special public safety applications for being applied to be related to property and life.
Ch 172 is mainly used for the communication of security application between V2V, it is intended to which avoid traffic accident generation, ensures the traffic safety of people.
Ch 184 is mainly used in the security application based on communal facility, is usually used in that cross junction is avoided to crash.
Existing distributed coordination function (Distributed Coordination Function, DFC) is 802.11 marks
Accurate MAC access technologies.The basis of its other access way.It mainly using CSMA/CA algorithms into advance to access, once hair
Binary exponential backoff is just used after raw collision.In order to allow node visit channel, DCF defines two kinds of channel access modes：One
Kind is that basic access access mechanism is also designated as secondary handshake mechanism；Another kind is request transmission/removing based on 4-Way Handshake
Transmission mechanism, the generation avoided collision as possible by carrier sense are exactly kept out of the way once colliding with back off algorithm.So
And 802.11DCF agreements compete node number increase when, handling capacity and delay performance can decline rapidly, from agreement propose with
Come, it has already been proposed many improvement projects：(1) change competition window regulation mechanism, such as DIDD (Double
Increase Double Decrease) agreement, gradually increase and decrease competition window.(2) the most optimized parameter, such as OCB are set
(Optimal Constant Window) agreement according to competition node number adjustment parameter, makes network saturation throughput reach most
It is excellent.Two improvements all there are problems that：(1) most so change competition window regulation mechanism and do not need to estimation nodes
Number, but be often not achieved because of parameter fixed performance optimal.(2) though the method that setting most has parameter can be optimal,
On-line Estimation is needed to compete node number, thus evaluated error is affected to network performance.
MAC protocol basic IEEE 802.11p is IEEE 802.11DCF mechanism, IEEE 802.11p MAC extension layers
It is based on IEEE 802.11e, using EDCA, (Enhanced Distributed Channel Access, enhancing are distributed
Channel Access Mechanism) mechanism access media.By EDCA mechanism, IEEE 802.11p can be by different data flows according to priority
It is divided into different access categories, can ensures the service quality of vehicular applications in this way.It defines four kinds based on IEEE 802.1D
Access type (AccessCategory, AC) i.e.：Voice, video are done one's best and background stream, use 8 kinds of User Priorities
Carry out access wireless channel, the different grades of service is provided for different types of service so that those real time business have higher excellent
First grade priority access channel.The mapping ruler of 8 kinds of priority (UP) and four kinds of access types (AC) is：One UP corresponds to one
AC；Each AC includes two UP；The high UP of priority preferentially enters channel in same AC.But answering due to Network status
Polygamy, it is optimal that the static parameter setting in EDCA can not realize system performance, it is many research shows that, in the situation of high load
Under due to there is higher collision rate in network, the performance of EDCA can cause simultaneously not as good as people's will in low-load
The waste of free timeslot.And present invention the problem of can well solving above.
Invention content
Present invention aims at provide a kind of method of the vehicle access network based on IEEE 802.11p, this method
Decision is accessed for a kind of completely new vehicle (referred to as：VeDA), vehicular ad hoc network security application is can adapt to time delay and acceptance rate
Requirement.VeDA is based on 802.11p/DSRC, and vehicle is allowed to be linked into contention free period in shared channel.VeDA schemes
Support the security service of two kinds of different priorities (i.e.：Emergency safety message and routing safety message) and provide stringent time delay
Boundary.Vehicle access decision is enough to surpass the access scheme based on back off algorithm, the especially situation in high traffic load well
Under, time delay can be effectively reduced and improve acceptance rate.
Method flow：
Step 1：DTIM is (i.e.：Transmission services instruction message) beacon frame be divided into multiple time slots, VDAOPs with 32 μ s
(i.e.：VeDA Opportunitys) scheduled access slot in advance when entering channel for access medium.VDAOP is contention free period
(CFP) the scheduled multiple time slots of institute, node pass through the orderly access channel of the time slot set in advance.
Step 2：Whenever having new access demand, need to carry out VDAOP request units (i.e.：Information
Element, IE) forwarding set up new VDAOP.Make the update VDAOP that the node in network is common, prevent the hair of collision
It is raw.
Above-mentioned steps 1 of the present invention include：DTIM beacon frames have been divided into multiple time slots with 32 μ s.When starting, node
It is carried out the predetermined of channel access by VDAOP, VDAOP is exactly in the scheduled multiple time slots of contention free period (CFP) institute, and CFP is with most
Big connected factor (MAF=α T) is defined as CFP=α T, and wherein T is the length of DTIM.The remaining parts of DTIM are the competition phase
(CP) those applications more sensitive and insensitive to time delay to throughput ratio are primarily directed to.
Above-mentioned steps 2 of the present invention include：VDAOP establishes priority, M for two kinds of security messagesePriority be higher than Mr
The scheme of similary VDAOP priority be also applied for CP during private message it is excellent because this kind of message is insensitive to time delay
First grade is relatively low.IE can be checked first by receiving VDAOP and establishing the network node of request message.Receive when the node this
Do not have when VDAOP does not conflict with other VDAOP of reception and with the VDAOP of the network node closed on and conflict, then the network section
Point will receive the foundation request of this VDAOP.Hereafter, VDAOP recipients and promoter can pass through broadcast or unicast
Form notifies foundation of the adjacent node about VDAOP.
Message is carried out priority division by the present invention, and emergency safety message has highest priority, routing safety message
Priority take second place, minimum is exactly the service message of some non-security applications.
Advantageous effect：
1st, the present invention reduces channel competition degree by predetermined channel access slot
2nd, the present invention reasonably distributes channel for competition node
Description of the drawings
Fig. 1 is DTIM frame structures.
Fig. 2 is Mr and Me message predetermined schemes in VeDA.
Fig. 3 is propagation schemes of the VDAOP in adjacent node.
Fig. 4 is the distribution of movement model of vehicle
Fig. 5 is VeDA and time delays of the DCF in the case of different size of traffic density and message package
Fig. 6 is time delay of the VeDA schemes under different messages
Fig. 7 is that the emergency message of VeDA schemes and road have the time delay of message and the comparison of DCF schemes
Fig. 8 is VeDA mechanism and the comparison of DCF mechanism acceptance rates (message frequency is 500 packets/s, message size 500B)
Fig. 9 is VeDA mechanism and the comparison of DCF mechanism acceptance rates (message frequency is 1250 packets/s, message size 200B)
Figure 10 is flow chart of the method for the present invention.
Specific embodiment
The invention is described in further detail with reference to the accompanying drawings of the specification.
1.VeDA interframe structures
The frame structure of VeDA as shown in Figure 1, VeDA by DTIM (Delivery Traffic Indication Message,
Transmission services instruction message) beacon frame is divided into multiple time slots with 32 μ s, and VDAOPs (VeDA Opportunitys) is access
Scheduled access slot in advance when medium enters channel.Medium access point is by sending VDAOP solicited message units
(Information Element, IE) sets up VDAOP.IE is asked to include as follows：
VDAOP length (1B length)
The VDAOP periods (1B length)
VDAOP offsets (2B length)
Therefore, a length of 4096 μ s of the largest frames of VDAOP.The so-called VDAOP periods are practical be exactly in a DTIM section,
The number in existing VDAOP subintervals.The period of VDAOP refers to only making a reservation for once for 0, will not repeat predetermined.VDAOP is deviated
Measure the distance for VDAOP starting points and DTIM sections starting point.
Mr's and Me is predetermined in 2.VeDA
The security information of vehicle has been divided into 2 types in 802.11p：Emergency safety information (Me) and the period newly mark information
That is routing safety information (Mr).Emergence message generation is more unexpected, and it needs good reliability, low collision, low time delay；
Routing iinformation, that is, beacon message is mainly used for broadcasting, and broadcasting frequency is generally 10~20 times per second.Routing iinformation is generally used for
Some essential informations such as position and direction of broadcasting van etc., so it needs relatively low reliability compared to urgency signal and prolongs
Shi Yaoqiu.
When starting, node is carried out the predetermined of channel access by MDAOP, and MDAOP is exactly pre- in contention free period (CFP) institute
Fixed multiple time slots, CFP are defined as CFP=α T with maximum connected factor (MAF=α T), and wherein T is the length of DTIM, wherein
The remaining parts of DTIM for the competition phase (CP) be primarily directed to those it is more sensitive to throughput ratio and to time delay it is insensitive should
With (the private services information M in such as VANETp)。
Fig. 2 illustrates M in VeDAeAnd MrDetail in the cfp, VeDA establish priority for two kinds of security messages,
MePriority be higher than MrThe scheme of similary VeDA priority be also applied for CP during private message, because of this kind of message pair
Time delay is insensitive, so priority is relatively low.It is worth noting that, even if CCH with SCH interval structures are different, the channel of WAVE is cut
Dehorn standard still allows for CCH and SCH to switch over, and switches as long as their two DTIM siding-to-siding block lengths are identical.Therefore, originally
Invention defines the percentage that residence time ratio is CCH and SCH, and (such as 75% CCH is resident ratio and the resident ratio of 25% SCH
Example).
The foundation of 3.VDAOP
IE can be checked first by receiving VDAOP and establishing the network node of request message.As this VDAOP that the node receives
Do not have when not conflicting with other VDAOP of reception and with the VDAOP of the network node closed on and conflict, then the network node will
Receive the foundation request of this VDAOP.Hereafter, VDAOP recipients and promoter can be led to by the form of broadcast or unicast
Know foundation of the adjacent node about VDAOP.It is reported in the TX-RX times and indicates that the message that MP is sent mainly includes：There is sender
The beacon of VDAOP, own or desired neighbor node with recipient are sent, other not available time slots.In addition should
Receiving node can also send an interference time report.This report is the backup reported the TX-RX times of receiving node adjoint point.
The predetermined information of VDAOP spread out between adjoint point directly or indirectly.The foundation of VDAOP is as shown in figure 3, wherein coordinate x and y
Length and offset are represented respectively.
The present invention is that the predetermined request that message k is established is expressed as each VDAOPWherein okFor
The offset of VDAOP distance DTIM starting points, φkPeriod for VDAOP is the number occurred in DTIM,During for VDAOP
The length of gap.Actually each the vehicle in communication range can be carried out as the requesting node or forward node of VDAOP
The broadcast of VeDA message, so as to which each vehicle be allowed to both know about the predetermined scheme of channel.VDAOP practical is exactly by VDAOP holders
The a cycle time slot in each DTIM sections established with purpose vehicle.
In VeDA predetermined schemes,The length (equation 3.1) of predetermined time slot for x class security messages, at eachSub-slots will defer to stringent time slot and limitThat is the maximum delay (equation 3.2) that m is jumped.While present invention assumes that
Mx∈{Me,MrThat is MxWhat is represented is the security information of x types, and what x was represented when being e is emergency message, r then route messages or
Beacon message.The present invention is allowing security message MxTransmission be happened atLater.The delay of single-hop is excessively high in order to prevent,
PeriodIt must satisfyHere the present invention is in the considerations of simple,Unified calculation, certainly here
It can also be allocated according to different loading conditions.As follows, equation 3.1 is the length of VDAOP；Equation 3.2 is its period：
Wherein τ refers to slot length,Refer to the size of packet,Refer to the transmission rate of IEEE 802.11p,Refer to the quantity of x message,Refer to the maximum delay of x message, its calculation formula such as equation 3.3
It is shown.
What is represented is exactly maximum delay, and what it referred to is exactly the stringent of maximum delay on the path jumped in maximum hop count m
Boundary.WhereinIt is exactly security message MxIt is required that time delay limit.
The delay that the present invention defines VeDA is service time delay and the summation of queuing delay.Service the pre- timing that time delay is VeDA
Prolong,The summation of data packet transmission delay.It is considered herein that the preset time delay of VeDA just waits for next packet hair
The time sent, this is that VDAOP scheduled in order to prevent does not generate competition when sending.It is considered herein that during the transmission of VDAOP
It is negligible to keep out of the way time delay, because when the VDAOP set in advance is sent, is seldom collided.Finally, this hair
It is bright to think that queuing delay is exactly the time that data packet waits in transmit queue.
For emergency message, the broadcast pattern that the present invention is jumped with one is transmitted, and has π in each DTIM sections1It is a
Packet needs to transmit.Therefore the service rate jumped for one is defined as rrate=π1/ DTIM, is expressed as r in the case of multi-hoprate=
πm/DTIM。
4. simulating scenes and parameter
The present invention is emulated using NS2, assesses and compare agreement proposed by the present invention i.e. VeDA and existing 802.11p
Under DCF agreements.The present invention is used by 6 recyclable speed ways (i.e.：Each each 3 tracks in direction) open up step network.
The value of the radio-frequency transmissions range r of transmitting node value in values below：150m、200m、250m.Set each vehicle node hair
Disturbance range R is generated when sending and can reach 550m.Although DSRC communication ranges can theoretically get to 1000m in 802.11p,
Be the range mainly used in the literature it is 150m, 200m and 250m.This mainly considers the specifically institute in security application
Desired communication range is not far, and when communication range is excessive, channel will easy congestion, and can be by the vehicle of distant place
Skimble-skamble communication between is interfered.In addition, the cooperation vehicle safety present invention primarily contemplates 8 kinds of high priorities should
With.This 8 kinds cooperation many aspects of vehicle safety applications are carried by the anticollision project of the National Highway Traffic Safety office in the U.S. and 2006
Out, and requirement of these security applications to delay is all very high, needs to define stringent the limit of time delay, example in advance
Such as, these applications of the southern hundred million Di Na digital technologies Co., Ltds in Nanjing (traffic signals destruction, forward direction anti-collision warning, lane change early warning,
Parking sign assist, turn left assist etc.) time delay be commonly defined as not being more than 100ms, and they transmit range divide
250m, 150m, 150m, 300m, 300m are not corresponded to.Following table illustrates some remaining parameters.
Simulation parameter table
| PHY rf-modes | SINR |
| Carrier sense range | 550m |
| Transmission range | 150、200、250m |
| DTIM | 32ms |
| Packet loss thresholding | 5% |
| α | 0.68 |
| Residence time ratio | 50%CCH |
| Time slot | 13μs |
| MAC layer type | (802.11 using DSRC) |
| Channel width (Mbps) | 6、9、12、24 |
| Type of service | CBR(UDP) |
| Message frequency (per car is per second) | 10~25,500,1250 |
| The size of message payload | 500、1000 |
| Vehicle number | 80 |
| Speed (km/h) | 80~120 |
| Traffic density (vehicle number/km/ tracks) | 10~100 |
| Number of track-lines | 6 |
| Simulation time (s) | 60 |
SINR：Signal-to-noise ratio；DTIM business transferring instruction messages；CCH：Control channel；MAC：Media access control layer；
DSRC：Dedicated short-range communication technology；CBR：Constant bit rate；UDP：User Datagram Protocol.
It is the ratio that data packet is successfully received that the present invention, which defines acceptance rate,.Acceptance rate can be seen as sending vehicle
All automobiles in transmission range are successfully received the probability of the security message of broadcast.Acceptance rate is denoted as P by the present inventionRR。
As shown in figure 4, present invention assumes that automobile all on same track, meets Poisson distribution, network density is β (vehicles
Number/rice).The present invention can represent that the acceptance rate of the v vehicle in the transmission range of R is as follows：
The present invention represents the N in the transmission range of C (subtracting transmission range R i.e. R'-R for carrier sense range R')C
The acceptance rate of vehicle is as follows：
N thereinCIt is exactly in the transmission range R for sending automobilesThe interior vehicle number that same time slot may be competed with it.
The present invention is in transmission range RsInterior transmission rate PRRIt represents as follows：
In the transmission range R of sender SsAcceptance rate of the acceptance rate of any one interior automobile X equal to automobile S is multiplied by
In RXInterior automobile X' not with RXThe probability that interior vehicle X collides.It is worth mentioning that X' will not be usedAnd OX, because this
It is to be allocated to about that while positioned at RsAnd RXInterior vehicle X's.
Therefore, in order to preferably describe PRR(S,RS), the present invention devises two schemes：
Scheme one：In RsI.e. (the N when not having vehicle and sender to compete same channel time slotC=0).
HereBecause sender is in RsIt is interior uniquely to possessAnd OSVehicle.It is since of the invention
The VeDA of decision access is introduced, the present invention is desirable to less collision, so present invention assumes that in the range of R, owns
Automobile average for 2 π R, and in range C, the vehicle interfered is NC=2 π C.
Scheme two：There is NCVehicle can occur to compete i.e. (N with it in the transmission range of senderC≠0)。
WhereinJust refer to when transmission vehicle S is in its transmission range RsWhen being inside transmitted, in CSDo not have inside
The probability that one automobile S' is at war with sender in CFP periods.
The present invention defines P0It is exactly that an automobile has occurred emergency or needs to send the probability of routing iinformation.For
Realize the decision access for sending vehicle S, the present invention needs to calculateI.e. in CSIn the range of be not present a vehicle
WithAnd OSThe probability being transmitted.
Therefore it just has to calculate to calculate equation 4.3 and 4.6In order to prove outThe present invention is first calculated when CEP has 2 time slots and NC>=2 (equatioies 4.6) and CEP have 3 time slots and NC
Value under >=3 (equation 4.7) both of these case.And it summarizesGeneral expression.
CFP=2 time slot；NC≥2
CFP=3 time slot；NC≥3
Reasoning is summarized as follows：
CFP=K time slot；NC>=K, the present invention release：
For NC≤K；
5. the NS2 simulation results of the present invention
Fig. 5 is illustrated under the size of different message packages and different traffic densities, VeDA and DCF schemes are in time delay
The performance of aspect.As can be seen that with the increase of message package size, the time delay of emergency message will increase the present invention from figure,
But compared with the time delay of DCF schemes, the time delay of VeDA schemes is still very low.In addition, when traffic density is higher, VeDA
The time delay performance under normal circumstances lower than the time delay of DCF scheme 97% of scheme.It can be carried using decision access for security information
For the guarantee of the limit of time delay, so as to send emergency message with acceptable low time delay.
Fig. 6 is illustrated in VeDA schemes, and emergency message has message to have higher priority compared to road, even logical
When believing that density is larger, VeDA can still ensure that emergency safety message has higher priority.In VANET networks,
Emergency message has message to have higher delay requirement compared to road, and the present invention can see in figure, proposed by the present invention
VeDA schemes can be very good to ensure the low time delay of emergency message, while the time delay that there is message on Ye Wei roads is provided with boundary, equally
Also can be good at adaptation road has the delay requirement of message.
It is illustrated in the figure 7 with the difference of communications range, VeDA schemes have with DCF schemes in emergency message and road
Time delay performance in message.The purpose of the invention is to detect in the case where channel scenario is more intensive i.e. traffic density compared with
Greatly, can appropriate change transmission range strengthen the performance of DCF, make DCF schemes get to VeDA schemes performance or close to it
Performance.These data of message frequency, traffic density, data rate and message size have given in simulation parameter table
Come.For the present invention as can be seen that under VeDA schemes, the time delay of emergency message is all minimum in all communication ranges from figure
, average delay is about 9.0003504s, this time delay is much lower compared to requirement of the VANET networks to time delay.But
The average delay of message is 0.0219s under DCF schemes, is as many as 62 times of emergency message time delay under VeDA schemes.Meanwhile such as
Shown in Fig. 7, in the case where using VeDA schemes, the time delay that there is message on general road is also entirely acceptable, even
When communication range is 200m, time delay highest has also only reached 0.0173s.This be also exactly present invention contemplates that see because
The present invention can find out that the priority of emergency message, which is better than road, has message, and there is the time delay of message on road from Fig. 2
It is acceptable.
For message, the present invention is accounted for its acceptance rate problem, thus the present invention need to consider with away from
From variation, two schemes have performance how in terms of acceptance rate.It is 500B that Fig. 8, which is illustrated in message size, transmits model
Enclose for 200m, in the case that message frequency is 500pkt/s and data rate is 6Mbps, DCF mechanism and VeDA mechanism about
The performance of acceptance rate.The acceptance rate of VeDA mechanism is averagely better than DCF mechanism about 25%.In addition, from this figure it can be seen that
When communicating more intensive (if distance is 50m), the receptance of VeDA schemes has reached 99%；And in the case of identical
DCF mechanism, acceptance rate have only reached 73%.
When the present invention increases the grade of channel loading (such as message frequency is 1250pkt/s, and message package size is 200B),
The figure of DCF schemes and VeDA schemes displaying such as Fig. 9.When communication distance is 50m, the acceptance rate of VeDA schemes is 89%, and
The acceptance rate of DCF schemes is 52%.It can also clearly be found out from figure, with the variation of communication distance, VeDA schemes exist
On acceptance rate, always better than DCF schemes.The average received rate of DCF is 46%, and the average receptance of VeDA schemes reaches
90%.
Claims (4)
1. it is a kind of based on IEEE 802.11p vehicle access network method, the program it is characterized in that, the method includes
Following steps：
Step 1：The beacon frame of transmission services instruction message DTIM is divided into multiple time slots with 32 μ s, and VDAOPs is access medium
Into scheduled access slot, node pass through the orderly access channel of the time slot set in advance in advance during channel；
Step 2：Whenever having new access demand, need the forwarding for carrying out VDAOP request units (IE) new to set up
VDAOP makes the update VDAOP that the node in network is common, prevents the generation of collision, and VDAOP is scheduled for contention free period more
A time slot.
2. a kind of method of vehicle access network based on IEEE 802.11p according to claim 1, which is characterized in that
The method by message carry out priority division, emergency safety message have highest priority, routing safety message it is preferential
Grade is taken second place, and minimum is exactly the service message of non-security application.
3. a kind of method of vehicle access network based on IEEE 802.11p according to claim 1, which is characterized in that
The step 1 includes：When starting, node carries out the predetermined of channel access by VDAOP, and the maximum of contention free period (CFP) connects
Enter coefficient and be defined as CFP=α T, wherein T is the length of DTIM, and α is the ratio that safe time slot accounts for total time slot, and DTIM is remaining
Part is directed to application to throughput sensitive and insensitive to time delay for the competition phase (CP).
4. a kind of method of vehicle access network based on IEEE 802.11p according to claim 1, which is characterized in that
The step 2 includes：VDAOP establishes priority for two kinds of security messages：Emergency safety information (Me) priority be higher than
Period newly marks information i.e. routing safety information (Mr) priority；The scheme of VDAOP priority is also applied for the competition phase (CP)
Private message, because this kind of message is insensitive to time delay, priority is relatively low；Receive the network that VDAOP establishes request message
Node can check VDAOP request units IE first；When this VDAOP that the node receives not with other VDAOP of reception
Do not have during conflict and with the VDAOP of the network node closed on and conflict, then the network node will receive this VDAOP foundation please
It asks；Hereafter, VDAOP recipients and promoter can notify adjacent node about VDAOP's by the form of broadcast or unicast
It establishes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201510293661.2A CN104967670B (en) | 2015-06-01 | 2015-06-01 | A kind of method of the vehicle access network based on IEEE 802.11p |
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| CN106817675B (en) * | 2015-12-01 | 2020-02-21 | 中国移动通信集团公司 | Channel access method and device applied to inter-vehicle communication system |
| JP6162278B1 (en) * | 2016-02-26 | 2017-07-12 | 日本電信電話株式会社 | Wireless environment determination method and wireless communication system |
| CN106102099B (en) * | 2016-06-08 | 2020-11-24 | 华南理工大学 | Heterogeneous Internet of vehicles switching method based on residence time |
| CN107094321B (en) * | 2017-03-31 | 2020-04-28 | 南京邮电大学 | Multi-agent Q learning-based vehicle-mounted communication MAC layer channel access method |
| CN107396453B (en) * | 2017-08-30 | 2019-12-10 | 福建师范大学 | SD-TDMA-based VANET channel access method |
| CN110087214B (en) * | 2019-04-16 | 2022-04-08 | 常熟理工学院 | DSRC/WAVE-based cooperative transmission method for safety messages in vehicle networking |
| CN110224888B (en) * | 2019-06-10 | 2023-03-07 | 公安部交通管理科学研究所 | Test method, device and system for vehicle-mounted V2X communication equipment |
| CN111313989B (en) * | 2019-12-04 | 2021-07-16 | 大连理工大学 | Vehicle-mounted network reliability analysis method based on signal-to-noise-and-interference ratio |
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