用CCA以及DSRC呈现一个车辆之间的无线传输架构.pdf

Vehicle-to-Vehicle Wireless Communication Protocols for Enhancing Highway Traffic Safety资科四张翔竣、郭弘毅Why?交通事故次数多、隼祠步直繁 人卷因素彳占90%，其他因素彳占10%用史人瓢法及日寺反，造成速璟隼祸(chain collisions)chain collisions（一般情形）煞隼警示燎 跟隼距离隹 一彳固前事故的彝生，醇致彼方一速串的 How to avoid?木目存1心、/Za假driver可看穿所有隼辆，先得知前 方意外樊生，因此不必依赖前隼的煞隼警作法嵇则 ll叩lm叫MIIIM|mllBBMMmMmMglH喝WM聊lllIIIIIMlmfflMMIfflllW.fll-l制陋ll聊唧IM唧聊哪|M|利用ITS中的 emerging wireless communication technology的 CCA(cooperative colission avoidance)ITS(Intelligent Transportation Systems)CCA(Cooperative Collision Avoidance)Car 2Car 1Car 0a：-Spacing=32 m-7s(1 s)Speed=32 m/s(72 mi/h)Deceleration=4 m/s/s Driver reaction time=1.5 sWarning messagesCruise directionEmergency event(E)3UUB1S5Time(s)CCACollision site(120 m)Cars 0 and 1 collideCarOCar 1,Car 2Car 2 stops at 115 mCar 2 collides1.5s jE)BwelsQ0.4 sCar 0 brakes and sends warning messageCar 1 brakesMessage delivery latency_ Car 2*s trajectory with wireless latency 0.1 sCar 2s trajectory with wireless latency 0.4 sTime(s)Driver reaction timeWarning message delivery latency(0.1 s)1.5s ICar 2 receives warning messageCar 2 brakes小结I Using a high-speed wireless communication network Reliable warning message delivery is a crucial requirement for such CCA systems现有的技彳而-DSRCI I:I I:I I:I I:I I:I I:I I:I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:I I:Dedicated Short Range Communication（事用短距离隹 通割由一些短距离隹通轩l的装置所余且成 The aim of this standard is to provide wireless communications capabilities for transportation applications within a 1000m range at typical highway speeds.大多指隼辆舆路俱U系统之的熊泉通现有的技彳年IEEE 802.11a Two limitations hop-unfairness problem self-competition Lack of MAC protocal stability（在高速行用史下）现有的技林亍-TDMA Synchronization problem-absence of a centralized scheduling entity high vehicular mobility makes MAC coordination much more difficult than the traditional distributed slot allocation scenarios.现有的技林A MANET Delivery-latency-require an explicit route establishment phase before the data transmission begins.其他考因素 Broadcast oriented and they should rely on packet forwarding based on geographic,directional,and other relevant temporal contexts of the source and the destination vehicles.COMMUNICATION PROTOCOLS FOR C O O P E R AT V E C。L L S 0 N AVOIDANCEDIRECTION-AWAREBROADCAST FORWARDING context-aware packet forwarding protocols 假言殳脩件：所有隼事雨都在同一彳固群条且内，而且每申雨隼 者B装IDSRC(Dedicated Short Range Communication)装置DIRECTION-AWAREBROADCAST FORWARDING阐 富一辆隼遇到聚急情，兄日寺，曾夸登出W-CWM 息来告知同一群在接面的其他隼辆 其他隼辆曾逗撵性地根撼收到息的方向来 forward W-CWMJfl息 本檄制可以保吉登群Ifi内所有隼辆都曾收到W-CWI/、DIRECTION-AWAREBROADCAST FORWARDING本械制的目襟：1.揩涉及建璟隼徜的隼辆数目最小化2.安全相信曷的ITS application data曾比低侵先J旗 序的ITS application data侵先停送3.在radio channel存在金磊吴的情，兄下限制隼辆碰 撞事故的彝生Naive Broadcast嬲豳I 侦测到事故的隼畅必须定期赞出W-CWM息 收到W-CWMl息的隼始减速加 往彼停遮息 富一彳固群a且内没有可以往彼停遮息的隼 事雨日寺,本檄制停止Naive Broadcast(Cont)，到W CWIO鸟鼬朝雨/*a WCWM message arrives at a vehicle*/If(Direction of Arrival=Front)Start vehicle deceleration;Start originating WCWM msg.periodically;)Pseudo code 1.Message interpret at ion loic for av intennediate vehicle executing NB.Naive Broadcast(Cont)侦测到事故的隼率雨/*a vehicle emergency event is detected*/doperiodic broadcast of WCWM with this eventJd;untilreceive the same packet with DOA=Back;Pseudo code 2.Message generation logic by an event-detect if ig vehicle executing I-BIA.Intelligent Broadcast with ImplicitA ckno wledgmen t NB的主要限制：谩多的轩1息停遮曾造成802.11 MAC collisions MAC collisions曾降低轩1息匍g的速度以及造成 轩I息的延遽 intelligent broadcast with implicit acknowledgment I-BlA）可以;咸少一彳固群内 的息停播量intelligent Broadcast with ImplicitA ckno wledgmen t(Con t)侦测到事故的隼辆若收到彳怎彼面傅来的WCWM 息，即侦测到事故的隼辆就可以停止赞出 WCWM 在群中的隼子判断哥1息来源方向及是否已 收谩同檬息来决定是否傅息 在一段日寺内若群IS中的隼子没有收到同檬的 WCWM息，即JIH始彝起WCWMl息保面 的隼子能收到息/*a W-CWM message arrives at a vehicle*/If(Direction of Arrival=BACK)Ignore message;Else/*message came from the front V If(this message was received before)Ignore message;Else/*first time reception of this message*/Start vehicle deceleration;Wait for a random duration for receiving any packet from behind,for the same event;if(such a packet was received)/*information about the event has already been propagated beyond this car*/no further action is needed;Else/*message generation is needed*/doperiodic broadcast of W-CWM with appropriate eventjd;untilreceive the same packet with DOA=Back;)Pseudo code 3.Message interpretation logic for an intermediate vehicle executing I-BIA.SAFETY PERFORMANCE OF COOPERATIVE COLLISION AVOIDANCE 余合定一些条件来旗崎式cooperative collision avoidance(CCA)的效能H Table 1.Baseline experimental parameters.Vehicle Related ParametersPlatoon Size50 vehiclesVehicle Speed70 m/hr(32 m/s)Inter-vehicle Spacing0.3 一 0.9 s 三9.6 一 28.8 mVehicle Length4 mEmergency Deceleration8 m/s2Regular Deceleration4.9 nVs2Drivers Reaction Time0.75-1.5 sNetwork Related ParametersMAC ProtocolIEEE 802.11 with custom link-layer priority for ITS safety applicationsRadio modelTwo ray groundRouting ProtocolDirection-aware broadcast forwardingW-CWM Message Size64 bytesW-CWM Period100 msl-BIA Random Wait Time0-10 msBackground ITS Traffic80 800 kb/s/vehicle效能比较 Effects of Intelligent Broadcast Effects of PrioritizedCommunication for CCA Traffic Effects of Channel Error0 80 200 410 820pw-ou U O O E d J。号 UJJX100806040200Background traffic(kb/s/car)(b)12q-10-Wireless collision warning message delivery latency 8-1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49Cars(number 0 at front of the platoon)60-|-Relative distance between consecutive cars after stop 45-:LUlHLjULUUlJjyMjO1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49Cars(number 0 at front of the platoon)Spsd difference between two consecutives cars after stop25201510 5 01 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49Cars(numb3 0 at front of the platoon)Figure 5.Message delivery latency and vehicle safety details for I-BIA(vehicle spacing 28.8 m).8010000p爸=ou uoop-d+0 后utd60-400 0 10 25 50 75Packet error rate(%)(a)GE)Relative message delivery latency between consecutive cars Figure 6.Vehicle collision performance atui relative network latency h:the presence of packet errors:a)CCA perfonnance with packet ernfrs;b)relative deHwry latency between vehicles.杀口 aw用CCA以及DSRC呈现一彳固隼辆之的拆东泉傅输架情 Packet routing protocol在DSRC的王晨境 下要行CCA存在某些特别的限制，透谩来展示data prioritization forsafety-critical applications