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IEEE Wireless Communications october2006,
vol.13 No. 5
指導老師：童曉儒
報告人：張益瑞
教授
2017/7/28
Cluster-Based Multi-Channel
Communications Protocols in Vehicle
Ad Hoc Networks
Outline
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INTRODUCTION
 SYSTEM ARCHITECTURE
 FUNCTIONS AND DESIGNS OF
PROTOCOLS
 THE CLUSTER CONFIGURATION
PROTOCOL
 THE INTRACLUSTER COORDINATION
AND COMMUNICATION PROTOCOL
 SIMULATION EVALUATIONS
 CONCLUSIONS

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INTRODUCTION(1/2)


2017/7/28

What is DSRC(Dedicated Short Range
Communication)?
V2V-based VANETs and V2R-based VANETs.
The data transmitted over the VANETs can be
classified into the real-time traffic and the nonreal-time traffic.
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DSRC
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
DSRC/802.11p

The standard of 802.11p is based on IEEE 802.11a
PHY layer and IEEE 802.11 MAC layer
Seven 10 MHz channels at 5.9GHz
 one control channel and six service channels

Vehicle to
vehicle
Service
channel
Service
channel
Control
channel
CH 172
CH 174
CH 176
CH 178
Optionally combined
service channels
CH 180
CH 182
CH 184
5.925
5.915
5.905
5.895
5.885
5.875
5.865
5.855
Frequency (GHz)
Intersection
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V2V-BASED VANETS AND V2R-BASED VANETS
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THE DATA TRANSMITTED OVER THE
VANETS

traffic
such as safety messages and video/audio
signals
 non-real-time

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 real-time
traffic
such as e-maps and road/vehicletraffic/weather information
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INTRODUCTION(2/2)
2017/7/28

Our proposed scheme mainly consists of following
three core protocols.
Cluster Configuration Protocol
 Intracluster Coordination and Communication
Protocol
 Intercluster Communication Protocol

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SYSTEM ARCHITECTURE
1.
2.
3.
4.
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 Four
Broadcasting Strategies
Probability-based
Location-based
Neighbor-based
Cluster-based
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FOUR BROADCASTING STRATEGIES
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 1.
Probability-based:
A given PDF determines the decision, for
example depending on the number of copies a
node has received.
 The strategy is often dynamic.


PDF = probability distribution function
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PROBABILITY-BASED
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Car A
PDF = 0.8
Car B
PDF = 0.5
Forwarding Node choose
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FOUR BROADCASTING STRATEGIES
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 Location-based
The selection criterion is the amount of
additional area that would be covered by
enabling a node to forward.
 Some proposal also computes position
prediction as useful input information.

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LOCATION-BASED
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Target
Car A
Car B
wants to turn right
Forwarding Node choose
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FOUR BROADCASTING STRATEGIES

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 Neighbor-based
A node is selected depending on its neighbors
status (for instance, the status concerns how a
neighbor is connected to the network).
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NEIGHBOR-BASED
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Target
Car A
Collect the information of neighbors
Car B
Forwarding Node choose
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FOUR BROADCASTING STRATEGIES
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 Cluster-based
Nodes are grouped in clusters represented by
an elected cluster-head. Only cluster-heads
forward packets.
 Nodes in the same cluster share some features
(e.g., relative speed in VANETs).
 Reclustering on-demand or periodically.

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CLUSTER-BASED
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Cluster-Header
Gateway-Node
Cluster-Header
Forwarding Node choose
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SYSTEM ARCHITECTURE
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SYSTEM ARCHITECTURE
proposed scheme handles the
following three tasks



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 Our
Cluster-membership management
Real-time traffic (such as safety messages
delivery)
Non-real-time data communications (such as
e-maps download, movies download, etc.)
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SYSTEM ARCHITECTURE
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有限狀態機( FINITE STATE
MACHINE, FSM)
在現實中，有許多事情可以用有限個狀態來表達。

紅綠燈運作的原理相當簡單，從一開始綠燈，經過一
段時間後，將變為黃燈，再隔一會兒，就會變成紅燈，
如此不斷反覆。
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
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FUNCTIONS AND DESIGNS OF
PROTOCOLS
use the Finite State Machine (FSM)
 Each vehicle operates under one and only
one of the following four states at any
given time:




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 We
cluster-head (CH)
quasi-cluster-head (QCH)
cluster-member (CM)
quasi-cluster-member (QCM)
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FUNCTIONS AND DESIGNS OF
PROTOCOLS
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Finite state machine of our proposed scheme. T1 and T2
represent Transceiver 1 and Transceiver 2
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THE INTRACLUSTER COORDINATION
AND COMMUNICATION PROTOCOL
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Time division in the CRC channel
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THE INTRACLUSTER COORDINATION
AND COMMUNICATION PROTOCOL
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Tt = 分時多工時間區段
N = 叢集內群組成員
gap = 平均車間距離
v = 平均車輛長度
Lc = 半徑
Nlane = 位於公路上的車道數量
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THE INTRACLUSTER COORDINATION
AND COMMUNICATION PROTOCOL
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T = repetition period(重複期間，預設為200ms)
R = channel rate
Tsafety = 更新安全訊息的間隔時間
Hsafety = 安全訊息的packet size，預設為200bytes
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SIMULATION EVALUATIONS
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 實驗情境設定
環境：單向3線道
 進入時間：2100秒，變異數：180秒
 平均速率：35m/s，變異數：15m2 / s2

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SIMULATION EVALUATIONS
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實驗工具：Matlab
 參數設定：
 車距：25m
 車長：5m
 車內半徑：150m
 車間半徑：400ms
 接收時間：150ms
 發送時間：50ms
 安全訊息封包大小：200bytes

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SIMULATION EVALUATIONS
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The performance of three protocols against non-real-time
traffic arrival rate: a) Probability of safety-message-delivery
failure; and b) aggregate throughput of non-real-time traffics.
The size of the non-real-time traffic packet is 512 bytes.
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SIMULATION EVALUATIONS
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Channel busy rates of the seven different channels. The size of
the non-real-time traffic packet is 512 bytes and the packet
arrival rate of the non real-time traffic is
200packets/sec/vehicle.
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CONCLUSIONS
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Reduce data-congestion
 Support QoS for real-time delivery of safety
messages
 High throughput

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