protocols for v2v networksc3%… · · 2012-03-20wave architecture ieee 1609.0 describes the...

Protocols for V2V Networks

Nakjung Choi ([email protected])

Bell Labs Seoul

June 22, 2010

All Rights Reserved © Alcatel-Lucent 20102 |Protocols for V2V Networks| June 2010

Contents

Introduction

Vehicular Mobility Models

Wireless Access in Vehicular Environment (WAVE)

Inter-Vehicle Routing Protocols

Conclusion

Introduction


Introduction

Vehicular Ad-hoc Networks

Vehicle-to-infrastructure (V2I or I2V)

Vehicle-to-vehicle (V2V)

Application

Transportation safety

Transportation efficiency

User services


Applications[1]

Transportation Safety


Applications[1]

Transportation efficiency

Service to users

Vehicular Mobility Models


Motivation & Background

Motivation

Simulation

The first step in development of protocols

Need to have mobility models for simulation

Background

Two perspectives to consider a mobility model

Macroscopic: considers traffic density, traffic flow, etc

Microscopic: focuses on the movement of each individual vehicle and on the vehicle behavior with respect to others

Simple Mobilitycan’t reflect real-world traffic !


Realistic Mobility Model Components

Proposed concept map for the generation of realistic vehicular mobility models[2]

From Reference [xx]


Realistic Mobility Model Components

Two fundamental blocks

Motion Constraints

Describes how each vehicle moves (its relative degree of freedom)

Traffic Generator

Generates different kinds of cars

Deals with their interactions according to the environment

Other blocks

Accurate/realistic topological maps, smooth deceleration and

acceleration, obstacles, attraction points, simulation time, non-

random distribution of vehicles, intelligent driving patterns


Generating Mobility Models

Classification of vehicular mobility models[2]


Synthetic Model

Based on mathematical models

Can be further separated into 5 classes

Stochastic: containing purely random motions

Traffic stream: based on hydrodynamic phenomenon

Car following: based on the motion of cars ahead

Queue: model roads as FIFO queues

Behavior: based on rules imposed by social influences

Major drawback: lack of realism towards human behavior

General Schemefor Car Following Models


Survey-based Model

Important source of macroscopic mobility information

Use extensive statistics of people’s behaviors

Commuting time, lunch time, traveling distance, etc

Example) UDel Mobility Model

Based on major large-scale surveys

Provided by US department of Labor

Major drawback: survey/statistical data only able to providecoarse grain mobility


Trace-based Models

Extracting generic mobility patterns from movement traces

Various measurement campaigns

CrawDaD, UMASSDieselNet, MIT Reality Mining, USC MobiLib, etc

Some drawbacks

Difficult to extrapolate patterns not observed directly by traces

An extrapolated model from motion traces for bus systems cannot be applied to the traffic of personal vehicles

Limited availability of vehicular traces


Traffic Simulator-based Models

Use simulators that built on real traces or behavior surveys

Fine grain simulators developed for urban traffic engineering

PARAMICS, CORSIM, VISSIM, TRANSIMS, SUMO, etc

Some drawbacks

Can’t be used straightaway for network simulators (no interfaces)

Purchase of a license (commercial products)

Mobility Models and Network Simulators have been developed independentlySo, there is a need to bridge them !


Isolated Mobility Models

Interaction between Network and Traffic Simulators

Pros

Independent developments in mobility and network modeling

Cons

Mobility must be generated prior to simulation

No interaction between them


Embedded Mobility Models


Pros

Both models natively and efficiently interacting

Cons

Poor quality of the (simplified) network simulator


Federated Mobility Models


Pros

Benefit from the best of both worlds (state-of-the-art mobility models with modern and efficient network simulators)

Cons

Both simulators need to be run simultaneously

Development of the interlinking interface


Trium Vira in Realistic Simulation

Interaction between Network, Traffic, and Radio Propagation Simulators[2]

Realistic radio propagation and fading model

Quality of the radio channel between two vehicles significantly depends on the mutual mobility


Motion Constraints Featuresin Major Vehicular Mobility Models[2]


Features included by the Traffic Generatorin Major Vehicular Mobility Models[2]

Wireless Access in Vehicular

Environment (WAVE)


Background

ITSA (Intelligent Transportation Society of America)

FCC (Federal Communications Commission)

Grant in October of 1999

DSRC (Dedicated Short-Range Communications)-based ITS radio services

75 MHz of spectrum in the 5.85-5.925 GHz range

ASTM (America Society of Testing and Materials)

ITSA recommended the adoption of a single standard for PHY and MAC layers of

architecture and proposed one developed by the ASTM based on IEEE 802.11

IEEE

IEEE 802.11p (in 2004)

IEEE 1609 standards set

WAVE(Wireless Access in Vehicular Environments)


Wireless Data Links[1]


WAVE Standard Family

WAVE communication stack

Protocols Standard

Document

Purpose of the standard OSI model

layer numbers

WAVE PHY & MAC IEEE 802.11p Specifies the PHY & MAC functions required of an IEEE

802.11 device to work in the rapidly varying vehicular

environment

1 & 2

WAVE Architecture IEEE 1609.0 Describes the WAVE/DSRC architecture and services

necessary for multi-channel DSRC/WAVE devices to

communicate in a mobile vehicular environment

1 - 4

WAVE resource

manager

IEEE 1609.1 Describes an application that allows the interaction of

OBUs with limited computing resources and complex

processes running outside the OBUs in order to give the

impression that the processes are running in the OBUs

N/A

WAVE security

services

IEEE 1609.2 Covers the format of secure messages and their

processing

N/A


WAVE Standard Family

WAVE communication stackProtocols Standard

Document

Purpose of the standard OSI model

layer numbers

WAVE networking

services

IEEE 1609.3 Provides addressing and routing services within a WAVE

system

2 - 4

Multichannel

operation

IEEE 1609.4 Provides enhancements to the IEEE 802.11p MAC to

support multichannel operation

2

Communication

manager

IEEE 1609.5 Specifies communication management services for WAVE

(To collect in a single document, the communication

management services previously included in 1609.3 and

1609.4 based on experience in use during the trial-use

period)

2 - 4

Electronic Payment

Services

IEEE 1609.11 Provides an open standard for the relevant interface in

DSRC based transaction systems, providing a common

interoperable service for device identity and payment

authentication, and payment data transfer

7


General Terms

Terminologies

RoadSide Unit (RSU)

Operate only when stationary and support information exchange with OBUs

On-Board Unit (OBU)

Operate when in motion and support the information exchange with RSUs or other OBUs

Provider

Advertiser of a service

User

One that associates with a service


General Terms

Terminologies

Control Channel (CCH)

A radio channel used for exchange of management frames and WAVE Short Messages

Service Channel (SCH)

Secondary channels used for application specific information exchanges

Persistent Service

One that is announced periodically, during each CCH interval

Non-persistent Service

One that is announced only when it is established


General Terms

Terminologies

WAVE Management Entity (WME)

WAVE Routing Advertisement (WRA)

WAVE Service Advertisement (WSA)

WAVE Short Message (WSM)

WAVE Short Message Protocol (WSMP)

PSID (Provider Service IDentifier)


IEEE 802.11[3]

Architecture

MAC

DCF (Distributed Coordination Function)

PCF (Point Coordination Function)

EDCA (Enhanced Distributed Coordinated Access)

Ad hoc network

Infrastructure network


IEEE 802.11

Frame type

Management

Control

Data


IEEE 802.11

DCF

CSMA/CA

Because stations are unable to listen while transmitting

Physical carrier sensing

–Analyze all packets

Virtual carrier sensing

–Duration field of request-to-send (RTS), clear-to-send (CTS)

Network allocation vector (NAV)

Inter-Frame Space (IFS)

–SIFS, PIFS, DIFS, EIFS


IEEE 802.11

Authentication/association

Active/passive probing


IEEE 802.11a[4]

IEEE 802.11a-1999 or 802.11a

An amendment to the IEEE 802.11 specification

A higher data rate of up to 54 Mbit/s using the 5 GHz

52-subcarrier OFDM (Orthogonal Frequency-Division Multiplexing)

Modulation TechniqueOFDM operating bands and channels


IEEE 802.11e[5]

EDCA (Enhanced distributed channel access)

Contention-based part of HCF

Prioritized QoS

Packets with priority value

Mapping intoa corresponding ACs(4 Access Categories)

EDCA (MAC Layer)

Higher Layer

Priority Access category (AC) Designation

(informative)

Lowest

Highest

AC_BK Background

AC_BK Background

AC_BE Best Effort

AC_BE Best Effort

AC_VI Video

AC_VI Video

AC_VO Voice

AC_VO Voice

Channel access mapping (User priority Access category)


IEEE 802.11e

EDCA

4 AC functions

▶ Own contention parameters

: CWmin, CWmax, AIFS, TXOP

Transmission attempt

▶ New Inter-Frame Space (IFS) for each AC- Arbitration Inter-Frame Space (AIFS)

- AIFS[AC] = SIFS + AIFSN[AC] ∙ SlotTime

Default EDCA parameter set


IEEE 802.11p[6]

Purpose

Describe the functions and services that allow an IEEE 802.11TM-

compliant device to communicate directly with another such device

outside of an independent or infrastructure network

At PHY level

Adaptation of IEEE 802.11a radio

10 MHz wide channels (75 MHz of DSRC spectrum at 5.9GHz)

Improved receiver performance requirements

Improved transmission mask


IEEE 802.11p

Outside the context of a BSS

Only if dot11OCBEnable is true

Set the BSSID field to the wildcard BSSID value

No authentication, association, data confidentiality services

Vendor Specific Action frame: one means for STAs to exchange management information prior to communicating data frames outside the context of a BSS


IEEE 802.11p

Format of individual frame types

Management frames

Timing Advertisement frame format

Information Notes

Timestamp The value of the timing synchronization function (TSF) timer of a frame’s

source

Capability

Country Optional

Power Constraint Optional and may only be present if the Country element is present

Time Advertisement Optional

Extended Capabilities Optional

Vendor Specific One or more vendor specific information elements may appear in this

frame. This information element follows all other information elements


IEEE 802.11p


Management frames

Information elements

–Vendor Specific information element

–Time Advertisement information element

Element ID Length Organization Identifier Vendor specific content

Octets 1 1 j n-j

Element ID Length TimingCapabilities

Time Value (if needed)

Octets 1 1

Time Error(if needed)

1 10 5


IEEE 802.11p


Management frames

Information elements

– EDCA Parameter Set element

Default EDCA parameter set for STA operation if dot11OCBEnabled is true


IEEE 1609.0 WAVE Architecture[7]

Purpose

Describe the architecture of the DSRC/WAVE operations currently

represented by the family of IEEE 1609 standards and IEEE 802.11p

References (selective)

ASTM E2213-03 - 2003

IEEE Std 1609.1-2006, IEEE Std 1609.2-2006, IEEE Std 1609.3-2007, IEEE

Std 1609.4-2006,

IEEE Std 802.2–1998, IEEE Std 802.11-2007, IEEE P802.11p/D6.0 – 2009


IEEE 1609.0 WAVE Architecture

Objective of WAVE

Provide a networked environment supporting very high speed

transactions among vehicles (V2V), and between vehicles and

infrastructure components (V2I) or hand held devices (V2D) to enable

numerous safety and mobility applications

WAVE System Components

The purpose of the communication provided by WAVE is to provide the application access to resources of a remote peer in a consistent,

interoperable, and timely manner to meet the application requirements



Protocol Architecture

Note: The figure illustrates the relationship among the IEEE 1609 and

IEEE 802.11 standards (before adding Communication Manager (P1609.5)

and Over-the-air Data Exchange for e-Payment Systems (P1609.11)

project proposals.

A sending application must also provide the MAC address of the destination device, including the possibility of a group address

WSMs are delivered to the correct application at a destination based on the PSID

Time synchronization for channel coordination, processing service requests and advertisements

IEEE 1609.3 - WAVE Management Entity (WME)

IEEE 1609.4 - extensions to MLME

UDP / TCP

LLC

PHY

WAVE MAC

(including channel coordination)

Air

Inte

rfa

ce

IPv6

WSMP

Data PlaneManagement Plane

TSAP

PHY SAP

MAC SAP

LSAP

WSM SAP

WAVE Management

Entity (WME)WM

E

SA

P

MLME Extension

PHY Sublayer

Management Entity

(PLME)

WAVE Security

Services

SE

C

SA

P

MAC Sublayer

Management Entity

(MLME)

LSAP

ML

ME

X

SA

P

ML

ME

SA

P

PL

ME

SA

P



Channel Types

A single Control Channel (CCH) [default for WAVE devices]

Multiple Service Channels (SCH)

Communication Services

Applications may choose to send their traffic in the context of a WAVE

service or not

If use WAVE service, devices associated with a service tune to the designated SCH in order to exchange data

Otherwise, their communication options are limited to WSMs sent on the CCH



Device Roles

Provider

User

Priorities

A service priority level (application)

MAC transmission “user” priority (lower layers)

The MAC priority for WSM packets is assigned by the generating application on a packet-by-packet basis



• Channel Coordination

– Time & Frequency Resources

• Segmented to provide a range of communications options

– Management & high priority (e.g., safety) traffic on CCH

– General application traffic on SCHs

• WAVE channels (default for single-channel device)

– Coordinated based on intervals that are synchronized using a

common system time base, preferably generated by a global time

reference, e.g., Coordinated Universal Time (UTC) such as that

provided by the Global Positioning System (GPS)

• Synchronization

– Also required for security purpose



• Service Initiation– By a provider application via a request to the WME

• Provider Service Context (PSC)

• Persistence

• Destination MAC address of intended recipient device(s)

• The number of advertisement repetitions (for a persistent service)

• SCH to use

• Optionally, direct the WME to choose the best available SCH

– On receipt of a WAVE advertisement

• Checks whether the provider application indicated by the PSID in the advertisement is of interest to any user applications

• Tune the local device to the correct SCH at the correct time(set any other layer configuration appropriately to support the communications)



• WAVE System Operations

– Attention to interactions of the applications and the WAVE

Cf) The set of channels on which services may be established is contained in

the WME MIB (depending upon the regulatory domain in which the unit is

operating)

– Communications without a service

• WSMP on the CCH only



• WAVE System Operations

– Communications with a service

• WAVE Service

– Supported by time and frequency (channel) resources allocated at

some set of participating devices within communication range, in

support of one or more applications

– Initiated at the request of the application at one device (provider)

and announced on the CCH

• Two types of services

– Persistent

– Non-persistent


Provider Service Table

WAVE Routing Advertisement

Timing Quality Information


The WAVE Advertisement

A WAVE management frame



• SCH Communications

– Upon receipt of an indication from the WME informing it of the service

association

• An application (whether provider or user) is free to generate data packets

(WSM or IP) for transmission on the SCH

• Service termination

– Example reasons

• Completion of the application activity

• Loss of connectivity

• Local communication resources being used for higher priority services



Adding/subtracting applications from an advertisement

For a persistent service

Different sets of services may be offered over time on the same SCH (i.e., the contents of the announced Provider Service Table may be dynamic)

Time synchronization and channel coordination



• Addresses and Identifiers in WAVE

– MAC address (included in the service advertisements for portal)

• Unicast/Broadcast

• Multicast

– Permitted but not required

• MAC anonymity (not yet)

– IPv6 address (included in the service advertisements for service provider devices)

• Global/Link-local/Multicast

– Protocol (UDP/TCP)/Port (included in the service advertisements for service

provider applications)



• Addresses and Identifiers in WAVE

– Application identification using PSID and PSC (included in the service

advertisements for service provider applications)

• PSC

– Associated PSID and contain supplementary information

• PSID

– Also used by the receiving device to deliver received WSMs ti the

appropriate higher layer entity

• IPv6 Neighbor Cache

• Security consideration (not yet)

Inter-Vehicle Routing Protocols


V2V Routing Protocols

VADD & SADV

Moving Vehicles

Stationary Sites

Local broadcasting info-stations

Sensors

Hotspots

Delivery a message from mobile vehicle

to the fixed site besides street miles away

For delay tolerant applications (DTN)

Multi-hop forwarding through VANET

Assumptions)

1. A vehicle knows its own location via GPS,knows its neighbors’ location by beacon message.

2. Vehicles are equipped with pre-loaded digital maps → Road information and

traffic statistics available

All Rights Reserved © Alcatel-Lucent 2010

Vehicle-Assisted Data Delivery in Vehicular Ad-hoc Networks

Store, Carry and Forward

Use predictable traffic pattern and vehicle mobility to assist efficient

data delivery

Key issue

Select a forwarding path with the smallest packet delivery delay

Guidelines

Make the best use of wireless transmission

Forward the packet via high density area

Use intersection as an opportunityto switch the forwarding direction andoptimize the forwarding path

58 |Protocols for V2V Networks| June 2010

VADD[8]


VADD

VADD: Three Modes

Intersection Mode

Optimize the packet forwarding direction

Straight Mode

Geographically greedy forwardingtowards next target intersection

Destination Mode

Broadcast packet to destination



VADD

VADD Model

Find out the next forwarding direction

with probabilistically the shortest delay

Probabilistic Method

Estimate the expected delivery delayfrom current intersection to the destinationfor each possible forwarding directions



VADD

Intersection Forwarding Protocol

Known the priority list of outgoing directions, check the available

carriers to ensure packet is forwarded to the preferred directions

Need to consider Location & Mobility

VADD Intersection Protocols

Location First VADD (L-VADD)

Direction First VADD (D-VADD)

Multi-Path D-VADD (M-VADD)

Hybrid VADD (H-VADD)



VADD (basic)

L-VADD

D-VADD


Simple Loop-free

Drawback

1. Vulnerable to Forwarding Loop

2. Negative on delivery ratio


VADD (advanced)

MD-VADD

H-VADD

Try and Error

Try L-VADD first, switch to D-VADD/MD-VADD when L-VADD fails



SADV[9]

Motivation

Performance of VADD under different vehicle densities


Mean Packet Delivery Delay Packet Delivery Delayunder 100 Vehicles


SADV

A Static-Node Assisted Adaptive Routing Protocol in Vehicular Networks

Improve the routing performance under low vehicle densities

Vehicle densities vary with time everyday

Gradual deployment of vehicular networks

SADV design

Deploy static nodes (can be embedded in traffic lights) at intersections to assist packet delivery

Prevent packets from being delivered through detoured paths


SADV


Basic idea

A packet in node A wants to be delivered to a destination

The best path to deliver the packet is through the northward road

The packet is stored in the static node for a while

The packet is delivered northward when node C comes


SADV


Static Node Assisted Routing

State Transition Diagram of the Intersection Mode


SADV


Link Delay Update

Expected link delay are estimated based on statistical information

– Vehicle densities on the roads vary with time

– Vehicle density is quite stable during a period of time

Use static nodes to help get more accurate delay estimation

Multi-Path Data Dissemination

Multi-path routing has the potential to further decrease packet delivery delay

– Link delay estimation may not be very accurate

– Increase the chance of hitting a better path

Packets are delivered through multiple paths only at static nodes


SADV


Performance of SADV under Different Vehicle Densities

Mean Packet Delivery Delay Packet Delivery Delayfor Individual Packets


CAR[10]

Connectivity-Aware Routing in Vehicular Ad Hoc Networks

Key idea

Position-based routing protocol that is able to not only locate positions of destinations but also to find connected paths between source and destination pairs

These paths are auto–adjusted on the fly, without a new discovery process

Main features

Destination location and path discovery

Data packet forwarding along the found path

Path maintenance

Error recovery

Conclusion


Conclusion

Other related technologies

Mobile IPv6, Mobile Networks (NEMOs), Delay and Disruption Tolerant Network (DTN), etc

Main challenges of VANETs

Technical challenges

Socio-economic challenges

Modeling

Mobility model (how to couple simulators)

Accident model (for safety-related studies)

Radio channel model

Packet reception capabilities of the receiving interface (ex. Capturing)


Reference

[1] Papadimitratos, P. La Fortelle, A. Evenssen, K. Brignolo, R. Cosenza, S., “Vehicular

communication systems: Enabling technologies, applications, and future outlook on

intelligent transportation,” IEEE Communications Magazine, Vol. 47, Issue 11, 2009

[2] Harri, J., Filali, F., Bonnet, C., “Mobility models for vehicular ad hoc networks: a

survey and taxonomy,” IEEE Communications Surveys & Tutorials, Vol. 11, Issue 4, 2009

[3] IEEE 802.11TM-2007, Information Technology – Telecommunications and information

exchange between systems – Local and metropolitan area networks – Specific requirements

– Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specification,

June 2007

[4] IEEE WG, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)

Specifications: High-speed Physical Layer in the 5GHz Band,” IEEE 802.11 Standard, 1999.

[5] IEEE WG, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)

Specifications: Medium Access Control (MAC) Quality of Service Enhancement,” IEEE 802.11

Standard, 2005.



Reference

[6] IEEE P802.11pTM D11.0 Draft Standard for Information Technology - Telecommunications

and information exchange between systems – Local and metropolitan area networks –

Specific requirements – Part 11: Wireless LAN Medium Access Control (MAC) and Physical

Layer (PHY) specification: Amendment 6: Wireless Access in Vehicular Environments

(WAVE), March 2010.

[7] IEEE P1609.0TM/D0.8 Draft Standard for Wireless Access in Vehicular Environment

(WAVE) – Architecture, May 2009.

[8] Jing Zhao and Guohong Cao, ”VADD: Vehicle-Assisted Data Delivery in Vehicular Ad Hoc

Networks ,” IEEE Transactions on Vehicular Technology, Vol. 57, Issue 3, May 2008.

[9] Yong Ding, Chen Wang, and Li Xiao, “A static-node assisted adaptive routing protocol in

vehicular networks,” ACM VANET 2007, Montreal QC, Canada, 2007.

[10] V. Naumov and T. R. Gross, “Connectivity-Aware Routing (CAR) in Vehicular Ad-hoc

Networks,” IEEE INFOCOM, Anchorage, Alaska, USA, 2007.



Q&A

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