An Experimental Mobile Ad Hoc Networking Testbed
description
Transcript of An Experimental Mobile Ad Hoc Networking Testbed
CMU/GM Collaborative Research Lab
An Experimental Mobile Ad Hoc Networking Testbed
Project Kick-off MeetingMarch 1, 2004
CMU/GM Collaborative Research Lab
Mobile Network Connections
Internet
Connect via 3G
Ad hoc relaying
Connect via Hotspot
3G coverage
Hot spot coverage
Car range
CMU/GM Collaborative Research Lab
Peer-to-Peer Networking
• Exchange of emergency/traffic information• Exchange of diagnostic information• Active safety applications• Allow one vehicle to function as a network portal for
nearby vehicles• Vehicle as sensor
CMU/GM Collaborative Research Lab
IETF Draft Protocols• On Demand Protocols
– Pro: minimize network overhead since routes are refreshed only when needed
– Con: excess latency when invoking seldom-used routes– IETF Drafts:
• Dynamic Source Routing (DSR)• Ad Hoc On Demand Distance Vector Routing (AODV)
• Proactive Protocols– Pro: minimize latency since routes are fresh– Con: excess network overhead to update routes even if not used– IETF Drafts:
• Optimized Link State Routing Protocol (OLSRP)• Topology Dissemination Based on Reversed-Path Forwarding (TBRPF)
CMU/GM Collaborative Research Lab
Specific Requirements for Telematics Applications
• Epidemic Flood-Fill protocols with hop limits– Perhaps more appropriate than protocols used with specific
destinations in mind• May not want to propagate to near-by but
distinct roads/highways (e.g., highway crossings without interconnects, etc.)
• Proprietary Solutions– MeshNetworks?
• Implementations of IETF protocols are almost all in UNIX (BSD, Linux, etc.)
CMU/GM Collaborative Research Lab
Proposed Ad Hoc Testbed
V
GPS
Internet
1XRTT
MN
Site Office
DGPS reference station beacons
Network can operate wherever DGPS beacons and 1XRTT are available
CMU/GM Collaborative Research Lab
Network Components• Mobile Node
– 5.8 GHz 802.11a (Represents DSRC)– 1XRTT Cellular/PCS 3G data– Ad Hoc Protocol (DSR?)– Differential GPS
• Site Office– Bird’s eye view of test track (tests not limited to track,
however)– Visualizer & Analysis tools
CMU/GM Collaborative Research Lab
Vizualizer Example
CMU/GM Collaborative Research Lab
Video
CMU/GM Collaborative Research Lab
Example Measured & Modeled Signal Strength
-120
-100
-80
-60
-40
0 100 200 300 400 500 600
sign
al s
tren
gth
(dBW
)
Time (s)(Data from Prior Ad Hoc Network supported by Caterpillar)
CMU/GM Collaborative Research Lab
Example Dropped Packet Performance
(Data from Prior Ad Hoc Network supported by Caterpillar)
CMU/GM Collaborative Research Lab
Research Objectives: Physical & Link Layers
a. Collect extensive peer-to-peer channel RSSI data and extract path loss exponents for classes of environments (e.g., Urban, suburban, rural, etc.).
b. Investigate the expected range, reliability, throughput of 802.11a/DSRC in this mobile environment
c. Implement the capability of real-time power control for sparse/dense traffic, and evaluate performance
d. Management of channels, e.g., control & datae. Collaborate with HRL to integrate findings with their
simulations
CMU/GM Collaborative Research Lab
Improved Channel Measurement Options:Sliding Correlator Method
• N=code sequence length• Rc=transmit chip rate
• Rc-d = receive chip rate
• Time resolution ~1/Rc
• E.g., Rc=12.5 Mbps, gives resolution ~ 80 ns
• Gives measurement of RMS delay spread
time
N/d
time
N/d Devasirvatham ‘86
CMU/GM Collaborative Research Lab
Sliding Correlator Implementation Possibilities
• Without pilot locking: phase drift is 90 deg/s
• Should also permit analysis of Doppler
Bandpassfilter
Low noise amplifier
Local oscillator
Agilent 89610A vector signal analyzer
Matlab post-processing
Agilent E4433B digital signal generator
Bandpassfilter
Low noise amplifier
Local oscillator
Agilent 89610A vector signal analyzer
Matlab post-processing
Agilent E4433B digital signal generator BPSK + CW pilot
CMU/GM Collaborative Research Lab
Multi-carrier Probing
Bandpassfilter
Low noise amplifier
Local oscillator
Agilent 89610A vector signal analyzer
Matlab post-processing
Agilent E4433B digital signal generator
Bandpassfilter
Low noise amplifier
Local oscillator
Agilent 89610A vector signal analyzer
Matlab post-processing
Agilent E4433B digital signal generator
MCM
CMU/GM Collaborative Research Lab
Research Objectives: Network & Higher Layers
a. Evaluate the performance of leading ad hoc protocols for the automotive/ITS application environment
b. Develop suite of protocols for active safety/telematics applications
c. Define latency requirements d. Explore multi-hop relaying, and attempt to determine the
limiting factors to the range (i.e., number of hops)e. Identify and implement “hooks” throughout the stack that
will facilitate delivery of the required QoSf. Collaborate with HRL to integrate findings with their
simulations
CMU/GM Collaborative Research Lab
GM Contributions• Application concepts• Antenna and mounting issues• System and vehicle integration architecture• Standards activities• Vehicles
CMU/GM Collaborative Research Lab
TimelinePhase I Tasks Q1-04 Q2-04 Q3-04 Q4-04 Q1-05 Q2-05 Q3-05 Q4-051. Construction a. Site selection b.Protocol select c. Vehicle acq. d. MN integ. e. MN install f. SO integ. g. SO install h. Visualizer i. System integ. 2. Layer 1,2 Res. a. Chan. Model b. Ch. Mod. Opt c. 802.11a perf. d. Power control 3. Layer 3-6 Res. a.Platform select b. Protocol Eval c. Protocol Suite d. Latency Req. e. Hop limits f. Hooks in stack 4. MANET stds 5. HRL collab.
CMU/GM Collaborative Research Lab
Summary• Ad hoc network using 5-6 vehicles to be constructed• Network capable of operation anywhere DGPS
beacons are available (also 1XRTT for site office connectivity)
• Develop 5-6 GHz peer-peer propagation model• Develop suite of protocols optimized for
telematics/active safety applications• Collect real data on network operation to use in
validating simulations• Timeline: construct in ~ 9 mo; operate for 15+ mo