Transcript The Mobile Multi-hop Solution in Ad hoc Networks

The Mobile Multi-hop
Solution in Ad hoc
Networks
Speaker : Yu-Che Lin
Adviser : Prof. Jian-Jiun Ding
National Taiwan University
Institute of Communication Engineering
May 2007
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Outlines
 Preview of Development on Wireless Network
 Properties for Mobile Ad hoc Networks (MANET)
 Access in MANET
 The Unfairness Conditions in typical CSMA
 Topology-Aware Fair Access (TAFA)
 Routing in MANET
 Broadcast – Efficiently Flooding
 Unicast – Routing Protocols
 Proactive Routing
 Reactive Routing (On-Demand)
 Conclusions & Future Works
 References
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Preview of Development on
Wireless Network (1)
 Wireless Wide Area Network & Wireless Local Area Network
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Large coverage
Large power consume
Complex distributed system
Long bit address
 Personal Area Network
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Low coverage
Low power consume
TDMA or FH-SS
Short bit address
Ad hoc networks exist in those two modes
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Preview of Development on
Wireless Network (2)
 Ad hoc
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Wireless local area network (WLAN)
PAN - Bluetooth
Packet radio
Infrastructure-free
 Cellular
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GSM
WAP
GPRS
3G
 Satellite
 Low Earth Orbit (LEO)
 Geostationary Earth Orbit (GEO)
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Standards or Protocols
 Mobile Ad hoc Networks (MANET)
 Protocols in MAC layer and IP layer (routing)
 WLAN - 802.11 Standards
 Protocols in physical layer and MAC layer
 PAN - 802.15 Standards
 Protocols in physical layer and MAC layer
 MANET Maintain the Physical and MAC Layers in 802.11 or 802.15 !
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Properties for Mobile Ad hoc
Networks (MANET)
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Dynamic Topologies
Bandwidth-Constrained ; Variable Capacity Links
Energy-Constrained
Limited Physical Security
Sparse Density
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Access in MANET
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The Unfairness Conditions in
typical CSMA
 The Near-Far problem
 Square law under radio intensity
 Consequently collisions occurs
 Solutions
 Adaptively adjust the mobiles’ powers
 Adaptively configure the mobiles’ contention windows
 Original or Derivative Flows
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Four Targets in TopologyAware Fair Access (TAFA)
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Exchange and Maintenance of Flow Information
Adaptive Backoff Algorithm
Switching Sender-Initiated and Receiver-Initiated Scheme as Appropriate
Dealing with Two-Way Flows (TCP)
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1.Exchange and Maintenance
of Flow Information
 The Service Tag
 The measurement for channel resource on the flow
 Updated by the sender after receiving ACK
 The Direct Flag
 Directly listening to channel
 Indirectly listening to channel
 The position Flag
 Original flows (data streams)
 Derivative flows (ACKs)
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a
c
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b
d
In d’s flow table :
1- Directly listening to b.
2- Indirectly known by the b’s
advertisement.
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2.Flow-Aware Adaptive backoff
algorithm
 Among the Two Flags
 The service tag
 The direct flag
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3. Switching Sender-Initiated (SI)
and Receiver-Initiated (RI) Scheme
 The Hybrid Scheme Alternate in Two Modes
 Sender-initiated (SI)
 Typically RTS – CTS – data - ACK
 Receiver-initiated (RI)
 Consequently fail in RTS
 Sender invite the receiver to start next transmission
 CTS – data – ACK
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Routing in MANET
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Broadcast – Efficiently
Flooding
 Distributed Heuristic
 Find a dominating set (DS) in a heuristic way
 Partial nodes in DS, partial nodes connect to DS
 Multiple Relaying
 2-hop neighbors
 The neighbor of the neighbor
 Multipoint relays (MPRs)
 Nodes that rebroadcast datagram
 Decided by its 1-hop neighbors
 Contain all the 2-hop neighbors
 MPR selector
MPR nodes
2-hop nodes
s
s
MPR selector
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Unicast – Routing Protocols
 Proactive Routing
 All nodes maintain the routing table and have the topology
information before transmitting
 Reactive Routing (On-Demand)
 Discover the present route by transmitter querying instead
maintain the huge information
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Proactive Routing (1)
 Distance Vector Protocols (Local Algorithm)
 Destination-Sequenced Distance-Vector (DSDV)
 Routing table
 Using destination sequence numbers
 Wireless Routing Protocol (WRP)
 Routing table
 Sequence numbers on next hop and next-to-last hop
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Proactive Routing (2)
 Link State Protocols (Global Algorithm)
 Optimized Link State Routing (OLSR)
 Routing table
 Using multipoint relays (MPRs)
 Routing table exists in links between MPRs and their MPR-selectors
 Suitable for large and dense networks
 Topology Broadcast Based on Reverse-Path Forwarding (TBRPF)
 Routing table
RT
Reject
 hop-by-hop routing along shortest paths
forwarding
 Source Tree based on topology table
 Reported Tree (RT)
 Path of each node to its shortest neighbor(s)
 Nodes maintain only RTs
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Reactive Routing (On-Demand)
 Dynamic Source Routing (DSR)
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Route request (RREQ)
Route Reply (RREP)
The intermediate nodes record a route through RREP (route cache)
Path establish after RREP
 Ad hoc On-demand Distance Vector (AODV)
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Route request (RREQ)
Route Reply (RREP)
Using sequence numbers
Maintain the latest sequence number
Ad hoc On-demand Multipath Distance Vector (AOMDV) offer multipath
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Conclusions & Future Works
 Demand-based routing offers quick adaptation to dynamic link conditions,
low processing and memory overhead, low network utilization, and
determines unicast routes to destinations within the ad hoc network .
 proactive routing is desirable in a few of situations that only the bandwidth
and the energy resources permission.
 It seams that the bounded improvement are in the result without the
physical handling.
 Future work about antenna diversity is put in the next discussion.
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REFERENCES
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Akyildiz. I.F., Xudong Wang, “A Survey on Wireless Mesh Networks,” IEEE
Communications Magazine, vol. 43, issue 9, pp. S23-S30, Sept. 2005.
D. Cox, ”Wireless Personal Communications: What is it?,” IEEE Personal
Communication Magazine, pp.20-35, April 1995.
IETF Mobile Ad hoc Networks Working Group,
http://www.ietf.org/html.charters/manet-charter.html.
Presant Mohapatra, Srikanth Krishnamurthy, “Ad Hoc Networks: Technologies
and Protocols,” Springer, New York, 2005.
Pathmasuntharam J.S., Das A., Mohapatra P., “A Flow Control Framework for
Improving Throughput and Energy Efficiency in CSMA/CA Based Wireless
Multi-hop networks,” World of Wireless, Mobile and Multimedia Networks, 2006.
WoWMoM 2006, June 2006.
Zhu J., Metzier B., Guo X., Liu Y., “Adaptive CSMA for Scalable Network
Capacity in High-Density WLAN: A Hardware Prototyping Approach,”
INFOCOM 2006. 25th IEEE International Conference on Computer
Communications. Proceedings, pp. 1-10, April 2006.
Towsley D., Kurose J., Pingali S., “A Comparison of Sender-Initiated and
Receiver-Initiated Reliable Multicast Protocols,” IEEE Journal on Selected
Areas in Communications, vol. 15, issue 3, p.p. 398-406, April 1997.
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