Proposed ad hoc Routing Approaches
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Transcript of Proposed ad hoc Routing Approaches
Proposed ad hoc Routing Approaches• Conventional wired-type schemes (global routing,
proactive):– Distance Vector; Link State
• Proactive ad hoc routing:– OLSR, TBRPF
• On- Demand, reactive routing:• DSR (Source routing), MSR • AODV (Backward learning)• AODV-DFR
• Scalable routing :– Hierarchical routing: HSR, Fisheye– OLSR + Fisheye– LANMAR (for teams/swarms)
• Geo-routing: • GPSR, GeRaF, etc• Motion assisted routing
“Direction” forwarding for mobile, large scale ad hoc networks
• In Distance Vector Routing (e.g., Bellman Ford, AODV etc.) node keeps pointer to “predecessor”
• When the predecessor moves, the path is broken • Alternate paths, even when available, are not used
Sink
Source
DV updatePredecessorData flow
Proposed solution: direction forwarding
Distance Vector not robust to mobility
Dest
Source
Primary PredecessorPrimary Path
Direction to Dest
Alternate Data Path
DV Update
Direction Forwarding
• Distance Vector update creates not only “predecessor”, but also “direction” entry
• Select “most productive” neighbor in forward direction
• If the network is reasonably dense, the path is salvaged
How to compute the “direction” Need “stable” local orientation system (say,
virtual compass) to determine direction of update Local (rather than global) reference is
required; Local reference system must be refreshed
fast enough to track avg local motion GPS will do (e.g., neighbors exchange (X, Y)
coordinates) If GPS not available, several non-GPS
coordinate systems have been recently published Sextant [Mobihoc ’05]; beacon DV; RFID’s
etc
Computing the “direction”(cont)
Compute “direction” to a destination when DV updates are received: If a DV update packet with a more recent
Seq # or smaller hop distance is received: New “direction” replaces the old one
The “direction” to the predecessor is used as the “direction” to the destination
If multiple DV updates received from different “predecessors” with same hop distance and seq # for the destination Take vector sum of directions
Computation of the “direction”
)(tan
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−−
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−+−=
−θ
Computation of the “direction”
Where the polar angle is the radian from the x-axis that is used as the direction of the predecessor node.
Suppose node A receives DV update packets from B & C
Compute the “directions” to predecessors node B & C, respectively,
A
C
B),( bb rθ
),( cc rθ
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“Direction” to a destination
Unit vectors are used to combine the two “directions”
Directions to predecessors
Direction Forwarding vs Geo routing
• Geo-routing:– Direction points to destination– This direction may be unfeasible (holes, etc)– Global geo-coordinates (eg, GPS)– Geo Location Server– Robust to mobility
• Direction Forwarding– Direction of updates (always feasible)– Local (not global) position reference system– Advertisements from destination– Robust to mobility
Robust Ad Hoc Routing for Lossy Wireless Environment
• Challenges for routing in mobile ad hoc network
– Route breakage
– High BER
– Scalability
• The shortcomings of on-demand routing
• Not scalable for mobility
• The shortcomings of proactive routing
• Constant and high routing overhead
• The shortcomings of current Geo-routing
• Need Geo-Location Service, GLS
• “Face routing” is inefficient
Hybrid Routing: AODV-DFR
(AODV with Directional Forwarding Routing) • Combines on-demand and proactive routing
– When a source starts comm, it first finds the destination as in an on-demand fashion
– Once the destination is notified, it initiates periodic routing updates in a proactive fashion
• Utilizing an alternate path instantly based on “direction” to the destination if a path fails– resemblance with Georouting in the update
message– No location server system is required (not
like GPSR)
AODV-DFR
• Source initiates route discovery a la AODV – Destination, or any node that has a route,
replies– The path is set up
• Destination begins proactive advertisements (a la DV) after receiving data pkts from source – Intermediate nodes rebroadcast ads– Only for active connections– Period increases with distance from
destination (Fisheye concept)• Packet routing assisted by Direction Forward• The destination stops advertisement if it does
not receive pkts for some time
Performance Evaluation
• Compare AODV, AODV-DFR, GPSR and ADV (proactive and on-demand Hybrid Routing)– Performance: Delivery ratio, Packet delay,
Routing Overhead– Mobile & lossy network: UDP and TCP traffic
• Mobility Speed• Packet loss: uniformly distributed on a link
• Simulation– 100 nodes randomly moving in 1000x1000m– The traffic pairs are randomly distributed
over the network– UDP flows: pkt size 512 bytes, rate 1pkt/sec– TCP flows: NewReno, pkt size 1460 bytes
Mobile Network: Delivery Ratio
80 UDP flows
Mobile Network: Packet delay
80 UDP flows
Mobile Network: Routing Overhead
80 UDP flows
Mobile & Lossy Network: Delivery Ratio
UDP Flow number: 80 Mobility Speed: 10 m/s
Mobile & Lossy Network: Routing Overhead
UDP Flow number: 80 Mobility Speed: 10 m/s
TCP in Mobile Network
40 TCP flows
TCP in Mobile & Lossy Network
TCP flow number: 40 Mobility: 10 m/s
AODV-DFR Contributions
• A hybrid routing: proactive + on-demand• Robust to mobility and packet loss• Utilize location information for directional
forwarding with only local updates.• Low overhead• Provide better performance than AODV and
GPSR• Enhances AODV• Competitive with GPSR (does not require
“global” positioning such as GPS)• Ongoing work: local coordinate system;
integration of local and global coordinates (indoor+outdoor)
Robust Ad Hoc Routing for Lossy Wireless Environment
CS 218 Fall 08
UCLA: Jiwei Chen, Yeng-Zhong Lee, Mario Gerla
TJU: He Zhou, Yantai Shu
Milcom 2006
Introduction
• Challenges for routing in mobile ad hoc network– Route breakage– High BER– Scalability
• The shortcomings of on-demand routing• Not scalable for mobility
• The shortcomings of proactive routing• Constant and high routing overhead
• The shortcomings of current Geo-routing• Need Geo-Location Service, GLS• “Face routing” is inefficient
ENTER AODV-DFR!
Related Work• Proactive Routing
– OLSR, DSDV
• On-demand Routing– AODV, DSR
• Geographic Routing– GPSR and several others– greedy + face algorithm– GLS (geo location service)
• Hybrid Routing– ZRP, SHARP, LANMAR zone and group concept– ADV, proactive and on-demand– DREAM, proactive and geo-routing– AODV-DFR
AODV-DFR
• Source initiates route discovery a la AODV – Destination, or any node that has a route, replies– The path is set up
• Destination begins periodic advertisements (a la Distance Vector) after receiving data packets from source – Intermediate nodes rebroadcast advertisements - interval increases
with distance from destination (Fisheye concept)• Packet routing assisted by Direction Forwarding• The destination stops advertisement if it does not receive packets for
some time.
Proactive Advertising in AODV-DFR
• Only for active connections • “Fisheye” updating frequency
Dest
Source
Primary PredecessorPrimary Path
Direction to Dest
Alternate Data Path
DV Update
Direction Forwarding
• Distance Vector update creates not only “predecessor”, but also “direction” entry
Sink
• “Predecessor only” forwarding fails• DFR selects “most productive” neighbor in right direction• If the network is reasonably dense, the path is salvaged
Source
DV updatePredecessorData flow
“Direction” to Sink
Directional Forwarding
• Each node remembers the local advertised directional
• Only local coordinates needed • Direction is computed by the
aggregation of local updates• “Multiple hop” direction can
also be available.• Next node with min-hop and
minimal deviation from the direction is selected.
A
C
B
A
C
B
(XC, YC)
(XB, YB)
(XA, YA)|AB|
AB
|AC|
AC→
+
→
Routing Tables at a Node
• Neighbor Table – Direction to all
neighborsNB ID
Seq
Num
Direction to NB
Dest ID
Hop Count
• Routing table– Routes to all active
destinations
Dest ID
Direction to Dest
Next Hop
Hop Count
Performance Evaluation
• Compare AODV, AODV-DFR, ADV, and GPSR (without charge for GLS overhead).
• Performance in mobile network– Delivery ratio– Routing Overhead
• Performance in mobile & lossy network– Packet loss: uniformly distributed on a link– UDP and TCP traffic
Simulation Environment
• 100 nodes randomly moving in a 1000x1000m space
• The traffic pairs are randomly distributed over the network.
• UDP flows: pkt size 512 bytes, rate 1pkt/sec
• TCP flows: data pkt size 1460 bytes, NewReno
Mobile Network: Delivery Ratio
80 UDP flows
Mobile Network: Routing Overhead
80 UDP flows
Mobile & Lossy Network: Delivery Ratio
UDP Flow number: 80 Mobility Speed: 10 m/s
TCP in Mobile Network
40 TCP flows
AODV-DFR Contributions• A hybrid routing: proactive + on-demand• Robust to mobility and packet loss• Utilize location information for directional forwarding with
only local updates.• Low overhead• Enhances AODV• Competitive with GPSR:
– not affected by GLS and by face routing issues; – does not require “global” positioning such as GPS
• Ongoing work: local coordinate system; integration of local and global coordinates (indoor+outdoor)