Dynamic LoadAware Routing in Ad Hoc Networks

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Dynamic LoadAware Routing in Ad Hoc Networks

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Title: Dynamic LoadAware Routing in Ad Hoc Networks

1
Dynamic Load-Aware Routing in Ad Hoc
Networks Sung-Ju Lee and Mario Gerla
2
Routing in Ad Hoc Networks

Most ad hoc routing protocols use shortest hop as
the main route selection metric
Shortest hop however can lead to congestion and
thus path failure
In fact, multiplexing all flows on shortest
routes can aggravate network congestion
Also, reply from caches in on-demand routing (DSR
and AODV) causes routing load concentration on
certain nodes

3
Dynamic Load-Aware Routing (DLAR)

DLAR uses the intermediate node routing load as
the route selection metric
The protocol monitors the congestion status of
active routes and reconstructs the path when
overloaded
On-demand routing
Reply from cache is not allowed

4
Related Work

Routing with load balancing is well studied for
wired networks
In wireless ABR (Associativity-Based Routing)
Routing load is the secondary metric
Load is measured in the number of routes a node
is a part of
Does not account for various traffic loads of
each data session

5
Route Discovery

Builds routes on demand
Backward learning
Each node includes its load information (the
number of packets buffered in its queue) when
forwarding Route Request packets
Intermediate nodes not allowed to reply from
cache
The destination accepts duplicate Route Requests
received from different previous nodes to learn
all possible routes

6
Route Selection Algorithms

Scheme 1
adds the load of each intermediate node and
selects the one with the least sum
tie breaker hop count and shortest delay
Scheme 2
instead of the sum, it uses the average
tie breaker shortest delay
Scheme 3
defines a threshold value that indicates overload
selects the route with the least number of
intermediate nodes that have their load exceeding
the threshold
tie breaker hop count and shortest delay

7
Example
8
Monitoring Route Status

During active data sessions, intermediate nodes
periodically include their load information on
data header
The destination node monitors the load status of
the route
If the route is congested, it sends a Route
Request to the source
The source selects the route in the same manner
as the destination, and uses that route for the
next data packet

9
Performance Evaluation

GloMoSim
Protocols three schemes of DLAR and DSR
50 nodes
1000 meter X 1000 meter area
Free space propagation
IEEE 802.11 DCF
Traffic load is varied
Random waypoint mobility model
min and max speed 0 and 10 m/s
pause times 0, 30, 60, 150, and 300 sec

10
Packet Delivery Ratio (20 sources sending 4
packets per second)
11
Packet Delivery Ratio (20 sources sending 8
packets per second)
12
Packet Delivery Ratio (40 sources sending 4
packets per second)
13
Hop Distance
14
Latency
15
Normalized Routing Load
16
Conclusion

Using the least loaded routes helps balance the
load of the network nodes and utilize the network
resources efficiently
Monitoring the status of active routes allows
dynamic reconfiguration of congested routes
All three DLAR algorithms delivered more data
packets and yielded shorter latencies while
generating nearly equal number of control packets
as DSR

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