LAR utilizes location information to improve routing efficiency by reducing control overhead. It uses GPS to obtain geographical information. There are two zones in LAR - the ExpectedZone where the destination is expected to be based on past location/mobility, and the RequestZone where routing packets can propagate. A RequestZone is created around the source and ExpectedZone, and routing requests are only forwarded to neighbors in this zone. Replies include current location, time, and sometimes speed. Intermediate nodes only forward if their distance to the destination is less than the source's distance. LAR reduces overhead but requires GPS, limiting its applicability.

1. Location Aided Routing
(LAR) and Power Aware
Routing Metrics (PAR)
T S Pradeep Kumar!
http://www.nsnam.com

2. LAR
❖ Utilises the location information for improving the
efficiency of routing by reducing control overhead!
❖ It uses GPS for obtaining the Geographical information

3. Zones in LAR
❖ Two zones in LAR namely ExpectedZone and RequestZone!
❖ ExpectedZone is the zone where the destination is expected to be
present based on the past location and its mobility. if such an
information is not available, then the entire network is said to be the
ExpectedZone!
❖ RequestZone - It is the zone in which the path finding control packets
are permitted to be propagated. !
❖ If the sender nodes or the intermediate relay nodes are not present in this
zone, then additional area will be selected for propagation.!
❖ But usually, the nodes outside the RequestZone discards the control
packets.

4. LAR1
❖ A RequestZone is framed that includes the Source node
and the ExpectedZone (rectangle region). When the
source node is inside the ExpectedZone, the size reduces
to be the ExpectedZone.!
❖ RREQ packet is forwarded every neighbor node and the
packet will be discarded if the node is outside the
RequestZone!
❖ RREP can be with current location, current time and in
some cases speed of the node also.

6. LAR2
❖ This is based on the distance from the source to
Destination node in the RREQ packet. !
❖ When an intermediate node receives this packet, it
computes the distance to Destination and if it less, then
it forwards the packet, else the packet is dropped.

8. Pros and Cons of LAR
❖ Pros!
❖ Reduces the control overhead!
❖ Bandwidth utilisation!
❖ Cons !
❖ Since this is based on GPS, may not be suitable if no
such facility available

9. Power Aware Routing Metrics
❖ Minimal Energy Consumption per packet!
❖ Energy consumed by a packet is the sum of energies required at every
intermediate hops!
❖ Maximum Network Connectivity!
❖ Minimum variance in node power levels!
❖ distribution of load among all nodes to that all the nodes' power
consumption distribute uniformly!
❖ Minimum Cost per packet!
❖ Function of state of node's battery!
❖ Cost of a node is calculated based on the battery discharge

10. Ref: Siva Ram Murthy, B S Manoj, Adhoc Wireless
Networks, Architectures and Protocols