7. LOCATION BASED ROUTING PROTOCOL (LOR)
When a source node wants to transmit a packet, it gets the location of the destination first and then
attaches it to the packet header. Due to the destination node’s movement, the multihop path may diverge from
the true location of the final destination and a packet would be dropped even if it has already been delivered
into the neighbourhood of the destination. To deal with such issue, additional check for the destination node is
introduced. At each hop, the node that forwards the packet will check its neighbour list to see whether the
destination is within its transmission range. In conventional opportunistic forwarding, to have a packet
received by multiple candidates, either IP broadcast or an integration of routing and MAC protocol is adopted.
The former is susceptible to MAC collision because of the lack of collision avoidance support for
broadcast packet in current 802.11, while the latter requires complex coordination and is not easy to be
implemented. If a packet with the same ID is received again, it will be discarded. Otherwise, it will be
forwarded at once if the receiver is the next hop, or cached in a Packet List if it is received by a forwarding
candidate, or dropped if the receiver is not specified. The packet in the Packet List will be sent out after
waiting for a certain number of time slots or discarded if the same packet is received again during the waiting
period (this implicitly means a better forwarder has already carried out the task).