The document discusses key issues in designing ad-hoc wireless routing protocols. It outlines challenges like mobility, bandwidth constraints from a shared radio channel, and hidden/exposed terminal problems. It also notes resource constraints from limited battery, processing power, and size. The document proposes ideal characteristics for routing protocols, including being fully distributed, adaptive to topology changes, loop-free, and minimizing overhead through localized routing and limited broadcasts. It suggests protocols should converge quickly and use resources sparingly.

1. Issues in Designing
Adhoc Wireless routing
Protocols
T S Pradeep kumar
h"p://www.nsnam.com

2. Issues in routing
Mobility
Bandwidth constraint
Error prone shared broadcast radio channel
hidden and exposed terminal problems
Resource Constraints

3. Mobility
highly dynamic
frequent path breaks
frequent topology changes

4. Bandwidth constraints
Radio band is limited, hence the data rates are
smaller when compared with the wired network
so bandwidth has to be used carefully to avoid
overheads
topology changes incur more control overhead in
turn consumes more bandwidth

5. shared broadcast radio
channel
wireless links have time varying characteristics
the routing protocols interacts with the MAC
layer for finding the routes or alternate routes
so collision of data and control packets

6. Hidden terminal problem
Assuming B is the intermediate node between A and C.
A and C are sending data to B. A is hidden to C and C
is hidden to A. But both are visible to B.
Since A and C are hidden terminals, the packets sent by
both the nodes at the same time causes collision at
node B.
This can be avoided by using RTS-CTS messages and
also using RTS- CTS- Data- ACK.

7. Exposed Terminal
Problem
Node arrangement is A<-->B<-->C<-->D
B is sending to A and at the same time C wants to
send to D, but it cannot, because of inability of
use of radio spectrum.
when B-> A and C->D to happen simultaneously,
then the transmitting frequency of C to be
different from the receiving frequency.

8. Resource Constraints
Battery life
processing power
size and weight constraints

9. Ideal characteristics of
routing protocol
Fully distributed (it is more fault tolerant than centralized)
adaptive to frequent topology changes
route computation and maintenance must involve minimum
number of nodes
localized,
loop free and free from stale routes
number of broadcasts to be limited to avoid packet collisions
must converge to optimal route in case of path break or path failure

10. Ideal characteristics of
routing protocol
Scarce use of battery, bandwidth, computing
power, memory, etc.
store information locally within the nodes (to
store only the stable local route, rather than the
remote unstable route)
Should support some Quality of service and also
to support time sensitive traffic

11. !!!???Any questions???!!!