Mobile Intelligence

3.4 ENHANCEMENTS FOR EFFICIENT CHANNEL UTILIZATION

In this section, we present three different approaches and their modification for optimal use of otherwise wasted channel capacity in MANET. In our proposed schemes, we tried to unlock the unnecessarily blocked channel by using NAV update and also tried some aggressive methods to recover as much as possible and minimize the channel lose due to false blocking.

We have described each of our proposed schemes (i) modification of NAV operation, (ii) extra frame transmission (EFT), (iii) combination of schemes, and (iv) reverse extra frame transmission (R-EFT) in different subsequent subsections.

3.4.1 Modification of NAV Operation

In case of RTS validation mechanism [5], when the node has already been deferred, it cannot set NAV back to the previous value that has already been set by other RTS frames. Besides that, RTS validation may not be always available. Higher the amount of network traffic, more frequent the unavailability of RTS validation. As a result, RTS validation can not fully utilize the unused channel. Thus, the efficiency of channel reuse will be reduced. Improvement is possible if RTS validation works irrespective of NAV set.

With the above considerations, we modify the NAV operation with three new variables as follows:

(i) We divided the original NAV in two parts: one is set of NAV_k indexed with the corresponding node's ID and the other is NAV_other.

(ii) NAV used for the operation is calculated by the maximum value in ...