The goal of this project is to use Bandwidth Exchange to enhance the performance of a cognitive radio network . The whole idea is implemented using GNU Radio Framework, and can be best explained visually by the following pictures and graph(s) :
Direct Transmission : In direct transmission both node 1 and node 2 are transmitting to the base station which is node 0 . The graph bellow represents the Rate at which both nodes are transmitting with respect to the transfered Bandwidth. We can see from the graph that the rate is a horizontal line (continuous line) which does not depend on the transfered bandwidth ( obviousely no bandwidth is transfered in this case!). The other observation is that Node 1 is transferring its data at a better rate than node 0 is transfering his which confirms the idea of the closer the node to the base station , the better the rate at which data are transferred!.
Relay Transmission : For this case, node 2 is transferring some of his bandwidth to node 1 which also sending his data along with the received data from node2 to the base station (node 0) . The graph bellow is the Rate at which each node ( node 1 and 2) are sending their data versus the transferred bandwidth.
We use the following formula :
The following is the graph of the Rate at which the data is transferred (Mb/s) versus the transferred Bandwidth :
From the graph we can conclude that node 1 and node 2 are sending their data at a better rate than the direct transmission's rate when (X=deltaW= [9.5 16]). At this interval, node 1 and node 2 are better offtransmitting data using the idea of Bandwidth Exchange ( 'sharing of Bandwidth') .