Interference Analysis in Cooperative Linear Multi-Hop Networks Subject to Multiple Flows

We study the effects of allowing multiple packets to flow simultaneously in a cooperative multi-hop transmission system, where a group of nodes in each hop transmits the same message to another group of nodes in a cooperative manner. Although, the packet delivery rate may increase with multiple packet flows, however, the desired signals of one packet may get interfered with the signals of the other packets in the network; increasing the outage probability at a hop, and thereby causing some of the packets to die off. We analyze this phenomenon by modeling the multi-hop transmission of data packets as a conditional Markov process, followed by the derivation of its transition matrix. The transition matrix incorporates the outage probability, which we obtain by studying the distribution of signal-to-interference ratio as the ratio of two hypoexponential random variables (RVs). Each hypoexponential RV is a sum of independent but non-identically distributed exponential RVs. The resulting distribution is used to calculate the outage probability of a node in a cooperative environment in the presence of desired as well as interfering signals. We then use the model to obtain the network coverage, until which a packet can travel for a given packet delivery ratio constraint and perform numerical simulations to validate the analytical model.