The performance (throughput and delay) of the multihop broadcast communication networks is studied via a simulation model that includes channel access, transmission scheduling, buffer, management, and hop-by-hop acknowledgment protocols. The parameters considered are the data and acknowledgment packets transmission probabilities, timeout periods, and buffer sizes. The performance of echo acknowledgment, all-active acknowledgment, and a mixed acknowledgment scheme based on nodes connectivities are also studied.

We analyze the performance of a window multiaccess protocol with collision size feedback. We obtain bounds on the throughput and the expected packet delay, and assess the sensitivity of the performance to collision recognition time and packet transmission time. An approximate optimal window reduction factor to minimize packet isolation time is {equation}, where n is the collision size and R the collision recognition time (in units of packet propagation delay). The WCSF protocol, which requires more information than CSMA-CD, is shown to have at least 30% more capacity than CSMA-CD for high bandwidth channels; that is, when packet transmission time is comparable to propagation delay. The capacity gain of the WCSF protocol decreases as the propagation delay decreases and the collision recognition time increases. Our study also reveals the inherent stability of WCSF. When the input load increases beyond saturation. The throughput remains at its maximum value.

In distributed random access communication, collision occurs when two or more transmissions overlap in time. After a transmission a user should know whether his attempt was successful so that he can decide his next action. Acknowledgments are commonly used to indicate whether a transmission is successful. We study the effect of acknowledgments on the performance of a star broadcast network. We evaluate the network performance for the following four cases: free and instantaneous acknowledgment, common channel for data and acknowledgments, split channel for data and acknowledgments, and a common channel with high-power acknowledgments. Our study reveals that the split channel has the highest capacity, and that the high-power scheme provides an attractive economical alternative when data packets are short.