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Since delay and throughput are important Quality of Service parameters in many wireless applications, we study the performance of different multi-channel Media Access Control (MAC) protocols in ad hoc networks by considering these measures in this paper. For this, we derive average access delays and throughputs in closedform for different multi-channel MAC approaches in case of Poisson arrivals. Correctness of theoretical results is verified by simulations. Performance of the protocols is analyzed with respect to various critical operation parameters such as number of available channels, packet size and arrival rate. Presented results can be used to evaluate the performance of multi-channel MAC approaches in various scenarios and to study the impact of multichannel communications on different wireless applications. More importantly, the derived theoretical results can be exploited in network design to ensure system stability.

Multiple Cognitive Radio (CR) networks may exist in the same spatial domain in many cases. In this paper we consider two uncoordinated and geographically overlapping CR networks coexisting together with a primary network. We specifically study the achievable per-node throughput performance of the CR networks. Firstly, an interference model is specified which models the situation. By using this model we derive the pernode throughput for overlapping CR networks. Furthermore, the upper bound for the probability of false alarm, which is required to achieve a certain throughput, is deduced. The results of this paper illustrate how the different CR network parameters, such as network density, transmission probability, and sensing performance, affect the achievable per-node throughput in overlapping CR networks. In addition, these results serve as guidance for the deployment of multiple CR networks.