Effect of Fading on Maximum Sum Rate of Aloha

In the literature, the network throughput of slotted Aloha with the capture model over fading channels has been found to be higher than e(-1), the maximum network throughput of slotted Aloha with the collision model over ideal channel conditions. Such an improvement is often misinterpreted as the result of channel fading, which as we will demonstrate in this paper, indeed comes from the receiver. Specifically, based on the analytical framework proposed in our recent work [15], the optimal network throughput and sum rate performance of slotted Aloha with the capture model over Additive-White-Gaussian-Noise (AWGN) channels is characterized. Explicit expressions of the maximum network throughput and the maximum sum rate are obtained, and the comparison to Rayleigh fading channels shows that substantial gains in both the maximum network throughput and the maximum sum rate are observed in the AWGN case.