Performance analysis and design of CQBT algorithm for a ring network with spatial reuse

A full-duplex ring network combined with destination removal can achieve a network throughput level much higher than the channel's data rate. However, such a network exhibits fairness problems, particularly under asymmetric-loading conditions. In this paper, we propose and study a local regulation protocol, the check-quota-before-transmission (CQBT) algorithm, to effectively reduce the unfairness features associated with such a network. Under this algorithm, each heavily loaded node monitors its local traffic conditions to determine the access opportunities provided to its downstream neighboring nodes. A procedure to determine the value of regulation parameters associated with such an algorithm is also presented. Illustrative performance examples are shown to demonstrate the effectiveness of this algorithm. In addition, through the use of analytical approximations, we present a discrete time vector Markov chain model to analyze the queueing behavior of such a full-duplex slotted ring. The analytical performance results are shown to be close to those obtained by simulations.