Saturated Throughput of a Cognitive IEEE 802.15.3c MAC in the Directional Contention Access Period

Abstract

Coexistence between networks is an emerging challenge in the 60 GHz unlicensed band. An approximate analytical formulation of the saturated throughput of a cognitive IEEE 802.15.3c MAC in the directional contention access period (D-CAP) in the presence of contention time allocation period (CTAP) is presented in this paper. The analytical framework is formulated for N devices, including the pico-net controller (PNC). The state transition diagram is modeled by a two-dimensional discrete-time Markov chain. One dimension of the Markov chain is for the backoff stage and the second dimension is for the value of the backoff counter. The saturated throughput is approximated by the product of a weighted ratio of the throughput of the regular sub-CAP (RS-CAP) and the throughput of the RS-CAP minus the period necessary to transmit a packet before the end of the current RS-CAP, the probability of the number of devices in a beam sector, the number of beam sectors and the probability of false alarm. Numerical results of the saturated throughput corresponding to typical parameter values are presented. These results show the advantage of the cognitive IEEE 802.15.3c MAC in the D-CAP using the single carrier mode when the number of devices in the WPAN is large.