A dynamic CAP allocation algorithm using directional antennas in IEEE 802.15.3c WPANs

Directional antennas have considerable benefits of higher antenna gain, long transmission distance and spatial reuse compared to omni-directional antenna. To support directional antenna, IEEE 802.15.3c specifies high data transmission rate and short frequency range communication based on characteristics of 60GHz frequency band. However, IEEE 802.15.3c has the room to be enhanced in terms of the use of its own characteristics with directional antenna during contention access period (CAP). For example, there are assigned same CAP and initial value of the contention window (CW) per each direction. Therefore this paper proposes dynamic allocation of CAP considering the number of devices per each direction during contention period. In addition, this paper also proposes an algorithm increasing system efficiency by adjusting an initial value of the CW. Given proposed algorithm numerical results show the proposed algorithm has less overhead than the legacy CSMA/CA mechanism based on IEEE 802.15.3c. The simulation results also show the proposed algorithm has maximum 5% of performance improvement comparing to existing CSMA/CA mechanism in terms of throughput.