Saturation performance analysis of directional CSMA/CA in mmWave WPANs

摘要

The millimeter-wave (mmWave) band offers the potential for multi-gigabit indoor wireless personal area networks (WPANs). However, there are problems such as the short wavelength and high propagation losses. In order to compensate for these, it is highly recommended to use directional antennas at the physical layer. In this paper, directional carrier sense multiple access/collision avoidance (CSMA/CA) is analyzed in IEEE 802.15.3c, a standard for mmWave WPANs, under a saturated environment. A Markov chain model is presented and analyzed for the no-acknowledgment (No-ACK) mode. For the analysis, the device interaction is considered using directional antennas over a shared channel. A Markov chain model is presented in which the features of IEEE 802.15.3c such as backoff counter freezing and the effects of using directional antennas are incorporated. The maximal number of frames that can be transmitted concurrently and successfully is derived by an algorithm, and the system throughput and the average transmission delay are obtained in the closed forms. Numerical results show that the effects of using directional antennas in CSMA/CA and the overall analysis are verified by the simulation. The obtained results illustrate the physical layer impact on the CSMA/CA medium access control protocol, and these insights can be helpful in developing a medium access control protocol for enhancing the performance of mmWave WPANs.