Analytical Modeling of Ad Hoc Networks that Utilize Space-Time Coding

This paper presents the first analytical model for ad hoc networks equipped with multiple-input multiple-output (MIMO) radios using space-time coding (STC) that considers the impact of the underlying radio-based topology on network performance. In particular, we consider the space-time block coding (STBC) technique known as the “Alamouti scheme.” We derive the effective signal-to-interference-plus-noise density ratio (SINR) of the Alamouti scheme under multiple access interference (MAI), and we propose the moment generating function (MGF) method to derive closed-form expressions for its symbol error probability under different modulation schemes when fading paths are independent but not necessarily identically distributed. The impact of the Alamouti scheme on IEEE 802.11 ad hoc networks is studied by introducing a new analytical model for the IEEE 802.11 DCF MAC. The model we introduce takes into account the impact of errors in both control and data frames, the carrier-sensing activity, and the finite-retry limit of frame retransmissions. Both PHY- and MAC-layer analytical models are incorporated into our previously-designed, general analytical model for ad hoc networks based on interference matrices. We apply the Alamouti scheme to different antenna system configurations and compare their performance with respect to the basic single-input-single-output (SISO) IEEE 802.11 DCF MAC.