Performance of multiuser MIMO communication system using chirp modulation

Multiple-Input and Multiple-Output (MIMO) system is widely recognized as an effective means to combat the effects of multipath fading in wireless communications. In this paper, we propose the use of chirp modulation technique in a MIMO system, as the modulated signals have inherent interference rejection capability and immunity against Doppler shift and fading due to multipath propagation. The performance of chirp-based MIMO system is examined using Monte Carlo simulations over Rayleigh fading channel. For example, it is shown that a simple 2 × 2 MIMO system can offer a significant gain in performance relative to maximal ratio combining (MRC) using chirp modulation. Next, a multiuser MIMO (MU-MIMO) system is proposed, where each user is assigned a unique orthogonal chirp signal that efficiently modulates each user´s incoming data as well as identifies them at the receiver. Numerical results show that chirp modulation is very effective in MU-MIMO system in eliminating the effects of multiple-access interference (MAI).