On the Design of Coherent Zero-Forcing Receiver for the Flat Fading MIMO Multiple-Access Channels

Design of low-complexity receiver for space-time block coded (STBC) transmission over multiple-input multiple-output (MIMO) multiple-access channels has been subject of interest over the years. In this regard, zero-forcing receiver, as a low complexity receiver needing as many receive antennas as the numbers of users, has received increasing attention.

This paper investigates multiuser detection for STBC transmission over a flat-fading MIMO multiple-access channel consisting of  co-channel users each with  antennas and a zero-forcing coherent receiver equipping with  receiving antennas. For the cases in which , it was previously claimed that it is impossible to extend this receiver to general scenarios of orthogonal STBC transmission with  and .

We provide a theorem allowing this extension to any scenarios satisfying the theorem condition. Describing in more details, we first prove that zero-forcing receiver of  antennas can successfully extend to any STBC transmission over MIMO multiple-access systems which provides an Alamouti-like structure for the inner product of equivalent channels between different receive antennas and users. Then, in order to gain more insight, the theorem role on extending zero-forcing receiver for transmission of orthogonal STBC over MIMO multiple-access systems with  and , and also to other STBC schemes like generalized coordinate interleaved orthogonal design and Quasi-orthogonal STBC is investigated in more details. Finally, the average symbol error rate of considered scenarios are numerically evaluated and compered for different STBC schemes with various numbers of  and .

Generally speaking, it is concluded that extension of zero-forcing receiver to any scenarios of OSTBC transmissions over MIMO multiple-access channels exactly depends on satisfaction of the provided theorem and this receiver can be successfully employed in all scenarios providing an Alamouti-like structure for the inner product of equivalent channels between different receiving antennas and users.