Non-Symmetrical Joint Zero-Diagonalization and MIMO Zero-Division Multiple Access

This paper addresses the problem of non-symmetrical joint zero-diagonalization (NSJZD) of a given set of matrices and its use in user interference cancellation for a new multiple-access multiple-input multiple-output (MIMO) wireless transmission scheme. First, sufficient conditions for uniqueness of the non-symmetrical zero-diagonalizer are described, and we propose a non-iterative efficient algorithm, termed non-symmetrical joint algebraic zero-diagonalization (NSJAZ), based on the reformulation of the initial problem into a joint generalized eigendecomposition problem. Second, we define the new concept of MIMO zero-division multiple access (ZDMA) allowing training-sequence free and simultaneous multiple access to a wireless receiver base station over a single frequency channel. Each ZDMA emitter combines two types of modulation (FSK/AM). The multiple-antenna ZDMA access point performs an NSJAZ-based blind separation of the different accesses assuming a flat fading channel. Computer simulations of such a system are presented both in analog and digital cases. Finally, to demonstrate that our multiple access scheme is technically feasible and works in a real environment, we present some preliminary results obtained with a full-analog ZDMA-based hardware prototype system that we have developed.