Multi-User Non-Coherent Detection for Downlink MIMO Communication

Abstract

Current cellular technologies are based on the concept of coherent communication, in which the channel matrix used for demodulation is estimated via reference or pilot signals. Coherent systems, however, involve a significant increase of the signalling overhead, especially when the number of transmission points is increased or when the mobile channel changes rapidly, which motivates the use of non-coherent techniques. This letter extends the use of non-coherent communications to a multi-user (MU) multiple-input multiple-output (MIMO) framework by combining superposition coding with a reduced-complexity detection method. Numerical results confirm that our scheme achieves higher user rates than non-coherent MU transmission based on time multiplexing. In addition to the well-known sumrate gain of MU systems, an extra performance gain given by downlink non-coherent MU communication is shown and qualitatively justified.

METIS research advances towards the 5G mobile and wireless system definition

“…A beamforming scheme based on the channel estimates obtained from contaminated pilots results in interferences directed to those transmitters using the same pilot [48]. Therefore, new transmission schemes based on blind channel estimation are to be designed for the next generation mobile [49].…”

On the integration of Grassmannian Constellations into LTE networks: A link-level performance study

“…The main problems of coherent training-based communication motivated the increasing research on non-coherent MIMO communication techniques, which are able to perform data detection without any knowledge of the channel coefficients at the receiver side and, thus, they do no longer require the transmission of pilots [6][7][8][9][10][11]. Non-coherent MIMO communication schemes specifically designed for block-fading channels were proposed in [6], [7].…”

“…In [10], the use of these constellations was generalized from the block-fading channel, traditionally invariant in time, to a block-fading channel, invariant not only in time but also in frequency. In [11], authors extended the use of GCs in a multiuser downlink communication and proposed a suboptimum detection scheme of linear complexity whose performance provided, in some cases, gain in the user rates with respect to the single-user detection.…”