Dispensing with Channel Estimation: Differentially Modulated Cooperative Wireless Communications

Abstract

Abstract-As a benefit of bypassing the potentially excessivecomplexity and yet inaccurate channel estimation, differentially encoded modulation in conjunction with low-complexity noncoherent detection constitutes a viable candidate for usercooperative systems, where estimating all the links by the relays is unrealistic. In order to stimulate further research on differentially modulated cooperative systems, a number of fundamental challenges encountered in their practical implementations are addressed, including the time-variant-channel-induced performance erosion, flexible cooperative protocol designs, resource allocation as well as its high-spectral-efficiency transceiver design. Our investigations demonstrate the quantitative benefits of cooperative wireless networks both from a pure capacity perspective as well as from a practical system design perspective.

Analysis of the performance of a non-coherent large scale SIMO system based on M-DPSK under Rician fading

“…The NC detection has indeed compelling benefits in terms of dispensing with powerthirsty channel estimation, as also argued in [7]- [8]. In our previous work [8], we demonstrated these advantages of NC LS-single input multiple output (LS-SIMO) under Rayleigh propagation conditions.…”

A Noncoherent Multiuser Large-Scale SIMO System Relying on M-Ary DPSK and BICM-ID

“…The design dilemma between coherent and NC communication has intrigued the community since 1991 [2]. NC detection has indeed compelling benefits in terms of dispensing with power-thirsty channel estimation, as also argued in [3]- [4]. Indeed, we will demonstrate in this paper that upon taking into account the pilot-overhead in the throughput calculation and the detrimental effects of realistic imperfect estimation, NC systems are potentially capable of outperforming their coherent counterparts.…”

Reduced-Complexity Noncoherent Soft-Decision-Aided DAPSK Dispensing With Channel Estimation

“…For cooperative communication systems [8], [19], [20], N R may refer to the number of relay nodes. Due to the increasing number of virtual antenna array links and the requirement of imposing low signal processing complexity at the relay nodes, it becomes unrealistic to require accurate channel estimation; hence, DAPSK is preferred.…”

“…Considering 16-DAPSK (2,8) as an example, the subsets for index v are given by (v ∈ {1, 3}) and (v = 2), when we fix b 4 to 1 and 0, respectively, as seen in (21). 5) When detecting the first two bits, which determine the quadrant, (37) is replaced by…”

“…As a remedy, differential amplitude phase-shift keying (DAPSK), which is also known as star QAM, was proposed in [7] to dispense with high-complexity CSI estimation and, hence, to eliminate the pilot overhead. It is demonstrated in [8] that low-complexity noncoherent schemes are particularly important in the context of relay-aided cooperative systems, where it is unrealistic to expect that the relay can altruistically estimate the source-relay channel.…”