Partially-Coherent Distributed Space-Time Codes with Differential Encoder and Decoder

Abstract

Abstract-Distributed space-time coding is a means of achieving diversity through cooperative communication in a wireless relay network. In this paper, we consider a transmission protocol that follows a two-stage model: transmission from source to relays in the first stage, followed by a simple relaying technique from relays to destination. The relays transmit a vector, which is a transformation of the received vector by a relay-specific unitary transformation. We assume that the relays do not have any channel information, while the destination has only a partialchannel knowledge, by which we mean that destination knows only the relay-to-destination channel. We derive a Chernoff bound on the pairwise error probability and propose code design criteria. A second contribution is the differential encoding and decoding scheme for this setup, which is different from the existing ones. Furthermore, differential codes from cyclic division algebra are proposed that achieve full diversity. For our setup with two relays, a Generalized PSK code is shown to achieve full diversity, for which the decoding complexity is independent of code size.

Distributed Beamforming for Relay Networks Based on Second-Order Statistics of the Channel State Information

“…where and denote the real and imaginary parts, we obtain that (14) Equating to zero, we obtain that (15) It follows from (15) that should be chosen as one of the eigenvectors of the matrix and is the corresponding eigenvalue. Multiplying both sides of (15) with yields (16) where in the last equality we have used the constraint in (12).…”

“…Of all these schemes, the amplify-and-forward approach, due to its simplicity, is of particular interest. Recently, the amplify-and-forward approach has been extended to develop space-time coding strategies for relay networks, thereby opening a new research avenue called distributed space-time coding [9]- [15]. While the aforementioned cooperative approaches assume different levels of CSI availability in the network, they all share the common assumption that the relay nodes operate at their maximum allowable power.…”

Algebraic distributed differential space-time codes with low decoding complexity

“…Obtaining the knowledge of the fading coefficients between the users at the destination requires additional resources. To solve this problem, in [2], Kiran et al have proposed a differential encoding/decoding setup for cooperative wireless networks that does not require the knowledge of fading coefficients between the users at the destination. Such codes were named as partially coherent distributed space-time codes in [2].…”

“…To solve this problem, in [2], Kiran et al have proposed a differential encoding/decoding setup for cooperative wireless networks that does not require the knowledge of fading coefficients between the users at the destination. Such codes were named as partially coherent distributed space-time codes in [2]. In a recent work [4], it has been shown that the same strategy of [2] offers full diversity with a suboptimal receiver that does not require the knowledge of any of the fading coefficients.…”

“…Such codes were named as partially coherent distributed space-time codes in [2]. In a recent work [4], it has been shown that the same strategy of [2] offers full diversity with a suboptimal receiver that does not require the knowledge of any of the fading coefficients. In an independent work [3], Jing and Jafarkhani have proposed a differential encoding/decoding setup for cooperative wireless relay networks which is more general than the setup proposed in [2], [4] and they have also provided few code constructions.…”