Fast-Decodable Space–Time Codes for the -Relay and Multiple-Access MIMO Channel

Abstract

In this article, the first general constructions of fast-decodable, more specifically (conditionally) ggroup decodable, space-time block codes for the Nonorthogonal Amplify and Forward (NAF) Multiple-Input Multiple-Output (MIMO) relay channel under the half-duplex constraint are proposed. In this scenario, the source and the intermediate relays used for data amplification are allowed to employ multiple antennas for data transmission and reception. The worst-case decoding complexity of the obtained codes is reduced by up to 75%. In addition to being fast-decodable, the proposed codes achieve full-diversity and have nonvanishing determinants, which has been shown to be useful for achieving the optimal Diversity-Multiplexing Tradeoff (DMT) of the NAF channel.Further, it is shown that the same techniques as in the cooperative scenario can be utilized to achieve fast-decodability for K-user MIMO Multiple-Access Channel (MAC) space-time block codes.The resulting codes in addition exhibit the conditional nonvanishing determinant property which, for its part, has been shown to be useful for achieving the optimal MAC-DMT. Index TermsCentral simple algebras, distributed space-time block codes, fading channels, fast-decodability, lattices, multiple-access channel (MAC), multiple-input multiple-output (MIMO), relay channel.

Non-Orthogonal Multiple Access with applications :A Survey

“…Rayleigh, Ricean, Nakagami, Weibull etc and it is also useful for MIMO and shows that the ergodic and outage capacities does not depend upon a number of transmit antennas and channel parameters if high number of antennas are considered. Non Orthogonal Amplify and forward (NAF) MIMO technique is proposed [52] but for half duplex and all the relays here are employed with a multiple number of antennas and provides full diversity. [53] and their capacities are compared.…”

On Fast-Decodable Algebraic Space--Time Codes

“…We henceforth refer to such a code X simply as a space-time code. As the transmit power consumption is directly related to the Frobenius norm of the transmitted codeword, the finite codebook is usually carved out to consist of a desired number of lattice elements with smallest possible Frobenius norms 3 .…”

“…Consider a space-time code X , and let X ∈ X be the transmitted codeword. A receiver observes its channel output Y and, as it is assumed to know the channel H and the noise is zero-mean, decodes a maximum-likelihood 3 The smallest Frobenius norms correspond to the shortest Euclidean norms of the vectorised matrices. Directly, this would mean spherical constellation shaping.…”

“…In this scenario, enabling cooperation and dividing the allocated transmission time allows for the M inactive users to aid the active source in communicating with the destination by acting as intermediate relays. For more details on the transmission model we refer to [3,42]. While this is a more involved transmission scheme, from the destinations point of view it can be modeled as a virtual MIMO channel.…”