Sub-optimum detection scheme for asynchronous cooperative relay networks

Near‐optimum detection scheme with relay selection technique for asynchronous cooperative relay networks

“…0 dB) for t k = 0.5 T and β = 0.25 (i.e. −6 dB) for t k = 0.125 T [10]. † Finally, the best relay node chosen above and the relay node with the smallest time delay error are used to forward the received signals towards the destination node.…”

“…4, the effect of ISI from the previous symbols is represented by g i2 (l ), i ∈ 1, 2, and l ∈ −1, −2. We note that that g i2 (−2) is generally a much smaller coefficient [8,10]. Therefore the strengths of g i2 (l ) can be expressed as a ratio as…”

“…where β 12 (l ) = β 22 (l ) = β(l ) denotes a sample of a pulse shaping waveform and the effect of the time delay t i2 , i ∈ 1, Fig. 3 Basic structure of distributed CL EO-STBC with outer coding using two-bit feedback based on phase rotation for an asynchronous wireless relay with two antennas in each relay node and one antenna in the source and the destination node with two phases for the cooperative transmission process and time delay offset between the antennas of R 2 and the destination node 2 [8,10], between transmission from the antennas of the relay node R 1 and the antennas of the relay node R 2 at the destination node. The received signals r rd (1, n) and r * rd (2, n) conjugated for convenience in (6) and (7) can be represented in vector form as r rd (n) = Hs(n) + I int (n) + w rd (n) (11) where…”

“…The sub-optimum detection scheme in [10] was proposed for the case of four relay nodes to mitigate asynchronism effects utilising the closed-loop extended orthogonal STBC (CL EO-STBC) with phase rotated feedback as in [11]. This scheme cancelled the interference components caused by asynchronism effectively with near-Alamouti simplicity, unity rate code and achieved the full diversity order between the relay nodes and the destination node.…”

“…In this paper, a near-optimum detection scheme is proposed for two dual-antenna cooperative relay nodes. The approach eliminates the interference components at the destination because of a time misalignment caused by the asynchronism in the transmission from the antennas of the relay nodes with the equivalent simplicity of the decoding as in [8,10], but with the advantage of overcoming their drawbacks, that is, the achievement of a full diversity order of four from the cooperating relay nodes to the destination node, as well as completely dispensing with the DT link assumed in [10] and hence reducing the detection complexity at the destination node and modelling a more realistic wireless cooperative transmission scenario. In addition, a new relay selection (RS) technique for two dual-antenna relay nodes is considered in this paper to select the best channel quality as well as the channel with the minimum time misalignment.…”