Marwan H. Azmi

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We investigate LDPC code design for a multi-source single-relay system, with uniform phase-fading Gaussian channels. We specifically consider the asymmetric channels for multiple sources, where the channel condition for each source in the system is different. We focus on LDPC code design when network coding (NC) at the relay is utilized. For the asymmetric(More)
This paper proposes a new soft decode-and-forward (SDF) protocol using LDPC codes in the half-duplex relay channels. In order for the encoding of the additional parity-check symbols at the relay to be linear and systematic, we introduce a structured rate-compatible (RC) LDPC code. We then develop the soft-decoding and soft-re-encoding algorithms for the(More)
This paper presents an improved LDPC code design for decode-and-forward relay system. Our design is based on the recent work of bilayer LDPC code structures. We introduce an irregular check node degree distribution for the lower and hyper (overall) bilayer LDPC code Tanner graphs. We derive the exact relationship between the lower and hyper graphs in terms(More)
We consider the design of bilayer-expurgated lowdensity parity-check (BE-LDPC) codes as part of a decode-andforward protocol for use over the full-duplex relay channel. A new ensemble of codes, termed multi-edge-type bilayer-expurgated LDPC (MET-BE-LDPC) codes, is introduced where the BELDPC code design problem is transformed into the problem of optimizing(More)
This paper presents a new bilayer-expurgated LDPC (BE-LDPC) code design for decode-and-forward relay system. The code design is based on the multi-edge type LDPC (MET-LDPC) code structure. The lower and upper graphs' edges of the BE-LDPC codes are represented via different edge types. We call the codes as multi-edge type bilayer-expurgated LDPC(More)
Cooperative communication is a well known technique to yield transmit diversity in the case of fading channels and to increase the spectral efficiency in the case of Gaussian channels. Error-correcting codes have to be carefully designed to achieve the promised gains. Good LDPC codes are known for fading channels and for Gaussian channels, but an LDPC code(More)
This paper presents an LDPC code design for decode-and-forward (DF) relay systems. Our design is based on the graphical family of the bilayer-lengthened LDPC codes (BL-LDPC) when joint decoding is performed over the overall expanded graph. To design the BL-LDPC codes under joint decoding, we use the framework of the multi-edge type LDPC (MET-LDPC) codes to(More)
This paper studies the problem of finding the optimum degree distribution for the distributed LDPC codes in the two-way relay channels. Based on the framework of multi-edge type (MET) LDPC codes, we propose a methodology to asymptotically optimize the code’s ensemble when different segments within the distributed codeword have been transmitted through(More)
In this paper we study LDPC code design in block-fading (BF) channels. Our main purpose is to introduce a new Root Check (RC)-LDPC code design which obtains full diversity whilst delivering improved coding gain relative the other LDPC code designs. More specifically, we show that when our codes are combined with the check splitting method for the ARQ BF(More)