On hierarchical network coding versus opportunistic user selection for two-way relay channels with asymmetric data rates
We address in this paper the challenge of coping with asymmetric data rates in two-way relay channels. We consider a relay network comprising two sources and one relay. The sources communicate at different rates through the relay. That is, we assume that one source uses M 1 -QAM (quadrature amplitude modulation) and the other uses M 1 /M 2 -QAM hierarchical modulation where M 1 ≠ M 2 . For the underlying network, we consider two decode-and-forward (DF) relaying schemes. One scheme combines hierarchical zero padding and network coding (HZPNC) at the relay. The novelty of this scheme lies in the way the two signals (that have different lengths) are network-coded at the relay. The other scheme is referred to as opportunistic user selection (OUS) where the user with a better end-to-end channel quality is given priority for transmission. We analyze both schemes where we derive closedform expressions for the end-to-end (E2E) bit error rate (BER). Since the two schemes offer a trade-off between performance and throughput, we analyze and compare both schemes in terms of channel access probability and average throughput. We show that HZPNC offers better throughput and fairness for both users, whereas OUS offers better performance. We also compare the performance of HZPNC with existing schemes including the original zero padding, nesting constellation modulation and superposition modulation. We show through examples the superiority of the proposed HZPNC scheme in terms of performance and/or reduced complexity.
- Electrical Engineering [2027 items ]
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Hussain S.I.; Alouini M.-S.; Hasna , Mazen; Qaraqe K. ( IEEE , 2012 , Conference Paper)In a communication system with multiple cooperative relays, selecting the best relay utilizes the available spectrum more efficiently. However, selective relaying poses a different problem in underlay cognitive networks ...
Performance analysis of best relay selection scheme for fixed gain cooperative networks in non-identical Nakagami-m channels Hussain S.I.; Hasna , Mazen; Alouini M.-S. ( IEEE , 2010 , Conference Paper)Selecting the best relay among all the relays ready to cooperate saves system resources and utilizes the available bandwidth more efficiently compared to the regular all-relay cooperation. This scheme also achieves the ...
Mousavifar S.A.; Khattab T.; Hasna , Mazen ( IEEE , 2010 , Conference Paper)In a wireless sensor network with relaying capability, intermediate relay nodes are with limited energy budget. To maximize lifetime of relay nodes, selective relay strategies, requiring full channel state information ...