Zhenhong Li

Selective Random Cyclic Delay Diversity for HARQ in Cooperative Relay

In the next generation cellular system, relay has been considered to increase coverage extension and cell-edge throughput. Cooperative relay can provide transmission diversity gain to improve outage probability, overall throughput and energy efficiency. Cooperative beamforming has been considered as one of the cooperative relay if the relay nodes can get the feedback information from the destination. In this paper, a new cooperative relay scheme is proposed for hop-by-hop HARQ in cooperative relay. The scheme is to adopt selective random cyclic delay diversity (CDD) to the retransmission in HARQ, which can get rid of the relative bad relay nodes and form a better frequency selective channel to exploit diversity gain when channel coding is used. Performance evaluation and analysis have shown that the selective random CDD can achieve higher throughput and lower transmission delay than the conventional cooperative beamforming.

Centralized Proportional Fair (PF) Scheduling with Concurrent Transmission Enabled in Wireless Multi-Hop OFDMA Networks

The paper proposes the scheduling method to not only implement the proportional fairness between terminal users but also improve spectral efficiency by enabling concurrent transmission (CT) in wireless multi-hop OFDMA networks. The overhead reduction of channel quality information (CQI) is presented in coupling with the proposed scheduling and hereafter its performance with the reduced CQI is discussed. Simulation results illustrate the proposed scheme outperforms the prior art on both spectral efficiency and fairness.

Coordinated Transmission in Distributed Ad Hoc Peer-To-Peer (P2P) Communications

The centralized transmission (Tx) coordination is presented for P2P networks to mitigate the strong near-far interference (NFI) by aligning the transmissions of nearby P2P pairs. With the concern of signaling overhead, all nodes measure and feedback the sum co-channel interference (CCI) exclusively to the central node. With the same principle, the more practical distributed Tx coordination is proposed, where every P2P pair exchanges the CCI measurements and coordinates the Tx order locally. Simulations illustrate that the distributed Tx coordination provides the similar performance to the heuristic centralized method and outperforms the prior art dramatically. In addition, the latency is quite low in the distributed coordination.