Performance Assessment of Single and Multiple Antenna Relays for the Uplink OFDM Systems

The aim of this paper is to propose and assess the performance of cooperative schemes designed for the uplink OFDM based systems with mobile relays with an antenna array. We consider the use of an antenna array at the base station and a single antenna at the user terminal. We compare the situations at which the relay is equipped with one or two antennas. We assume that some of the user terminals deployed in a certain area could act as relaying-able terminals for the communication of other users. Two types of relay assisted protocols are considered: equalize-and-forward and decode-and-forward. The performance of the proposed relay-assisted schemes is evaluated under realistic scenarios, considering typical pedestrian scenarios based on WiMAX specifications. The proposed schemes are also compared against the OFDM based non-cooperative systems. Numerical results show that the availability of antenna arrays at the relays significantly improves the cooperative systems performance, which outperform the non-cooperative ones in all studied scenarios.

[1]  Gerhard Bauch,et al.  Cooperative Transmission Schemes for Decode-and-Forward Relaying , 2007, 2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications.

[2]  Robert W. Heath,et al.  The future of WiMAX: Multihop relaying with IEEE 802.16j , 2009, IEEE Communications Magazine.

[3]  Jonathon A. Chambers,et al.  Exploitation of Quasi-Orthogonal Space Time Block Codes in Virtual Antenna Arrays: Part I - Theoretical Capacity and throughput Gains , 2008, VTC Spring 2008 - IEEE Vehicular Technology Conference.

[4]  M. J. Gans,et al.  On Limits of Wireless Communications in a Fading Environment when Using Multiple Antennas , 1998, Wirel. Pers. Commun..

[5]  Stefan Kaiser.  Space frequency block codes and code division multiplexing in OFDM systems , 2003, GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489).

[6]  B. Sundar Rajan,et al.  Distributed Space-Time Codes for Cooperative Networks with Partial CSI , 2007, 2007 IEEE Wireless Communications and Networking Conference.

[7]  Frank H. P. Fitzek,et al.  Cooperation in Wireless Networks: Principles and Applications , 2006 .

[8]  Abbas El Gamal,et al.  Capacity theorems for the relay channel , 1979, IEEE Trans. Inf. Theory.

[9]  Vahid Tarokh,et al.  Design of an OFDM Cooperative Space-Time Diversity System , 2007, IEEE Transactions on Vehicular Technology.

[10]  A. Silva,et al.  Performance Evaluation of Virtual MIMO Schemes for the UL OFDMA Based Systems , 2008, 2008 The Fourth International Conference on Wireless and Mobile Communications.