Channel Estimation for OFDM Modulated Two-Way Relay Networks

• Published in: IEEE transactions on signal processing 2009-11, Vol.57 (11), p.4443-4455
• Main Authors: Feifei Gao, Feifei Gao, Rui Zhang, Rui Zhang, Ying-Chang Liang, Ying-Chang Liang
• Format: Article
• Language: English
• Subjects: Algorithm design and analysis; Algorithms; Amplification; Amplify-and-forward (AF); Applied sciences; Bit error rate; Broadcasting; Channel estimation; channel identifiability; Channels; Data communication; Detection, estimation, filtering, equalization, prediction; Digital relays; Estimates; Exact sciences and technology; Information, signal and communications theory; Miscellaneous; Modulation, demodulation; Multiplexing; Network coding; OFDM modulation; Orthogonal Frequency Division Multiplexing; orthogonal-frequency-division multiplexing (OFDM); Protocols; Relay; Relay networks; Signal and communications theory; Signal processing; Signal, noise; Studies; Telecommunications and information theory; Terminals; Training; Transceivers; two-way relay network (TWRN)
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2009.2026537

In this work, we introduce the model of employing orthogonal-frequency-division multiplexing (OFDM) for transmission over time-dispersive channels in the two-way relay network (TWRN), where two source terminals exchange their information through a relay terminal using the amplify-and-forward (AF) relaying scheme. We propose a two-phase training protocol for the channel estimation, which is compatible with the two-phase data transmission scheme. In the first phase, the two source terminals send their individual training sequences concurrently to the relay, while in the second phase the relay amplifies the received training sequences and broadcasts them to both source terminals. We propose two different types of training methods as well as develop their corresponding channel estimation algorithms at each of the two source terminals. The first type of training is block based, for which we first estimate the cascaded source-relay-source channels, and then design algorithms to recover the individual channels between sources and relay. The second type of training is pilot-tone (PT) based, for which we propose to directly estimate the individual channels between sources and relay. Moreover, the identifiability issues on the nonambiguous estimate of the channels in both types of proposed training are carefully addressed. Finally, various numerical examples are presented to corroborate our analytical results.