Pilot-assisted Channel Estimation for Broadband ANC without Relay Feedback

Broadband analog network coding (ANC) has been recently introduced to further increase the network capacity by exploiting the broadcasting nature of the wireless channel. However, channel state information (CSI) knowledge is required for self-information removal and signal detection. Recently, a pilot-assisted channel estimation (PACE) scheme has been presented for broadband ANC; however, feedback of the channel estimates from the relay to the users is required. In this paper, we present a PACE scheme for broadband ANC, based on orthogonal frequency-division multiplexing (OFDM) radio access, without feedback from the relay. In the first time slot, the users transmit their respective pilots to the relay and then, in the second time slot, the relay amplifies and forwards the received pilot signals to both users. Each user can then estimate all the CSI it needs for self-information removal and signal detection, without requiring any feedback from the relay. The bit error rate (BER) performance of broadband ANC using the proposed PACE is evaluated by computer simulation. It was shown that the proposed PACE scheme can achieve almost the same BER performance as the conventional PACE scheme, while eliminating the feedback channel requirement.