Institute of Electrical & Electronic Engineers
In this paper, the Filter-and-Forward (FF) relay design for Orthogonal Frequency-Division Multiplexing (OFDM) transmission systems is considered to improve the system performance over simple Amplify-and-Forward (AF) relaying. Unlike conventional OFDM relays performing OFDM demodulation and re-modulating, to reduce processing complexity, the proposed FF relay directly filters the incoming signal with a Finite Impulse Response (FIR) and forwards the filtered signal to the destination. Two design criteria are considered to optimize the relay filter for given source power allocation. One is to minimize the relay transmit power subject to per-subcarrier Signal-to-Noise Ratio (SNR) constraints and the other is to maximize the worst subcarrier channel SNR subject to the total relay transmit power constraint.