Active INI Cancellation for Mixed-Numerology OFDM System in Uplink Transmission

Mixed-numerology transmission is a flexible physical layer waveform technology to support different service. The coexistence of different numerologies causes inter-numerology interference (INI) and deteriorates the system performance. In uplink transmission, the detection of mixed-numerology signal is based on Least common multiple (LCM) symbols to ensure the integrity of symbol sampling for each numerology. However, the LCM symbol-based detection increases the latency for delay sensitive services, which adopt numerologies with short symbols. In this paper, we propose an active INI cancellation (A-INIC) algorithm at the transmitter and a soft iterative INI cancellation (soft I-INIC) algorithm at receiver for uplink mixed-numerology transmission. Based on the proposed algorithms, we construct an A-INIC transceiver which can pre-cancel the INI with multi-path fading channel. In the transmitter, the A-INIC module actively compensate for the INI generated by the user itself to adjacent subbands as well as the corresponding secondary INI in target subband, which facilitate symbol-based detection at receiver for latency reduction. In the receiver, a soft I-INIC module is applied to cancel the residual INI when the feedback channel state information (CSI) for INI pre-compensation is imperfect. Simulation results demonstrate the superiority of the proposed algorithms in block error ratio (BLER) performance even without any guard subcarrier.