We consider a new uplink multiple access system based on orthogonal frequency-division multiplexing (OFDM), subcarrier hopping, and super-orthogonal convolutional codes (SOCC) that can achieve high coding gain and frequency diversity without sacrificing latency. Such a system is of significant importance for future wireless communications targeting motion controls of machines and vehicles. In order to improve the spectral usage, multiple users should share the same subcarriers with multiuser detection and decoding (MUD) at the receiver. In this work, we focus on super-trellis decoding (STD) and successive interference cancellation (SIC) in the framework of our proposed multiple access system. Through the extensive analysis based on simulations, we reveal that 1) properly designed SIC can achieve almost the same performance as the optimum STD with much lower complexity than the STD, and 2) our proposed system with SIC can outperform the conventional orthogonal frequency-division multiple access (OFDMA) with twice as much spectrum efficiency as OFDMA. The major drawback of SIC is its increased latency as the number of the users increases. Therefore, we also propose an alternative multiple access approach based on STD that can achieve optimum performance and low latency.
['Yuta Hori', 'Hideki Ochiai']
A design of multiuser detection and decoding for subcarrier hopping multiple access based on coded OFDM