Location-guided Precoded OFDM for Asynchronous Uplink Access

Abstract:
The reduction of signaling overhead in order to increase the efficiency, for instance in massive Machine Type Communications (mMTC), does not allow a closed-loop coordination of the transmission timing between the base station and the user equipments in uplink direction. Consequently, considerable multi-user interference occurs due to the asynchronicity in the uplink transmission, which is desired to be handled at the waveform level. In addition, the recent developments in 5G demand transparency of user’s transmitted waveform to the CPOFDM receiver. Following these constraints, a waveform design is proposed that can inherently maintain nearly equal signal quality for all users regardless of their distance to the receiver. In an LTE-conformable setting, a considerably small variance in Signal to Interference plus Noise (SINR) of randomly located users is shown at the price of having a lower peak SINR.