Generalized subband-filtered and pulse-shaped multicarrier for quasi-synchronous uplink access

Abstract

In this paper, a new subband-filtered and pulse-shaped multicarrier (SBF-PS-MC) scheme is introduced and investigated in a generalized framework. The main motivation behind is to capture inter-user quasi-synchronicity (QS) and channel spread in 5G massive machine-type communication (mMTC) use case where uplink (UL) synchronization and other control procedures need to be simplified or even dropped to reduce signaling/protocol overhead. Based on downlink synchronization, UL transmissions from geographically distant users can entail severe relative symbol time and carrier frequency offsets by fractional amounts of multicarrier (MC) symbol interval and subcarrier spacing, respectively (i.e., interuser QS). SBF-PS-MC scheme can take advantage both of subband filtering and pulse shaping, whereby, on the one hand, other-subband (or other-user) interference (OBI) is effectively suppressed by subband filtering and, on the other hand, intra-subband and inter-symbol interference is reduced and OBI even further mitigated by pulse shaping. A main contribution is to provide a generalized framework for SBF-PS-MC scheme to handle each of the interference terms analytically dependent on the used subband filter and prototype pulse. Eventually, SBF-PS-MC is numerically evaluated over inter-user QS in time and delay spread channel that per-subband average signal to interference plus noise ratio (SINR) of SBF-PS-MC is superior to those of conventional cyclic prefix orthogonal frequency division multiplexing (OFDM), weighted overlap-add OFDM, universal filtered OFDM, and subband-filtered OFDM.