Channel Coding Rate for Finite Blocklength Faster-Than-Nyquist Signaling

Abstract

The fundamental tradeoff between low latency and high reliability makes the design of ultra-reliable low-latency communications (URLLC) wireless systems challenging. To support URLLC for a fixed bandwidth, faster-than-Nyquist (FTN) signaling is a promising approach since it increases the degrees of freedom (i.e., channel uses) per time interval, which can be exploited to improve reliability. In this letter, we derive analytical expressions for the approximate maximum channel coding rate (MCCR) for finite blocklength FTN signaling for water-filling and equal power allocations. We show that for practical non-sinc square-root Nyquist pulses, the penalty on the rate incurred due to the finite blocklength can be significantly reduced by non-orthogonal FTN transmission. Our results reveal that the MCCR for finite blocklength FTN signaling exceeds the Shannon capacity achieved for infinite blocklength and orthogonal transmission.