FINITE BLOCKLENGTH SYMMETRIC INFORMATION RATE OF SOQPSK

Abstract

In this paper we compute a lower bound, namely the dependence testing (DT) bound, on the maximum achievable rates (expressed in bits/channel use) with military standard shaped-offset quadrature phase shift-keying (SOQPSK-MIL) and aeronautical telemetry SOQPSK (SOQPSK-TG) schemes over additive white Gaussian noise (AWGN) channels under finite code blocklength, probability block error and equiprobable input constraints. The DT bound results for SOQPSK-MIL and SOQPSK-TG are used to lower bound their respective spectral efficiencies (expressed in bits/s/Hz). We simulate a serially concatenated convolutional code (SCCC) using SOQPSK-MIL as the inner code, and show that it performs within 1:1 dB of the SOQPSK-MIL DT bound for various coding rates. The numerical results also demonstrate the performance loss compared to the channel capacity due to the finite blocklength constraint.