Polar code performance with Doppler shifts and reflections in Rayleigh fading for Industrial channels

Abstract

Industry 4.0 has created a strong pull for wireless communications. Industrial applications have tight communication constraints putting them in the class of Ultra Reliable, Low Latency Communication (URLLC). Polar codes have recently become a primary contender for satisfying URLLC requirements. Their performance is heavily dependent on the channel state and with industrial environments presenting extreme conditions with highly dynamic radio channels, obtaining high reliability from polar codes is challenging. Pilot Assisted Transmission allows channel estimation and can improve the reliability of polar codes in fading channels. However a detailed analysis of the impact of the channel dynamics and PAT scheme on the polar code performance is not available. This paper models the industrial radio channel as a Rayleigh channel affected by Doppler shift and delay spread. We evaluate the channel estimation and Bit Error Rate improvements that can be achieved using PAT with variable pilot interval. We detail the behaviour of polar codes subjected to Doppler shift and delay spread. Finally, we investigate the trade-off between reliability and maximum achievable data rate based on PAT interval and code rate. The existence of a trade-off indicates scope for optimization of PAT parameters depending on channel conditions.