Neural Network Equalisation and Symbol Detection for 802.11p V2V Communication at 5.9GHz

Abstract

Neural networks are shown to be a viable implementation for joint channel equalisation and symbol detection in a vehicular network. Experimental results using a hardware-in-theloop approach at 5.9GHz validate the efficacy of the proposed implementation following the 802.11p parameters using orthogonal frequency division multiplexing (OFDM). Further results are obtained using a more spectrally efficient waveform, namely spectrally efficient frequency division multiplexing (SEFDM), to show a trade-off between loss of orthogonality, and therefore bit-error rate (BER) performance, versus increased spectral efficiency to enable higher data rates or the ability to service more users. SEFDM is tested with compression factors ranging from 20% up to 60% bandwidth compression. The results show the neural network is able to achieve an acceptable BER performance in a highway non-line-of-sight (NLOS) channel which is a well established harsh and dynamic vehicular channel. This is further validated via measurements of the error vector magnitude.

Experimental Validation of Zero Padding in SEFDM Systems Using Over-the-Air Transmission

“…Hence, the received signal is affected by the self-induced ICI combined with multipath effects. Therefore, channel estimation and equalisation becomes more challenging in comparison to OFDM systems [7]- [11].…”

Using Zero Padding for Robust Channel Estimation in SEFDM Systems

“…In addition, SEFDM has been implemented successfully in various communication systems, such as long-term evolution (LTE) [8], visible light communication (VLC) [9] and optical communication systems [10]. More recently, SEFDM signal modulation is used in vehicular communication systems [11], with bandwidth savings ranging from 20% to 60%. Such savings could be utilised to increase the number of users or improve data rate in future vehicular communication systems.…”

Alignment Signal Aided CP-Free SEFDM

“…This widely accepted paradigm of using OFDM signals for multi-carrier systems, however, has been challenged in the recent years where non-orthogonal signals (in particular spectral efficient frequency division multiplexing (SEFDM)) is considered to offer higher spectral efficiency in comparison to OFDM ones. SEFDM saves the signal bandwidth by compressing the frequency spacing between the subcarriers and hence enhancing the spectral efficiency [7], which makes it a topic of current interest [8]- [12].…”