  In some Internet of Things (IoT) applications, multi-path propagation is a
main constraint of communication channel. Recently, the chaotic baseband
wireless communication system (CBWCS) is promising to eliminate the
inter-symbol interference (ISI) caused by multipath propagation. However, the
current technique is only capable of removing the partial effect of ISI, due to
only past decoded bits are available for the suboptimal decoding threshold
calculation. However, the future transmitting bits also contribute to the
threshold. The unavailable future information bits needed by the optimal
decoding threshold are an obstacle to further improve the bit error rate (BER)
performance. Different from the previous method using echo state network (ESN)
to predict one future information bit, the proposed method in this paper
predicts the optimal threshold directly using ESN. The proposed ESN-based
threshold prediction method simplifies the symbol decoding operation by
removing the threshold calculation from the transmitting symbols and channel
information, which achieves better BER performance as compared to the previous
method. The reason for this superior result lies in two folds, first, the
proposed ESN is capable of using more future symbols information conveyed by
the ESN input to get more accurate threshold; second, the proposed method here
does not need to estimate the channel information using Least Square method,
which avoids the extra error caused by inaccurate channel information
estimation. By this way, the calculation complexity is decreased as compared to
the previous method. Simulation results and experiment based on a wireless
open-access research platform under a practical wireless channel, show the
effectiveness and superiority of the proposed method.

Signal Processing