Abstract
Industrial wireless channels feature rich multipath components and strong noise. Massively deployed nodes in an industrial network are often cheap devices. Under such circumstances, the received packets are prone to errors. The conventional method for guaranteeing data quality relies on the MAC layer approach, such as retransmissions. However, this approach creates a data misalignment problem that degrades the performance of multidevice cooperation. Therefore, we propose a robust quadrature ergodic chaotic parameter modulation (QECPM)-based receiver to avoid retransmission. The proposed method does not require timing synchronization. This method eliminates the possibility of cycle slipping, which has a major effect on performance. The bit error rate (BER) performance of the proposed receiver in the Nakagami-m channel is derived and verified by simulation. Using the proposed receiver, the multipath effect can be mitigated using a single scalar. We use software-defined radios (SDRs) to show that the proposed method is robust against timing synchronization errors in practice. Furthermore, we show that as long as there are retransmissions, misaligned packets are to be expected; however, when using the proposed receiver, the error bits are sparse enough to utilize the non-retransmission mode to maintain stable link rates. Our results show that the proposed receiver is robust to multipath, timing synchronization errors and data misalignment.
Highlights
W IRELESS connectivity plays a key role in modern industry [1]
We show that direct sequence spread spectrum (DSSS), which is the modulation specified in IEEE 802.15.4, may suffer from severe performance degradation with imperfect timing synchronization
Assuming four samples per symbol, the practical where L is the number of multipaths, al is the amplitude of a multipath component, φl is the phase and τl is the tap delay
Summary
W IRELESS connectivity plays a key role in modern industry [1]. In smart grids, sensory data are sent through the Industrial Internet of Things (IIoT) to help balance load and power generation [2], and to monitor wind and solar farms [3]. When precise synchronization and accurate channel knowledge are available, the RAKE receiver [25] can be deployed in DSSS to achieve improved performance. The M-ary DCSK was combined with index modulation in [35] to further increase the data rate and improve BER performance. Using the correlation property of a chaotic sequence, several branches of chaotic position modulation were combined to enhance the spectrum efficiency. All these chaotic modulations suffer from poor BER performance compared to that of DSSS; this can be seen as a trade-off for their robustness. While a wireless receiver does not usually have prior information on propagation delay, it is vital to sample the signal at correct time instants; timing synchronization is required. Sample disruption can be problematic because it will not be corrected until frame synchronization in the data packet, rendering the current packet useless
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