Zero‐pseudorandom noise training OFDM

Abstract

A novel transmission scheme called zero-pseudorandom noise training sequence orthogonal frequency division multiplexing (ZPN-OFDM) is proposed, where the frame structure of dual-pseudorandom noise (PN) padding time domain synchronous OFDM is modified by replacing the first PN sequence by a zero sequence. The new ZPN-OFDM system offers better energy efficiency than previous OFDM systems. The ZPN-OFDM system is tested for significant tap delay multipath channels. Simulation results show that ZPN-OFDM can provide significant bit error rate improvement as well as energy efficiency improvement.Introduction: There are three basic types of orthogonal frequency division multiplexing (OFDM): cyclic prefix OFDM (CP-OFDM), zero padding OFDM (ZP-OFDM) and time domain synchronous OFDM (TDS-OFDM). The popular CP-OFDM utilises a CP as a guard interval to alleviate inter-block-interference (IBI) in multipath channels. The CP is replaced by a ZP in ZP-OFDM to tackle the problem of channel transmission zeros. Unlike CP-OFDM or ZP-OFDM, TDS-OFDM adopts a known pseudorandom noise (PN) sequence as a guard interval as well as a training sequence (TS) for synchronisation and channel estimation. Consequently, it does not require any frequency-domain pilots as usually used in CP-OFDM and ZP-OFDM, leading to a better spectrum and energy efficiency [1].However, TDS-OFDM suffers from IBI due to the mutual interference between the PN TS and OFDM data block. To address this issue, a DPN-OFDM scheme has been proposed with two periodical PN sequences, where the second PN sequence is not affected by the IBI from the previous OFDM data block, and hence can be used for accurate channel estimation [1,2]. Because of its simplicity and good performance, DPN-OFDM is currently under extensive investigation and hardware implementation for the evolution standard of digital television terrestrial broadcasting (DTMB) [1][2][3].In multipath channels with significant tap delays, such as in underwater acoustic (UWA) channels, ZP-OFDM is preferred to the CP-OFDM because it consumes less transmission energy [4,5]. In this Letter, a novel transmission scheme called zero-PN-OFDM (ZPN-OFDM) for a significant tap delay multipath channel with good energy efficiency is proposed.

Fully generalised spatial modulation technique for underwater communication

“…Introduction: One of the challenges of underwater communication is the availability of a sustainable energy source for the battery feed sensor nodes [1]. Since the underwater sensor (UWS) nodes are battery based, researchers have tried very hard to increase the battery life as much as possible.…”

Underwater Image Transmission Using Spatial Modulation Unequal Error Protection for Internet of Underwater Things

“…Then, these asymptotic ABER analytical formulations are confirmed by using Monte Carlo simulations. The simulation results are gotten for 10 6 symbols conveyed at each SNR for 10 6 iterations over the simulated channel and the measured underwater acoustic channel collected from sea experiment, ASCOT01 conducted off the coast of New England in June 2001 as reported in [25] and used in [26]. The ABER performance for SM (index/data) and the unseparated SM are shown in Figure 6, using SM technique with 9-bit per channel use (9-bpcu) using SM with Nt=4 and 128-QAM modulation.…”

Enhanced Fully Generalized Spatial Modulation for the Internet of Underwater Things

“…In the following, computer simulation outcomes are presented for the proposed EFGSM over an uncorrelated underwater acoustic channel by using simulation outcomes achieved for 106 symbols conveyed over a regular underwater acoustic channel as in [15,26]. In the receiver, the ML detection technique is used to estimate the transmitted symbols and indices and the average BER performances is obtained by the Monte Carlo simulation method using different transmission techniques.…”

“…Unfortunately, such a problem reduces the lifetime of IoUT nodes, and is exacerbated by the limitations of their recharging capability. Such a problem can be solved by using an efficient modulation technique [25,26]. In this subsection, the saving in the power consumption of the proposed EFGSM scheme is considered in reference to the M-QAM modulation technique as in [15].…”