An efficient OFDM-based system with an insufficient cyclic prefix via a novel constellation algorithm

Abstract

Abstract:In this paper, a new special triangular constellation scheme is introduced to replace the commonly used rectangular QAM constellation in orthogonal frequency division multiplexing (OFDM) modulation. We have shown that this new scheme has 3 major advantages with respect to the well-known QAM. The first advantage is its lower error probability performance, which results from better usage of the constellation space with longer minimum distances. The 2 other advantages are a lower peak to average power ratio (PAPR) and higher noise immunity. Both mathematical analysis and simulation results demonstrate that by applying standard channels in 2 cases, i.e. channels with AWGN and channels with burst noise and also with intersymbol interference (ISI) impairment simultaneously, the proposed constellation exhibits superior performance compared to the well-known QAM. As a result, this constellation is a good choice for high-speed and real-time OFDM multicarrier applications such as WiFi, WiMAX, DVB, and DAB at no extra cost.

A General Framework for Estimating Channel of Orthogonal Frequency Division Multiplexing Systems by Utilizing Sparse Representation

“…These pilots are known at the receiver side, and their position in the stream is gathered at a set P={p1,p2,...,pL}, which L is the number of estimation pilots. After performing some other operations such as cyclic prefix doi: 10.5829/ije.2021.34.06c.11 (CP) insertion, parallel to serial (P/S), and digital to analog conversion (DAC), an OFDM symbol is transmitted through a wireless channel [1,3,4]. At the receiver side, after passing through some processing blocks, estimation pilots are extracted, and the receiver estimates the wireless channel from noisy observed samples /, ff pilot X = = + p p P p h r h z [3], [5], where rp contains received symbols at the positions of estimationpilot P, Xpilot is the estimation pilot, hp f contains samples of the frequency response of the channel, and zP is the channel noise at the related positions.…”