Open AccessLow‐complexity frequency‐domain turbo equalisation for doubly‐selective HF channel on GPP‐based SDR platform
Author(s) -
Ravaei Yahya,
Mahdi Nejad Mohammad,
Madani Mohammad Hossein
Publication year - 2017
Publication title -
iet communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.355
H-Index - 62
eISSN - 1751-8636
pISSN - 1751-8628
DOI - 10.1049/iet-com.2017.0021
Subject(s) - computer science , turbo , cyclic prefix , computational complexity theory , frequency domain , software defined radio , algorithm , bit error rate , time domain , frequency offset , channel (broadcasting) , turbo equalizer , electronic engineering , low density parity check code , orthogonal frequency division multiplexing , decoding methods , telecommunications , engineering , error floor , automotive engineering , computer vision
In this study, the authors propose a low‐complexity frequency‐domain turbo equalisation scheme for doubly‐selective high‐frequency (HF) channel. The performance of time‐ and frequency‐domain turbo equalisers (TD/FD‐TE) by applying them to the waveforms of STANAG 4539 is compared. Compared with TD‐TE, FD‐TE has reduced computational complexity. However, its performance degrades for time‐varying channels. To improve the performance of FD‐TE, they divide the received blocks into consecutive sub‐blocks where the channel impulse response remains fixed for each sub‐block. Due to the absence of cyclic prefix in the sub‐blocks, the overlap frequency‐domain equalisation (FDE) is used in the first iteration. In the following iterations, the authors remove the interference term, therefore the channel matrix becomes circular and low‐complexity FDE is used. Simulation results show that compared with the TD‐TE, the performance loss of FD‐TE equipped with the authors’ proposed scheme at the bit error rate of 1 × 10 −5 is <1 dB with much lower computational complexity. By real‐time software defined radio (SDR) implementation of the proposed receiver on a general purpose processor (GPP), the authors ensure real‐time feasibility of their algorithm. They use GNU radio tool for SDR implementation. It is shown that with GNU radio capabilities such as multi‐threading and pipelining, further reduction in processing time can be achieved.