Int. J. Computer Aided Engineering and Technology, Vol. 12, No. 2, 2020 219 Copyright © 2020 Inderscience Enterprises Ltd. A combining technique based on channel shortening equalisation for ultra wideband cooperative systems Asma Ouardas* and Sid Ahmed Elahmar TTNS Laboratory, Department of Telecommunication, University of Djillali Liabès, 22000 Sidi Bel Abbes, Algeria Email: asma_telecom2@hotmail.fr Email: silahmar@yahoo.fr *Corresponding author Abstract: This paper presents a novel combining technique based on the channel shortening approach for cooperative diversity in the context of time hopping ultra wideband (TH-UWB) systems. Since UWB channel has very long impulse response, TH-UWB performances are affected by inter-symbol interference (ISI). Therefore, the use of the rake diversity combining is very effective, but it increases the receiver complexity due to its large number of correlations. The idea is to introduce a channel shortening equaliser (CSE) before the rake reception in first and second time slots at the relay and destination, respectively. The decode and forward (DF) is used as a relay protocol to retransmit signals and the relay is supposed equipped with multiple antennas and antenna selection criterion is used to exploit the diversity. Numerical results show that significant improvement in the BER is obtained by our proposed structure comparing to cases where the relay is equipped with a single antenna and multiple antennas (full diversity). Keywords: time hopping ultra wideband; TH-UWB; rake receiver; cooperative diversity; antenna selection; decode-and-forward; channel shortening equaliser; CSE; inter-symbol interference; ISI; full diversity. Reference to this paper should be made as follows: Ouardas, A. and Elahmar, S.A. (2020) ‘A combining technique based on channel shortening equalisation for ultra wideband cooperative systems’, Int. J. Computer Aided Engineering and Technology, Vol. 12, No. 2, pp.219–236. Biographical notes: Asma Ouardas graduated from the University of Dr. Tahar Moulay of Saida. Presently, she is pursuing her post-graduation in the Sidi Bel Abbes University in the area of telecommunication systems, UWB, cooperative diversity, communication over multipath channel and channel shortening. Sid Ahmed Elahmar did his PhD in the area of telecommunication. He received his Engineer degree in Electrical Engineering, his MASc from the USTO University, Oran. Currently, he is working as a Professor of Communications Engineering in the Department of Telecommunication at the University of Sidi Bel Abbes. His research interests include signal processing for telecommunications, wireless networks, high-speed communications and optical OFDM communication networks.