Digital blind despreading method for intermediate frequency short‐code DSSS signal. Issue 14 (1st August 2020)

• Record Type: Journal Article
• Authors: Qiu, Zhaoyang; Peng, Hua; Li, Tianyun
• Is Part Of: IET communications. Volume 14:Issue 14(2020)
• Page Start: 2360
• Page End: 2368
• Publication Date: 2020-08-01
• Subjects: eigenvalues and eigenfunctions -- demodulation -- spread spectrum communication -- synchronisation -- random sequences -- code division multiple access -- decomposition -- communication complexity -- codes; EVD algorithm -- code synchronisation -- blind despreading process -- PN code estimation -- digital blind despreading method -- intermediate frequency short‐code DSSS signal -- direct sequence spread spectrum signals -- military communication systems -- civilian communication systems -- signal‐to‐noise ratio -- strong antijamming capability -- multipath fading -- pseudorandom sequence -- baseband signal -- PN sequence -- noncooperative context -- received signals -- neural network algorithm -- clustering method -- IF DSSS -- eigenvalue decomposition -- Crammer‐Rao bound; Telecommunication systems -- Periodicals; Speech processing systems -- Periodicals; 621.38205
• DOI: 10.1049/iet-com.2019.0351
• Languages: English
• ISSNs: 1751-8628

Abstract

Abstract : Direct sequence spread spectrum (DSSS) signals are widely used in various military and civilian communication systems owing to its useful properties, such as lower working signal‐to‐noise ratio, strong anti‐jamming capability, and robustness to multi‐path fading. In past few years, the estimation for spreading sequence in non‐cooperative context has attracted lots of attention. Several methods are developed to realise a recovery of the sequence. Eigenvalue decomposition (EVD) is a classical method to obtain an effective estimation by extracting the main eigenvectors. The only obstacle to apply EVD method into practical systems is high complexity of computation when spreading sequence is long. Alternative algorithms such as neural network and clustering method have lower complexity, but an evident loss in performance. In this work, the authors propose to generalise the EVD algorithm to intermediate frequency (IF) short‐code DSSS with an unknown carrier offset. The blind despreading process is designed to complete correlation demodulation. As a result, the computational afford is largely decreased due to the operation on IF real signal. To evaluate the performance, they derive the Crammer‐Rao bound for spreading code estimation and compare the performance of several methods. Simulation demonstrates the superiority of the proposed method in estimation accuracy and runtime.