Blind classification of the short-code and the long-code direct sequence spread spectrum signals

Qiu, P.Y.; Huang, Zhitao; Jiang, Wentao; Zhang, C.

doi:10.1049/iet-spr.2009.0033

Cited by 9 publications

(3 citation statements)

References 6 publications

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“…In the last few years, reconstructing transmitter elements when their specifications are unknown has attracted considerable research interesting. For example, results and findings on recovery of spreading codes have been published in [14]- [17]. However, considering a scrambler that destroys the correlation exiting in the spreading stream, we cannot normally use the algorithms.…”

Section: Discussionmentioning

confidence: 96%

Reconstructing Synchronous Scrambler With Robust Detection Capability in the Presence of Noise

Zhang

Wang

2015

IEEE Trans.Inform.Forensic Secur.

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Considering the channel noise was present, we presented techniques to reconstruct the feedback polynomial as well as the initial state of a scrambler placed after a channel encoder. The previous algorithms could not keep the detection performance over the design requirements, such as a false-alarm probability. Thus, we proposed a modified scheme to improve the detection capability. With multiple output sequences of matched filter that were scrambled by the same scrambler, we reduced the number of samples required for the reconstruction of the feedback polynomial when the signal-to-noise ratio was <0 dB. Meanwhile, we proposed a scheme to restore the initial state of the scrambler in the presence of channel noise. We also developed two lemmas and two theorems to reconstruct the synchronous scrambler with block summation. Following the lemmas and the theorems, we could use the blocks to generate a new sequence with certain method such as multiplying a dual word, and detect the optimal multiple of the original scrambler's feedback polynomial, or even the correct one.Index Terms-Synchronous scrambler, linear feedback shift register, linear block codes.

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Section: Discussionmentioning

confidence: 96%

Reconstructing Synchronous Scrambler With Robust Detection Capability in the Presence of Noise

Zhang

Wang

2015

IEEE Trans.Inform.Forensic Secur.

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“…According to [30], the correlation matrix can be represented as

R = \sum_{k = 1}^{K} A_{k} {bold-italicS}_{k}^{false(d_{k}^{c} false)} E (}{, {bold-italich}_{k}^{false(d_{k}^{b} false)} {bold-italich}_{k}^{false(d_{k}^{b} false) T}) {bold-italicS}_{k}^{false(d_{k}^{c} false) T} + σ_{w}^{2} I

E (}{, {bold-italich}_{k}^{false(d_{k}^{b} false)} {bold-italich}_{k}^{false(d_{k}^{b} false) T}) = E (}{, b_{k, i}^{false(d_{k}^{b} false)} b_{k, j}^{false(d_{k}^{b} false)}) = ({, \begin{matrix} right leftthickmathspace.5em \\ 1 i = j \\ 0 falsefalse| i - j falsefalse| \geq G, \\ c_{i, j}^{false(d false)_{k}^{b}} otherwise \end{matrix})

where

E falsefalse{\cdot falsefalse}

denotes expectation,

{(\cdot)}^{normalT}

denotes transpose,

{bold-italich}_{k}^{false(d_{k}^{b} false)} = diag false({bold-italicH}_{k}^{false(d_{k}^{b} false)} false)^{normalT}

and

{bold-italicS}_{k}^{}

…”

Section: Projection Principle For Ds‐cdma Signalmentioning

confidence: 99%

Blind spreading sequence estimation algorithm for long‐code DS‐CDMA signals in asynchronous multi‐user systems

Liang

Wang

et al. 2017

IET signal process.

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Despreading signal at receiver side requires prior knowledge of the spreading sequences in direct-sequence code division multiple access (DS-CDMA) system. However, the knowledge of spreading sequences is always unknown to the receiver in non-cooperative communication. Therefore the receiver has to estimate the spreading sequences in a blind manner. This study presents a novel algorithm to estimate the spreading sequences for asynchronous long-code (LC) DS-CDMA signals. By investigating the projection characteristics of the signal subspace, the authors treat the spreading sequence estimation problem as a discrete optimisation search problem that can be solved efficiently by modern optimisation search methods. Moreover, they design a successive subspace deflation scheme to alleviate interference from other users. Numerical experiments demonstrate that the proposed algorithm provides good estimation of the spreading sequences for LC-DS-CDMA signals. Compared with the existing algorithms, the proposed algorithm exhibits much better performance in large system load scenario with low signal-to-noise ratio.

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“…Gouda and Ali [15] gave a method of m ‐sequence detection by using code image print obtained from the co‐set summing of triple auto‐correlation peaks. Triple correlation theory has also been used in the detection and estimation of spreading sequence of LC‐DSSS signals [16]. However, PN codes estimation of LSC‐DSSS signals by using triple correlation theory has not been reported at present.…”

Section: Introductionmentioning

confidence: 99%

Blind estimation of pseudo‐random codes in periodic long code direct sequence spread spectrum signals

Zhao

Shen

2016

IET Communications

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Blind classification of the short-code and the long-code direct sequence spread spectrum signals

Cited by 9 publications

References 6 publications

Reconstructing Synchronous Scrambler With Robust Detection Capability in the Presence of Noise

Reconstructing Synchronous Scrambler With Robust Detection Capability in the Presence of Noise

Blind spreading sequence estimation algorithm for long‐code DS‐CDMA signals in asynchronous multi‐user systems

Blind estimation of pseudo‐random codes in periodic long code direct sequence spread spectrum signals

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