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This paper proposes a novel chaotic PN (pseudo-noise) sequence for ultra wideband (UWB) impulse radio time-hopping pulse-position-modulation (TH-PPM). The proposed chaotic sequence is generated by a novel chaotic system, and its randomness characteristics are analyzed and tested via FIPS 140- 1 standard. Then the PN sequence is applied to the TH-PPM-UWB system to enhance its antinoise performance...
A DS-CDMA system is said to be Overloaded if the number of users supported is more than the spreading factor N. Overloading is an attractive candidate for next generation cellular telephony that calls for a higher user capacity than that supported by conventional DS-CDMA systems. This work derives an accurate analytical model for Overloaded DS-CDMA system under imperfect synchronization. The Model...
In this paper, a joint blind synchronization and demodulation scheme is developed for ultra-wideband (UWB) impulse radio systems. Based on the prior knowledge of the direct-sequence (DS) spread codes, the proposed approach can achieve frame-level synchronization with the help of frame-rate samples. Taking advantage of the periodicity of the DS spread codes, the frame-level synchronization can be carried...
In this paper, a blind two-step synchronization algorithm is proposed for direct-sequence (DS) ultra-wideband (UWB) communication systems. In the first step, the start of individual frames is estimated via simple square, overlap-add operation and energy detection technique. Then the first frame in each symbol is identified by exploiting the randomicity of DS codes and information symbols at the second...
A novel spread spectrum communication system is proposed, being characterized by a very compact yet efficient implementation. A particular elementary cellular automaton with rule 45 is used as the generator of spreading sequences while it also has synchronization capabilities. Simulations demonstrate that generated sequences are orthogonal and the performances of the proposed system are comparable...
In this paper, a two-step synchronization is firstly presented for direct-sequence (DS) ultra-wideband (UWB) communication systems, and then the corresponding demodulation scheme are proposed. During the synchronization process, the start of individual frames is estimated via simple square and overlap-add operation at the first step. Then the first frame in each symbol is identified by exploiting...
Cell overloading is a bandwidth efficient scheme to increase the number of users in a fixed bandwidth for mobile applications. One of the efficient schemes to overload a CDMA system is to use two sets of orthogonal signal waveforms (O/O) [2]. An iterative soft decision interference cancellation receiver (SDIC) scheme is used to cancel interference between the two sets of users. In this paper, the...
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