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The sensitivity of the system capacity to the synchronization error is analyzed for a time-hopping direct-sequence binary phase shift keying transmitted-reference ultra-wide bandwidth receiver. Both additive white Gaussian noise and multipath fading channels are considered. Numerical results show that the Gaussian distributed synchronization error gives the highest capacity and that there is an optimum...
In this paper, we introduce ways to improve the robustness by lowering the packet loss rates of transmissions using ultra-wideband impulse radio (UWB-IR). It has been shown that the packet loss rate caused by erroneous synchronization can be tremendously decreased compared to the preamble specified in the standard IEEE 802.15.4a by our approach. These improvements are particularly intended for low-power,...
In this paper, a novel synchronization algorithm dispensing with searching is proposed for UWB communications. By adopting a stream of alternating orthogonal pulses, frame-level synchronization can be achieved without training sequence involved. Without any searching procedure, the timing offset estimator is obtained in a closed form, therefore considerably reducing the synchronization time. Simulations...
Extremely short duration of pulse introduces stringent requirements to the UWB system synchronization. Especially in RAKE scheme, a small timing jitter of system causes performance degradation severely due to the decreased energy acquired by local template. In this paper, a novel method of timing jitter suppression is proposed, in which the cross-correlation function between local template and received...
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...
One of the biggest challenges in ultra-wideband (UWB) communications is the accurate and rapid timing acquisition for the receiver. This paper presents a timing acquisition scheme dispensing with searching for UWB communications. Without training sequence involved, timing offset parameter is estimated by exploiting a stream of alternating orthogonal pulses, and frame-level synchronization can be achieved...
Wireless biomedical applications require low power operations for long, uninterrupted durations of use. In order to harness the low power characteristics of Ultra Wideband (UWB) systems, issues involving the synchronization of extremely short pulses have to be resolved as they surface as major bottlenecks of the design of such systems. The situation is particularly adverse in short range communication...
The use of OFDM for UWB applications is a promising choice to simplify the receiver design and to maximize the bandwidth scalability, as well as to adapt to various spectrum allocations. However, most OFDM analyses assume idealized conditions when it comes to the waveform characteristics at the receiver. A cyclic prefix (CP) duration longer than the channel delay spread, and perfect time/frequency...
In this paper, a novel quasi-4PPM modulation is presented firstly for UWB systems, and then the corresponding synchronization and demodulation schemes are proposed. Due to the nature of the unique signal structure, the information bits are transmitted and demodulated by twos, which doubles the transmission efficiency compared with conventional existing methods under the same condition. Besides, the...
The impulsive UWB pulses require extremely high sampling rates as well as accurate timing synchronization. Such coherent transceivers as RAKE are too complicated for current applications. The low complexity receiver provides the first commercially feasible solution to a broad class of low-data-rate applications. One approach is time reversed UWB communication as an alternative to coherent reception...
Time synchronization is a major challenge and a rich area of study in chirp ultra-wideband (UWB) communication systems. Since the pulse compressed by the matched filter is very short, the performance of chirp receivers is closely relative to precise timing acquisition. However, the existent method is very sensitive to noise. In this paper, we propose an improved synchronization method that allows...
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