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The following topics are dealt with: acquisition-synchronization; coding-modulation; UWB-impulse radio; signal generation; transceiver design; channel modeling; OFDM; transmitted reference; antennas; energy and bandwidth in wideband systems; networks and applications; diversity; circuits; positioning-localization
The satisfactory performance of classical tracking circuits presumes that acquisition (coarse synchronization) has provided a good estimate of the correct symbol or frame timing (typically within a fraction of the chip duration). This might not be a reasonable assumption for pilot-assisted UWB receivers in dense multipath, where initial acquisition of the LOS component is highly problematic, and coarse...
This paper addresses the problem of coarse synchronization of ultra wideband (UWB) signals in the dense multipath channel. We propose a very simple search strategy, based on successive constant integer jumps, which practically achieves minimum mean acquisition time (MAT) without using any channel knowledge. There is a parallelism between the popular bit reversal search, which is valid when the size...
We consider initial timing acquisition, frame synchronization and code acquisition for asynchronous DS-UWB transmissions in a distributed network topology, i.e., no common timing reference and neither synchronization among terminals are provided. Thus, when an arbitrary terminal in active mode needs to establish communication with reachable terminals, it listens for a common synchronization signal...
A two stage acquisition scheme for IR-UWB has been proposed to reduce the acquisition time of the spreading sequence. It has been shown that the performance of this scheme is better than that of the conventional scheme on AWGN channel. In this paper, the proposed scheme is investigated on the channel models of IEEE 802.15.4a. It is shown through the computer simulation that the proposed scheme can...
Ultra-wideband (UWB) impulse radio systems based on non-coherent on-off keying (OOK) energy detection are relatively simpler to implement than their coherent counterparts, because the strict synchronization requirements are relaxed. However, the design challenge is to set a hard decision threshold value after energy detection because the detected energy may vary due to multipath fading and inter-pulse...
In this paper, the ability of well-known energy detection (ED) and transmitted reference (TR) receivers for ultra wideband (UWB) low data rate (LDR) communications to detect synchronization sequences is studied. We focus especially on the degradation caused if, with an objective of low complexity, a hard decision is done on every chip of the sequence. The probability of missed detection and false...
Precise positioning is one attractive application of ultra wideband (UWB) systems. Its enormous bandwidth has generated high expectation on the spatial resolution that it could achieve. However, synchronization in the presence of dense multipath is challenging, since the first arrival is not necessarily the strongest one due to channel fading. It is unclear how high a spatial resolution can be realized...
One of the characteristics of UWB signals is pulse distortion, inherently determined by its huge bandwidth. Using cylinder model as an example, pulse distortion and its impacts on UWB system performance have been investigated. Although a lot of papers addressed the pulse distortion issue, quantifying the impacts of pulse distortion on the system performance appears to be novel. The simulation result...
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