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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...
This paper is concerned with timing acquisition for ultra-wideband (UWB) communication systems operating in a dense multipath environment with a modest clock frequency offset (CFO). A low complexity maximum likelihood acquisition scheme based on a practical energy detector is considered in this paper where the dwell time for observing the signal at a given trial offset is fixed. This dwell time interval...
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...
In this paper, we present an analog Viterbi decoder structure suitable for direct sequence UWB applications. Since the UWB receiver has data rates of several hundreds of megabits per second, the elimination of the power consuming A/D converter makes an analog Viterbi decoder a promising alternative to conventional digital decoders. Moreover, the high-speed implementation of the Viterbi decoder is...
Ultra wideband (UWB) communication systems are generally applied to short-range wireless communications. In order to achieve higher rates or to support multiple access capabilities, direct sequence spread spectrum (DSSS) techniques have been introduced to UWB systems. Furthermore, the concept of M-ary code shift keying (M-CSK) was introduced into DSSS systems to achieve higher rates. In this work,...
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