Low-Sampling Rate UWB Channel Characterization and Synchronization

We consider the problem of low-sampling rate high-resolution channel estimation and timing for digital ultra-wideband (UWB) receivers. We extend some of our recent results in sampling of certain classes of parametric non-bandlimited signals and develop a frequency domain method for channel estimation and synchronization in ultra-wideband systems, which uses sub-Nyquist uniform sampling and well-studied computational procedures. In particular, the proposed method can be used for identification of more realistic channel models, where different propagation paths undergo different frequency-selective fading. Moreover, we show that it is possible to obtain high-resolution estimates of all relevant channel parameters by sampling a received signal below the traditional Nyquist rate. Our approach leads to faster acquisition compared to current digital solutions, allows for slower A/D converters, and potentially reduces power consumption of digital UWB receivers significantly

Energy Detection UWB Receiver Design using a Multi-resolution VHDL-AMS Description

Ultra Wide Band (UWB) impulse radio systems are appealing for location-aware applications. There is a growing interest in the design of UWB transceivers with reduced complexity and power consumption. Non-coherent approaches for the design of the receiver based on energy detection schemes seem suitable to this aim and have been adopted in the project the preliminary results of which are reported in this paper. The objective is the design of a UWB receiver with a top-down methodology, starting from Matlab-like models and refining the description down to the final transistor level. This goal will be achieved with an integrated use of VHDL for the digital blocks and VHDL-AMS for the mixed-signal and analog circuits. Coherent results are obtained using VHDL-AMS and Matlab. However, the CPU time cost strongly depends on the description used in the VHDL-AMS models. In order to show the functionality of the UWB architecture, the receiver most critical functions are simulated showing results in good agreement with the expectations

Multi Detector Fusion of Dynamic TOA Estimation using Kalman Filter

In this paper, we propose fusion of dynamic TOA (time of arrival) from multiple non-coherent detectors like energy detectors operating at sub-Nyquist rate through Kalman filtering. We also show that by using multiple of these energy detectors, we can achieve the performance of a digital matched filter implementation in the AWGN (additive white Gaussian noise) setting. We derive analytical expression for number of energy detectors needed to achieve the matched filter performance. We demonstrate in simulation the validity of our analytical approach. Results indicate that number of energy detectors needed will be high at low SNRs and converge to a constant number as the SNR increases. We also study the performance of the strategy proposed using IEEE 802.15.4a CM1 channel model and show in simulation that two sub-Nyquist detectors are sufficient to match the performance of digital matched filter

Low complexity TOA estimator for multiuser DS-UWB system

International audienceIn this paper, we present a low complexity Time Of Arrival (TOA) estimator for direct-sequence ultra-wideband (DS-UWB) ranging system. With the assumption that TOA is the integer multiples of chip duration, our decoupled multiuser ranging (DEMR) estimator employs integrate-and-dump filter (IDF) in chip sampling rate instead of matched filter (MF) as the front-end to reduce sampling rate and to simplify the structure of estimator. This subsampling estimator is simplified substantially in dense multipath environment furthermore due to the long repetition time of DS-UWB pulse. Simulation results show that compared with other low complexity TOA estimator, DEMR estimator is not only quite near-far resistant, but also can obtain noticeable ranging performance in the fully loaded system

A Low-Complexity Joint Synchronization and Detection Algorithm for Single-Band DS-CDMA UWB Communications

The problem of asynchronous direct-sequence code-division multiple-access (DS-CDMA) detection over the ultra-wideband (UWB) multipath channel is considered. A joint synchronization, channel-estimation, and multiuser detection scheme based on the adaptive linear minimum mean square error (LMMSE) receiver is presented and evaluated. Further, a novel nonrecursive least-squares algorithm capable of reducing the complexity of the adaptation in the receiver while preserving the advantages of the recursive least-squares (RLS) algorithm is presented

A dual-mode Ultra-Wideband wireless platform for remote patient monitoring systems

The combination of two factors demands the need to find a solution that guarantees the well-being of the people suffering from chronic diseases. On the one hand, the increase of the life expectancy leads to an older world's population. On the other hand, the aged are more likely to suffer from chronic diseases and/or injuries. This thesis deals with the design of an Ultra-Wideband-based node of a Remote Patient Monitoring (RPM) network. This node must be able to measure, collect and transmit some medical parameters of a patient. Existing RPM networks use two different hardware platforms: one for measuring and another one for transmitting. This leads to high cost and high power consumption. Since a RPM network is typically composed by hundreds or thousands of nodes, a new platform with lower cost and power consumption is vital to make such a system work. This thesis explores the viability to achieve the dual-mode operation: Radar Mode (RM) to obtain a certain parameter and Data Transmission Mode (DTM) to send it to another node. A platform using Impulse-Radio Ultra-Wideband (IR-UWB) has been proposed to accomplish this goal. The simulations done verified its feasibility. Moreover, the physical experiments carried out validated the transmitter. Nevertheless, due to time and hardware limitations, the receiver has not been experimentally validated yet