A VHDL-AMS Simulation Environment for an UWB Impulse Radio Transceiver

Ultra-Wide-Band (UWB) communication based on the impulse radio paradigm is becoming increasingly popular. According to the IEEE 802.15 WPAN Low Rate Alternative PHY Task Group 4a, UWB will play a major role in localization applications, due to the high time resolution of UWB signals which allow accurate indirect measurements of distance between transceivers. Key for the successful implementation of UWB transceivers is the level of integration that will be reached, for which a simulation environment that helps take appropriate design decisions is crucial. Owing to this motivation, in this paper we propose a multiresolution UWB simulation environment based on the VHDL-AMS hardware description language, along with a proper methodology which helps tackle the complexity of designing a mixed-signal UWB System-on-Chip. We applied the methodology and used the simulation environment for the specification and design of an UWB transceiver based on the energy detection principle. As a by-product, simulation results show the effectiveness of UWB in the so-called ranging application, that is the accurate evaluation of the distance between a couple of transceivers using the two-way-ranging metho

Implementation Aspects of a Transmitted-Reference UWB Receiver

In this paper, we discuss the design issues of an ultra wide band (UWB) receiver targeting a single-chip CMOS implementation for low data-rate applications like ad hoc wireless sensor networks. A non-coherent transmitted reference (TR) receiver is chosen because of its small complexity compared to other architectures. After a brief recapitulation of the UWB fundamentals and a short discussion on the major differences between coherent and non-coherent receivers, we discuss issues, challenges and possible design solutions. Several simulation results obtained by means of a behavioral model are presented, together with an analysis of the trade-off between performance and complexity in an integrated circuit implementation

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

Performance Comparison of TR and FSRUWB System Using Particle Filter: Effects of Frequency, Data Rate, Multi-Path and Multi-Channel Communication

In this study, we introduced a novel scheme based on Transmitted References (TR) and Frequency Shifted Reference (FSR) for ultra-wideband (UWB) system. By taking into account tracking loop-based particle filtering together with a data collecting approach for single and multi-path channel situations, the suggested method is an enhanced model. Each particle's location is determined using this filtering technique, which is then utilised to calculate the timing inaccuracy and regulate the UWB system's timing pulse. Also, it can tackle the multimodal distribution of errors then effectively approximate the optimal solution. The data distribution is discretised via a number of particles that are weighted samples evolving concerning time duration. The simulation results show that, in terms of error rate, number of particles, and delay response, the recommended model of FSR-UWB with particle filter performs better than the TR-UWB with and without considering particle filter

Wi-PoS : a low-cost, open source ultra-wideband (UWB) hardware platform with long range sub-GHz backbone

Ultra-wideband (UWB) localization is one of the most promising approaches for indoor localization due to its accurate positioning capabilities, immunity against multipath fading, and excellent resilience against narrowband interference. However, UWB researchers are currently limited by the small amount of feasible open source hardware that is publicly available. We developed a new open source hardware platform, Wi-PoS, for precise UWB localization based on Decawave’s DW1000 UWB transceiver with several unique features: support of both long-range sub-GHz and 2.4 GHz back-end communication between nodes, flexible interfacing with external UWB antennas, and an easy implementation of the MAC layer with the Time-Annotated Instruction Set Computer (TAISC) framework. Both hardware and software are open source and all parameters of the UWB ranging can be adjusted, calibrated, and analyzed. This paper explains the main specifications of the hardware platform, illustrates design decisions, and evaluates the performance of the board in terms of range, accuracy, and energy consumption. The accuracy of the ranging system was below 10 cm in an indoor lab environment at distances up to 5 m, and accuracy smaller than 5 cm was obtained at 50 and 75 m in an outdoor environment. A theoretical model was derived for predicting the path loss and the influence of the most important ground reflection. At the same time, the average energy consumption of the hardware was very low with only 81 mA for a tag node and 63 mA for the active anchor nodes, permitting the system to run for several days on a mobile battery pack and allowing easy and fast deployment on sites without an accessible power supply or backbone network. The UWB hardware platform demonstrated flexibility, easy installation, and low power consumption

Timing Acquisition Performance Metrics of Tc-DTR UWB Receivers over Frequency-Selective Fading Channels with Narrow-Band Interference: Performance Analysis and Optimization

International audienceThe successful deployment of Impulse Radio (IR) Ultra Wide Band (UWB) wireless communication systems requie that they coexist and contend with a variety of interfering signals co–located over the same transmission band. In fact, if on the one hand the large transmission bandwidth of IR–UWB signals allows them to resolve multipath components and exploit multipath diversity, on the other hand it yields some new coexistence challenges for both unlicensed commercial and military communication systems, which are required to be robust to unintentional and intentional jammers, respectively. In particular, the design and analysis of low–complexity receiver schemes with good synchronization capabilities and high robustness to Narrow–Band Interference (NBI) is acknowledged as an important issue in IR–UWB research. Motivated by this consideration, in [1] we have recently proposed a low–complexity receiver design, the so–called Chip–Time Differential Transmitted–Reference (Tc–DTR) scheme, and have shown that it is more robust to NBI than other non–coherent receiver schemes available in the literature. In this paper, we aim at generalizing the results in [1] and at developing the enabling analytical tools for the analysis and design of timing acquisition algorithms for non–coherent receivers over frequency–selective fading channels with NBI. Furthermore, we move from the proposed analytical framework to tackle the optimization problem of devising optimal signature codes to reduce the impact of NBI on the performance of the Tc–DTR synchronizer. Analytical frameworks and findings are substantiated via Monte Carlo simulations

UWB communication systems acquisition at symbol rate sampling for IEEE standard channel models

For ultra-wideband (UWB) communications, acquisition is challenging. The reason is from the ultra short pulse shape and ultra dense multipath interference. Ultra short pulse indicates the acquisition region is very narrow. Sampling is another challenge for UWB design due to the need for ultra high speed analog-to digital converter.A sub-optimum and under-sampling scheme using pilot codes as transmitted reference is proposed here for acquisition. The sampling rate for the receiver is at the symbol rate. A new architecture, the reference aided matched filter is studied in this project. The reference aided matched filter method avoids using complex rake receiver to estimate channel parameters and high sampling rate for interpolation. A limited number of matched filters are used as a filter bank to search for the strongest path. Timing offset for acquisition is then estimated and passed to an advanced verification algorithm. For optimum performance of acquisition, the adaptive post detection integration is proposed to solve the problem from dense inter-symbol interference during the acquisition. A low-complex early-late gate tracking loop is one element of the adaptive post detection integration. This tracking scheme assists in improving acquisition accuracy. The proposed scheme is evaluated using Matlab Simulink simulations in term of mean acquisition time, system performance and false alarm. Simulation results show proposed algorithm is very effective in ultra dense multipath channels. This research proves reference aided acquisition with tracking loop is promising in UWB application

Performance Analysis and Optimization of Tc-DTR IR-UWB Receivers over Multipath Fading Channels with Tone Interference

International audienceIn this paper, we analyze the performance of a particular class of transmitted-reference receivers for impulse radio ultra wideband communication systems, which is called chip-time differential transmitted-reference (Tc-DTR). The analysis aims at investigating the robustness of this receiver to single-tone and multi-tone narrowband interference (NBI) and comparing its performance with other non-coherent receivers that are proposed in the literature. It is shown that the Tc-DTR scheme provides more degrees of freedom for performance optimization and that it is inherently more robust to NBI than other non-coherent receivers. More specifically, it is analytically proved that the performance improvement is due to the chip-time-level differential encoding/decoding of the direct sequence (DS) code and to an adequate design of DS code and average pulse repetition time. The analysis encompasses performance metrics that are useful for both data detection (i.e., average bit error probability) and timing acquisition (i.e., false-alarm probability Pfa and detection probability Pd). Moving from the proposed sem-analytical framework, the optimal code design and system parameters are derived, and it is highlighted that the same optimization criteria can be applied to all the performance metrics considered in this paper. In addition, analytical frameworks and theoretical findings are substantiated through Monte Carlo simulations

Waveform-independent frame-timing acquisition for UWB signals

In this paper, the problem of frame-level symbol timing acquisition for UWB signals is addressed. The main goal is the derivation of a frame-level timing estimator which does not require any prior knowledge of neither the transmitted symbols nor the received template waveform. The independence with respect to the received waveform is of special interest in UWB communication systems, where a fast and accurate estimation of the end-to-end channel response is a challenging and computationally demanding task. The proposed estimator is derived under the unconditional maximum likelihood criterion, and because of the low power of UWB signals, the low-SNR assumption is adopted. As a result, an optimal frame-level timing estimator is derived which outperforms existing acquisition methods in low-SNR scenarios.Peer Reviewe