Detection of PPM-UWB Random Signals (original) (raw)

Fast Multi-Symbol Based Iterative Detectors for UWB Communications

EURASIP Journal on Advances in Signal Processing, 2010

Ultra-wideband (UWB) impulse radios have shown great potential in wireless local area networks for localization, coexistence with other services, and low probability of interception and detection. However, low transmission power and high multipath effect make the detection of UWB signals challenging. Recently, multi-symbol based detection has caught attention for UWB communications because it provides good performance and does not require explicit channel estimation. Most of the existing multi-symbol based methods incur a higher computational cost than can be afforded in the envisioned UWB systems. In this paper, we propose an iterative multi-symbol based method that has low complexity and provides near optimal performance. Our method uses only one initial symbol to start and applies a decision directed approach to iteratively update a filter template and information symbols. Simulations show that our method converges in only a few iterations (less than 5), and that when the number of symbols increases, the performance of our method approaches that of the ideal Rake receiver.

Sample-wise differential detection of Impulse-Radio Ultra-Wideband Pulse Position modulated symbols

2012 6th International Symposium on Medical Information and Communication Technology (ISMICT), 2012

The paper describes technique for differential detection of Impulse Radio Ultra-Wideband (IR-UWB) Pulse Position Modulated (PPM) symbols. An expression for probability of error in noise is derived. The numerical results show the method's performance enhancement compared to the energy detection in noise and considerable performance enhancement in multiuser interference. The method is applicable to the mandatory mode of the IEEE 802.15.6 Body Area Network (BAN) IR-UWB standard.

A New Approach for UWB Channel Estimation

2005

In this paper, a new channel estimation approach is proposed for ultra-wideband (UWB) communication systems. Performance of UWB systems employing RAKE receivers highly depends on the channel knowledge. Because UWB systems operate in dense multipath environments, channel estimation task becomes more complicated. Some channel estimation methods have been proposed for UWB systems. Here a very simple and cost effective channel estimation method is presented. We develop a data-aided estimation of channel parameters in UWB systems employing time-hopping pulse-position-modulation (TH-PPM). This method can be used in time-hopping pulse-amplitude-modulation (TH-PAM) and direct-sequence (DS) spread-spectrum systems as well. Computer simulations show that the proposed method is competitive with the maximum likelihood (ML) method, in both single-user and multi-user scenarios, with less computational complexity and the ability to extract the exact parameters of the impulse response of the channel. The latter property does not exist in the ML method in dense multipath environments

An Effective Selective Detection Scheme Based on Pulse Repetition for Noncoherent UWB Systems

IEEE Transactions on Circuits and Systems II: Express Briefs, 2008

We propose a selective detection scheme based on pulse repetition considering the bit-error rate (BER) performance and complexity of noncoherent ultra-wide-band (UWB) systems. To take system complexity into account, the proposed scheme transmits the UWB signals by simple pulse repetition at the transmitter, like conventional pulse repetition coding (PRC). However, to effectively improve the BER performance, the proposed scheme performs selective detection by estimating the signal-to-noise ratio of the received pulse-repeated signals at the UWB receiver. Hence, the proposed scheme effectively improves the BER performance of the noncoherent UWB systems without much increasing system complexity, as compared to the conventional PRC.

Detection of UWB signal using dirty template approach

Signal, Image and Video Processing, 2013

This paper handles the problem of detecting ultra-wideband signals in the presence of dense multipath channel and ambient noise. To design a low-complexity high-performance signal detection process, the dirty template approach is proposed. We first explain the dirty template technique and its implementation in UWB communication systems. Then, the Neyman-Pearson theorem is applied to derive the UWB signal detector and select the suitable detection threshold values. Finally, the performance of the proposed dirty template detector is evaluated in terms of the detection and false alarm probabilities for different threshold values, signal-to-noise ratio and number of dataaided symbols.

Orthogonal on–off-based near–far-resistant detection with diversity technique in UWB systems

IET Communications, 2007

A convenient signalling scheme, called orthogonal on-off (O 3), together with a simple one-shot linear decorrelating detector (LDD) and a RAKE bank, is adopted in asynchronous ultrawideband (UWB) systems. The performance of the proposed system is evaluated over multipath fading channels. This investigation also analyses mathematically the effect of the maximal-ratio combining diversity technique on the O 3 UWB LDD performance over lognormal fading channels. The analytical and simulation results indicate that the diversity technique significantly improves the performance of the O 3 UWB LDD scheme over fading channels, and the proposed receiver still demonstrates a better near-far-resistant property than a conventional UWB receiver.

Optimum multi-user detection in ultra-wideband (UWB) multiple-access communication systems

2003

This paper investigates multiuser detection in multiple-access communicaton systems based on ultrawideband (UWB) technology. As user numbers increase and the bandwidth to pulse repetition frequency (PRF) decreases, multiple-access interference (MAI) is expected to adversely affect system capacity and performance. The paper presents a framework for the design of multiuser detectors and proposes the optimum multiuser detector for UWB. Numerical examples illustrate the performance of the optimum detector versus that of the conventional single-user UWB detector. I. INTRODUCTION Ultra-wideband (UWB) or impulse radio for commercial communication applications is a recent innovation [1, 2, 3, 4]. UWB transmitters employ short carrierless pulses at low power with bandwidths of up to or more than several GHz [1, 2]. The technology has many advantages which stem from its ultra-wideband nature. It not only experiences significantly less fading margins as reported recently in [5, 6, 7]. It also offers extremely fine time-resolution and the possibility of achieving processing gains much larger than those of typical direct-sequence spread-spectrum communication systems [5]. In particular, the absence of a sinusoidal carrier obviates the need for radio frequency (RF) or intermediate frequency (IF) mixers. It is important to note the many challenges of UWB deployment [8, 4]. These include regulatory issues and, in particular, coexistence and interference-related issues with Global Positioning System (GPS) receivers. Potential applications include wireless local area networks (LAN), ranging devices and multiple-access communication systems for short-range or indoor applications [3]. This report considers the application of UWB technology to multiple-access communication systems. The idea of multiple-access communications using UWB (UWB-MA) appears to have been first proposed by Scholtz in [9] with subsequent analyses in [3, 10, 11]. Such systems are conceptually similar to asynchronous code-division multiple-access (CDMA) systems in certain aspects. The

On the Variance-Based Detection for Impulse Radio UWB Systems

IEEE Transactions on Wireless Communications, 2016

A variance-detection (VD) based impulse radio ultra-wideband (IR-UWB) system has a potential of mitigating narrowband interference (NBI), even in multipath environments. However, as a highly nonlinear system which involves fourth-order multiplications, comprehensive analysis and evaluations of its performances have not been seen so far. In this paper, we address the issues by developing a log-normal random distribution model for the VD-based IR-UWB receiver and deriving the analytical bit-error-rate formulas for the system in both additive white Gaussian noise and CM1 multipath channels with and without NBIs for the first time. Furthermore, through both theoretical analysis and simulations, we show that the presented VD-based receivers can outperform the conventional energydetection based and the fourth-order detection based receivers and have a stronger inherent ability to mitigate destructive performance degradation caused by strong NBIs. This makes the VD-based IR-UWB system a good candidate as a non-coherent IR-UWB receiver for low power and low complexity applications.

Frequency domain detectors for different data-rate short-range UWB communications

IEEE International Symposium on Spread Spectrum Techniques and Applications, 2006

Low and high data-rate applications can be foreseen for future ultra-wideband systems which are based on impulse radio and proper detection schemes have to be designed for the most general scenarios. In this paper, we study the performance of a suitable communication scheme in two different short-range communication scenarios where a base station transmits low or high data-rate flows to several mobile terminals in an indoor environment characterized by severe multipath propagation. The proposed system relies on both the introduction of the cyclic prefix at the transmitter and the use of a frequency domain detector at the receiver. Two different detection strategies based either on the Zero Forcing (ZF) or on the Minimum Mean Square Error (MMSE) criteria have been investigated and compared with the classical RAKE. The results show that the proposed approach is well suited in indoor wireless environment where multipath propagation tends to increase the effects of the interference.