• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.5C
• /
• pp.555-560
• /
• 2009

A vehicle radar has been studied to avoid the collision of vehicles. A vehicle radar using direct sequence-ultra wideband (DS-UWB) measures the distance between a vehicle and an objective with a sufficient time margin. Therefore, the receiver should estimate the distance by processing the short UWB pulse rapidly. There have been several investigations for distance measuring based on DS-UWB signals. In this paper, we propose a novel method for rapid measuring processing time. Simulation results show that the proposed method has a shorter processing time than the conventional method.

• Journal of Communications and Networks
• /
• v.11 no.3
• /
• pp.287-296
• /
• 2009

Although asymptotic bounds of wireless network capacity have been heavily pursued, the answers to the following questions are still critical for network planning, protocol and architecture design: Given a three-dimensional (3D) network space with the number of active users randomly located in the space and using the wireless communication technology, what are the expected per-flow throughput, network capacity, and network transport capacity? In addition, how can the protocol parameters be tuned to enhance network performance? In this paper, we focus on the ultra wideband (UWB) based wireless personal area networks (WPANs) and provide answers to these questions, considering the salient features of UWB communications, i.e., low transmission/interference power level, accurate ranging capability, etc. Specifically, we demonstrate how to explore the spatial multiplexing gain of UWB networks by allowing appropriate concurrent transmissions. Given 3D space and the number of active users, we derive the expected number of concurrent transmissions, network capacity and transport capacity of the UWB network. The results reveal the main factors affecting network (transport) capacity, and how to determine the best protocol parameters, e.g., exclusive region size, in order to maximize the capacity. Extensive simulation results are given to validate the analytical results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.3A
• /
• pp.205-212
• /
• 2009

A novel channel estimation scheme is proposed for coherent Impulse Radio Ultra Wideband (IR-UWB) system based on IEEE 802.15.4a specification. By extracting and utilizing the information on the frequency synchronization, the proposed channel estimation algorithm improves the receiver performance even under the restricted number of preamble symbols in IEEE 802.15.4a signal format. Simulation results over the IEEE 802.15.4a channel models show the performance gain with the proposed algorithm compared to ordinary channel estimation method.

• Journal of electromagnetic engineering and science
• /
• v.14 no.1
• /
• pp.31-35
• /
• 2014

An ultra-wideband (UWB) circular monopole antenna with a multiband-notched characteristic is proposed. The multiband-notched filter consists of three different sized folded slots, which are distinctly assigned for the notched band at the 3.5-GHz WiMAX, 5-GHz WLAN, and 8-GHz ITU bands. The proposed antenna results in a measured ${\mid}S_{11}{\mid}$ < -10 dB, which completely covers the UWB band (3.1 10.6 GHz) with three notched bands at 3.5, 5.5, and 8.0 GHz. The antenna yields an omnidirectional radiation pattern and high radiation efficiency.

• Journal of Communications and Networks
• /
• v.10 no.3
• /
• pp.297-300
• /
• 2008

The capacity of ultra-wideband (UWB) systems in presence of narrowband interference (NBI) is studied. By appropriately modifying the Shannon capacity formula, an analytical expression for the capacity of M-ary pulse position modulation (PPM) signals in the presence of NBI is obtained. Performance evaluation results for the capacity of such signals as a function of the NBI carrier frequency and power are also presented.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.229-233
• /
• 2003

In this paper we theoretically analyze the probability of error for M-ary pulse position modulation (PPM) ultra-wideband (UWB) multiple access system using Gaussian monopulse. The optimum detection of UWB signals using M-ary orthogonal PPM in additive white Gaussian noise (AWGN) and multiple access interference (MAI) is considered, then receiver signal to noise power ratio (SNR) and upper bound fur the bit error rate (BER) are derived. Numerical results considering some practical parameters are presented.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.1
• /
• pp.41-48
• /
• 2004

In this paper, we analyzed channel performance of PPM modulated UWB communication system in indoor radio fading environment that consider amplitude characteristic of channel. Fading channel considered various channel environments by fading index m utilizing Nakagami-m distribution model with data through an UBW radio signal experiment that announced in existing. Also, we improved performance of system that it is decreased in fading environment employing convolution encoding techniques.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.5
• /
• pp.884-891
• /
• 2001

In this paper, We use Antipodal signal for data modulation of Ultra Wideband(UWB) system. This has maximum Euclidean distance and -1 or 0 of correlation values. With adapting this signal to M-ary that and time hopped pattern, We designed multiple access system. UWB Antipodal signal employes Gaussian monopulse and Rayleigh monopulse. Using these signals, we analysis and compare error probability, the number of user and data rate of the two systems under the AWGN.

• ETRI Journal
• /
• v.32 no.3
• /
• pp.460-463
• /
• 2010

This letter proposes an energy-detection-based non-data-aided weighted non-coherent receiver (NDA-WNCR) scheme for impulse radio ultra-wideband (IR-UWB) pulse-position modulated signals. Compared to the conventional WNCR, the optimal weights of the proposed NDA-WNCR are tremendously simplified as the maximum eigenvector of the IR-UWB signal energy sample autocorrelation matrix. The NDA-WNCR serves to blindly obtain the optimal weights and entirely circumvent the transmission of training symbols or channel estimation in practice. Analysis and simulation results verify that the bit error rate (BER) performance of the NDA-WNCR closely approaches the ideal BER of the conventional WNCRs.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.12C
• /
• pp.1125-1132
• /
• 2005

Ultra-wideband (UWB) ranging poses a set of time delay estimation problems for designers. The possibility of a large error can be a challenging problem for accurate ranging and positioning. An approximate analysis of large error performance of UWB ranging in multipath and multiuser environments is posed. Both analytical and experimental approaches are taken to evaluate the large error variance in a correlation-based serial search scenario.