Seong-soo Lee

Statistical characterization of the UWB propagation channel in indoor residential environment

This paper presents a statistical characterization of an ultra wideband (UWB) indoor propagation channel based on measurements conducted in various types of high-rise apartments in several cities of Korea. Measurements were carried out in the frequency band of 3–10 GHz. Various communication links were considered including both line-of-sight (LOS) and non-LOS (NLOS) scenarios, which covered within-the-room and room-to-room propagations. The measurement procedure allows us to characterize both the large-scale and the small-scale statistics of the channel. The aim here is to study in more detail the statistical characteristics of the UWB propagation channel and to provide insight for future statistical channel modeling work. Channel characteristics examined include the distance and frequency dependency of path loss, shadowing fading statistics, and multipath temporal-domain parameter statistics such as the mean excess delay, RMS delay spread, and the number of dominant paths. Copyright

A modified S-V clustering channel model for the UWB indoor residential environment

In this paper, a new modified Saleh-Valenzuela (S-V) clustering channel model is proposed based on the measurement data collected in various types of high-rise apartments under different propagation scenarios in the ultra-wideband (UWB) frequency band of 3-10 GHz. A new distribution, namely, mixtures of two Poisson processes is proposed to model the ray arrival times. This new distribution fits the empirical data much better than the single Poisson process proposed in the conventional S-V model. The measurement procedure allows the small-scale amplitude fading statistics to be studied. Analysis results show that they can be well modeled by either lognormal, Nakagami or Weibull distributions whose parameters i.e. standard deviation, m-parameter and b-shape parameter, respectively, are lognormal distributed random variables. These parameters are found to be invariant across the excess delay. Additionally, the temporal correlation between adjacent path amplitudes is also investigated. The amplitude temporal correlation coefficients are found to be relatively small and thus, can be assumed to be negligible in reality. The proposed model can provide a more realistic simulation platform for the UWB communication systems.

Statistical characterization of the UWB propagation channel in various types of high-rise apartments

The paper presents a statistical characterization of an ultra-wideband (UWB) indoor propagation channel based on measurements conducted in various types of high-rise apartments in several cities in Korea. Measurements were carried out in the frequency band of 3-10 GHz. Various communication links were considered including both line-of-sight (LOS) and non-LOS (NLOS) scenarios which cover within-the-room and room-to-room propagation. The measurement procedure allows us to characterize both the small-scale and the large-scale statistics of the channel. The aim is to study in more detail the behavior of the UWB propagation channel and to provide more of the measurement data required for the standardization activities in the IEEE 802.15.4a channel modeling subgroup. Channel characteristics examined include the distance and frequency dependency of path loss, shadowing fading statistics and multipath temporal-domain parameter statistics, such as the mean excess delay, RMS delay spread and the number of dominant paths.

UWB indoor propagation channel measurements and data analysis in various types of high-rise apartments

This paper presents the extensive ultra wideband (UWB) indoor propagation channel measurements conducted in various types of high-rise apartments based in several cities in Korea. A vector network analyzer was used to measure the channel transfer functions in the frequency band of 3-10 GHz. The corresponding channel impulse responses were calculated by taking inverse Fourier transforms of the recorded channel transfer functions. Measurements were made in 8-10 distinct receiver (RX) local points throughout the apartment ranging from 1-20 m apart from the fixed transmitter location. At each RX local point; the RX was moved 25 times over a square grid of 5/spl times/5 spatial points spaced 15 cm apart. This measurement procedure allows us to characterize both the small-scale and the large-scale statistics of the channel. Various communication links were considered including both line-of-sight (LOS) and non-LOS (NLOS) scenarios. Both data analysis technique and measurement results are presented in the form of power delay profile and rms delay spread. The aim here is to study in more detail the behavior of the UWB propagation channel and to provide more measurement data required for the standardization activities in the IEEE 802.15.4a channel modeling subgroup.

A CR Platform for Applications in TV Whitespace Spectrum

A cognitive radio platform for whitespace spectrum in UHF TV band is introduced. The purpose of the CR platform is to evaluate the feasibility of the unlicensed wireless service in the UHF TV band. The platform consists of RF, baseband modem and MAC including spectrum sensing function. The performance of the spectrum sensing function combined with wideband RF IC which is designed for mobile broadcasting service in multiple bands is presented.

Low power UWB RF transceiver for wireless headset

In this paper, the UWB RF transceiver architecture based on a direct chaotic communication system is introduced for wireless headset applications. The direct chaotic communication technology can realize excellent low data rate UWB communication. The low power RF transceiver with chaotic UWB signal of 3 GHz /spl sim/ 5 GHz is implemented for MP3 audio transmission. This simply configured system prototype performs non-coherent detection without up/down mixers. The system is expected E/sub b//N/sub 0/ of 18 dB for PER /spl les/ 10/sup -2/ at 32 bytes length of PSDU, and power consumption of 20 mW in case of 0.13 micron CMOS RFIC fabrication.

UWB-DCSK communication systems for low rate WPAN applications

In this paper, a ultra wideband direct chaotic communications technology is proposed for the low-rate wireless personal area network applications. Based on this system, a 2 GHz wide chaotic signal is directly generated into the lower band of the UWB spectrum i.e. 3.1-5.1 GHz. The information component is modulated by the chaotic signal based on the differential chaos shift keying modulation scheme. At the receiver, a correlator based receiver is used to demodulate the received signal. Various system design parameters are discussed in the paper and the tradeoffs between these parameters are highlighted. These issues include band plan, PHY service access point payload bit rates, scalability, power consumptions and link budget for various operating conditions are also addressed. Additionally, the system performance in both AWGN channel and multipath channel are provided in order to further demonstrate the capability of the proposed system

Low-Rate Chaotic UWB Transceiver System Based on IEEE 802.15.4a

The chaotic UWB communication system based on IEEE 802.15.4a is proposed for wireless headset applications. A compact architecture can be implemented by using a chaotic UWB signal and a non-coherent detection scheme. The chaotic UWB generator is designed with the BW of 3.1 to 5.1 GHz, and a baseband process is realized on an FPGA including an adaptive decision and a channel code for non-source coded data stream. The system performance is evaluated by transmitting MP3 audio/voice and measuring PERs at 32 byte length of a PSDU for the system sensitivity and the interferer compatibility. The proposed system can be an excellent candidate for short-range connectivity services, as well as an inexpensive system with good capability for narrow-band interferences

Space-frequency correlation model for multi antenna, multi-band OFDM in UWB communication systems

In this paper space-frequency correlation model for multi antennas, multi band orthogonal frequency division multiplexing (OFDM) is developed. The correlation model is expressed in closed-form in terms of azimuth spread, elevation spread, mean azimuth-of-arrival and mean elevation-of-arrival of the underlying angle of arrival statistics, delay spread, antenna separation, antenna positions and frequencies of the band of interest in multi band OFDM proposal. We show that for an array that exploits space-frequency diversity, the spatial correlation of the array is jointly contributed by the actual spatial correlation and the inherent frequency correlation due to different frequency components used. Furthermore, with this model, optimum parameters can also be deduced for system employing space-frequency diversity schemes. The developed model can also be used for capacity analysis of future multi-band OFDM based multiple-input-multiple-output systems.

A statistical based UWB multipath channel model for the indoor environments WPAN applications

In this paper, a statistical-based ultra-wideband (UWB) indoor channel model which incorporates the clustering of multipath components (MPCs) is proposed. The model is derived based on measurement data collected in the frequency band of 3-10 GHz in various types of high-rise apartments under different propagation scenarios. The aim here is to investigate in more detail the clustering of MPCs phenomenon. The description of clustering observed within the channel relies on two classes of parameters, namely, inter-cluster and intra-cluster parameters which characterize the cluster and MPC, respectively. All parameters are described by a set of empirical probability density functions derived from the measured data such as the distribution of clusters and MPCs, clusters and MPCs arrivals. In addition, the measurement procedure and data analysis techniques are also discussed. This model is suitable for performance analysis of WPAN systems that employ UWB technology e.g. IEEE 802.15.3a and IEEE 802.15.4a