Duje Čoko

RMS Delay Spread Assessment for Indoor UWB Propagation Channels

AbstractThe RMS delay spread is often used to quantify the probability of inter-symbol interference in a propagation channel. A novel and straightforward procedure to assess this parameter is presented in this paper. A ray-tracing algorithm was used in an extensive set of Monte Carlo simulations to investigate the dependence of RMS delay spread on room parameters, namely its dimensions and average reflectivity. A multiple regression analysis was performed to obtain an empirical model for RMS delay spread assessment for indoor UWB propagation channels. The resulting model consists of a linear dependence of RMS delay spread on room dimensions combined with non-linear dependence on average reflectivity.

Inter-Floor Wide Band Radio Channel Measurements and Simulation Applying Saleh-Valenzuela Model

This paper explores the accuracy of Saleh-Valenzuela (SV) statistical simulation model in time of arrival domain (ToA) applied on inter-floor wide band indoor radio channels. In order to extract the model parameters, an extensive measurement campaign was performed inside a modern building by applying vector network analyzer method at frequency of 1.8 GHz. The measurement results are presented in form of path loss exponent and delay spread statistics for each number-of-floors (NOF) distance between the antennas (up to 4). Path loss exponent was found to be around 3 for antennas on a same floor and around 5.5 for any other case when antennas were on separated floors. CDFs of rms delay spread may be divided into two groups: the first group is made of single-floor (SF) case and distanced-floors (DF) cases (three or more floors separated antennas) which showed similarities performing median value at 20 ns. For neighboring-floors (NF) cases (one and two floors separation) this value was increased to 35 ns. SV simulation, run with the extracted parameters, assessed delay spread statistics sufficiently good for the first group of CDFs. In order to assess the second group results, it was necessary to introduce simple corrections in SV model application.

Effects of Bandwidth on Estimation of UWB Channel Parameters

The subject of this chapter is to investigate the effect of bandwidth on a short range indoor UWB channel performance. This research is based on a measurement campaign performed on a wooden desk surface placed in an office room at our faculty building. A vector network analyzer (VNA) is used to sweep the 1 GHz, 2 GHz, 5 GHz and 7.5 GHz bandwidths centered at 6.85 GHz, obtaining the frequency response of the channel. Using the VNA time domain capability we obtain the channel impulse responses. This is equivalent to sounding the channel with frequency chirp pulses equal in duration to the inverse of the frequency bandwidth. In other words, a narrower bandwidth results in a wider pulse in time domain. Although the measurements are performed in same environment for all bandwidths, it is expected that an UWB channel itself would not be equally perceived by different pulse widths. A wider system bandwidth results in shorter pulses, which in turn account for finer temporal and spatial resolution. In this way more multipath components can be resolved and pulses overlap in a lesser extent.

A wideband indoor radio channel based on Non-LOS measurements at 2.4 GHz

The paper describes the results of non-line-of-sight measurements at 2.4 GHz conducted in our university building during the working hours. We introduced the measurements with omni and directional transmitting antenna at height h and on the floor within two rooms, an office and a laboratory. Delay-spread and coherence bandwidth are estimated for the different antenna settings and compared upon. Among other things, it is observed that placing transmitter on the floor, we obtain significantly decreased signal-to-noise ratio at the receiving point together with increased coherence bandwidth of the channel.