Performance estimation for indoor wireless systems using FDTD method

Abstract

A three-dimensional implementation of the finite-difference timedomain method is used to estimate the down-link outage probability of a direct-sequence code division multiple access system operating in a multi-storey office building in the presence of co-channel interference. The numerical analysis is supported by experimental measurements and good agreement is found for the outage probability. Both simulation and measured results indicate that vertically aligned cochannel base stations have lower outage than a vertically staggered configuration, which is explained by examining the correlation between the desired and interfering signals.Introduction: Achieving reliable performance within highly confined areas, such as multi-storey buildings, remains a challenge for contemporary wireless systems. Co-channel interference from neighbouring systems is significant, as transmit powers are relatively high, frequency reuse separations are generally shorter, and unlike outdoor deployments, three-dimensional (3D) reuse strategies are possible [1]. Furthermore, predicting the system performance for indoor environments is complicated by the large variability in building layout, architectural styles, and building materials. Currently, empirical models based on experimental measurements are widely used, e.g. [2,3]. However, many of the parameters in these models lack an electromagnetic basis and can vary considerably between buildings, and thus often require further tuning measurements (which can be time-consuming and expensive) [2]. To investigate the factors limiting system performance, a 3D model of a multi-storey office building is analysed using the finitedifference time-domain (FDTD) method. The FDTD method has been shown to accurately model radiowave propagation within and around buildings, e.g. [4][5][6][7]. However, the previous research has largely focused on characterising propagation mechanisms, and not on the system performance. This Letter focuses on how the FDTD method can be applied to directly estimate the outage probabilities of a directsequence code division multiple access (DS-CDMA) system in the presence of co-channel interference.

Local Average Signal Strength Estimation for Indoor Multipath Propagation

“…In [9] the authors performed RSS averaging over regions of dimensions (2λ) 2 . In [10] averaging was performed over regions of dimensions (3λ) 2 , while in [11] and [12] the regions were of size (3λ) 3 . In [13] averaging was conducted over a 10λ interval while the minimum spacing between samples was set to 0.38λ.…”

Determination of the Effective Electromagnetic Parameters of Complex Building Materials for Numerical Analysis of Wireless Transmission Networks

“…The structure of a wireless network requires taking into account the number of access points and their locations [5]. The discussed problems become particularly important when wireless networks are installed inside buildings, where complex geometry [3,4,[9][10][11][12][13][14] and electrical properties of materials [15,16] influence the propagation of electromagnetic (EM) waves. The impact of these viabilities was confirmed by the measurements of mobile phone signal attenuation by different building structures [12] in Global System for Mobile Communications (GDM) networks.…”

“…Numerical analysis of the propagation of electromagnetic waves allows for taking into account the building structure as well as to perform multi-variant analysis of the wireless communication system [5,6,11]. The analysis of the electromagnetic phenomena can be performed using numerical methods such as finite element method (FEM) [18,19] or finite-difference time-domain method (FDTD) [3,9,11,20,21]. Despite the approximations in the models and calculation errors, numerical methods allow to obtain solutions for complex models.…”

Improved propagation modeling in ultra-wideband indoor communication systems utilizing vector fitting technique of the dielectric properties of building materials

“…This method is very appealing, since it rigorously takes into account wave-matter interaction. In several works [5]- [13], FDTD formulations are exploited in 2-and 3-D implementations for the study of propagation mechanisms for indoor or between nearby buildings communications. In all the aforementioned works the material modeling is restricted either to non-dispersive media or lossy materials with a static conductivity term.…”