Modeling the Frequency Dependence of Ultra-Wideband Spatio-Temporal Indoor Radio Channels

In ultra-wideband (UWB) wireless propagation channels, each multipath component (MPC) can exhibit delay dispersion or, equivalently, frequency dependence; even more, this dispersion can be different for different MPCs. While this effect is understood to have important implications for UWB system design, extraction of the frequency-dependence parameters from measurements has been lacking. This paper will provide both the theoretical tools for the parameter extraction, and provide experimental results of such parameters in UWB indoor channels. We first develop a method that extracts a single MPC. Based on the image principle, the method identifies locations and intensity of radio sources including both original and image sources (corresponding to MPCs) by a distributed antenna array. We show that the method provides spatial resolution better than 0.5 m and is robust against possible measurement errors. Having applied the method to the measured channels in indoor line-of-sight scenarios, we track the detected image sources over (partially overlapping) frequency subbands to obtain frequency dependent properties of their intensity and location. The variation of the source intensity over the frequency was found to be significant. Furthermore, the locations of the image sources can vary as the frequency changes. Comparison of the results with models that do not describe varying per-path frequency dependence revealed noticeable difference in the shape of the CIRs, and as a result, in the delay spread and the number of significant delay bins for Rake reception.

[1]  J. Kunisch,et al.  An ultra-wideband space-variant multipath indoor radio channel model , 2003, IEEE Conference on Ultra Wideband Systems and Technologies, 2003.

[2]  Andreas F. Molisch,et al.  Ultrawideband propagation channels-theory, measurement, and modeling , 2005, IEEE Transactions on Vehicular Technology.

[3]  Moe Z. Win,et al.  Evaluation of an ultra-wide-band propagation channel , 2002 .

[4]  Andreas F. Molisch,et al.  Channel models for ultrawideband personal area networks , 2003, IEEE Wireless Communications.

[5]  Moe Z. Win,et al.  Low Complexity Rake Receivers in Ultra-Wideband Channels , 2007, IEEE Transactions on Wireless Communications.

[6]  P. Bello.  Characterization of Randomly Time-Variant Linear Channels , 1963 .

[7]  Y. Oda,et al.  Measured path loss and multipath propagation characteristics in UHF and microwave frequency bands for urban mobile communications , 2001, IEEE VTS 53rd Vehicular Technology Conference, Spring 2001. Proceedings (Cat. No.01CH37202).

[8]  Jonas Medbo,et al.  Carrier Frequency Effects on Path Loss , 2006, 2006 IEEE 63rd Vehicular Technology Conference.

[9]  Jun-ichi Takada,et al.  Experimental investigation of frequency dependence in spatio-temporal propagation behaviour , 2007 .

[10]  Ada S. Y. Poon,et al.  Indoor multiple-antenna channel characterization from 2 to 8 GHz , 2003, IEEE International Conference on Communications, 2003. ICC '03..

[11]  J. Kunisch,et al.  Measurement results and modeling aspects for the UWB radio channel , 2002, 2002 IEEE Conference on Ultra Wideband Systems and Technologies (IEEE Cat. No.02EX580).

[12]  Andreas Richter,et al.  Estimation of Radio Channel Parameters , 2005 .

[13]  Moe Z. Win,et al.  Impulse radio: how it works , 1998, IEEE Communications Letters.

[14]  Takehiko Kobayashi,et al.  Development of an Omnidirectional and Low-VSWR Ultra Wideband Antenna , 2006, Int. J. Wirel. Opt. Commun..

[15]  Fredrik Tufvesson,et al.  Modeling the Ultra-Wideband Outdoor Channel: Model Specification and Validation , 2010, IEEE Transactions on Wireless Communications.

[17]  Robert C. Qiu,et al.  A study of the ultra-wideband wireless propagation channel and optimum UWB receiver design , 2002, IEEE J. Sel. Areas Commun..

[18]  I-Tai Lu,et al.  Multipath resolving with frequency dependence for wide-band wireless channel modeling , 1999 .

[19]  Fredrik Tufvesson,et al.  A Measurement-Based Statistical Model for Industrial Ultra-Wideband Channels , 2007, IEEE Transactions on Wireless Communications.

[20]  L. J. Greenstein,et al.  A quantification of link budget differences between the cellular and PCS bands , 1999 .

[21]  Alle-Jan van der Veen,et al.  Radio-astronomical imaging in the presence of strong radio interference , 2000, IEEE Transactions on Information Theory.

[22]  Koshiro Kitao,et al.  Path Loss Prediction Formula in Urban Area for the Fourth-Generation Mobile Communication Systems , 2008, IEICE Trans. Commun..

[23]  M. Hata,et al.  Empirical formula for propagation loss in land mobile radio services , 1980, IEEE Transactions on Vehicular Technology.

[24]  Chia-Chin Chong,et al.  A Comprehensive Standardized Model for Ultrawideband Propagation Channels , 2006, IEEE Transactions on Antennas and Propagation.

[25]  H. Ishikawa,et al.  Frequency range extension of path loss prediction formula for over-rooftops propagation in microwave band , 2006, 2006 IEEE Antennas and Propagation Society International Symposium.

[26]  Geoffrey Ye Li,et al.  Effect of timing jitter on OFDM-based UWB systems , 2006, IEEE Journal on Selected Areas in Communications.