Multipath Delay Profile Research Articles

Performance of asynchronous DS-CDMA using a maximal ratio combining diversity over a Rician fading channel

The final closed-form expression for bit error probability (BEP) is presented for a DS-CDMA system using a maximal ratio combining (MRC) diversity over a Rician fading channel. The accuracy of the BEP estimate evaluated by this expression is verified by comparison with a semi-analytic simulation result. The effect that diversity order has on the BEP is also considered for typical multipath delay profiles with different Rician ratios.

Superresolution of multipath delay profiles measured by PN correlation method

Time resolution of multipath delay profiles measured by using the autocorrelation of a pseudonoise (PN) code sequence is generally limited by the chip interval of the PN code sequence. A superresolution PN correlation method (SPM) is proposed which improves the time resolution of delay profiles measured by the conventional PN correlation method. The SPM is based on a decomposition of the eigenvector space of the correlation matrix of the delay profile data vector and gives the number of paths and their delay times with higher resolution. It is verified by computer simulations and experiments using coaxial delay lines that the SPM can resolve two paths with a delay difference of a few tenths of the chip interval. The applicability of the SPM to the analysis of an indoor multipath environment in which many delayed waves arrive with short delay differences is demonstrated by an indoor radio propagation experiment at 2.3 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Dispersive fading effects in CDMA radio systems

The effect of multipath delay spread in a code division multiple access (CDMA) radio communications system where multiple PN receivers are used is reported. Ten multipath power delay profiles obtained from measurements in New York City are examined. Results show that the increase of interference due to diffuse uncaptured energy is about 1 to 1.4 dB on the average. This increase in interference results in at least 20% capacity reduction in CDMA radio systems. >

Multipath delay prediction on workstation for urban mobile radio environments

A multipath delay profile prediction system has been implemented on a workstation. The proposed system predicts profiles on the basis of a topological building database by assuming a propagation model that consists of, at each receiving point, a direct-diffracted wave and waves scattered by those walls visible from the transmitting antenna.

Statistical channel impulse response models for factory and open plan building radio communicate system design

Statistical radio channel impulse response models are presented for the analysis and design of wireless factory and open plan office communication systems. The models incorporate first- and second-order statistics to characterize the discrete impulse responses of indoor radio channels for both line-of-sight (LOS) and obstructed (OBS) topographies. The effects of large-scale transmitter-receiver separation distance, small-scale receiver movement, and models for the correlation of multipath component amplitudes over 1 m local areas are developed from 1.3 GHz measurements. SIRCIM, a computer simulator based on the models presented, has recreated multipath power delay profiles and CW fading profiles that are representative of measured data. Large-scale models for path loss are implicitly included in this work. >

900-MHz multipath propagation measurements for US digital cellular radiotelephone

The results of multipath power delay profile measurements of 900-MHz mobile radio channels in Washington, DC, Greenbelt, MD, Oakland, CA, and San Francisco, CA, are presented. The measurements have focused on acquiring worst-case profiles for typical operating locations. The data reveal that at over 98% of the measured locations, root mean square (RMS) delay spreads are less than 12 mu s. Urban areas typically have RMS delay spreads on the order of 2-3 mu s and continuous multipath power out to excess delays of 5 mu s. In hilly residential areas and in open areas within a city, RMS delay spreads are slightly larger, typically having values of 5-7 mu s. In very rare instances, reflections from city skylines and mountains can cause RMS delay spreads in excess of 20 mu s. The worst-case profiles show resolvable diffuse multipath components at excess delays of 100 mu s and amplitudes 18 dB below that of the first arriving signal. >

900 MHz multipath propagation measurements in four United States cities

This letter describes multipath power delay profile measurements of 900 MHz mobile radio channels in four US cities. Preliminary data show that for over 98% of the measured locations, RMS delay spreads are less than 12 μs. In very rare instances, reflections from city skylines and mountains can cause RMS delay spreads which exceed 20 μs and excess delays which exceed 100 μs. Such large excess delays have not been previously reported in the literature.

Characterising the UHF factory radio channel

Portable UHF factory multipath measurement apparatus is being used to measure multipath delay profiles and narrowband fading at five large manufacturing sites in the mid-western US. Preliminary data indicate that typical RMS delay spreads range from 100 to 250 ns and that average CW path loss varies as distance to the power 2-2. This work is the first report of extensive multipath measurements in factory environments.