Veikko Hovinen

On the UWB system coexistence with GSM900, UMTS/WCDMA, and GPS

This paper evaluates the level of interference caused by different ultra-wideband (UWB) signals to other various radio systems, as well as the performance degradation of UWB systems in the presence of narrowband interference and pulsed jamming. The in-band interference caused by a selection of UWB signals is calculated at GSM900, UMTS/wideband code-division multiple-access (WCDMA), and Global Position System (GPS) frequency bands as a function of the UWB pulsewidth. Several short-pulse waveforms, based on the Gaussian pulse, can be used to generate UWB transmission. The two UWB system concepts studied here are time hopping and direct sequence spread spectrum. Baseband binary pulse amplitude modulation is used as the data modulation scheme. Proper selection of pulse waveform and pulsewidth allows one to avoid some rejected frequency bands up to a certain limit. However, the pulse shape is also intertwined with the data rate demands. If short-pulses are used in UWB communication the high-pass filtered waveforms are preferred according to the results. The use of long pulses, however, favors the generic Gaussian waveform instead. An UWB system suffers most from narrowband systems if the narrowband interference and the nominal center frequency of the UWB signal overlap. This is proved by bit-error rate simulations in an additive white Gaussian noise (AWGN) channel with interference at global system for mobile communication (GSM) and UMTS/WCDMA frequencies.

Ultra wideband indoor radio channel models: preliminary results

Knowledge of the signal propagation mechanisms in the channel is vital for the radio system design and the system performance analysis. However, currently published wideband or narrowband radio channel models do not offer spatial resolution high enough for the ultra wideband (UWB) applications and real channel measurements are needed. The preliminary UWB radio channel model for a selected radio link-configuration in an indoor environment is given.

In-band interference power caused by different kinds of UWB signals at UMTS/WCDMA frequency bands

This paper studies in-band interference caused by different kinds of ultra wideband signals in UMTS frequency bands as a function of UWB pulse width. UWB frequency spectra are produced by using several types of narrow pulse waveforms. Due to the extremely wide bandwidth these signals will spread over the frequency bands allocated to other RF-systems. Study revealed that one can reduce interfering UWB power by using different waveforms and pulse widths to avoid UMTS frequencies without any additional filtering. The simulations did not make a significant difference between time hopping and direct sequence concepts when interference was calculated at the UMTS bands.

On the performance comparison of different UWB data modulation schemes in AWGN channel in the presence of jamming

This paper studies the performance of ultra wideband (UWB) communication systems in AWGN channels. The studied UWB systems are utilizing different kinds of modulation schemes. The propagating information signal is jammed with a signal having a spectrum in the UMTS or in the GSM band. The simulations showed that the time hopping UWB system utilizing binary PAM modulation outperforms the other studied modulation schemes in the AWGN channel when a jamming signal is present. The simulation results showed that the rank order of the studied modulation schemes in the AWGN channel in the presence of jamming is time-hopping binary pulse amplitude modulation. direct sequence based binary pulse amplitude modulation, time hopping pulse position modulation and direct sequence based on-off-keying.

A wideband, directional model for the satellite‐to‐indoor propagation channel at S‐band

This paper presents a hybrid empirical-statistical model for the satellite-to-indoor propagation channel at S-band derived from measurements using a helicopter to simulate the satellite. The measurements have been carried out by means of a wideband, circularly polarized channel sounder in a SIMO (Single Input Multiple Output) configuration, allowing the derivation of entry loss, wideband and spatial model parameters. It is hoped that this paper will provide relevant information on the satellite-to-indoor channel given the large amount of experimental data available, covering a significant member of different buildings of various types, and the amount of measurement configurations: elevations and azimuths. Copyright

Wideband radio channel measurement in a mine

The paper presents a propagation characterization based on wideband radio channel measurements made in a mine at a center frequency of 1 GHz. The main attention is focused on the path loss and the delay profile analysis. The path loss has been found to be 40 dB/dec in a straight cave and 80 dB/dec in a curved cave. the delay spread was less than 0.5 /spl mu/s. The radio channel in the mine proved to be non-reciprocal.

On the multi-user interference study for ultra wideband communication systems in AWGN and modified Saleh-Valenzuela channel

This paper studies the effects of multiple access interference (MAI) for ultra wideband (UWB) systems in AWGN and multipath fading channels. Time hopping (TH) and direct sequence (DS) based UWB spreading approaches are performed, utilizing binary pulse amplitude modulation (PAM) and pulse shape modulation (PSM). Both the possibilities of having synchronous and asynchronous users have been taken into account. In the fading channel case, different coherent and non-coherent detection methods have been considered. Simulated performance results are depicted for the above mentioned UWB systems when a variable number of equally powered users are operating in the channel. Results show that in both the AWGN and fading channel the DS system performance shows sensibly different results in the synchronous and asynchronous case. This is due to the continuous time transmission of the different users. This problem does not occur in systems using TH spreading since the different users are less overlapped in time, due to the spreading approach used. In the fading channel, TH systems show a general higher performance loss in all cases compared to DS, in contrast to what happens in the AWGN case. That is, the allocation of the TH codes creates a higher interfering effect due to MAI in the presence of multipath fading. In general, DS-based systems outperform the corresponding TH ones.

Geometry-Based Stochastic Channel Model for Two-Story Lobby Environment at 10 GHz

This paper presents a complete parametrization for a three-dimensional (3-D) geometry-based stochastic radio channel model (GSCM) at 10.1 GHz based on a measurement campaign. The radio channel measurements were carried out with a vector network analyzer over a 500 MHz bandwidth in a two-story lobby environment. The measurements were conducted with 9 × 324 dual polarized virtual antenna arrays in line-of-sight (LOS) and non-LOS propagation conditions. The recorded data was post-processed using the estimation of signal parameters via rotation invariance algorithm. The statistical analysis was carried out to provide full 3-D parametrization for the GSCM. The parametrization was verified by radio channel simulations. Multiple-input multiple-output (MIMO) channel is reconstructed from the estimated propagation paths and equivalently the channel simulations are performed by quasi-deterministic radio channel generator using our measurements-based parameters. The channel capacity, Demmel condition number, and relative condition numbers are used as the verification metrics. The results show that the reconstructed MIMO channel matches well the simulated MIMO channel.

Wideband Dual-Polarized Cross-Shaped Vivaldi Antenna

This communication presents a wideband, dual-polarized Vivaldi antenna or tapered slot antenna with over a decade (10.7:1) of bandwidth. The dual-polarized antenna structure is achieved by inserting two orthogonal Vivaldi antennas in a cross-shaped form without a galvanic contact. The measured -10 dB impedance bandwidth (S11) is approximately from 0.7 up to 7.30 GHz, corresponding to a 166% relative frequency bandwidth. The isolation (S21) between the antenna ports is better than 30 dB, and the measured maximum gain is 3.8-11.2 dB at the aforementioned frequency bandwidth. Orthogonal polarizations have the same maximum gain within the 0.7-3.6 GHz band, and a slight variation up from 3.6 GHz. The cross-polarization discrimination (XPD) is better than 19 dB across the measured 0.7-6.0 GHz frequency bandwidth, and better than 25 dB up to 4.5 GHz. The measured results are compared with the numerical ones in terms of S-parameters, maximum gain, and XPD.

In-band interference of three kinds of UWB signals in GPS L1 band and GSM900 uplink band

This paper studies in-band interference of different kind of ultra wideband (UWB) signals. UWB frequency spectra are produced by using several types of narrow pulse waveforms, all based on the Gaussian pulse. Due to the extremely wide bandwidth, these signals spread over the frequency bands allocated to other radio systems. In-band interference power is calculated over the IF bandwidths of two victim receivers as a function of pulse width. Also, the signal attenuation with distance is presented. The victim systems under the study are GPS (L1-band) and GSM900. Based on the results, the 3/sup rd/ derivative of a Gaussian pulse seems to be the best choice, from the interference point of view, among the waveforms included in this study. It causes less interference than the Gaussian pulse or Gaussian doublet if the pulse widths are shorter than 1 ns. The system utilizing the direct sequence concept caused less in-band interference power than the system utilizing time hopping amongst all waveforms studied. The studied UWB systems are based on bi-phase baseband data modulation.