Kim Olesen

Investigations of outdoor-to-indoor mobile-to-mobile radio communication channels

The mobile-to-mobile radio channel was investigated in different suburban outdoor-to-indoor environments. System performance parameters in terms of un-encoded BER and outage probability have been extracted from hardware and software TETRA simulations. In several scenarios, the measured signal envelope statistics were found to be a combination of single and double Rayleigh distributions. The system performances obtained in these scenarios were in general lower than the reference ETSI limits.

Bodyloss for handheld phones

Measurements in an anechoic room of three-dimensional radiation patterns for 44 test persons using a handheld phone with two antennas are investigated in order to find the bodyloss. The measured bodyloss range from 0.9 dB to 16 dB. From the measurements is was possible to separate the absorption and the loss due to mis-match of the antenna. The antenna mis-tuning accounted for less than 2 dB to the bodyloss. The uncertainties in the measurements is in the order of one dB.

Ultra wideband radio propagation in body area network scenarios

This work presents novel, very-short range UWB radio channel investigations performed in typical body area network (BAN) scenarios using small size, low profile terminal antennas. A novel RF fiber optic connection has been employed for the small antenna set-up in order to maximize the accuracy of the measurements. Several test users have been investigated and significant changes of the UWB antenna radiation characteristics when close to the human body were disclosed using numerical simulations. The measurements with different UWB device positions on the human body showed drastic changes in the calculated radio channel parameters (frequency and time-delay domain) not only due to the body area but also due to the total propagation environment.

Preliminary measurement results from an adaptive antenna array testbed for GSM/UMTS

This paper presents preliminary measurement results for an 8 element adaptive antenna array in an urban environment. The results show that in most cases the received signal consists of a single narrowly scattered component impinging from the direction towards the mobile. The angular spread (AS) is found to be no larger than 5 degrees for the test measurements. The correlation coefficient between slow fading and AS is -0.56, indicating that the AS increases when the local signal strength fades. The paper also shows the results for a direction of arrival (DoA) algorithm, which is designed for downlink beamsteering in a GSM related system. The results indicate that an averaging window size of one SACCH frame (0.48 s) is a wise choice for DoA estimation in a non-FH network.

Statistics of measured body loss for mobile phones

The variation in body loss for different users of a cellular handset is investigated. Measurements involving 200 test users of mobile communications (GSM) handsets have been performed and statistics are presented for a handset with three types of antennas. Differences in the body loss of up to 10 dB have been observed between users, thus indicating that body loss measurements for handsets should include several test persons. Depending on the antenna type, 8-13 test persons are required to obtain an estimate of the mean body loss with a /spl plusmn/1 dB confidence interval at a 90% level.

A hardware testbed for evaluation of adaptive antennas in GSM/UMTS

This paper gives a description of a hardware testbed for evaluation of adaptive base station antenna arrays in the GSM/UMTS. The testbed is aimed at the spatial and temporal characterisation of the radio channel and at the performance evaluation of array processing algorithms. The testbed consists of two test mobiles and an 8 element adaptive array receiver. The array processing is implemented by means of real-time digital signal processing hardware.

Penetration effects on XPD with GSM 1800 handset antennas, relevant for BS polarization diversity for indoor coverage

This paper presents dual polarized wideband radio investigations in urban and suburban microcell conditions in the 1800 MHz band. The aim of the investigations is to disclose the factors determining base station (BS) polarization diversity gain. It is found that handset antenna type and handset orientation are the determining factors for polarization cross coupling, which is the prime variable responsible for the diversity gain, Environment and body proximity are of less importance for the polarization state, though they have a noticeable influence on the total received power, It is concluded that BS polarization diversity can function with comparable results as a traditional space diversity system, under typical handset usage conditions, thus providing a very compact antenna system, less intrusive than space diversity antenna setups.

Radio channel characterisation for forest environments in the VHF and UHF frequency bands

The paper describes short range VHF-UHF radio propagation measurements performed in a forested environment using low TX/RX antenna elevations. An empirical path loss model is proposed having as parameters the frequency, antenna heights and forest geometry. Furthermore the short term fading dynamics are also presented.

Assessment of Capacity Support and Scattering in Experimental High Speed Vehicle to Vehicle MIMO Links

Preliminary results on the use of the vehicle to vehicle MIMO channel in a rural highway environment are presented. This is looked at both in terms of the available spatial multiplexing through singular value decomposition and also angular distribution within the channel. Results indicate a strong predominant line of sight link in general while instances of scattering from other vehicles will cause changes in the Doppler spectrum as well as beamforming jitter.

Measurements of indoor 16/spl times/32 wideband MIMO channels at 5.8 GHz

A wideband 16/spl times/32 MIMO channel sounder has been developed for the 5.8 GHz band. The paper reports on a series of measurements with the purpose of investigating both temporal and spatial aspects of channel changes in a number of widely different indoor environments. The measurements are carried out using two planar arrays of monopoles. The results include statistics on capacity, coherence bandwidth, and Doppler spreading for the various measurement scenarios.