Showing papers by "Preben Mogensen published in 1999"
01 Jan 1999
94 citations
19 Sep 1999
TL;DR: A method to generate correlated shadow fading processes is proposed, which makes it possible to study position dependent correlation models between multiple base stations (BS) and study the C/I outage gain for different frequency reuse patterns and BS sectorizations.
Abstract: This paper considers the influence of the cross-correlated shadowing between base-stations on network level simulations. A method to generate correlated shadow fading processes is proposed, which makes it possible to study position dependent correlation models between multiple base stations (BS). The method has been used for static network level simulations with different synthetic correlation models, both angle-of-arrival- and distance-dependent, in order to study the C/I outage gain for different frequency reuse patterns and BS sectorizations.
84 citations
16 May 1999
TL;DR: A simple time-variant stochastic radio channel model is proposed that includes temporal and azimuthal dispersion, polarization effects, fast fading, and dynamic evolution of paths.
Abstract: A simple time-variant stochastic radio channel model is proposed. The model includes temporal and azimuthal dispersion, polarization effects, fast fading, and dynamic evolution of paths. All relevant model parameters are extracted from extensive measurement campaigns in a typical urban environment.
37 citations
TL;DR: The directional properties of the uplink and downlink channel are compared experimentally and it is found that the first- and second-order moments of the power azimuth spectrum can be assumed to be identical for the UL and DL bands.
Abstract: The directional properties of the uplink (UL) and downlink (DL) channel are compared experimentally for a duplex distance of 68 MHz. It is found that the first- and second-order moments of the power azimuth spectrum, for all practical purposes, can be assumed to be identical for the UL and DL bands.
25 citations
19 Sep 1999
TL;DR: The analog interface to the digital receiver is analyzed and an architecture including AGC and ADC is suggested and it is analyzed that an ADC with 4-5 bit and sampling of 4 times the chip rate will give an acceptable performance.
Abstract: The theoretical BER is calculated for downlink in UMTS including interpath interference and multiple access interference. The analog interface to the digital receiver is analyzed and an architecture including AGC and ADC is suggested. It is further analyzed that an ADC with 4-5 bit and sampling of 4 times the chip rate will give an acceptable performance within 0.2 dB from the theoretical performance.
18 citations
01 Jan 1999
TL;DR: This paper presents a feasibility study of DC offset filtering for direct-conversion UTRA-FDD/WCDMA receivers with design equations for DC offset power to down-converted signal power ratio and the impact on bit error rate of high-pass filtering WCDMA signals is evaluated by UTRA/FDD system simulations.
Abstract: This paper presents a feasibility study of DC offset filtering for direct-conversion UTRA-FDD/WCDMA receivers. Spectral characteristics and properties of continuous transmission facilitate the use of simple high-pass filtering and this method is evaluated in the paper. Design equations for DC offset power to down-converted signal power ratio are presented and the impact on bit error rate of high-pass filtering WCDMA signals is evaluated by UTRA-FDD system simulations.
18 citations
01 Jan 1999
TL;DR: In this article, a simple method for simulating a propagation environment with temporal, azimuthal, and polarization dispersion is proposed, where each path is controlled by a birth death process in order to make the channel as dynamic as possible.
Abstract: A simple method for simulating a propagation environment with temporal, azimuthal, and polarization dispersion is proposed. The channel is simply modeled by a time-variant number of discrete paths with different amplitude, delay, and azimuth. Each path is controlled by a birth death process in order to make the channel as dynamic as possible. All model parameters are extracted from experimental data. Simulation results are presented in order to illustrate how the model behaves.
13 citations
01 Jan 1999
TL;DR: A method for generation of correlated multipath fading is described, taking the spaced frequency correlation into account, and can be used to emulate frequency hopping in a wideband channel, and is usable with both network and link level simulations.
Abstract: The spaced frequency correlation affects the frequency diversity gain in frequency hopping (FH) GSM systems. However, GSM link level simulations have not taken this into account. In this paper, a method for generation of correlated multipath fading is described, taking the spaced frequency correlation into account. The method can be used to emulate frequency hopping in a wideband channel, and is usable with both network and link level simulations. FH-GSM link simulations with low-speed mobiles exhibit a loss in frequency diversity gain due to the spaced frequency correlation. Two factors influence this loss: the frequency reuse factor and the channel coherence bandwidth. In networks with frequency reuse 1, the loss in diversity gain is up to 0.5 dB in outdoor urban environments and up to 4 dB in indoor environments.
12 citations
TL;DR: In this study, it is proven that an array with four dual polarized elements is very attractive for urban environments compared to an arrayWith eight single polarized elements, which is a loss of up to 2.0 dB.
Abstract: Three potential vector RAKE (V-RAKE) receiverswith different complexity levels are compared. Thecomparison is conducted by using either single polarizedor dual polarized antenna arrays. An approach where either maximal ratio combining (MRC) orconventional beamforming (BF) is applied at each delay(RAKE finger) is considered. A simpler scheme where onlyone common beam pattern is synthesized for all RAKE fingers is also investigated. In this study itis proven that an array with four dual polarizedelements is very attractive for urban environmentscompared to an array with eight single polarizedelements. It is furthermore found that there is amarginal difference in the overall performance fromusing a V-RAKE receiver with MRC or conventional BF intypical urban environments. However, a loss of up to 2.0 dB is observed for the scheme with one commonbeam pattern for all RAKE fingers.
11 citations
16 May 1999
TL;DR: It is concluded that the best solution is to use dual polarized antenna arrays, while there is only found to be a minor difference between the considered combining schemes provided the azimuth spread is smaller than the antenna beamwidth.
Abstract: Three potential structures of vector-RAKE (V-RAKE) receivers are compared. An approach where maximal ratio combining (MRC) or conventional beamforming (BF) is applied at each RAKE finger, and a simpler solution where one common BF is used for all fingers. The comparison is conducted by using either single or dual polarized antenna arrays. All results are based on theoretical investigations and analysis of measurement data collected in typical urban environments. It is concluded that the best solution is to use dual polarized antenna arrays, while there is only found to be a minor difference between the considered combining schemes provided the azimuth spread is smaller than the antenna beamwidth.
10 citations
19 Sep 1999
TL;DR: A theoretical analysis is carried out in order to find the optimum slot structure for UMTS and the best performance is reached, when the downlink slot structure is changed.
Abstract: The effect of high mobile speed in UMTS is examined in this paper. A theoretical analysis is carried out in order to find the optimum slot structure for UMTS. This analysis is supported by numerical results. Several channel estimation algorithms have been examined and the best performance is reached, when the downlink slot structure is changed.
01 Jan 1999
TL;DR: An algorithm doing this for a PCS1900/GSM/DCS1800 type of network with a performance enhancement of around 20% is achieved compared to an operating reference frequency plan.
Abstract: Resource allocation in a frequency hopping network is even more problematic than in a traditional network. The combined effect from all serving frequencies has to be considered directly in the allocation process. An algorithm doing this for a PCS1900/GSM/DCS1800 type of network is presented. The frequency as well as the interference diversity gain from frequency hopping is included directly in the allocation process. Exploiting a cost function, which includes the gain from frequency hopping, a performance enhancement of around 20% is achieved compared to an operating reference frequency plan. A graphical visualisation tool has been developed as well. This tool uses a network quality measure tightly linked to the FER rather than the traditional C/I or BER. Using these statistics an increase in network quality is shown.
16 May 1999
TL;DR: In this article, an algorithm for a PCS1900/GSM/DCS1800 type of network is presented, where the frequency as well as the interference diversity gain from frequency hopping is included directly in the allocation process.
Abstract: Resource allocation in a frequency hopping network is even more problematic than in a traditional network. The combined effect from all serving frequencies has to be considered directly in the allocation process. An algorithm doing this for a PCS1900/GSM/DCS1800 type of network is presented. The frequency as well as the interference diversity gain from frequency hopping is included directly in the allocation process. Exploiting a cost function, which includes the gain from frequency hopping, a performance enhancement of around 20% is achieved compared to an operating reference frequency plan. A graphical visualisation tool has been developed as well. This tool uses a network quality measure tightly linked to the FER rather than the traditional C/I or BER. Using these statistics an increase in network quality is shown.
01 Jan 1999
TL;DR: Investigations based on simultaneous dual band signal strength measurements using a test measurement system, neighbour channel measurements from a dual band GSM phone, and Abis trace data indicate that base station antennas with dissimilar radiation patterns for the two bands will effect a change in mean signal level difference.
Abstract: In this paper we investigate the possibility of operating a dual band GSM network having co-located GSM900 and GSM1800 cells, with a single broadcast channel (BCCH). Our investigations are based on simultaneous dual band signal strength measurements using a test measurement system, neighbour channel measurements from a dual band GSM phone, and Abis trace data. Our results indicate that base station antennas with dissimilar radiation patterns for the two bands will effect a change in mean signal level difference. The characteristics of the dual band antenna on the mobile station, especially when interacting with the hand and head of the user, tend to strongly de-correlate the mean signal level variations in the two bands. Both issues, and in particular the latter, may negatively influence the performance of single BCCH operation of co-located GSM900 and GSM1800 cells.