Showing papers by "Preben Mogensen published in 2000"
TL;DR: It is found that in typical urban environments the power azimuth spectrum (PAS) is accurately described by a Laplacian function, while a Gaussian PDF matches the Azimuth PDF.
Abstract: A simple statistical model of azimuthal and temporal dispersion in mobile radio channels is proposed. The model includes the probability density function (PDF) of the delay and azimuth of the impinging waves as well as their expected power conditioned on the delay and azimuth. The statistical properties are extracted from macrocellular measurements conducted in a variety of urban environments. It is found that in typical urban environments the power azimuth spectrum (PAS) is accurately described by a Laplacian function, while a Gaussian PDF matches the azimuth PDF. Moreover, the power delay spectrum (PDS) and the delay PDF are accurately modeled by an exponential decaying function. In bad urban environments, channel dispersion is better characterized by a multicluster model, where the PAS and PDS are modeled as a sum of Laplacian functions and exponential decaying functions, respectively.
647 citations
24 Sep 2000
TL;DR: A simple framework for Monte Carlo simulations of a multiple-input-multiple-output radio channel is proposed and it is demonstrated that the Shannon capacity of the channel is highly dependent on the considered environment.
Abstract: A simple framework for Monte Carlo simulations of a multiple-input-multiple-output radio channel is proposed. The derived model includes the partial correlation between the paths in the channel, as well as fast fading and time dispersion. The only input parameters required for the model are the shape of the power delay spectrum and the spatial correlation functions at the transmit and receive end. Thus, the required parameters are available in the open literature for a large variety of environments. It is furthermore demonstrated that the Shannon capacity of the channel is highly dependent on the considered environment.
302 citations
24 Sep 2000
TL;DR: In this article, the set-up for the measurement of MIMO (multi-input-multi-output) radio channels as part of the European project METRA (Multi Element Transmit and Receive Antenna) is described.
Abstract: The present paper describes the set-up for the measurement of MIMO (multi-input-multi-output) radio channels as part of the European project METRA (Multi Element Transmit and Receive Antenna). Inputs for the stochastic model described by Pedersen, Andersen, Kermoal and Mogensen (see IEEE Vehicular Technology Conference VTC 2000 Fall, Boston, USA, 2000) are extracted from the measurement results and fed into a COSSAP(R) block implementing this model. A good matching between the eigenanalysis performed on both measured and simulated signals is shown.
140 citations
15 May 2000
TL;DR: In this article, the performance of the M/spl times/N concept is evaluated in terms of the number of independent parallel channels, diversity gain and total capacity in an outdoor to indoor microcellular environment.
Abstract: The multi-element antenna arrays concept with M elements at the mobile station (MS) in combination with N elements at the base station (BS) is experimentally investigated. Forschini (1996) has shown very promising results to improve the spectral efficiency in a rich scattering environment. The performance of the M/spl times/N concept is evaluated in terms of the number of independent parallel channels, diversity gain and total capacity in an outdoor to indoor microcellular environment. It is shown that the eigenanalysis provides a tool to describe the effective number of parallel channels in a multi-element array configuration. Practical results on spectral efficiency are presented for different antenna setups applied to different propagation scenarios. Also it is shown that polarization diversity is an attractive solution to achieve decorrelated antenna elements and subsequently provide a more robust system in terms of spectral efficiency within the microcell. Results show that a total capacity of 27.9 b/s/Hz can be achieved for an uncorrelated propagation environment and 17 b/s/Hz for a correlated one with a mean signal to noise ratio (SNR) of 30 dB in the case of a 4/spl times/4 antenna set-up.
77 citations
24 Sep 2000
TL;DR: A link adaptation algorithm based on a block error rate (BLER) estimation is proposed and analyzed and the mean user throughput for the fixed coding schemes and for link adaptation has been estimated from GSM network reported measurements, and a network operator planning tool.
Abstract: In GPRS four coding schemes have been defined with different degrees of data protection The selection of a fixed one for a certain packet transmission would lead to a throughput loss if the channel quality conditions vary during the connection, therefore, a link adaptation algorithm based on a block error rate (BLER) estimation is proposed and analyzed The BLER is calculated from the acknowledgement messages reported by the receiver; so the acknowledgement frequency impacts the link adaptation, and therefore, is studied in the present article The resulting link adaptation algorithm has been analyzed with a dynamic network simulator, under different frequency reuse patterns and frequency hopping strategies Furthermore, the mean user throughput for the fixed coding schemes and for link adaptation has been estimated from GSM network reported measurements, and a network operator planning tool
27 citations
01 Jan 2000
TL;DR: In this paper, a simple framework for Monte-Carlo simulations of a multiple-input-multiple-output (MIMO) radio channel is presented, including a stochastic model including the partial correlation between the paths in the MIMO channel, as well as fast fading and time dispersion.
Abstract: This document presents a simple framework for Monte-Carlo simulations of a multipleinput-multiple-output (MIMO) radio channel. A stochastic model including the partial correlation between the paths in the MIMO channel, as well as fast fading and time dispersion is proposed. Its implementation in a COSSAP primitive model is described. Simulations verify the features of this primitive model. However, the stochastic model still needs to be validated by comparison with results of measurement campaigns currently in progress [1,2]. This COSSAP block will later help to investigate combined transmit/receive diversity concepts as part of the European IST (Information Society Technologies) METRA (Multi Element Transmit and Receive Antennas) project [3].
12 citations
15 May 2000
TL;DR: In this article, the effective frequency load concept (EFLP) is used to compare networks under different circumstances, like for example different weekdays or networks using different configurations, and the simulations results show that networks using high frequency reuse factors give the best quality.
Abstract: Networks with different reuses, with and without DTX are compared by using the effective frequency load concept (EFL). EFL makes it possible to compare networks under different circumstances, like for example different weekdays or networks using different configurations. The simulations results show that networks using high frequency reuse factors give the best quality, while the gain from DTX is higher than the gain from power control. Both features can be combined to get an even higher gain. Field trial results show the same tendencies.
12 citations
15 May 2000
TL;DR: In this paper, a group of RAKE fingers with equal spacing around the detected code phase is assigned to reduce the overhead for delay tracking for direct-sequence spread-spectrum systems.
Abstract: A RAKE finger allocation algorithm for direct-sequence spread-spectrum systems is presented and analyzed. The RAKE finger allocation method is based on grouped RAKE finger assignment. The detected code phases with greatest power are assigned a group of RAKE fingers with equal spacing around the detected code phase. Allocating the RAKE fingers with spacing less than one chip period can reduce overhead for delay tracking. The grouped RAKE finger allocation principle is compared to single RAKE finger allocation. Allocating three RAKE fingers with T/sub c//2 spacing gives a 0.2-0.4 dB gain compared to single RAKE finger assignment with the same number of RAKE and tracking fingers.
11 citations
TL;DR: It is concluded that the designed beamforming implementation facilitates a potential capacity gain of ×3 in a 1/3 reuse FH-GSM network for an array size of M = 4–6.5 dB (which should becompared to the theoretical value of 9 dB for a pointsource).
Abstract: This paper presents the performance of adaptive antennas in a 1/3 reuse frequency hopping GSM network using conventional beamforming. It mainly focuses on C/I improvement for the purpose of capacity enhancement. The performance evaluation has been conducted by means of network computer simulations, where measured time-space radio channel impulse responses are applied for the desired user in the network. Measurements with an M = 8 element uniform linear array were conducted in the cities of Aarhus, Denmark, and Stockholm, Sweden. The simulated C/I improvement shows an almost 10 a log10(M) behavior for low azimuth spread values. For large values of azimuth spread (relative to the antenna beamwidth), the performance gain is reduced significantly. For an azimuth spread of 10°–12°, which has been measured in urban macro-cellular environments, the C/I gain for M = 8 is reduced to approx. 5.5–7.5 dB (which should be compared to the theoretical value of 9 dB for a point source). The designed DoA algorithm is very robust to co-channel interference and only a small degradation in performance is observed for single element C/I down to approx. –8 dB. We conclude that the designed beamforming implementation facilitates a potential capacity gain of ×3 in a 1/3 reuse FH-GSM network for an array size of M = 4–6.
4 citations
15 May 2000
TL;DR: A method to model the W-CDMA radio receiver performance, which is usable in network simulation tools for third generation mobile cellular systems, and an extension of the method to a soft handover situation is considered.
Abstract: This article presents a method to model the W-CDMA radio receiver performance, which is usable in network simulation tools for third generation mobile cellular systems. The method represents a technique to combine link level simulations with network level simulations. The method is derived from that of Malkamaki, de Ryck and Mourot (1994), which defines a stochastic mapping function from a signal-to-interference ratio into a bit-error-rate for a TDMA system. However, in order to work in a W-CDMA based system, the fact that the multiple access interference in the downlink consists of both Gaussian inter-cell interference and orthogonal intra-cell interference must to taken into account. The mapping function was used to estimate the BER for a number of different simulation setups, and good agreement with link simulation results is demonstrated. Finally, an extension of the method to a soft handover situation is considered.
4 citations
01 Jan 2000
TL;DR: In this article, the authors present a method to model the W-CDMA radio receiver performance, which is usable in network simulation tools for third generation mobile cellular systems, by combining link level simulations with network level simulations.
Abstract: This article presents a method to model the W-CDMA radio receiver performance, which is usable in network simulation tools for third generation mobile cellular systems. The method represents a technique to combine link level simulations with network level simulations. The method is derived from that of Malkamaki, de Ryck and Mourot (1994), which defines a stochastic mapping function from a signal-to-interference ratio into a bit-error-rate for a TDMA system. However, in order to work in a W-CDMA based system, the fact that the multiple access interference in the downlink consists of both Gaussian inter-cell interference and orthogonal intra-cell interference must to taken into account. The mapping function was used to estimate the BER for a number of different simulation setups, and good agreement with link simulation results is demonstrated. Finally, an extension of the method to a soft handover situation is considered.
15 May 2000
TL;DR: In this article, a concatenated receiver structure is proposed, where an antenna array is used to form a simple spatial filter which provides protection against fast fading and spatial white interference and noise.
Abstract: A concatenated receiver structure is proposed, where an antenna array is used to form a simple spatial filter which provides protection against fast fading and spatial white interference and noise. Subsequently, a multiuser detector (MUD) is applied, which cancels the residual interference from the dominant high bit rate users. Low bit rate users are not considered in the MUD. A decision directed MUD is implemented, where a new adaptive scheme for reducing the cost of wrong interference estimates is proposed. Simulation results indicate that such a structure provides a significant gain of 69% in throughput when implemented for UMTS.
15 May 2000
TL;DR: An algorithm for code phase acquisition in direct-sequence spread-spectrum systems is presented and analyzed and the algorithm is a window based double dwell searcher that has shorter acquisition than the immediate verification algorithm has-especially at low SNR.
Abstract: An algorithm for code phase acquisition in direct-sequence spread-spectrum systems is presented and analyzed. The algorithm is a window based double dwell searcher. The algorithm with a moderate window size has shorter acquisition than the immediate verification algorithm has-especially at low SNR. The first-dwell uses a robust method based on a rank filter while the second dwell uses known threshold hypothesis. The code phase acquisition algorithm is compared with both single and double threshold hypothesis algorithms.
01 Jan 2000
TL;DR: The present paper describes the set-up for the measurement of MIMO (Multi-InputMulti-Output) radio channels as part of the European IST (Information Society Technologies) project METRA (Multi Element Transmit and Receive Antenna).
Abstract: The present paper describes the set-up for the measurement of MIMO (Multi-InputMulti-Output) radio channels as part of the European IST (Information Society Technologies) project METRA (Multi Element Transmit and Receive Antenna). Exploitation of the measurements showed that 0.4λ separation, where λ is the wavelength, between the elements of the antenna array is sufficient to have them decorrelated even in a LOS scenario. Moreover a gain of 18 dB at 10% outage can be achieved using a 4×4 MIMO set-up. Inputs for the stochastic model described in [2] are extracted from the measurement results and fed into a COSSAP block implementing this model. A good matching between the eigenanalysis performed on both measured and simulated signals is shown.