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Five different radio network topologies, in the following referred to as "scenario", have been analyzed with regard to their capability to cover a medium size city with 3G mobile services. T-Mobile launched this study to assess different radio network topologies in terms of exposure. Thus, the main focus is to examine if, for exposure reasons, a medium size city can be covered with outer-city located sites. The radio network topologies discussed in this paper can generally be divided into two categories: In category one, the sites are located in the city, and in the other, the sites are located outside of the built-up area. In both cases the number of sites per scenario varies, and additionally the antenna height and site distance to the built-up area vary for the second category. The investigations are performed with a ray optical propagation model based on 3-D building data and a dynamic 3G network simulator. A mix of four services and a realistic spatial traffic distribution based on land usage is assumed. The performance of the scenarios, assessed by the evaluation of coverage and capacity, is examined together with the exposure. It is shown that network topologies with sites located only outside the city are not an adequate solution due to capacity constraints and coverage problems with high data services. A promising network topology is a reduced set of inner-city sites with higher order sectorization.

Broadband wireless access is emerging as one of the hottest areas of growth within mobile communication. It enables users to enjoy the same QoS they have at home, in the office or wherever they go. WiMAX is an innovative technology, which is specified in IEEE 802.16. Members of the WiMAX- forum are currently testing the first WiMAX equipments. The first commercial mobile WiMAX products are expected to be introduced into the market in the first quarter of 2007 and will be followed in the second half of the year by equipment with advanced multiple antenna capabilities - MIMO and beam forming - for higher throughput and capacity. For the planning of WiMAX networks, the investigation of radio transmission in and into buildings is getting more important. Therefore a new approach for the prediction of the field strength in hybrid scenarios (urban and indoor) is used. The prediction concept does not rely only on the direct ray (like empirical models) and it does not consider hundreds of rays for a single radio link (like ray tracing). The new model focuses on the most dominant path between transmitter and receiver. It allows the computation of the transition from an urban to an indoor scenario and vice versa, thus it is ideally suited for the planning of WiMAX networks.

With the growing demand for wireless communication systems, wireless concepts for the data exchange in time variant ad-hoc networks become more and more interesting. In order to describe and thus assess the mobile radio channels in such networks, simulations are required. The main aspect is the time-variance of the channel impulse response and the modeling of large scenarios. This paper discusses the demands for a model to describe the radio channel in time variant environments and presents an appropriate ray tracing approach. A new concept is introduced to substitute complex polygonal objects by several radar cross sections. The performance of the Ray Tracing algorithm is demonstrated by a comparison from predictions to measured channel characteristics.

In this paper path loss, delay and angular spread predictions of a 3D ray tracing propagation tool are compared to spatially resolved wideband radio channel measurements performed in a modern office building. Measurements were carried out in the 5 GHz band by using a wideband radio channel sounder, which gives out complex channel impulse responses. Reference rms delay spread and angular spreads at transmitter and receiver were obtained from SAGE processed super-resolution data, and path losses were available from sounder matched filter outputs after appropriate calibrations. Comparisons between propagation predictions and measurements were made in different indoor scenarios including office, lobby and cafeteria environments. For propagation modelling a full 3D ray optical model was used.

With the growing interest for broadband mobile services in mobile communication networks, the investigation of radio transmission in and into buildings is getting more important. Popular empirical and deterministic models for the propagation inside buildings compute the field strength based on the inner structure of the buildings (walls, furniture). But for current and future wireless networks (3G, B3G, WLAN, WiMax,..), the neighboring buildings must also be considered to avoid interference problems in these buildings. Additionally the indoor coverage of outdoor transmitters must be analyzed to guarantee a high QoS even inside buildings. A new concept for the prediction of the field strength in such hybrid scenarios (urban and indoor) is presented in this paper. This new concept does not rely only on the direct ray (like empirical models) and it does not consider hundreds of rays for a single radio link (like ray tracing). The new model focuses on the most dominant path between transmitter and receiver. It allows the computation of the transition from an urban to an indoor scenario and vice versa, thus allowing an accurate computation of the received power inside and around buildings. The new model is validated with various measurements and shows a good accuracy.

The accuracy of predictions with wave propagation models depends siginficantly on the quality of the building databases, as they show discrepanices when compared to reality. This is due to the inaccuracies of the photometric methods used to create these databases, but also to the fact that new buildings are raised or old buildings are pulled down. However, propagation models should feature a certain robustness against these inaccuracies. In this paper, the sensitivity of different propagation models for urban scenarios with respect to building database inaccuracies is analyzed. The main focus is the comparison of the Dominant Path model with a Ray Tracing model, but the results are also put in relation to the empirical COST 231 Walfisch-Ikegami model. Furthermore, the possibilities of an automatic database simplification to reduce calculation times are investigated, and it is shown that Ray Tracing computation times can be reduced up to 50% with only slight decreases in the accuracy by applying suitable simplification algorithms. For the evaluation of the influence on the accuracy also path loss measurements in different scenarios were used.

With the growing interest for broadband mobile services in mobile communication networks, the investigation of radio transmission in and into buildings is getting more important. Popular empirical and deterministic models for the propagation inside buildings compute the Field strength based on the inner structure of the buildings (walls, furniture). But for current and future wireless networks (3G, B3G, W-LAN, WiMax,..), the neighboring buildings must also be considered to avoid interference problems in these buildings. Additionally the indoor coverage of outdoor transmitters must be analyzed to guarantee a high QoS even inside buildings. A new concept for the prediction of the field strength in such hybrid scenarios (urban and indoor) is presented in this paper. This new concept does not rely only on the direct ray (like empirical models) and it does not consider hundreds of rays for a single radio link (like ray tracing). The new model focuses on the most dominant path(s) between transmitter and receiver. The parameters of these paths are determined (e.g. path length, number and type of interactions, material properties of objects, ...) and are used for the prediction of the path loss. This model allows also the computation of the transition from an urban to an indoor scenario and vice versa, thus allowing an accurate computation of the received power inside and around buildings. For the validation of the new model, measurements were made

With the increasing number of subscribers in mobile communications there is a growing interest in propagation models for the mobile radio channel in urban scenarios and inside buildings. Because of the increasing transmission rates propagation models should be able to predict the field strength coverage as well as the wideband properties for these scenarios.

In system simulations of WCDMA radio networks, a constant value for the orthogonality factor is often assumed in the whole considered area of interest to determine the network performance. This factor is used to scale the intra-cell interference, which has an important impact on the network performance. However, the orthogonality factor is not constant, but depends on the individual channel profile between transmitter and receiver, as well as on the receiver implementation. Therefore, this factor is different for every particular user. In a new approach, the orthogonality factor is calculated dependent on the above parameters for each receiver point individually. Comparisons of this new approach with the simple constant value approach are presented. The results show that the assumption of a constant orthogonality factor within a cell may lead to unrealistic results in system level simulations, especially if interference sensitive high bit rate services are considered, e.g., the packet transmission technology HSDPA (high speed downlink packet access). Especially in the field of performance analysis for network planning and design, it is important to obtain an accurate performance estimate with a correlation to the predicted area, instead of average values for the whole simulation area.

Many new services for mobile radio networks rely on a precise location of the mobile terminal. Especially in urban environments, multipath propagation leads to very complex scenarios without line-of-sight between the mobile and the different base stations. In these situations, a location technique based on simple delay evaluations and/or GPS is not accurate enough or not applicable. In this paper, a database correlation method for the positioning of mobile terminals is presented which yields precise results in urban environments. The approach is based on propagation models utilized for the planning of mobile radio networks. The results of the propagation models during the planning process define a look-up-table. By evaluating the measured path losses and available propagation times between the mobile terminal and several base stations, the positions of mobile terminals in urban environments can reliably be predicted.

The planning of WLAN infrastructures that supply large buildings or areas requires the consideration of many aspects and therefore is a difficult task if done manually. In this paper, a method is presented that allows one to optimize such networks automatically. The approach is based on predictions of the received power to account for the propagation conditions that have a major impact on the performance of WLANs. The optimization is applied to a set of possible locations where access points can be installed. Out of this set, a minimum selection of locations is made to meet the given requirements. These consist of the determination of areas with different priorities and the definition of further parameters. It not only takes into account the required coverage and capacity but also the interference situation. The arising co-channel interference is minimized by an appropriate assignment of the available carrier frequencies. The discussed approach may not find the global optimum in all cases, but it yields a suggestive result based on the locations defined by the network planner. Due to the very short computation time, different configurations can be analyzed very quickly.

High speed downlink packet access (HSDPA) is a technology to extend the peak data rates and capacity of 3G mobile data transmission systems. It targets especially favorable radio channel environments with the possibility to use higher order modulation and higher code rates. Furthermore fast retransmissions and enhanced scheduling algorithms can be used to boost data rates and to provide the required quality of service (QoS). A dynamic W-CDMA system level simulator has been extended to enable the simulation of packet switched services with special focus on HSDPA. The complete simulation system contains traffic sources that create sequences of packets for each active user equipment (UE), models the protocol stack and provides the possibility to collect performance indicators, e.g. sector packet data throughput, page throughput, and packet delays, in different scenarios for offline analysis. The simulation tool will be described and some example results concerning packet data performance of HSDPA will be shown.

With the growing interest for broadband mobile services in 3rd generation mobile communication networks, the investigation of radio transmission into vehicles and buildings is getting more important. Models for the propagation into vehicles and buildings enable the calculation of the field strength or received power inside these objects. The inner structure of the vehicles (e.g. metal parts) and buildings (inner walls, furniture) as well as the surroundings (other vehicles, buildings) must be considered, and also different construction materials must be taken into account. A deterministic ray tracing approach has been developed, enabling the computation of the transition from an urban scenario to an indoor scenario and vice versa, thus allowing a very accurate computation of the field strength or received power inside vehicles or buildings. Due to the ray tracing technique, the approach can also be utilized to evaluate wideband properties of the mobile radio channel by computing its impulse response. In order to validate such propagation models, measurements inside and outside a building were made.

With the growing demand for sensors and actors in the automotive technology, a wireless concept for the data exchange between different system components inside a vehicle becomes interesting. In order to describe and thus assess the mobile radio channel in the vehicle, simulations are required. For low frequencies, full wave simulations using the method of moments are well suited. For higher frequencies, these models become inadequate as regards the computational effort. This paper discusses the demand for models that can describe the radio channel inside vehicles at high frequencies and presents an appropriate ray tracing approach. The results of a measurement campaign are used to validate the proposed ray optical model.

In this paper path loss and delay spread predictions of a 3D ray tracing software are compared to wideband radio channel measurements made in Helsinki city center. Measurements were carried out in the 2 GHz band by using a wideband radio channel sounder, which gives out complex channel impulse responses. Reference delay spreads were obtained from power delay profiles, and path losses were available after appropriate cable calibration measurements. Comparisons between measurement and propagation predictions were made in cases where a realistic directional BS antenna was placed (a) slightly below the rooftop level and (b) slightly above the rooftop level. For propagation modeling a fully 3D ray optical model was used.

Ray optical modeling of wave propagation is often used for the prediction of the field strength (and delay spread) in wireless mobile communication networks. However, the practical use of these deterministic models is limited due to their high computational demands. For large areas in urban or indoor scenarios the computation times are in the range of hours which is too long for the planning of mobile radio networks. A new method for the acceleration of ray optical models is presented. It is based on a single intelligent preprocessing of the database in which the mutual visibility relations between the walls and the edges of the buildings are determined. The propagation model is implemented for urban and indoor scenarios and comparisons with measurements show the gain in computation efficiency as well as in achieved prediction accuracy.

With the growing interest for broadband mobile services in 3rd generation mobile communication networks, the investigation of radio transmission into vehicles and buildings is getting more important. Models for the propagation into vehicles and buildings enable the calculation of the field strength or received power inside these objects. The inner structure of the vehicles (e.g. metal parts) and buildings (inner walls, furniture) as well as the surroundings (other vehicles, buildings) must be considered, and also different construction materials must be taken into account. A deterministic ray tracing approach has been developed, enabling the computation of the transition from an urban scenario to an indoor scenario and vice versa, thus allowing a very accurate computation of the field strength or received power inside vehicles or buildings. Due to the ray tracing technique, the approach can also be utilized to evaluate wideband properties of the mobile radio channel by computing its impulse response. In order to validate such propagation models, measurements inside and outside a building were made.

With micro- and even picocells becoming an ever more important part of modern network design, deterministic wave propagation modeling has become a widely discussed solution. The necessity of acquiring high resolution-high quality data as well as extensive computation time pose severe challenges to practical planning scenarios however. A number of solutions and accelerating techniques are known in literature, all of them performing quite well under certain preconditions, but are unsatisfactory when conditions change. Therefore, the basic principles of accelerating rigorous 3-D ray tracing are presented under the aspect of their impact on prediction accuracy. A software has been developed which is able to make 'intelligent' decisions with regard to the application of various accelerating algorithms and by consequence gives optimized performance in all types of propagation scenarios. Comparison with measurements shows the gain in computation efficiency as well as the achieved prediction accuracy.

A new model for the field strength prediction for mobile communication networks inside buildings is presented. The model is based on artificial neural networks, trained with measurements. In contrast to other neural prediction models a good generalization is achieved, so the prediction results are also very accurate in buildings not used for the training of the neural network. Two algorithms for the selection of the training patterns for the neural networks are presented and compared to each other.

With the introduction of 3/sup rd/ generation cellular networks and their high bit rate services, new techniques in the field of radio network planning and dimensioning are required. This paper presents a simulation tool to support the planning process by analysing the performance of a given network constellation. Additionally, an example for a coverage and capacity analysis is given and simulation results gained with the dynamic simulator are discussed.

The introduction of 3/sup rd/ generation cellular networks and their various bit rate services require new techniques in the field of radio network planning and dimensioning. This paper describes a simulation tool on the system level in order to support the planning process by analyzing the performance of a given network constellation. Finally, an example scenario for a coverage and capacity analysis is presented and simulation results gained with the system simulator are discussed.

With the introduction of wireless broadband services in indoor environments there is a growing interest in propagation models for the mobile radio channel inside buildings. Because of the increasing transmission rates propagation models should be able to calculate the field strength coverage as well as the wideband properties for these indoor scenarios. This paper presents a new ray optical approach, which enables the prediction of field strength, delay spread and impulse response within a very short computation time. Additionally, simulation results gained with the new model are compared to measurements of the different wideband channel parameters.

A new model for the field strength prediction for mobile communication networks inside buildings is presented. The model consists of a neural network, trained with measurements and combines the advantages of empirical models (short computation time) with the advantages of deterministic models (waveguiding). The prediction results compare favourably with measurements.