UMTS Cell Research Articles

A New Analytical Model of UMTS Cell

Abstract This paper discusses a new analytical model of the WCDMA radio interface. The proposed model is based on Erlang’s Ideal Grading with multi-rate traffic and different availability characteristics. Thanks to the application this model, it is possible in the proposed model to take into consideration not only the influence of interference from different cells, but also different traffic management mechanisms. The operation of the new model is presented with the example of the WCDMA interface in which selected classes of calls have introduced traffic constraint. The proposed model is characterized by its simplicity, while the results obtained with its application are characterized by accuracy that is acceptable for the model to be used in engineering calculations.

A Method for Soft-Decision UMTS Cell Reselection Based on a Database Solution

A novel idea of cell reselection in a UMTS system is presented in this article. The proposed method offers performance enhancements when compared to the algorithm that complies with the 3GPP specifications. This reselection algorithm specifics new criteria that are iteratively computed in every measurement cycle. And to continuously perform the iterative nature of the algorithm, a database solution also is proposed. The database must follow certain rules to maintain the required efficiency.

Minimizing the Electromagnetic Exposure Using Hybrid (DVB-H/UMTS) Networks

A hybrid mobile communication network as considered in this paper consists of a point-to-point network (UMTS) and a point-to-multipoint network (DVB-H). The benefit of combining these two networks is an optimized transfer of data by collecting several user requests for a single response via the broadcast network. Thus, capacity can be saved, UMTS cells can be unloaded and the mean response time of the system can be reduced. Besides these advantages, hybrid networks can be applied to decrease electromagnetic exposure, especially at hot spot areas. In this paper, it is analysed how the hybrid network structure influences the electromagnetic exposure. Therefore, different scenarios have been developed consisting of different user behavior and different network structures. In order to evaluate the grade of exposure, criteria have been defined. These criteria have been used for comparing a hybrid network with a single UMTS network in terms of electromagnetic exposure. The results are shown for the different network structures and network configurations

Market Driven Dynamic Spectrum Allocation over Space and Time among Radio-Access Networks: DVB-T and B3G CDMA with Heterogeneous Terminals

The radio frequency spectrum is a naturally limited resource of extraordinary value, as the key to the provision of important communication and information services. Traditionally, spectrum has been allocated first to specific access technologies, and then sub-allocated to specific access networks, on very long term basis (up to decades). The traditional scheme can be very inefficient when demand patterns ("loads") exhibit high temporal and spatial variations. Dynamic spectrum allocation (DSA) improves radio spectrum efficiency by adjusting the allocation as demand changes in time and/or space. In previous work, we introduced a DSA scheme in which a spectrum manager periodically auctions short-term spectrum licenses. The scheme can be supported by a realistic "pooling" business model, and can work with many radio-access technologies. But our previous analysis only considers a code-division multiple access (CDMA) technology; and DSA provides the greatest benefits with the participation of networks having complementary "busy hours," such as video entertainment services and cellular telephony. Here, a digital video broadcast (DVB) terrestrial network joins the scheme. A typical DVB terrestrial cell is (much) larger than a UMTS cell. This brings to the forefront inter-cell interference, and inter-related auctions in different cells. To capture the essence of these issues we focus first on a situation where one DVB terrestrial cell overlays two adjacent CDMA cells. Subsequently we discuss extensions to richer scenarios. The contributions of the present work over our previous publications include to : (i) address the impact of inter-cell interference among several CDMA cells, (ii) introduce the DVB access technology into the DSA scheme, (iii) modify the auction scheme to consider that a DVB cell overlays several CDMA cells, (iv) characterise analytically the marketing and bidding behaviour of the DVB network.

Performance of Queueing Model of one UMTS Cell with R Virtual Zones by the Maximum Entropy Solution

UMTS stands for Universal Mobile Telecommunications System, which is one of the third generation (i.e., 3G) cellular systems, will come into full commercial phase by year 2005 and the first UMTS services are launched commercially in 2001. Therefore, the research of UMTS is an important and urgent task. In this paper, the performance of UMTS systems is studied through a queueing model which consists of one UMTS with many virtual zones to evaluate the system uplink traffic performance. The two performance measures: blocking probability and system utilization are obtained by the Maximum Entropy Principle, i.e., ME solutions for S RXR (GGeo/GGeo/1)/N queue. S RXR (GGeo/GGeo/1)/N system means that arrival time and service time are both GGeo (Generalized Geometric) distributed, each output port has a single server and the maximum capacity is N. After the theoretical analysis, the numerical results are found for the idiographic example, 8×8 (GGeo/GGeo/1)/512 queueing model. Additionally, the performance of this queueing model is discussed with the effect of the parameters Ca 2 (squared coefficient of variation of the interarrival time), Cs 2 (squared coefficient of variation of the service time) and the arrival rate, ?.

A Comparative Capacity/Coverage Analysis for CDMA Cell in Different Propagation Environments

In the design of cells in mobile communication systems, path loss prediction models play an important role and have been the subject of the study for some time (M.F. Ibrahim and J.D. Parsons, IEE Proceedings, Vol. 130, No. 5, 1983). This paper presents the analysis of two main factors that affect the capacity bounds in a UMTS cell for different propagation models. These are the (i) interference levels at Node B, which increases with the number of active users, and (ii) the limited sending power of the user equipment (UE) which may not be able to send signals with enough power to reach Node B with the required received power level due to path loss. The aim of this paper is to analyse the capacity/coverage of the uplink of UMTS system in different propagation environments (free space, suburban, urban, dense urban, rural) and derive the capacity bounds for the UMTS cell. The capacity bounds have been extracted based on the extended COST-231 Hata model (http://cost.cordis.lu/src/whatiscost.cfm). COST-231 Hata is an extension of the Okumura–Hata model which covers the higher frequencies (G.L. Stuber, “Principles of Mobile Communications,” Kluwer, 1996) necessary for WCDMA. The basic model describes the propagation loss in an urban environment, but a number of correction factors can be applied to extend its application to a broader range of environments. The analysis takes into account a number of capacity influencing factors such as the CDMA code non-orthogonality, the inter-cell interference, imperfect power control, and different service specific factors. The simulation results show the effect of different system and varying environmental parameters upon the system's capacity in different environments. The results clearly demonstrate that it is too optimistic to rely on studies based on free space assumptions.