WCDMA Cellular Networks Research Articles

Active Set Size Effects at HSUPA in WCDMA Systems

WCDMA cellular networks support soft handover, which guarantees the continuity of wireless services and enhanced communication quality. Cellular networks performance depends upon Soft handover parameters. In this paper, we have shown the effect of soft handover parameters on the performance of WCDMA cellular networks. We consider timeToTrigger1a, timeToTrigger1b, timeToTrigger1c and maxactivesize as the Soft handover parameters. A very useful statistical measure for characterizing the performance of WCDMA cellular system is the mean active set size and soft handover region. It is shown through numerical results that above parameters have decisive effect on HSUPA, mean active set size and soft handover region and hence on the overall performance of the soft handover algorithm.

A Geometrical-Based Model for Cochannel Interference Analysis and Capacity Estimation of CDMA Cellular Systems

A common assumption in cellular communications is the circular-cell approximation. In this paper, an alternative analysis based on the hexagonal shape of the cells is presented. A geometrical-based stochastic model is proposed to describe the angle of arrival of the interfering signals in the reverse link of a cellular system. Explicit closed form expressions are derived, and simulations performed exhibit the characteristics and validate the accuracy of the proposed model. Applications in the capacity estimation of WCDMA cellular networks are presented. Dependence of system capacity of the sectorization of the cells and the base station antenna radiation pattern is explored. Comparisons with data in literature validate the accuracy of the proposed model. The degree of error of the hexagonal and the circular-cell approaches has been investigated indicating the validity of the proposed model. Results have also shown that, in many cases, the two approaches give similar results when the radius of the circle equals to the hexagon inradius. A brief discussion on how the proposed technique may be applied to broadband access networks is finally made.

Single Code-Based Dynamic Grouping with Cycle Interleaving Algorithm for Reducing Waste Rate in WCDMA Cellular Networks

3G must offer high data rates since it should support real-time multimedia services; one performance enhancement, the use of the OVSF code tree, has adopted in 3G WCDMA networks. Unfortunately, this technique allows the link capacity to be set at the base rate times powers of two. This results in wasting bandwidth while the required rate is not powers of two of the basic rate. Several multi-code assignment mechanisms have been proposed to reduce the waste rate, but incur some drawbacks, including high complexity of handling multiple codes and increasing cost of using more rake combiners. Our solution is a dynamic grouping code assignment that allows any rate to be achieved with a single code for any possible rate of traffic. The dynamic grouping approach first forms several calls into a group. It then allocates a subtree to the group and dynamically shares the subtree codes based on time-sharing of slots within a group cycle time. The waste rate and code blocking is thus reduced significantly. Since transmission delay and jitter may occur in such a time-sharing approach, two schemes of cycle interleaving are proposed to minimize delay and jitter. Numerical results demonstrate that the proposed approach reduces the waste rate and increases the system utilization obviously, and the proposed cycle interleaving schemes minimizes delay and jitter significantly.

Other-Cell-Interference Factor Distribution Model in Downlink WCDMA Systems

Interference performance is among the most important issues especially in WCDMA cellular networks planning coverage and capacity. F-factor has been introduced in previous works to model the interference in WCDMA downlink dimensioning process. In this paper, we establish its PDF expression assuming one interferer in the serving cell both with and without correlated shadowing effect. Uniform and non-uniform traffic situations are distinguished through the study of both uniform and non-uniform traffic load cases. Then, we generalize the expression for multiple interfering cell tiers. We show the impact of this evaluation on the design process in order to increase the capacity of a network.

On the Analysis of Switched-Beam Antennas for the W-CDMA Downlink

Smart antennas are widely recognized as an enabling technology for addressing the demand of future wireless network capacity when employed in place of traditional fixed-coverage sector antennas. Furthermore, switched-beam antenna systems offer a robust implementation against multipath propagation effects and reduced complexity that is inherent with fully adaptive implementations. This paper introduces a simple closed-form expression for evaluating the capacity increase of W-CDMA cellular networks employing switched-beam antennas. The expression incorporates the effect of practical antenna patterns and the impact of multipath scattering on code orthogonality, as well as that of pilot signal power. The results show that a reduction in downlink interference of approximately 6 dB can be achieved by installing an eight-beam antenna system in a 120/spl deg/ sector configuration when representative values of these parameters are taken into account.

Estimation of Implementation Losses in MAC Protocols for Wireless CDMA Networks

This paper presents an analysis of implementation losses in feedback channel state information (FCSI) based MAC protocols for the up-link (UL) of a centralized asynchronous CDMA packet radio system. Such protocol can be used in different segments (or domains) of the future wireless IP networks including WCDMA cellular networks, wireless LANs and Ad Hoc networks. The motivation behind these protocols is to control the channel access by statically or dynamically changing packet transmission permission probability (TPP), also referred to as persistence probability, depending on FCSI. This is supposed to keep the UL load under a certain threshold depending on the QoS requirements. As the main contribution of this paper, effects of the feedback delay, access delay, and imperfect channel sensing are taken into account simultaneously in the analysis. These effects are referred to as imperfections. For performance analysis the system sensitivity functions are introduced. These functions represent the relative performance losses due to the imperfections, which are also referred to as implementation losses. The tradeoff between throughput, outage probability and packet delay in the presence of imperfections is discussed based on numerical results for a number of queuing system models.

Experimental Performance Analysis for 2G/3G Cellular Networks based on Mobile Terminals

This work presents the experimental results related to performance measurements in GSM, EDGE and WCDMA cellular data networks. Two Mobile Terminals were used, in order to take place the scenario. Power Level, Power vs Time, Modulation Analysis, Modulation Spectrum, (BER) Bit Error Rate and Throughput were considered in this analysis.Keywords: Component; GSM; EDGE; WCDMA; BER/BLER; ThroughputDOI: http://dx.doi.org/10.3126/jie.v8i1-2.5094Journal of the Institute of Engineering Vol. 8, No. 1&2, 2010/2011Page : 25-38Uploaded Date: 19 July, 2011