An Adaptive Soft Handover Scheme Using Fuzzy Load Balancing for WCDMA Systems

In cellular systems, user distribution variations can cause load imbalance between cells. Embedding a load balancing strategy within the handover scheme means that ensuing traffic congestion can be alleviated by dynamically reallocating load between neighbouring cells. An adaptive soft handover scheme for multimedia cellular communication systems is proposed in this paper, that considers both the cell load factors as well as the pilot channel signal-to-interference-and-noise-ratio (SINR) for soft handovers. By using fuzzy principles, the soft handover thresholds and time hysteresis are adapted dependent upon the loads of the neighbouring cells. Simulation results show that the new algorithm provides improved system performance in terms of a more evenly distributed load, lower blocking probabilities and higher throughput

HANDOVER MANAGEABILITY AND PERFORMANCE MODELING IN MOBILE COMMUNICATION NETWORKS

In cellular Networks, a mobile station (MS’s) move from one cell region to another on seamless Communicationscheduling.. Handoff or Handover is an essential issue for the seamless communication. Several approaches havebeen proposed for handoff performance analysis in mobile communication systems. In Code-Division Multiple-Access (CDMA) systems with soft handoff, mobile stations (MS’s) within a soft-handoff region (SR) use multipleradio channels and receive their signals from multiple base stations (BS’s) simultaneously. Consequently, SR’sshould be investigated for handoff analysis in CDMA systems. In this paper, a model for soft handoff in CDMAnetworks is developed by initiating an overlap region between adjacent cells facilitating the derivation of handoffmanageability performance model. We employed an empirical modelling approach to support our analyticalfindings, measure and investigated the performance characteristics of typical communication network over a specificperiod from March to June, 2013 in an established cellular communication network operator in Nigeria. Theobserved data parameters were used as model predictors during the simulation phase. Simulation results revealedthat increased system capacity degrades the performance of the network due to congestion, dropping and callblocking, which the system is most likely to experience, but the rate of those factors could be minimized by properlyconsidering the handoff probabilities level. Comparing our results, we determined the effective and efficientperformance model and recommend it to network operators for an enhanced Quality of Service (QoS), which willpotentially improve the cost-value ratio for mobile users and thus confirmed that Soft Handoff (SH) performancemodel should be carefully implemented to minimize cellular communication system defects.Keywords: CDMA, QoS, optimization, Handoff Manageability, Congestion, Call Blocking and Call Dropping,

Soft handover issues in radio resource management for 3G WCDMA networks

PhDMobile terminals allow users to access services while on the move. This unique feature has driven the rapid growth in the mobile network industry, changing it from a new technology into a massive industry within less than two decades. Handover is the essential functionality for dealing with the mobility of the mobile users. Compared with the conventional hard handover employed in the GSM mobile networks, the soft handover used in IS-95 and being proposed for 3G has better performance on both link and system level. Previous work on soft handover has led to several algorithms being proposed and extensive research has been conducted on the performance analysis and parameters optimisation of these algorithms. Most of the previous analysis focused on the uplink direction. However, in future mobile networks, the downlink is more likely to be the bottleneck of the system capacity because of the asymmetric nature of new services, such as Internet traffic. In this thesis, an in-depth study of the soft handover effects on the downlink direction of WCDMA networks is carried out, leading to a new method of optimising soft handover for maximising the downlink capacity and a new power control approach

System modeling and performance evaluation of rate allocation schemes for packet data services in wideband CDMA systems

To fully exploit the potential of a wideband CDMA-based mobile Internet computing system, an efficient algorithm is needed for judiciously performing rate allocation, so as to orchestrate and allocate bandwidth for voice services and high data rate applications. However, in existing standards (e.g., cdma2000), only a first-come-first-served equal sharing allocation algorithm is used, potentially leading to a low bandwidth utilization and inadequate support of high data rate multimedia mobile applications (e.g., video/audio files swapping, multimedia messaging services, etc.). In this paper, we first analytically model the rate allocation problem that captures realistic system constraints such as downlink power limits and control, uplink Interference effects, physical channel adaptation, and soft handoff. We then suggest six efficient rate allocation schemes that are designed based on different philosophies: rate optimal, fairness-based, and user-oriented. Simulations are performed to evaluate the effectiveness of the rate allocation schemes using realistic system parameters In our model.published_or_final_versio

Call admission control using cell breathing concept for wideband CDMA

This paper presents a Call Admission Control (CAC) algorithm based fuzzy logic to maintain the quality of service using cell breathing concept. When a new call is accepted by a cell, its current user is generally affected due to cell breathing. The proposed CAC algorithm accepts a new call only if the current users in the cell are not jeopardized. Performance evaluation is done for single-cell and multicell scenarios. In multicell scenario dynamic assignment of users to the neighboring cell, so called handoff, has been considered to achieve a lower blocking probability. Handoff and new call requests are assumed with handoff being given preference using a reserved channel scheme. CAC for different types of services are shown which depend upon the bandwidth requirement for voice, data and video. Distance, arrival rate, bandwidth and nonorthogonality factor of the signal are considered for making the call acceptance decision. The paper demonstrates that fuzzy logic with the cell breathing concept can be used to develop a CAC algorithm to achieve a better performance evaluation

A Comparative study on Handoff Algorithms for GSM and CDMA Cellular Networks

The GSM, CDMA cellular systems are most trendy 2G and 3G digital cellular telecommunications systems, which is widely used throughout the world. These systems have many advantages such as high security, higher quality of call transmission over the long distances, low transmitted power, and enhanced capacity with more efficient utilization of the frequency spectrum. With these advantages these cellular systems have attracted more subscribers with more attention in the field of mobile communications. One of the most attractive features of cellular system is handoff which is a continuation of an active call when the mobile is moving from one cell to another without disconnecting the call. Usually, continuous service is achieved by efficiently designed handoff algorithms. So, efficient handoff algorithms are necessary for enhancing the capacity and QoS of cellular system. In this paper, the handoff analysis for GSM, CDMA cellular networks are done under various propagation models. Various handoff algorithms of GSM are described and also a novel received signal strength (RSS) based GSM handoff algorithm with adaptive hysteresis is analyzed. CDMA Soft handoff algorithm is analyzed and effective soft handoff parameters are estimated for better performance. The Comparison of handoff algorithms is studied based on results