A New QoS Driven Call Admission Strategy Enabling Soft Capacity in GSM Networks

1. 0,6 0,8 0,7 0,5 0,6 0,4 0,5 b values α values 0,3 0,4 0,3 0,2 0,2 0,1 0,1 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Iteration Steps Iteration Steps New Call or Handover Neighbor cell Resource Monitoring Neighbor cell Resource Monitoring Accept Accept QoS Estimator QoS Estimator Substitute Substitute Central cell Resource Monitoring Central cell Resource Monitoring N Block Drop Accept Accept Hand it over Hand it over A New QoS Driven Call Admission Strategy Enabling Soft Capacity in GSM Networks UNIVERSITY OF PATRAS Department of Electrical & Computer Engineering Wireless Telecommunications Laboratory I. D. Politis, G. S. Paschos, S. A. Kotsopoulos ipolitis@ee.upatras.gr, gpaschos@ee.upatras.gr, kotsop@ee.upatras.gr Wireless Telecommunications Laboratory PROPOSED ADMISSION STRATEGY INTRODUCTION An effective way to provide improved QoS is the use of an efficient Call Admission Control (CAC) scheme. A CAC policy surveys the QoS requirements and manages the resources in order to offer improved network performance. Soft Capacity is a feature of the 3G networks which enables optimized resource utilization from a geographically asymmetric traffic. TARGET OF RESEARCH This paper proposes a new way of introducing soft capacity into GSM networks, via system-initiated handovers. The algorithm enables soft capacity by using the unoccupied channels of the neighbouring cells and redistributing the traffic along the cluster. QoS INDEX (QI) The traffic load is assumed largely centralized. Therefore the system, in order to preserve the QoS in the central cell, initiates system handover call requests to the neighbouring cells. The CAC scheme searches for available system resources every time a new call or a handover request is issued. If the ongoing traffic exceeds load threshold decided by the provider then the system scans all the established connection in order to find one that can be handed off to a neighbouring cell. This decision is called QoS estimation and is based on a QoS Index. INTERETION METHOD The convergence of avaluesfor several load cases. The convergence of bvaluesfor several load cases. RESULTS TELETRAFFIC ANALYSIS • Probability that a System Initiated Handover is granted by QoS Estimator: • Modified Markov Chain: Blocking Probability for the central cell Dropping Probability for the central cell The Markov chain modified for the needs of the proposed algorithm. • Markov Analysis: • Neighboring Cell Equations: • Central Cell Equations: Blocking Probability for the neighbor cell Dropping Probability for the neighbor cell • CONCLUSIONS & FURTHER RESEARCH • The implementation of the proposed algorithm concerning the QoS driven admission strategy, can take place on the already installed systems with small interventions. The proposed algorithm creates the soft capacity feature in a 2G system with fixed cells and resources. Hence it offers a satisfying improvement of QoS for asymmetrically loaded systems by adding an insignificantly • small fraction of complexity in the system. Further research is undertaken in the following fields: • Implementation of the proposed algorithm to the neighboring cells also. • Management of the algorithm in a distributed fashion throughout the cluster. • Incorporation of Mobility algorithms within the proposed CAC scheme. Representation of cluster structure with centralized traffic and parameters for calculating QI. Ilias Politis, ipolitis@ee.upatras.gr, Georgios Paschos, gpaschos@ee.upatras.gr, Prof. Stavros Kotsopoulos, kotsop@ee.upatras.gr Wireless Telecommunications Laboratory, University of Patras, Rion 26500 Greece, tel: +302610997301, fax: +302610997302