**7. Acknowledgments**

This research has been supported by the MICINN/FEDER project grant TEC2010-21405-C02-02/TCM (CALM) and it was also developed in the framework of

**0**

**6**

<sup>1</sup>*Latvia* <sup>2</sup>*Denmark*

**Call Admission Control in Cellular Networks**

The service area of a cellular network is divided into cells. Users are connected to base stations in the cells via radio links. Channel frequencies are reused in cells that are sufficiently separated in distance so that mutual interference is below tolerable levels. When a new call is originated in a cell, one of the channels assigned to the base station of the cell is used for communication between the mobile user and the base station (if any channel is available for the call). If all the channels assigned to this base station are in use, the call attempt is assumed to be blocked and cleared from the system (blocked calls cleared). When a new call gets a channel, it keeps the channel until either the call is completed inside the cell or the mobile station (user) moves out of the cell. When the call is completed, the channel is released and

When a mobile station moves across the cell boundary and enters a new cell, a handover is required. Handover is also named handoff. If an idle channel is available in the destination cell, a channel is assigned to it and the call stays on; otherwise the call is dropped. Two commonly used performance measures for cellular networks are dropping probability of

Call admission control (CAC) algorithms are used in order to keep control on dropping probability of handover calls and blocking probability of new calls. They determine whether a call should be accepted or rejected at the base station. Both the blocking probability of new calls and the dropping probability of handover calls are affected by the call admission algorithm used. The call admission algorithms must give priority to handover calls as

Dedicated to the memory of Janis Sedols, Doctor of Mathematics (Dr.sc.comp.), 24.03.1939–11.08.2011.

Paper financed from EDRF's project SATTEH (No. 2010/0189/2DP/2.1.1.2.0./10/APIA/VIAA/019) being implemented in Engineering Research Institute "Ventspils International Radio Astronomy

of new calls represents the probability that a new call is denied access to the

calls represents the probability that a handover call is dropped during handover. The

**1. Introduction**

probability

compared to new calls.

Dr. Sedols was active in writing this chapter.

Centre" of Ventspils University College (VIRAC).

network.

becomes available to serve another call.

handover calls and blocking probability of new calls. The

Manfred Schneps-Schneppe1 and Villy Bæk Iversen<sup>2</sup>

dropping

probability

of handover

blocking

<sup>1</sup>*Ventspils University College* <sup>2</sup>*Technical University of Denmark*

"Programa de Ayudas a Grupos de Excelencia de la Region de Murcia, Fundacion Seneca, Agencia de Ciencia y Tecnologia de la RM (Plan Regional de Ciencia y Tecnologia 2007/2010".
