Call management issues in CDMA cellular and optical core network domains

Abstract

CDMA scheme has becoming a most promising technology for the current cellular systems due to its various advantages such as outstanding voice and call quality, greatest coverage for lower cost, fewer dropped calls, improved security and privacy, greater capacity, etc. However, the explosive growth of mobile communication has presented some technical challenges relating to call management issues, which must be met in order to provide services with the smallest number of failures, good quality and the widest availability. First, we consider a call control policy at each cell, which gives priority to handoff calls over new calls while meeting the overall call quality. In the CDMA system, all (active) users share a common spectral frequency, thus being differentiated by uniquely assigned digital codes. Thus, the number of acceptable users is theoretically infinite. However, since other user signals interfere with the desired signal, the desired signal is always much smaller than the total of other interfered signals. Therefore, a CDMA cellular system requires call admission control which limits the number of new users. In a CDMA system, the key call control criterion is based on the outage probability, which is the fraction of time that servicing an ongoing call can be discontinued when a required level of the quality of service is not guaranteed any further owing to the increase of total interference. The mechanism of achieving the objective by limiting the number of active new calls within a threshold value is called the threshold-type call admission control (CAC) in the thesis. We consider a call control policy at each cell, which gives priority to handoff calls over new calls while meeting the overall call quality. New calls are first under the call control of the threshold type, and then receive services together with the handoff calls but under the outage restriction guaranteeing a pre-specified call quality. An optimization model with such quality-guaranteei...