MEASUREMENT BASED REPLANNING OF CELL CAPACITIES IN CELLULAR WIRELESS NETWORKS
Ertan Onur · 2001
MEASUREMENT BASED REPLANNING OF CELL CAPACITIES IN CELLULAR WIRELESS NETWORKS The wireless telephony systems rely on the teletraffic theory to accommodate a large number of users in a limited spectrum. Because of the scarcity of the spectral resources, the number of channels is limited. Teletraffic analysis exploits the statistical behavior of the on-demand transmission access of users to a pool of channels. When a particular user requests service and all of the channels are already occupied, the user is denied access to the system and the user is blocked by the network. In cellular wireless networks, two of the reasons that make cell capacity replanning difficult are the retrial and redial phenomena. Automatic retrials are carried out without the user knowledge upon being blocked by the network. Redials are the requests generated by the user after the original call and the automatic retrials are all blocked. All of the automatic retrials and redials are registered as separate calls. As a result, during the busy periods when blocking is observed in a cell, where the capacity planning is not done adequately, counters register a much larger volume than the effective call attempts. In terms of capacity replanning, a load appearing larger than the effective one will require more channels than needed to be assigned to the cell. In this thesis, simple analytical models as a solution to the automatic retrial and redial problem are presented. These models are used to compute the mean number of retrials and redials per effective call. Consequently, it will be possible to extract the retrials and redials out from the measured statistics. Finding out the effective number of call attempts, the capacity replanning of a cell can be done more accurately.