Calculation of forward link interference and erlang capacity in hierarchical CDMA systems

Abstract

High rate data services for the next generation networks would require more resources so that more efficient structures for providing large capacity will be needed. Microcells are one of the methods to increase capacity in a small hot spot areas where users demand high call setup. Due to increasing demand in the capacity of future cellular systems, Hierarchical Cell Structure(HCS) which configures a system where at least two types of cells operate is expected to be common in cellular syetem design. So, wireless operators can provide service to the high demand areas through microcells within macrocells and High user dense area is located randomly not fixed in many cities. Therefore, wireless operators have to install microcells randomly within each macrocell according to user dense area. Several studies have been done on the forward link erlang capacity with a mixed multirate traffic sources in homogeneous cell structure(consisting of only macrocells). This thesis also shows forward link erlang capacity analysis, however some different results particularly by considering microcells which are randomly located within each macrocells. Capacity analysis is performed for systems providing voice service and mixed traffic types(e.g, voice(9.6kbps) ,data(64kbps) and data(144kbps)) by considering two situation. First, we consider 19 macrocells which are consist of reference macrocell, 1``st tier(6 cells), 2``nd tier(12 cells), and one fixed microcell within the reference(central) macrocell. we derive different forward link erlang capacity by changing the distance between macrocell and microcell and power ratio between them. It is found that there are optimal parameters in terms of distance and power ratio. These parameters make the capacity of macrocell and microcell different and making the traffic planning is adjusted case by case. Second, we drive erlangcapacity by considering 19 macrocells which are the same as the first situation and 7random located microcell with...