Overlay of WB-CDMA-FDD on WB-TD/CDMA-TDD, reverse link capacity assessment

A reverse link capacity estimation of a two-layered hierarchical cellular structure (HCS) is presented making use of different multiple access schemes (MAS) in each layer. The HCS under study consists of a macrocell layer which uses wide-band code division multiple access with frequency division duplex (WB-CDMA-FDD). This macrocell layer overlays a microcell layer which uses wide-band time division/code division multiple access with asymmetric time division duplex (WB-TD/CDMA-TDD). System capacity in Erl/carrier/cluster and spectrum efficiency in Kbit/s/MHz/cluster are assessed for three different circuit-switched services and two combinations of them. The impact of different channel allocation strategies (CAS) on the system capacity is also assessed. For this purpose, two different resource allocation strategies are considered in the microcell layer using the WB-TD/CDMA-TDD multiple access scheme (MAS); they are the classic fixed channel assignment (FCA) and a simple dynamic channel allocation (SDCA). For the macrocell layer, using WB-CDMA, only FCA is used, The capacity of this system is also compared with the capacity of a HCS using WB-TD/CDMA-TDD in both layers.