Improved Erlang capacity of combined carrier channel assignment for hybrid FDMA/CDMA systems supporting voice and data services

Using analytical techniques, we determine the conditions under which the combined carrier channel assignment (CCCA) scheme of channel allocation is preferable to the independent carrier channel assignment (ICCA) in an FDMA/CDMA system providing voice and circuit-switched data services. We find out that, even though the benefit of the CCCA scheme over the ICCA scheme is negligible for small number of channel elements (CEs), the scenario changes significantly when the number of CEs increases beyond a certain point. An improvement of as much as 74% can be achieved in the Erlang capacity when 5 carriers are employed, each with 29 channels in a 3-sector per cell system. We also find the capacity knees for different number of carriers.