Receiver dimensioning in a hybrid multicarrier GSM base station

Wideband multicarrier receivers are an interesting technology for software-defined radios. When combined with suitable digital signal processing hardware and software, they enable flexible adjustment of the number of carriers as well as provide the capability of simultaneous reception of signals with differing bandwidths and modulation formats. Due to technological limitations, the required dynamic range may not be available in the near future, however. For this reason, it has been proposed to install two separate receivers in a base station: a high gain receiver for serving distant terminals and a low gain receiver for nearby terminals. In GSM base stations, it is also necessary to include a narrowband receiver with large dynamic range to enable random access capture. Since the low and high receivers will have only partly overlapping coverage areas, it is interesting to study what the relative traffic through each receiver would be. This will affect the number of carriers to be supported by each receiver. In GSM base stations, it is also important to consider the narrowband receiver, which can serve terminals anywhere within the cell. A series of simulations was performed in order to define the respective traffic capacity requirements in a suburban macrocellular and urban microcellular environment. The number of high input levels in a base station was found to be rather small. Therefore, in base stations of small or moderate capacity, the narrowband receiver can apparently serve those terminals which cannot be supported by the high gain receiver. Consequently, no low gain wideband receiver is needed, and the base station architecture can be simplified. The novel base station architecture brings about the need for a level-based intracell handover. Parameterization of this handover as well as the strategy of allocating channels in the different receivers should be done with care, in order to avoid loss of traffic capacity.