Radio resource management in a novel indoor GSM base station system

We study the problem of radio resource management in a novel indoor GSM base station (IBS) system. The system consists of one HUB station and several radio heads (RH). Thanks to the RHs, a true space division multiple access (SDMA) component is introduced to GSM system without a need for air-interface modifications. This will permit frequency reuse inside logical cells hence enhancing the spectral efficiency and enabling the support of very high traffic densities with only few carriers. There are various alternatives in dividing current GSM base station functions between the HUB and RHs. Regardless of the implementation, new functions, signal switching and additional measurements, are needed in the IBS. The new challenges with this kind of base station architecture include call set-up and handovers (HO). In the call set-up, the system allocates a call not only a carrier frequency and a time slot, but also a radio head. In addition to current intra-cell and intercell handovers, a new handover type, sub-cell HO, is needed.