Fixed-Mobile Convergence: Using Unlicensed DECT Frequencies in UMTS Femtocell Services Deployment

In this paper, we explore the possibility of using unlicensed DECT frequency bands to deploy UMTS Femtocells in the user homes. This solution gives the possibility for ISP providers to enter the mobile market without being forced to pay for the use of the frequencies licensed to the incumbent operators. This study starts from the analysis of the legislation on the use of the DECT and UMTS frequency bands for short-range voice communications and defines the changes required on the current UMTS handsets and Femtocells for the use of the DECT frequencies. Changes on both superheterodyne and homodyne transceivers have been investigated, as well as the modifications on the procedure the handset has to follow to select the DECT bands. The narrowness of the DECT bandwidth doesn't allow for having a safe guard band between the Uplink and Downlink channels, as it is for the current UMTS system. We then conducted simulations to evaluate the impact of this feature on the system performance.