Front end design of Software Defined BTS for interoperability between GSM and CDMA

Software defined radio aims at using the same hardware for different applications by the change in software parameters. The reconfigurable part in a software defined radio is the digital front-end and the parameters which can be modified for different standards and technologies include bandwidth, sampling frequency, down converted IF, up converted IF and filter cut-off frequencies. The major goal for an ideal software defined radio is to place the ADC as close to the antenna as possible. This can be achieved by band-pass sampling. Automatic modulation identification (AMI) can be used in conjunction with the design principles of software defined radio to make the transceiver more flexible. The main objective of this paper is to address the concepts involved in the design of RF front end of a software defined base transceiver station (BTS) which can be configured to support different technologies (here GSM/IS-95) depending on the software modifications.