Performance Model for Orthogonal Sub Channel in Noise-Limited Environment

Orthogonal Sub Channel (OSC) is a voice enhancement for the GSM evolution. It allows in principle a double capacity with the same hardware compared to the previous GSM Half Rate (HR) mode. This paper investigates the effects of OSC on the radio performance as function of the OSC capable handset penetration compared to the GSM HR mode. A set of test cases was carried out in GSM network in order to evaluate the radio performance of OSC in terms of the carrier per noise level. The tests were performed in noise-limited indoor environment, and the quality and received power level distributions were analyzed. As a main achievement, a generic model for estimating the effect of OSC on the GSM radio performance was developed. The model is based on the network statistics and performance indicators of GSM.