Avoidance of double encoding and decoding in digital cellular network

Abstract

A common problem faced in the case of wireless to wireless subscriber calls in cellular networks is the voice degradation due to the double encoding/decoding performed at the air interfaces. The voice degradation is in terms of the voice quality and the significant amount of delay introduced in the voice path. We present some of the methods employed in the GMH2000 system for doing away with the extra encoding/decoding step and the problems associated with this. To overcome this problem in the GMH2000 system the intermediate decoding/encoding at the base stations (BSSs) is avoided by setting up a transparent data channel between the 2 BSSs for transparently carrying the compressed voice packaged in inband messages, over the regular 64 kbps bit stream. This channel is setup once the call has been completely setup between the 2 subscribers and no more switch intervention is needed.