Efficient codebook design for digital communication through compressed voice channels

Abstract

The common voice channels existing in cellular communication networks provide reliable, ubiquitously available and top priority communication mediums. These properties make voice dedicated channels an ideal choice for high priority, real time communication. However, such channels include voice codecs that hamper the data flow by compressing the waveforms prior to transmission. This study designs codebooks of speech-like symbols for reliable data transfer through the voice channel of cellular networks. An efficient algorithm is proposed to select proper codebook symbols from a database of natural speech to optimise a desired objective. Two variants of this codebook optimisation algorithm are presented: One variant minimises the symbol error rate and the other maximises the capacity achievable by the codebook. It is shown both analytically and by the simulation results that under certain circumstances, these two objective functions reach the same performance. Simulation results also show that the proposed codebook optimisation algorithm achieves higher data rates and lower symbol error rates compared with previously reported results while requiring lower computational complexity for codebook optimisation. The Gilbert-Elliot channel model is utilised to study the effects of adaptive compression rate adjustment of the vocoder on overall voice channel capacity. Finally, practical implementation issues are addressed.

An alternative method of biomedical signal transmission through the GSM voice channel

“…This study indicates that transmission requirements can be satisfied by using a GSM voice channel and shows that this method of medical signal transmission over GSM voice channel is accurate enough and can be used as an alternative to the existing methods. The benefits of transmitting data through GSM voice channel have been explained in several studies [12][13][14][15][16][17][18]. However, none of these studies have used GSM voice channel for healthcare purposes.…”

“…However, none of these studies have used GSM voice channel for healthcare purposes. Using the voice channel of GSM makes the transmission channel more reachable and secure [13][14][15]19]. This becomes especially important in emergency situations such as in an ambulance, where data transmission might be critical.…”