Title :
The capacity of PCM voiceband channels
Author :
Kalet, I. ; Mazo, J.E. ; Saltzberg, B.R.
Author_Institution :
Dept. of Electr. Eng., Tel Aviv Univ., Ramat Aviv, Israel
Abstract :
It is theoretically shown that the capacity of a voiceband channel operating through a digital network is at least 56 kbps (for a 3.5 kHz baseband bandwidth). The capacity may actually be higher but how close one can come to 64 kbps, the limit imposed by the digital network itself, is unknown. The transmission method is based on generating nonuniformly pulsed PAM (pulse amplitude modulation) signals which at the network sampling instants go through one of the slicing levels of the A/D converter of the network. To accomplish this, both the slicing levels and the sampling clock times must be known. This is a hard practical problem and one can only conjecture if a reasonable solution will be possible. The signal may be recovered using a Viterbi detector to reduce intersymbol interference effects, but at present, the number of states required for this detector is very large
Keywords :
Viterbi detection; channel capacity; intersymbol interference; pulse code modulation links; signal sampling; voice communication; 3.5 kHz; 56 kbit/s; PCM voiceband channels; Viterbi detector; capacity; digital network; intersymbol interference; pulse amplitude modulation; sampling clock times; slicing levels; Amplitude modulation; Bandwidth; Baseband; Detectors; Phase change materials; Pulse generation; Pulse modulation; Pulse width modulation converters; Sampling methods; Signal generators;
Conference_Titel :
Communications, 1993. ICC '93 Geneva. Technical Program, Conference Record, IEEE International Conference on
Conference_Location :
Geneva
Print_ISBN :
0-7803-0950-2
DOI :
10.1109/ICC.1993.397316