Voice over ATM using AAL2 and bit dropping: Performance and call admissioncontrol

Asynchronous transfer mode (ATM) adaptation layer 2 (AAL2) has been designe d for efficient transport of voice, fax, and voiceband data (VBD) traffic o ver an ATM virtual circuit. The protocol helps achieve low latency and high bandwidth efficiency while applying suitable compression methods on voice/ VBD/fax calls and silence elimination on voice calls. We analyze the perfor mance and capacity of an ATM multiplexer based on AAL2 adaptation. We assum e that embedded adaptive differential pulse code modulation (ADPCM) is used to compress voice, and silence elimination is used to achieve statistical multiplexing gain. The embedded ADPCM coding scheme allows selective droppi ng of less significant bits of voice during congestion in the ATM/AAL2 mult iplexer. We compare the call capacities of voice multiplexers with and with out bit dropping (BD), The performance models and results presented here ar e based on fairly general assumptions and can be used for traffic engineeri ng and call admission control in land-line or wireless ATM systems for a va riety of voice/voiceband compression algorithms. A generalized algorithm fo r call admission control is also described.