DESIGN OF STATISTICAL TIME DIVISION MULTIPLEXER BASED ON RANDOM PACKET LOSS ALGORITHM

Abstract

Statistical Time Division Multiplexers (STDM) are used to accommodate more users on typical communication channel than the traditional multiplexers can afford. However, situations do arise when the number of users bandwidth requirement exceed the maximum capacity of a channel bandwidth. In such situations some users are allowed to continue communicating, while others are forced to drop small parts of their speech signals. In the proposed STDM design the excessive users are picked on random basis so that their small packets can be dropped to reduce congestion on the channel. Experimental results indicate that upto 3% of a speech signal can be dropped in addition to Voice Activity Detection (VAD) without affecting much of the quality of the speech for each user. In this design a 64 kbps channel is considered to transmit monologue speech. Each user's speech is compressed at 6.4 kbps. It is experienced that in addition to 10 users, 2 extra users can be further multiplexed on the channel