Novel adaptive playout algorithm for voice over IP applications and performance assessment over WANs
Mustafa H. Hintoglu, Faruk R. Ergul · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2001
Special purpose hardware and application software have been developed to implement and test Voice over IP protocols. The hardware has interface units to which ISDN telephone sets can be connected. It has Ethernet and RS-232 interfaces for connections to LANs and controlling PCs. The software has modules which are specific to telephone operations and simulation activities. The simulator acts as a WAN environment, generating delays in delivering speech packets according to delay distribution specified. By using WAN simulator, different algorithms can be tested and their performances can be compared. The novel algorithm developed correlates silence periods with received voice packets and delays play out until confidence is established that a significant phrase or sentence is stored in the playout buffer. The performance of this approach has been found to be either superior or comparable to performances of existing algorithms tested. This new algorithm has the advantage that at least a complete phrase or sentence is played out, thereby increasing the intelligibility considerably. The penalty of having larger delays compared to published algorithms operating under bursty traffic conditions is compensated by higher quality of service offered. In the paper, details of developed system and obtained test results will be presented.