Voice Over Wireless LAN Using Intelligent Control

In this chapter, we present a network framework in which Variable Bit Rate (VBR) voice is transported over a wireless Local Area Network (LAN) using two novel intelligent control systems. First, the Intelligent Multiple Access Control System (IMACS) at the base station governs the medium access of the uplink channel. In particular, IMACS supports both Available Bit Rate (ABR) data traffic and in-band signaling control (SCR) traffic for VBR voice based on a TDM-based contention access scheme. Significantly, dynamic allocation of contention bandwidth between ABR and SCR traffic is facilitated through predicting ABR self-similar traffic characteristics based on a neural-fuzzy approach. As a result, IMACS offers various QoS guarantees and a maximum of network throughput irrelevant to traffic variation. With such guarantees, the second system- Intelligent Voice Smoother (IVoS) at the application layer of each mobile terminal facilitates intramedia synchronization of voice data streams. The traffic predictor of IVoS predicts three traffic characteristics of every newly encountered talkspurt period. Based on the predicted characteristics, IVoS determines the corresponding buffering delay to be imposed on the first frame. All subsequent frames of the talkspurt can be playout in a quasi-ConstantBit-Rate (CBR) manner. Finally, we demonstrate via experimental results that with such intelligent control, the playout Quality of Service (QoS) of VBR voice can be guaranteed irrespective of any traffic and load variation.