Optimal delay estimation using complete bipartite graph method for VoIP over WLAN environments

Voice over wireless LAN (WLAN) is widely applied in modern Internet networks. In real-time wireless environments, the primary cause of an impaired speech quality is transmission delays. In wireless communications, the parameters employed for quality of service (QoS) estimations include the delay, the throughput, the blocking rate and the link cost. These parameters are significantly dependent on the type of topology pattern adopted. This study focuses primarily on the delay guarantee and optimal delay aspects of wireless communications. A tradeoff exists between the link number and the delay guarantee. A greater number of links is beneficial in reducing transmission delays, but leads to an increased cost. Conversely, a lower number of links reduces the system cost, but increases the delay. This study employs graph theory to determine the node topology pattern which minimizes the delay for voice over IP (VoIP) transmission in WLAN environments. The topology is optimized both for a variable link delay and a constant link delay. The optimization method presented in this study can be widely applied to the link topology design for multiparty conferencing in modern wireless networks.