Implement Push to Talk Function in WinCE Based Terminals

Fourth Generation (4G) mobile communications should not only focus on data rate increase and novel air interface, 4G mobile should converge the advanced wireless communications and high-speed wireless access. Considering the performance and cost, our research is now focusing on WLAN access. In order to study the 4G mobile handsets and other parts, we need a platform. Because no device provider could provide a commercial 4G phone, we implement our new features on some PDAs. This paper focuses on providing PTT group communication based on WinCE PDA using 802.11b wireless network interface cards in ad hoc mode. Considering the popularity of Windows products, we choose WinCE as the platform for our PDAs. We propose a framework to provide push-to-talk function on 4G phones. In order to implement that function, DSR/MSR routing protocols are ported to WinCE platform, and SIP signaling are modified and implemented on PDAs. Then the text messenger and media exchanging ability are added to the platform. Experiments show that our testbed could demonstrate the simplified PTT function and forward packet to correct mobile users.