Designing a Connection-Sustainable Mechanism for MSN Instant Messaging in Wireless Networks

In the recently years, IM (Instant Messaging) has become promising integrated tools for various communication needs. With the help of Windows Mobile, MSN IM is now also available in many smart phones, and MSN has been one of the most popular IMs in Taiwan. Since MSN IM can be used in the mobile system, unstable wireless network environments, such as WLAN, 3G or 3.5G, may become a new problem for the operation of IM application. Obviously, the high ratio of packet losses in an unstable wireless environment would lead to unexpected interrupts of IM services. e design a modified IM system based on the conventional IM architecture, which is called as the Service Enhancement Agent for Wireless IM (SEA-WIM). The goal of SEA-WIM is to improve the tolerant capacity of high packet loss rate. We split any TCP connection between the MSN IM client and the MSN IM server into three connections, two of them are used as TCP and the other is ptou. Ptou is a TCP-like protocol, it is based on UDP but is added some TCP features. Because we want to improve the tolerant capacity of packet loss rate, we only concern about the retransmission mechanism, which includes the sequence number, timeout and maximum retransmission number.eanwhile, it is more and more important for telecommunication providers to provide the lawful interception. For the judiciary needs, the lawful interception mechanism has been developed in many communication networks in the past decades, for examples, in e-mail services or circuit switch telephone systems. Since IM has become of the most communication methods, the SEA-WIM architecture also provides the ability of lawful interception.ecause there are many unnecessary packets transmitted between the MSN IM client and MSN IM servers, the mobile device will consume much power in transmitting and receiving these packets. By filtering these unnecessary packets in a third network device, the SEA-WIM system can also reduce the power consuming.