Long-lived TCP connection using ICMP messages in wireless mobile communications

摘要

A TCP connection provides a fast suspend-resume operation to deal with the problem of frequent disconnections of mobile users. When a mobile user is temporarily disconnected, TCP quickly suspends all data transmission between the mobile user and the fixed host. When the mobile user is reconnected, TCP resumes all data transmission between the mobile user and the fixed host.;The path between two users in a cellular communication system (mobile host and fixed host) is broken into two paths. First, the data is sent from the mobile host to a supervisor host. Next, the data is sent from the supervisor host to the mobile host. When a link disconnect occurs, the supervisor host closes the fixed host's window gradually, from its left window edge, by allowing the fixed host to continue to transmit the rest of TCP segments within its current window. The mobile host uses an ICMP probe request and a probe response failure timer to determine if the link is broken. The supervisor host uses an ICMP suspend request suspension timer to detect a link failure.;When the supervisor host receives the ICMP probe request, it determines that the link is operational and that the connection can be resumed. The supervisor host will forward stored TCP segments to the mobile host. In addition, the supervisor host sends an ICMP probe response message to the mobile host. As a result, the connection is resumed with the same characteristics as prior to the link failure.