Radio control apparatus and link securing method

Abstract

A radio control apparatus 10 is provided with a call management system 18 configured so that, when a mobile station in communication with a first base station by a first communication link requests diversity handover with a second base station, the call management system 18 retrieves a potential information rate that is not higher than an information rate of the first communication link and that is highest, from an information rate table 31 storing information about information rates of communication links securable in the second base station under other radio control apparatus; and a link management system 20 configured so that, when the potential information rate is lower than that of the first communication link, the link management system 20 instructs the first base station to change the first communication link to a second communication link communicable at the potential information rate; the call management system 18 requests the other radio control apparatus to secure a third communication link communicable at the potential information rate and to instruct the second base station to perform communication with the mobile station by the third communication link.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a radio control apparatus and a link securing method for securing a communication link between a mobile station and a base station of a handover destination when the mobile station performs handover in a mobile communication system. [0003] 2. Related Background Art [0004] In the mobile communication systems adopting the CDMA (Code Division Multiple Access) system, a mobile station simultaneously establishes communications with a base station of a handover source and with a base station of a handover destination on the occasion of handover, so as to perform diversity reception, thereby achieving improvement in communication quality and non-break communication during the handover (for example, refer to Japanese Patent Application Laid-Open No. 2001-251658). This handover technology is called diversity handover and, in general, a communication link is secured as below between the mobile...

AI Technical Summary

Benefits of technology

This approach increases the rate of securing communication links between the mobile station and the base station of the handover destination by establishing a communication link with a lower information rate, enhancing the certainty of maintaining continuous communication during handover.

Problems solved by technology

However, if there occurs traffic congestion at the base station of the handover destination, the radio control apparatus might fail to secure the foregoing communication link in certain cases.

In such cases, the mobile station repeats the request for diversity handover, and the problem of disconnection of communication will arise if no communication link is secured with the base station of the handover destination even after repetitive requests and if migration of the mobile station finally results in the cell of the base station of the handover destination becoming the first cell (a cell where the reception level of the pilot channel is maximum).

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