Ntt Docomo, Inc.

Ntt Mobile Communications Network, Inc.

Tomoyuki Ohtani

Hiroshi Nakamura

Kazuhiro Watanabe

Motoshi Tamura

Takaaki Sato

Takaaki Satoh

Hiroki Morikawa

Fumiaki Ishino

Akiko Nakashima

Hisashi Shimizu

Akihisa Nakajima

Hideo Morita

Yukichi Saito

Teruki Niwa

A 1-208 Hill House La Queste Nakashima

H B-412 Ntt Koigakubo-Ryo Shimizu

M 12 Ntt Shinomiya-Shataku Tamura

A branch candidate selecting method by a mobile station and a diversity handover control method on a network side in DHO performance are provided which consider a maximum cable branch number and maximum radio branch number of the mobile station, when the mobile station detects the plurality of addition branch candidates and deletion branch candidates. The mobile station inserts a plurality of addition branch candidates and deletion branch candidates, that is, all the DHO candidates into one handover trigger signal, and notifies the network. The addition branch candidates are put into addition information parameters in the handover trigger signal, and the deletion branch candidates are put into deletion information parameters. To simplify processing on the network side, the network side separates the addition branch candidates from the deletion branch candidates, and carries out sequential processing of them independently.

Mobile communication system, mobile station and diversity handover branch control method

A mobile station for communicating with base stations simultaneously in diversity handover. The mobile station monitors radio condition quality corresponding to a plurality of branches, selects one or more addition branch candidates based on the monitored radio condition quality. The mobile station arranges the addition branch candidates in order of the monitored radio condition quality; notifies a center of information on said plurality of branches including said addition branch candidates, the addition branch candidates being notified in the arranged order. Alternatively, the mobile station obtains a relative value of each of the addition branch candidates indicative of order of precedence to be used for the diversity handover based on the monitored radio condition quality of said addition branch candidates; and notifies a center of information on said plurality of branches including said addition branch candidates and their relative values.

Center for a mobile communication system performing diversity handover

Mobile communication system and mobile station performing diversity handover

A handover method for controlling communication between a mobile station and base station(s) in a wireless communication system. The method includes measuring signal qualities transmitted from the base station(s), the measured signal qualities including a measured quality of a signal received from a certain base station; identifying the base station as an addition candidate based on the measured quality exceeding an addition threshold; thereafter detecting that the measured quality of the signal received from the addition candidate has further exceeded an active threshold which is greater than the addition threshold. The active threshold is determined in accordance with a quality of a signal transmitted from one or more active base stations. In response, the base stations are notified of information about the addition candidate; and a handover process is performed on the bases on this information.

Disclosed is a mobile communication system including a network constituted of at least one switching center and a plurality of base stations, and a mobile station which communicates with the base stations simultaneously. The system permits varying transmission delay between the switching center and the base stations according to the type of services available to the mobile station. The object of the present invention is to propose a communication which permits varying transmission delay according to the type of service currently employed, and to promptly recover a synchronization state even if an out-of-sync state happens. To attain the object, a memory means (mobile switching center processor) stores transmission delay characteristics corresponding to services which are available to the mobile station. Furthermore, a communication timing setting means (diversity handover trunk) determines the timing of communication for the base stations according to the transmission delay characteristic selected according to the service.

Frame synchronization circuit

An address structure in mobile communications network facilitating routing of a packet. At the initial position of the address, is located a prefix or the like indicating the type of the address structure, which indicates the present mobile communications network system, for example. At the next position, a location address (LA) is located characterizing the present invention. The location address is usually placed at the position of a subnetwork address. The location address (LA) is provided for each mobile switching system, and constitutes part of an IP address of a user using a mobile station under the control of the mobile switching system. At the final position, is located a user identifier (user ID) which is used for identifying a user, and is provided uniquely for each user. The IP address in accordance with the present invention can be split into the foregoing three sections, part of which includes the location address and user identifier indicating the location of the mobile station in the mobile communications network, thereby enabling the identification of the user in the mobile communications network system and the control of the packet transmission.

Packet transmission method, packet transmission system and packet data transmission medium on mobile communications network system

A branch candidate selecting method by a mobile station and a diversity handover control method on a network side in DHO performance are provided which consider a maximum cable branch number and a maximum radio branch number of the mobile station, when the mobile station detects a plurality of addition branch candidates and deletion branch candidates. The mobile station inserts a plurality of addition branch candidates and deletion branch candidates, that is, all the DHO candidates into one handover trigger signal, and notifies the network. The addition branch candidates are put into addition information parameters in the handover trigger signal, and the deletion branch candidates are put into deletion information parameters. To simplify processing on the network side, the network side separates the addition branch candidates from the deletion branch candidates, and carries out sequential processing of them independently.

Mobile radio communication system, mobile station, and method for controlling diversity hand-over branch

Disclosed is a mobile communication system including a network constituted of at least one switching center and a plurality of base stations, and a mobile station which communicates with the base stations simultaneously. The system permits varying transmission delay between the switching center and the base stations according to the type of services available to the mobile station. The object of the present invention is to propose a communication which permits varying transmission delay according to the type of service currently employed, and to promptly recover a synchronization state even if an out-of-sync state happens. To attain the object, a memory means (mobile switching center processor ) stores transmission delay characteristics corresponding to services which are available to the mobile station. Furthermore, a communication timing setting means (diversity handover trunk ) determines the timing of communication for the base stations according to the transmission delay characteristic selected according to the service.

Growing community of inventors

Yokosuka, Japan

Tomoyuki Ohtani