The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 03, 2002
Filed:
Jun. 09, 1998
Hiroshi Mikami, Kanagawa, JP;
NEC Corporation, Tokyo, JP;
Abstract
A group communication system is disclosed, that comprises at least one controlling station, at least one base station connected to the controlling station through a wired circuit or a radio circuit, and a plurality of mobile stations connected to the base station, wherein the controlling station or the base station has a means for managing group communication numbers of the mobile stations, wherein the mobile stations each have a means for transmitting a mobile station identification number and a group communication number to the base station when a radio zone of each of the mobile stations is handed over and thereby a location registration operation is performed, wherein the controlling station or the base station has a zone area presence determining means for determining whether or not a particular mobile station is present in a radio zone to which the particular mobile station has been handed over when the controlling station or the base station receives the group communication number from the relevant mobile station, and wherein the base station has a means for releasing a communication channel when the relevant mobile station is not present in the radio zone as the determined result of the zone area presence determining means.