Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Patent
1996-04-22
1998-07-14
Crosland, Donnie L.
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
455403, 455422, 455438, 455 111, H04B 100, H04M 100
Patent
active
057818606
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for controlling subscriber stations in a radiotelecommunications system, in which at least some of the subscriber stations can communicate with one another on a direct mode channel.
The invention also relates to a radiotelecommunications system comprising one or more subscriber stations, at least some of which are able to communicate with one another on a direct mode channel, and a dispatcher controlling the subscriber stations.
The invention further relates to a subscriber station in a radiotelecommunications system, comprising a memory means, a transceiver for tuning to each radio channel used, a user interface for transmitting information between the user and the subscriber station, and a controller for controlling the operation of the subscriber station in response to the commands received from the user interface.
BACKGROUND OF THE INVENTION
The invention concerns trunked radiotelecommunications systems. A trunking system is a separate radio network offering the services of a company-specific radio network to a plurality of organizations by means of common use of radio channels. Trunking systems comprise exchanges, base stations and mobile stations, and they typically have a cellular structure, in which each cell comprises one or more radio channels, one or more of which are used for signalling while the others are used as traffic channels. Signalling channels are used for call set-up, registration, etc. Traffic channels are used for transmitting voice, and for switched data connections. In addition to these `system channels`, a radio system can employ `direct mode channels` (direct-mode channels), which are frequencies at which mobile stations can communicate directly with one another, without involving base stations of the system.
Typically, direct mode channels are used e.g. when a number of portable mobile stations communicate with one another so far away from the base station that system channels cannot be used. This is typical of radio systems in scarcely-populated areas, where radio coverage is provided in view of vehicle-mounted mobile stations with high transmission power. Portable mobile stations have lower transmission power, and so a signal transmitted by a mobile station does not reach the base station. For economic reasons, it is usually not sensible to provide peripheral areas with a dense base station network that would provide radio coverage for portable mobile stations. In operations taking place in these peripheral areas, communication within e.g. a working group can be implemented by portable mobile stations using direct-mode channels.
Another important use of direct-mode channels is that it provides additional capacity as traffic increases rapidly in one e.g. point-like part of the service area of the system. Typically this kind of need arises in closed radio networks used by authorities; in them, it is not economically sensible to provide so much base station capacity that the necessary channels would be available in the event of an incident. Such an incident is, for example, an airplane crash occurring in the countryside, whereby the authorities may need even hundreds of telephones instantaneously in an area where normally only a few mobile stations are used. Because of this, direct mode channels are used even if the mobile stations are within the coverage area of the base stations of the system.
A direct mode channel is also called a simplex channel or connection. A direct mode channel is a channel that is typically not used by the base station of the system at all. It is not a pair of frequencies, but only a single channel with the same width as the channels of the system, e.g. 12.5 kHz or 25 kHz. A transmitting mobile station operating on the direct mode channel has tuned its transmitter to the channel, and transmits voice or data. The other mobile stations in the direct mode have tuned their receivers to the same channel, and so they are able to directly listen to the transmitted message.
On a direct mode channel, b
REFERENCES:
patent: 4534061 (1985-08-01), Ulug
patent: 4716407 (1987-12-01), Borras et al.
patent: 4850033 (1989-07-01), Eizenhofer et al.
patent: 5355511 (1994-10-01), Hatano et al.
patent: 5423055 (1995-06-01), Diaz et al.
Using Radio Links, G.E. Dodrill et al, IRE National Meeting, Jan. 1993.
Heiskari Mika
Lopponen Jussi
Crosland Donnie L.
Nokia Telecommunications Oy
LandOfFree
Method for controlling subscriber stations in a radio-telecommun does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling subscriber stations in a radio-telecommun, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling subscriber stations in a radio-telecommun will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1893915