Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Patent
1995-11-16
1998-06-23
Eisenzopf, Reinhard J.
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
455509, H04B 100, H04B 700
Patent
active
057714630
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method for controlling a subscriber station communicating on a direct mode channel in a radio system, comprising at least one base station communicating via channels, and subscriber stations as well as at least one exchange of the radio system connected to the base stations for establishing telecommunication connections between the subscriber stations.
The invention belongs to the field of trunking radio telephone systems. A trunking system is a separate radio network offering services of a company-specific radio network to several organizations by means of common use of radio channels. Trunking systems comprise control exchanges, base stations and radio telephones and have typically a cellular structure, each cell comprising one or several radio channels, one or several of the channels being used for signalling and the others as traffic channels. Call establishment, registrations, etc., take place via signalling channels. Traffic channels are used for speech transmission and switched data connections. In addition to these so-called system channels, so-called direct mode channels can be used in connection with a radio system, which channels are frequencies at which radio telephones can communicate directly with each other without involving or relying on other elements of the system.
Direct mode channels are typically used in situations when, for instance, a number of hand-held radio phones communicate with each other at such a distance from a base station that system channels cannot be used. This situation is typical for radio systems in sparsely populated regions, where a radio coverage is built for radio telephones mounted in cars and having a high transmission power. Hand-held radio telephones have a lower transmission power, due to which a signal sent by a radio phone does not carry to the base station. For economical reasons, it is generally not sensible to cover peripheral areas with a dense network of base stations offering coverage for hand-held radio phones. In operations taking place in such peripheral areas, internal communication between working teams, etc., can be made possible by means of hand-held radios by using direct mode channels.
Another important use of direct mode channels consists in increasing the capacity, when the traffic of the system increases rapidly in some part of the service area of the system, e.g. in some dot-like part. Such a need occurs typically in closed radio networks of authorities, in which it is not economically sensible to build the base station capacity so as to offer necessary channels for a special incident.
The term direct or simplex channel or simplex connection is used for a direct mode channel. A direct mode channel is a channel which is typically not used by the system at all. It is not a pair of frequencies, but only one channel of, e.g. 12.5 kHz or 25 kHz, having the breadth of the channels of the system. A sender of the radio telephones operating on a direct mode channel has tuned his or her transmitter to the channel and transmits speech or data information. The other radio telephones arranged in a state of using direct mode channels have tuned their receivers to the same channel, due to which they hear a message directly.
On a direct mode channel, it is possible to operate by analog modulation or digital modulation. A radio telephone sending on the channel can also send signalling information, such as information of access rights and priorities or of a group operating on the channel. Encryption can be realized on the direct mode channel or plain speech can be transmitted.
When a radio system according to the prior art, such as a radio telephone system, wishes to communicate with a subscriber station communicating with other subscriber stations on a direct mode channel, the radio system has no possibility of providing a communication between the particular subscriber station and the radio system. Such a communication can be, for instance, an establishment of a radio telephone connection, a call se
REFERENCES:
patent: 4534061 (1985-08-01), Ulug
patent: 4540851 (1985-09-01), Hashimoto
patent: 4716407 (1987-12-01), Borras et al.
patent: 4982441 (1991-01-01), Hashimoto et al.
patent: 5046082 (1991-09-01), Zicker et al.
patent: 5077828 (1991-12-01), Waldroup
patent: 5109526 (1992-04-01), Reed
patent: 5423055 (1995-06-01), Diaz et al.
patent: 5428823 (1995-06-01), Ness-Cohn et al.
patent: 5515366 (1996-05-01), Chieu et al.
Heiskari Mika
Lehmusto Mika
Banks-Harold Marsha D.
Eisenzopf Reinhard J.
Nokia Telecommunications Oy
LandOfFree
Method for controlling a subscriber station in a radio system 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 a subscriber station in a radio system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling a subscriber station in a radio system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1401786