Communicating on a direct mode channel

Details Communicating on a direct mode channel Communicating on a direct mode channel

1996-09-20

1998-10-13

Vo, Nguyen

Telecommunications

Transmitter and receiver at separate stations

Distortion, noise, or other interference prevention,...

455 671, 455 69, 455450, 455522, 370260, 370349, H04B 110

Patent

active

058226826

DESCRIPTION:

BRIEF SUMMARY
This application claims benefit of international application PCT/Fl96/00039 filed Jan. 18, 1996.


FIELD OF THE INVENTION

The present invention relates to a method for communicating on a direct mode channel on which there is at least one communicating first radio unit, and a second radio unit which is equipped with a memory and which seeks to communicate on the direct mode channel with an intended transmit power.


BACKGROUND OF THE INVENTION

The invention relates to the field of mobile phone systems. A subscriber in a mobile phone system, i.e. a subscriber station, for instance a mobile phone or a mobile station, may be registered in a radio network or system, whereby it communicates with the radio network via system channels comprised of control and traffic channels maintained by the base stations of the radio network.
In addition to the system channels in mobile phone systems, so-called direct mode channels can also be used in connection with a radio system, i.e. direct mode operation is applied. Subscriber stations using direct mode operation do not communicate directly with the radio network or its base stations. Direct mode channels are frequencies on which mobile phones or other means of communication are able to communicate directly with each other without the system, or via repeater stations either with the base stations of the system or with other mobile stations.
Direct mode channels are typically used in situations where, for instance, a group of portable mobile phones are communicating with each other at such a long distance from the base station that system channels cannot be used.
Another important way of using direct mode channels is to increase the capacity when the traffic in the system increases fast in some part of the service area of the system, for instance in some point-like part of the radio network.
A direct mode channel is referred to with the terms direct or simplex channel, or a simplex connection. A direct mode channel is a channel which is typically not at all used by the system. For example, it may be a channel with the same channel spacing as the channels of the system, for instance 12,5 kHz or 25 kHz. Among the mobile phones operating on a direct mode channel, the transmitting station has tuned its transmitter onto the channel and transmits speech or data information. The other mobile phones set to direct mode operation have tuned their receivers onto the same channel, whereby they are able to directly hear the transmission.
Operation on a direct mode channel may take place on the analog or digital modulation principle. A mobile phone transmitting on the channel may also transmit signalling information, such as information on rights of use and priorities or on the group operating on the channel. On the direct mode channel, an encryption may be carried out or plain speech can be transmitted.
Subscriber stations using direct mode operation communicate with other subscriber stations on a direct mode channel without necessarily being in direct contact with the base stations of the radio network.
One of the forms of a direct mode channel is represented by a direct mode channel equipped with a repeater, where, in addition to subscriber stations, there is a separate repeater station which forwards traffic between subscriber stations using the direct mode channel. Such a repeater station exemplifies one type of a radio unit. In such a case, semiduplex mode of operation is employed on the direct mode channel. This makes it possible for subscriber stations employing the direct mode operation to communicate with the radio network via the repeater stations as well.
In prior art mobile phones capable of direct mode operation, the random access mechanism employed is very simple, resting entirely upon the use of a tangent by the users. When the tangent (i.e. a Push To Talk button, PTT) of a radio unit is pressed by its user, it transmits a signal onto the direct mode channel, i.e. to the radio path. Naturally, the pressing of the tangent may be represented by a signal supplied by a spee

REFERENCES:
patent: 4533263 (1985-08-01), Smith et al.
patent: 5003619 (1991-03-01), Morris et al.
patent: 5042083 (1991-08-01), Ichikawa
patent: 5247701 (1993-09-01), Comroe et al.
patent: 5390338 (1995-02-01), Bodin et al.
patent: 5450606 (1995-09-01), Rom
patent: 5515366 (1996-05-01), Chieu et al.
patent: 5564075 (1996-10-01), Grourgue
patent: 5666661 (1997-09-01), Grube et al.
patent: 5732077 (1998-03-01), Whitehead

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