Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Patent
1996-10-31
1999-04-13
Olms, Douglas W.
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
370321, 370458, 455450, H04J 316
Patent
active
058944729
DESCRIPTION:
BRIEF SUMMARY
The invention relates to data radiocommunications. The invention is particularly applicable to cellular digital radiocommunications systems for mobile stations, such as systems designed in compliance with the GSM (Global System for Mobile communications) public radiotelecommunications standard.
In general, a cellular digital radiocommunications system is implemented within a network of geographical cells through which mobile stations travel. A base station is associated with each cell, and a mobile station communicates via the base station that is associated with the cell in which the mobile station is located.
In this type of system, the calls in stable mode are conveyed over traffic channels (TCHs) in both transmission directions, namely in the direction from the mobile station to the base station (up direction), and in the direction from the base station to the mobile station (down direction).
In addition, this type of system implements time-division multiplexing using a technique referred to as "TDMA" (Time Division Multiple Access).
In known manner, the TDMA technique consists in dividing up time into frames of fixed and predetermined duration, which frames are themselves divided up into time slots. Thus, the signals conveyed by the system are organized in frames, and each time slot of a frame corresponds to a traffic channel on which a call in stable mode can be conveyed in one direction.
On transmission, in each frame in the up direction, a mobile station transmits data during the time slot which is allocated to it only. In each frame in the down direction, the base station transmits data in each of the time slots so as to communicate simultaneously with a plurality of mobile stations, each of which is associated with a respective one of the time slots.
On reception, each mobile station knows how to extract the time slot which is addressed to it from each frame in the down direction. Similarly, the base station knows which mobile station is associated with each of the time slots in the frames that it receives.
In conventional systems, of the type described above, a time slot is allocated to a mobile station for the entire duration of a call. This may be referred to as "circuit mode" allocation.
Such circuit mode allocation suffers from a major drawback, namely that the transmission resources are under-used. During a call between a mobile station and a base station, these two entities do not transmit data continuously. In other words, there are time slots during which no data is transmitted.
A known solution to remedy that drawback consists in using at least one of the time slots in each frame in packet mode. In packet mode, a time slot (i.e. a traffic channel) in the up direction is shared between a plurality of mobile stations. Thus, a mobile station which wishes to share a traffic channel with other mobile stations sends an allocation request over an access channel (the RACH or Random Access Channel in the GSM system). All of the mobile stations to which the system responds favorably for such allocation requests are associated with a shared traffic channel, and a virtual circuit is made available to each of them (unlike the real circuit made available to a mobile station to which a time slot has been allocated with no sharing for the entire duration of a call).
There are several known techniques for determining which of the mobile stations associated with the same shared traffic channel can actually transmit data.
A first known technique of allocating the right to transmit data operates as follows: the base station indicates to all of the associated mobile stations whether or not the shared traffic channel in the up direction is free. If it is free, a mobile station which wishes to transmit data to the base station sends an access request over the shared traffic channel in the up direction. The base station replies in the down direction by authorizing the mobile station to transmit data over the shared traffic channel in the up direction. The mobile station then monopolizes the traffic channel unt
REFERENCES:
patent: 5491741 (1996-02-01), Farwell et al.
patent: 5570352 (1996-10-01), Poghonen
patent: 5590133 (1996-12-01), Billstrom et al.
Nussler, The Public Packet Mode Mobile Data Service of the Deutsche Bundespost Telkeom, Mobile Radio Conference, Nov. 15, 1991, pp. 193-200.
Alcatel Alsthom Compagnie Generale d'Electricite
Hom Shick
Olms Douglas W.
LandOfFree
Packet access method in a cellular digital radio-communications does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Packet access method in a cellular digital radio-communications , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Packet access method in a cellular digital radio-communications will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-226408