Multiplex communications – Channel assignment techniques – Using time slots
Patent
1997-06-30
2000-03-28
Pham, Chi H.
Multiplex communications
Channel assignment techniques
Using time slots
370336, 370345, 455458, H04J 312, H04B 726
Patent
active
060440864
DESCRIPTION:
BRIEF SUMMARY
This invention relates to transmission of system control signals in time slots within fixed length time frames.
In Time division multiplex/time division multiple access (TDM/TDMA) systems, system control signals are broadcast from a base station to associated subscriber units. These system control signals can be paging messages addressed to a specific subscriber unit. They could be messages allocating traffic channels in response to a request from a subscriber unit to set up a call. The system control signals could include user-specific messages, addressed and sent to a specific subscriber unit despite no traffic channel having been allocated. The system control messages can include a list (Aloha slot list) of channels available to subscriber units for transmission of call set-up requests.
In conventional TDM/TDMA systems such as GSM (Global System for Mobile communications") systems, system control signals are sent over a dedicated channel, i.e. one slot in each TDM frame from the base station to the subscriber unit is dedicated for such signalling. This is known as a Broadcast channel.
The present invention is defined in the claims to which reference should now be made.
The present invention preferably provides a method of transmission of system control signals between a base station and subscriber units in a TDM/TDMA system, control signals comprising data units, in which each data unit is fragmented, each fragment being sent in a different time slot of a frame. Transmission is preferably from a base station to subscriber units.
The present invention also relates to a method of reception of control signals from a base station at a subscriber unit in a TDM.backslash.TDMA system, in which control signal data fragments are received at a subscriber unit over time for recombination to provide control signals, each fragment having been sent in a different time slot of a TDM frame.
The present invention also relates to a base station including control signal fragmentation means operative to fragment control signals into predetermined portions of different TDM time slots for transmission, and transmission means. The present invention further preferably provides a subscriber unit including reception means operative to receive signals from a base station, selection means operative to distinguish system control signal fragments, and recombination means operative to recombine said fragments to provide system control signals at said subscriber unit.
The present invention has the advantage of avoiding the need for a dedicated broadcast channel.
Preferably, the system control fragments are of predetermined length and take a predetermined position within each slot. The fragments can be of equal fixed length. Each slot can also include other data such as speech data. A TDM frame, preferably of ten slots, preferably includes a fragment in each slot. Accordingly, system control signals which are coded into standard length data units, are fragmented such that each data unit provides ten equal length fragments. Each data unit can include a header and error correction data in addition to system control signalling. The error correction data can be cyclic redundancy check data (CRC).
The correct transmission of system control signals is preferably further protected by forward error correction (FEC) in the TDM frame.
The system control data units are preferably replicated on all of the radio frequency carriers transmitted from a base station; and the transmission of TDM frames on all these radio frequency carriers are synchronised. Accordingly, a subscriber unit can correctly receive system control signalling irrespective of which RF carrier is received.
A preferred embodiment of the present invention will now be described, by way of example, with reference to the drawings in which:
FIG. 1 is a schematic diagram illustrating the system including a base station (BTE--Base Terminating Equipment) and subscriber unit (NTE--Network Terminating Equipment);
FIG. 2 is a diagram illustrating frame structure and timing for a duplex link;
REFERENCES:
patent: 4352955 (1982-10-01), Kai et al.
patent: 5210751 (1993-05-01), Onoe et al.
patent: 5404355 (1995-04-01), Raith
patent: 5440545 (1995-08-01), Buchholz et al.
patent: 5502721 (1996-03-01), Pohjakallio
patent: 5559804 (1996-09-01), Amada et al.
patent: 5603081 (1997-02-01), Raith et al.
Seizo Onoe et al, "Radio Link Control Techniques for Digital Cellular Systems", pp. 47-54, NTT Review, vol., 4, No. 1, Jan. 1992.
Copy of the International Search Report.
Albrow Richard John
Black Simon Alexander
Carter Leigh
Goodings Rupert Leslie Alexander
Martin Paul Maxwell
Duong Frank
Ionica International Limited
Pham Chi H.
LandOfFree
Control signal transmission in digital radio telephony does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control signal transmission in digital radio telephony, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control signal transmission in digital radio telephony will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1332295