Multiplex communications – Communication over free space – Combining or distributing information via time channels
Patent
1997-05-28
2000-02-15
Patel, Ajit
Multiplex communications
Communication over free space
Combining or distributing information via time channels
370444, H04B 7212
Patent
active
060260831
DESCRIPTION:
BRIEF SUMMARY
The invention relates to transmitting control messages in time slots within fixed length time frames, in particular, in time division multiplexing/time division multiple access (TDM/TDMA) digital telephony.
The present invention is defined in the claims to which reference should now be made.
The present invention relates to a method of transmitting control messages between nodes in a TDM/TDMA network in which control messages are assigned priorities dependent on message type, and the allocation of messages to TDM/TDMA time slots is dependent on the assigned priorities.
Each message has an assigned priority which can be designated by a value. For some messages, the associated priority value is incremented for each frame transmitted in which the message is of too low a priority to be sent.
The method is particularly applicable where a plurality of control messages are to be sent via a shared TDM/TDMA link. The various types of messages can be, for example, page requests, channel allocations, information/status requests, and a filling (idle) signal.
The present invention also relates to a TDM/TDMA transmitter including assignment means operative to assign priorities to control messages, and allocation means operative to assign the messages to TDM/TDMA time slots for transmission.
The node or transmitter can be a base station or a subscriber unit.
A preferred embodiment of the 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;
FIG. 3 is a schematic illustration of control message prioritisation in normal data packets for transmission in respective time slots; and
FIG. 4 is a schematic illustration of control message prioritisation in uplink pilot packets for transmission in respective time slots.
THE BASIC SYSTEM
As shown in FIG. 1, the preferred system is part of a telephone system in which the local wired loop from exchange to subscriber has been replaced by a full duplex radio link between a fixed base station and fixed subscriber. The preferred system includes the duplex radio link, and transmitters and receivers for implementing the necessary protocol.
There are similarities between the preferred system and digital cellular mobile telephone systems such as GSM which are known in the art. This system uses a protocol based on a layered model, in particular the following layers: PHY (Physical), MAC (Medium Access Control), DLC (Data Link Control), NWK (Network).
One difference compared with GSM is that, in the preferred system, subscriber units are at fixed locations and there is no need for hand-off arrangements or other features relating to mobility. This means, for example, that in the preferred system directional antennae and mains electricity can be used.
Each base station in the preferred system provides six duplex radio links at twelve frequencies chosen from the overall frequency allocation, so as to minimize interference between base stations nearby. The frame structure and timing for the duplex link is illustrated in FIG. 2. Each duplex radio link comprises an up-link from a subscriber unit to a base station and, at a fixed frequency offset, a down-link from the base station to the subscriber unit. The down-links are TDM, and the up-links are TDMA. Modulation for all links is .pi./4 --DQPSK, and the basic frame structure for all links is ten slots per frame of 2560 bits. The bit rate is 512 kbps. Down-links are continuously transmitted and incorporate a broadcast channel for essential system information. When there is no user information to be transmitted, the down-link transmissions continue to use the basic frame and slot structure and contain a suitable fill pattern.
For both up-link and down-link transmissions, there are two types of slot: normal slots which are used after call set-up, and pilot slots used
REFERENCES:
patent: 5175867 (1992-12-01), Wejke et al.
patent: 5237570 (1993-08-01), Smolinske et al.
patent: 5297142 (1994-03-01), Paggeot et al.
patent: 5353287 (1994-10-01), Kuddes et al.
patent: 5371780 (1994-12-01), Amitay
patent: 5373506 (1994-12-01), Tayloe et al.
patent: 5412650 (1995-05-01), Davies
patent: 5513183 (1996-04-01), Kay et al.
patent: 5515379 (1996-05-01), Crisler et al.
patent: 5521925 (1996-05-01), Merakos et al.
Albrow Richard John
Black Simon Alexander
Carter Leigh
Goodings Rupert Leslie Alexander
Martin Paul Maxwell
Ionica International Limited
Nguyen Brian
Patel Ajit
LandOfFree
Transmission of control messages in digital 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 Transmission of control messages in digital telephony, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transmission of control messages in digital telephony will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1911638