Multiplex communications – Wide area network – Packet switching
Patent
1992-06-16
1995-09-26
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
359110, H04J 316
Patent
active
054539889
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a passive optical network, and in particular to a head-end station for use in such a network.
2. Related Art
The present applicant has developed a bit transport system (BTS) for use in a TPON (telephony on a passive optical network) network. In this bit transport system a head-end station broadcasts time division multiple access (TDMA) frames to all the- terminations on the network. The transmitted frames include both traffic data and control data. Each termination recognises and responds to an appropriately addressed portion of the data in the broadcast frame and ignores the remainder of the frame.
In the upstream direction, each termination transmits data in a predetermined time slot and the data from the different terminations are assembled at the head-end into a TDMA frame of predetermined format.
Typically each TDMA frame includes a header containing bits relating to system functions such as coarse or fine ranging followed by a number of basic frames carrying the traffic data. In the preferred embodiment described below, each basic frame is 2496 bits long, comprising 2352 traffic bits followed by 144 control bits. The control bits may be used by the head-end station, for example, to control the timing and amplitude of the transmissions from the terminations on the network. The appropriate control data is generated by a CPU within the head-end station. On the transmit side of the head-end station it is therefore necessary to assemble the control and traffic data from different sources to form the basic frames. A corresponding function is required for the return data, with it being necessary to split the received frames into traffic and control data.
BRIEF SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a head-end station for a passive optical network system arranged to transmit and receive downstream and upstream TDMA frames including a plurality of basic frames, each basic frame comprising a plurality of traffic bits and a plurality of control bits, the head-end station including a data receiver comprising a control processor arranged to receive control data, a control data buffer arranged to provide a parallel data input to the control processor, a traffic interface arranged to receive traffic data and a serial-to-parallel converter arranged to receive incoming TDMA frames, the parallel output from the serial-to-parallel converter being connected in parallel to the respective inputs of the control data buffer and the traffic interface.
The present invention provides a structure for the data receivers and transmitters within the head-end station which is ideally adapted to the interleaving of control and traffic data within the TDMA frame and enables the use of such frame structures without requiring complex multiplexers or de-multiplexers. In the past the use of such multiplexers or de-multiplexers in the input and output stages have provided a bottleneck which seriously restricted the performance of the system.
Typically the traffic interface is an- exchange interface handling telephone traffic.
Preferably the upstream TDMA frames include a header preceding the plurality of basic frames and the control data buffer is arranged to read data from the serial-to-parallel converter both during the header portion and subsequently during the portions of the basic frames comprising the control bits. Preferably the header includes a phase-1 ranging portion as herein defined, and the control data buffer is arranged to capture any ranging pulses received in the phase-1 ranging portion.
The structure adopted in the present invention is found to be particularly advantageous when the frames include a header used for system control functions as well as the control bits associated with each of the basic frames. The present invention makes it possible to capture and process both these forms of data using the same hardware, thereby reducing the cost of that hardware and further si
REFERENCES:
patent: 4408307 (1983-10-01), Harris
patent: 4498169 (1985-02-01), Rozmus
patent: 4722093 (1988-01-01), Tejima
patent: 4768188 (1988-08-01), Barnhart et al.
patent: 4823312 (1989-04-01), Michael et al.
patent: 5241545 (1993-08-01), Natarajan et al.
British Telecommunications public limited company
Olms Douglas W.
Ton Dang
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