US 5,425,027 A · Wide area fiber and TV cable fast packet cell network

Abstract

53 byte length ATM compliant cells are transmitted over a digital optical fiber path to interconnect with a coaxial feeder cable TV system to support two-way digital services at a plurality of sites connected to the TV cable system. At the point of interconnection between the fiber optic path and the cable TV feeder subsystem, digital signals are converted to a UHF rf carrier frequency above the cutoff pass-band of the analog signal feeder amplifier carrying TV broadcast signals. This rf carrier conveys a high data rate digitally modulated signal limited to sections of feeder cable between the cable TV broadcast channel amplifiers. In-house access to this UHF carrier signal is via the normal TV cable tap and drop cable to a SIU, located near the subscriber's TV set. The feeder cable and the passive taps used in cable TV practice have a higher cutoff frequency than the feeder amplifiers themselves. This allows passage of an UHF signal over the feeder cable. Low pass filters at the feeder amplifiers prevent this UHF signal from being shorted out by the in-cable amplifiers. Each SIU so connected sends and receives the UHF carrier signal, which conveys the ATM type cells. Each cell's payload contains the local address of the source and destination of that cell. Each SIU decodes each cell's address and accepts only those cells that are for itself. The SIUs speak to and receive signals from an FTU located at the TV cable headend or at a fiber connection node. The common channel conveying the ATM cells alternatively sends and receives cells in a ping-pong fashion.

Claims18

Dependent claims

A packet cell communications system having an implicit dynamic adaptive polling arrangement to provide fair resource allocation for each transmission cycle suitable for the transmission of voice signals without variable buffering delays, wherein said system has a fixed maximum capacity of packet cells that can be transmitted thereon, said system comprising:

a plurality of slave units to receive downstream, and to transmit up-stream, packet cells, with the number of contiguous up-stream packet cells being transmittable by each of said plurality of slave units being individually controllable;
a FTU/headend processor to individually address, and to control the number of packet cells each of said slave units is permitted to transmit up-stream;
a cable system to interconnect said plurality of slave units to said FTU/headend processor, said cable system includes:
a downstream communications channel to convey downstream packet cells from said FTU/headend processor to each of said slave units;
and
an up-stream communications channel to transmit up-stream packet cells from each said slave unit to said FTU/headend processor;
said FTU/headend processor includes a program to:
poll said slave units during each transmission cycle;
issue downstream packet cells including authorization commands to individually instruct each slave unit as to when to transmit and the number of contiguous up-stream packet cells that said each slave unit is authorized to send during a subsequent transmission cycle;
and
implicitly determine the number of contiguous up-stream packet cells each slave unit is authorized to transmit up-stream based upon the difference between said maximum capacity of packet cells said each slave unit was authorized to transmit during previous transmission cycle minus the actual number of packet cells said slave unit transmitted during said previous transmission cycle.

8 more elements

A shared communication transmission distribution system for the bi-directional transmission of cell packets over a cable TV broadcast distribution system as a shared communications channel, said system comprising:

a first bi-directional transmission path;
and
a second bi-directional transmission path;
wherein said first bi-directional transmission path includes:
a first feeder cable having an up-stream end and a downstream end having a defined length therebetween divided into an up-stream section and a downstream section;
a first feeder amplifier serially connected between said up-stream and downstream sections of said first feeder cable to convey broadcast TV signals downstream on said first feeder cable, wherein said feeder amplifier has a downstream terminal;
a first bandpass filter having a first terminal coupled to said downstream terminal of said first feeder amplifier and a second terminal connected to said downstream section of said first feeder cable, said first bandpass filter having a lower cut-off frequency and an upper cut-off frequency with frequencies of the commercial TV band being between said lower and upper cut-off frequencies;
a first tap along the length of said downstream section of said first feeder cable downstream of said first bandpass filter, with said first tap having an upper cut-off frequency that is above the upper cut-off frequency of said first bandpass filter;
a first drop cable having an up-stream end connected to said first tap, and having a downstream end;
a first slave transceiver connected to the downstream end of said first drop cable to receive downstream signals from said first drop cable and to deliver up-stream signals to said first drop cable;
and
a first low ,pass filter having a downstream terminal and an up-stream terminal, said downstream terminal being connected to said second terminal of said first bandpass filter and said up-stream terminal being coupled to said up-stream section of said first feeder cable up-stream of said first feeder amplifier, said first low pass filter having an upper cut-off frequency that is below the lower cut-off frequency of said first bandpass filter;
wherein said second bi-directional transmission path includes:
a second feeder cable having a first section with said first section having a first end and a second end;
a first high pass filter having an up-stream terminal coupled to said second end of said first section of said second feeder cable and a downstream terminal connected to said downstream terminal of said first bandpass filter wherein said first high pass filter has a lower cut-off frequency that is above the upper cut-off frequency of said first bandpass filter;
and
an FTU/headend processor coupled to first end of said first section of said second feeder cable to send packet cells to and from said first slave transceiver ;
and
wherein said first slave transceiver, responsive only to packet cells addressed to itself, upon receipt of instructions from said FTU/headend processor transmits packet cells to said FTU/headend processor, and wherein the transmission of said packet cells is restricted to frequencies above the upper frequency of said commercial TV band.

16 more elements

Dependencies are inferred from the claim text.

Wide area fiber and TV cable fast packet cell network

Life of this patent

Wide area fiber and TV cable fast packet cell network

Life of this patent

Abstract

Claims18