US 7,548,549 B2 · Method and apparatus for transmission of digital signals over a coaxial cable

Abstract

Ethernet packets are transmitted in full duplex mode over a single coaxial cable, such as RG6 and RG59. Symmetrical full duplex operation is achieved by separating the upstream and downstream signals in the frequency domain whereby a 100BaseT signal is transmitted unmodified in one direction while the other is modulated upon a high frequency carrier to be transmitted in the other direction. In a second embodiment, the separation is in the time domain whereby the signals are sampled in blocks, each block compressed in time and transmitted at a higher rate, thus allowing for the interleaving of upstream and downstream blocks on the same coaxial cable. In a third embodiment, different rate upstream and downstream signals are separated in the frequency domain, but without modulation. The resulting asymmetrical 1000/100 Mb/s Ethernet over coax link is valuable in network architectures where asymmetry in the up and down traffic loads is expected.

Claims33

Dependent claims

A method for transmitting forward and backward sequences of Ethernet packets, each sequence coded to be suitable for uni-directional transmission over a physical medium, between a first and a second Ethernet interface over a single coaxial cable, the method comprising the steps of:

(a) forming a backward signal from the backward coded sequence of packets at the first Ethernet interface for the transmission over the coaxial cable to the second Ethernet interface;
(b) forming a forward signal from the forward coded sequence of packets at the second Ethernet interface for the transmission over the coaxial cable to the first Ethernet interface, including providing an asymmetry in frequency or time characteristics between the forward and backward signals to avoid interference between the backward and forward signals and allow the transmission of both signals at the same time;
wherein the step (a) comprises coupling the backward coded sequence through a passive device to the coaxial cable;
wherein the step (b) comprises the step of:
modulating the forward coded sequence into a modulated coded signal having frequency spectrum above that of the backward coded sequence;
and
coupling the modulated coded signal through a second passive device to the coaxial cable;
and
wherein the forward and backward coded sequences are 100BaseT signals or 10BaseT signals, the backward coded sequence having a spectrum limited to below about 125 MHz, and the modulated coded signal having a frequency spectrum above about 125 MHz and below about a 1250 MHz.

6 more elements

(a) forming a backward signal from the backward coded sequence of packets at the first Ethernet interface for the transmission over the coaxial cable to the second Ethernet interface;
(b) forming a forward signal from the forward coded sequence of packets at the second Ethernet interface for the transmission over the coaxial cable to the first Ethernet interface, including providing an asymmetry in frequency or time characteristics between the forward and backward signals to avoid interference between the backward and forward signals and allow the transmission of both signals at the same time;
wherein the backward coded sequence of Ethernet packets is a signal coded according to a format “B” having a spectrum limited to below about “X” MHz, and the forward coded sequence is a signal coded according to another format “A” having a spectrum with a lower limit above about “X” MHz, and wherein the step (a) comprises coupling the backward coded sequence through a low pass filter with an upper frequency limit of about “X” MHz and an isolator to the coaxial cable, and the step (b) comprises coupling the forward coded sequence through a high pass filter having a lower frequency limit of about “X” MHz and another isolator to the coaxial cable.

A system for transmitting forward and backward sequences of Ethernet packets, each sequence coded to be suitable for uni-directional transmission over a physical medium, between a first and a second Ethernet interface over a single coaxial cable, the system comprising:

(a) a means for forming a backward signal from the backward coded sequence of packets at the first Ethernet interface for the transmission over the coaxial cable to the second Ethernet interface;
(b) a means for forming a forward signal from the forward coded sequence of packets at the second Ethernet interface for the transmission over the coaxial cable to the first Ethernet interface, including a means for providing an asymmetry in frequency or time characteristics between the forward and backward signals so that to avoid interference between the backward and forward signals and allow the transmission of both signals at the same time;
(c) a means for receiving the backward coded sequence from the coaxial cable and forwarding it to the second Ethernet interface;
(d) a means for receiving the forward coded sequence from the coaxial cable and forwarding it to the first Ethernet interface;
wherein the means for providing the asymmetry in frequency comprises means for coding the backward coded sequence of Ethernet according to a format “B” having a spectrum limited to below about “X” MHz, and the backward coded sequence according to another format “A” having a spectrum with a lower limit above about “X” MHz, and wherein the means (a) comprises means for coupling the backward coded sequence through a low pass filter with an upper frequency limit of about “X” MHz and an isolator to the coaxial cable, and the means (b) comprises a means for coupling the forward coded sequence through a high pass filter having a lower frequency limit of about “X” MHz and another isolator to the coaxial cable.

2 more elements

(a) a means for forming a backward signal from the backward coded sequence of packets at the first Ethernet interface for the transmission over the coaxial cable to the second Ethernet interface;
(b) a means for forming a forward signal from the forward coded sequence of packets at the second Ethernet interface for the transmission over the coaxial cable to the first Ethernet interface, including a means for providing an asymmetry in frequency or time characteristics between the forward and backward signals so that to avoid interference between the backward and forward signals and allow the transmission of both signals at the same time;
(c) a means for receiving the backward coded sequence from the coaxial cable and forwarding it to the second Ethernet interface;
(d) a means for receiving the forward coded sequence from the coaxial cable and forwarding it to the first Ethernet interface;
the system providing the forward and backward sequences of Ethernet packets and interpacket gaps in the form of sequences of coded symbols, wherein the means (a) comprises a means for buffering “Y” coded symbols arriving at a rate “E” of the sequence of packets and sending them in blocks of “Y” symbols at a rate “Z”, leaving inter block gaps of a length which depends on the rate “Z”.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for transmission of digital signals over a coaxial cable

Life of this patent

Method and apparatus for transmission of digital signals over a coaxial cable

Life of this patent

Abstract

Claims33