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

• US 20060092967A1
• Filed: 11/03/2005
• Published: 05/04/2006
• Est. Priority Date: 11/04/2004
• Status: Active Grant

• Current Assignee: Jacobi Systems Corporation
• Original Assignee: Jacobi Systems Corporation
• Inventors: Remedios, Derrick, Bacque, James Benson, Loh, Huck Kung, Bergeron, Jeffrey James
• Granted Patent: US 7,548,549 B2
• Time in Patent Office: Days
• US Class Current: 370/463
• CPC Class Codes: H04L 12/2801 Broadband local area networks

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.

Claims

1. 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 forward 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 so that to avoid interference between the backward and forward signals and allow the transmission of both signals at the same time.

2. A method as described in claim 1, wherein the forward and backward sequences of Ethernet packets are coded according to the one or more of the following coding schemes:

4B/5B coding;

multi-level transmission encoding-3 levels (MLT-3 coding);

8B/10B coding;

non-return to zero (NRZ) coding; and

Pulse Amplitude Modulation (PAM) coding.

3. A method as described in claim 1, wherein the coaxial cable is a video coaxial cable.

4. A method as described in claim 1, wherein the physical medium is one of the following:

unshielded twisted pair (UTP);

fiber optic cable.

5. A method as described in claim 1, wherein the first and second Ethernet interfaces are standard Ethernet interfaces.

6. A method as described in claim 1, wherein the transmitting is performed in a full duplex mode.

7. A method as described in claim 1, wherein the step (a) comprises coupling the backward coded sequence through a passive device to the coaxial cable.

8. A method as described in claim 7, wherein the passive device is a diplexer.

9. A method as described in claim 7, wherein the step (b) comprises the steps 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 passive device to the coaxial cable.

10. A method as described in claim 9, wherein the passive device is another diplexer.

11. A method as described in claim 9, wherein the backward coded sequence is a differential coded signal, and wherein the step (a) comprises converting the differential coded signal into a single-ended coded signal.

12. A method as described in claim 11, wherein the step of modulating comprises modulating the forward coded sequence, which is a differential coded signal.

13. A method as described in claim 7, wherein any of the forward and backward coded sequences are one of the following signals:

100BaseT signals;

10BaseT signals;

100Base-X signals; and

1000BaseT signals.

14. A method as described in claim 9, 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.

15. A method as described in claim 1, 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.

16. A method as described in claim 15, wherein the format “

B”

is 100BaseT, format “

A”

is 1000Base-X or 1000BaseT, and the frequency limit “

X”

is about 125 MHz.

17. A method as described in claim 1, wherein the forward and backward sequences of Ethernet packets and interpacket gaps are sequences of coded symbols, and wherein the step (a) comprises 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”

.

18. A method as described in claim 17, wherein “

Z”

is less than or equal to “

2E”

.

19. A method as described in claim 17, wherein “

Z”

is more than “

2E”

.

20. A method as described in claim 19, wherein the step (b) comprises buffering “

Y”

coded symbols arriving at a rate “

E”

of the sequence of packets and sending them in blocks of “

Y”

symbols at the same rate “

Z”

during said inter block gaps.

21. A method as described in claim 20, wherein any of the forward and backward coded sequences are one of the following signals:

100BaseT signals;

10BaseT signals;

1000Base-X signals; and

1000BaseT signals.

22. 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.

23. A system as described in claim 22, wherein the means (a) comprises a first passive device coupling the backward signal into the coaxial cable.

24. A system as described in claim 23, wherein the means (b) comprises:

a mixer for modulating the forward coded sequence into a modulated coded signal having frequency spectrum above that of the backward coded sequence; and

a second passive device coupling the modulated coded signal to the coaxial cable.

25. A system as described in claim 24, wherein the first and second passive devices are diplexers.

26. A system as described in claim 24, wherein the means (c) comprises said second passive device for separating the backward signal and the modulated coded signal.

27. A system as described in claim 24, wherein the means (d) comprises said first passive device for separating the backward signal and the modulated coded signal, and a detector for converting the modulated coded signal into a copy of the forward coded sequence.

40. A system as described in claim 22, 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.

41. A system as described in claim 40, wherein the format “

B”

is 100BaseT, and format “

A”

is 1000Base-X or 1000BaseT, and the frequency limit “

X”

is about 125 MHz

42. A system as described in claim 22, 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”

.

43. A system as described in claim 42, wherein “

Z”

is less than or equal to “

2E”

.

44. A system as described in claim 42, wherein “

Z”

is more than “

2E”

.

45. A system as described in claim 44, wherein the means (b) 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 the same rate “

Z”

during said inter block gaps.

46. A system as described in claim 45, wherein any of the forward and backward coded sequences are one of the following signals:

100BaseT signals;

10BaseT signals;

1000Base-X signals; and

1000BaseT signals

47. An Ethernet link, comprising the system as described in claim 22, and a coaxial cable, wherein the means (a) and (d) are connected to the cable at one end, and the means (b) and (c) are connected to the cable at the other end.

48. An Ethernet network, comprising nodes and links between the nodes, where some of the links are the links as described in claim 47.

49. An Ethernet network as described in claim 48, the network being an access network.

50. An Ethernet network as described in claim 48, wherein the sequences of Ethernet packets carry any of the following services:

video;

data;

voice data;

voice over IP data;

images.

28. A B-type conversion device (B-type dongle) for adapting a standard Ethernet connector to a coaxial cable in a system for transmitting forward and backward sequences of Ethernet packets, each sequence coded to be suitable for unidirectional transmission over a physical medium, between a first and a second Ethernet interface over a single coaxial cable, the B-type dongle comprising:

(i) 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; and

(ii) a means for receiving a modulated coded sequence from the coaxial cable from an A-type dongle at the second Ethernet interface, demodulating the modulated coded signal into a copy of the forward coded sequence, and forwarding it to the first Ethernet interface.

29. A B-type dongle as described in claim 28, wherein the means (i) and (ii) comprise a passive device coupling the backward signal into the coaxial cable and receiving the modulated coded sequence from the coaxial cable.

30. A B-type dongle as described in claim 29, wherein the passive device is a diplexer.

31. An A-type conversion device (A-type dongle) for adapting a standard Ethernet connector to a coaxial cable in 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 A-type dongle comprising:

(iii) 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; and

(iv) a means for receiving the backward coded sequence from the coaxial cable from a B-type dongle and forwarding it to the second Ethernet interface.

32. An A-type dongle as described in claim 31, wherein the means for providing the asymmetry comprises a modulator for modulating the forward coded sequence into a modulated coded signal having frequency spectrum above that of the backward coded sequence and means for coupling the modulated coded signal through a passive device to the coaxial cable.

33. An A-type dongle as described in claim 32, wherein the passive device is a diplexer.

34. A B-type conversion circuit for adapting a standard Ethernet signal to a coaxial cable in 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 B-type conversion circuit comprising:

(i) 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; and

(ii) a means for receiving a modulated coded sequence from the coaxial cable from an A-type conversion circuit at the second Ethernet interface, demodulating the modulated coded signal into a copy of the forward coded sequence, and forwarding it to the first Ethernet interface.

35. A B-type conversion circuit as described in claim 34, wherein the means (i) and (ii) comprise a passive device coupling the backward signal into the coaxial cable and receiving the modulated coded sequence from the coaxial cable.

36. An A-type conversion circuit for adapting a standard Ethernet signal to a coaxial cable in 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 A-type conversion circuit comprising:

(iii) 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; and

(iv) a means for receiving the backward coded sequence from the coaxial cable from a B-type conversion circuit and forwarding it to the second Ethernet interface.

37. An A-type conversion circuit as described in claim 36, wherein the means for providing the asymmetry in frequency comprises a modulator for modulating the forward coded sequence into a modulated coded signal having frequency spectrum above that of the backward coded sequence and means for coupling the modulated coded signal through a passive device to the coaxial cable.

38. An Ethernet link 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 link comprising:

a coaxial cable;

a B-type conversion circuit comprising;

(i) 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; and

(ii) a means for receiving a modulated coded sequence from the coaxial cable from an A-type conversion circuit at the second Ethernet interface, demodulating the modulated coded signal into a copy of the forward coded sequence, and forwarding it to the first Ethernet interface; and

the A-type conversion circuit, comprising;

(iii) 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; and

(iv) a means for receiving the backward coded sequence from the coaxial cable from the B-type conversion circuit and forwarding it to the second Ethernet interface.

39. An Ethernet network, comprising nodes and links between the nodes, where some of the links are the links as described in claim 38.