Power line communication network

• US 20040075535A1
• Filed: 11/18/2003
• Published: 04/22/2004
• Est. Priority Date: 04/17/2000
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Adaptive Networks, Inc.
• Inventors: Do, Du Thi, Propp, David L, Saab, Khaled, Jakson, John, Propp, Michael B
• Granted Patent: US 7,406,094 B2
• Time in Patent Office: Days
• US Class Current: 340/310.01
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing
• CPC Class Codes: H04L 12/433 with asynchronous transmission, e.g. token ring, register insertion
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272

Abstract

A media access control (MAC) controller is disclosed for a network providing communication for network stations located at a plurality of customer premises and sharing a communication medium, each of the premises having a plurality of network stations. The MAC controller includes a virtual local area network (vLAN) controller, providing access to the communication medium for and communication among the stations located at a single customer'"'"'s premises, to define a vLAN between them. A group local area network (gLAN) controller provides access to the communication medium for and communication among interfering vLANs, two vLANs being considered to be interfering when one can sense communications over the medium from a station in the other. A MAC controller is provided in at least one station in a vLAN. The MAC controller is preferably connected to use as the communication medium the portion of a power line at the output of the last step down transformer and utilizes a token passing protocol to control access to the medium.

Claims

1. A media access control (MAC) controller for a network providing communication for network stations located at a plurality of customer premises and sharing a communication medium, each of the premises having a plurality of network stations, the MAC controller comprising:

a virtual local area network (vLAN) controller, providing access to the communication medium for and communication among the stations located at a single customer'"'"'s premises, to define a vLAN therebetween; and

a group local area network (gLAN) controller providing access to the communication medium for and communication among interfering vLANs, two vLANs being considered to be interfering when one can sense communications over the medium from a station in the other;

a MAC controller being provided in at least one station in a vLAN.

2. The MAC controller of claim 1 connected to use as the communication medium the portion of a power line at the output of the last step down transformer.

3. The MAC controller of claim 1 or 2 constructed to utilize a token passing protocol to control access to the medium.

4. The MAC controller of claim 3, wherein the gLAN controller is constructed to utilize a token passing protocol among vLANs to control access to the medium thereby, a vLAN being capable of retaining the token when received from one of the other vLANs, but must pass the token immediately when receiving it from any other vLAN, whereby, although the vLANs in a gLAN are connected in a bus configuration, they pass the token in a logical ring topology in which the ring includes vLANs that are unable to communicate directly.

5. The MAC controller of claim 4, wherein the gLAN controller is constructed to control the transfer of the token between two vLANs, an originator and a recipient, through a handshake procedure requiring a token pass message from the originator, an ACK message from the recipient in response to the token pass message, and a handshake message from the recipient in response to the ACK for the recipient to assume possession of the token:

the originator providing a predefined retry remaining count along with the token pass message and re-sending the token pass message together with a decremented retry remaining count, upon failure to receive an ACK message, until the retry remaining count is zero, whereupon the originator retains the token; and

the recipient responding to the token pass message by sending an ACK accompanied by a decremented retry count, and continuing to repeat these steps upon failure to receive a handshake message, until the retry remaining count is zero, whereupon the token transfer fails.

6. The MAC controller of claim 5, wherein the gLAN controller is constructed to provide a token master flag to one of the vLANs, defined as the token master, the token master computing a vLAN token hold time (vTHT), the token being passed around the logical loop together with vTHT, each vLAN other than the token master retaining the token for no longer than the vTHT before passing it on.

7. The MAC controller of claim 6, wherein the gLAN controller is constructed so that the token master flag is retained by one of the vLANs and sent to the next in the logical loop after the token has made a complete traversal of the entire loop, the vLAN in possession of the token master flag being the token master.

8. The MAC controller of claim 7, wherein the gLAN controller is constructed to maintain a token heartbeat which is incremented every time the token master flag is passed, a vLAN seizing possession of the token master flag upon encountering the same heartbeat consecutively, whereby loss of token mastership is avoided.

9. The MAC controller of claim 3, wherein the gLAN controller is constructed to control the transfer of the token between two vLANs, an originator and a recipient, through a handshake procedure requiring a token pass message from the originator, an ACK message from the recipient in response to the token pass message, and a handshake message from the recipient in response to the ACK for the recipient to assume possession of the token:

the originator providing a predefined retry remaining count along with the token pass message and re-sending the token pass message together with a decremented retry remaining count, upon failure to receive an ACK message, until the retry remaining count is zero, whereupon the originator retains the token; and

the recipient responding to the token pass message by sending an ACK accompanied by a decremented retry count, and continuing to repeat these steps upon failure to receive a handshake message, until the retry remaining count is zero, whereupon the token transfer fails.

10. The MAC controller of claim 9, wherein the gLAN controller is constructed to provide a token master flag to one of the vLANs, defined as the token master, the token master computing a vLAN token hold time (vTHT) by dividing the round trip time, TRT, of the token around the logical loop by the number of vLANs in the gLAN, the token being passed around the logical loop together with vTHT, each vLAN other than the token master retaining the token for no longer than the vTHT before passing it on.

11. The MAC controller of claim 10, wherein the gLAN controller is constructed so that the token master flag is retained by one of the vLANs and sent to the next in the logical loop after the token has made a complete traversal of the entire loop, the vLAN in possession of the token master flag being the token master.

12. The MAC controller of claim 11, wherein the gLAN controller is constructed to maintain a token heartbeat which is incremented every time the token master flag is passed, a vLAN seizing possession of the token master flag upon encountering the same heartbeat consecutively, whereby loss of token mastership is avoided.

13. The MAC controller of claim 3, wherein the gLAN controller is constructed to provide a token master flag to one of the vLANs, defined as the token master, the token master computing a vLAN token hold time (vTHT) by dividing the round trip time, TRT, of the token around the logical loop by the number of vLANs in the gLAN, the token being passed around the logical loop together with vTHT, each vLAN other than the token master retaining the token for no longer than the vTHT before passing it on.

14. The MAC controller of claim 13, wherein the gLAN controller is constructed so that the token master flag is retained by one of the vLANs and sent to the next in the logical loop after the token has made a complete traversal of the entire loop, the vLAN in possession of the token master flag being the token master.

15. The MAC controller of claim 14, wherein the gLAN controller is constructed to maintain a token heartbeat which is incremented every time the token master flag is passed, a vLAN seizing possession of the token master flag upon encountering the same heartbeat consecutively, whereby loss of token mastership is avoided.

16. The MAC controller of claim 13, wherein the vLAN controller is constructed to poll stations in the process of granting them access to the medium, the polling overhead being managed by granting medium access to a station with an active connection at a rate required to maintain quality of service guarantees, while a station without an active connection is granted access at a much slower rate determined at the convenience of the controller.

17. The MAC controller of claim 10, wherein the vLAN controller is constructed to poll stations in the process of granting them access to the medium, the polling overhead being managed by granting medium access to a station with an active connection at a rate required to maintain quality of service guarantees, while a station without an active connection is granted access at a much slower rate determined at the convenience of the controller.

18. The MAC controller of claim 9, wherein the vLAN controller is constructed to poll stations in the process of granting them access to the medium, the polling overhead being managed by granting medium access to a station with an active connection at a rate required to maintain quality of service guarantees, while a station without an active connection is granted access at a much slower rate determined at the convenience of the controller.

19. The MAC controller of claim 5, wherein the vLAN controller is constructed to poll stations in the process of granting them access to the medium, the polling overhead being managed by granting medium access to a station with an active connection at a rate required to maintain quality of service guarantees, while a station without an active connection is granted access at a much slower rate determined at the convenience of the controller.

20. The MAC controller of claim 4, wherein the vLAN controller is constructed to poll stations in the process of granting them access to the medium, the polling overhead being managed by granting medium access to a station with an active connection at a rate required to maintain quality of service guarantees, while a station without an active connection is granted access at a much slower rate determined at the convenience of the controller.

21. The MAC controller of claim 3, wherein the vLAN controller is constructed to poll stations in the process of granting them access to the medium, the polling overhead being managed by granting medium access to a station with an active connection at a rate required to maintain quality of service guarantees, while a station without an active connection is granted access at a much slower rate determined at the convenience of the controller.

22. The MAC controller of claim 3, wherein the procedure of claim 5 is used between a vLAN and one of its stations, one of which is the originator and the other of which is the recipient.

23. The MAC controller of claim 9, wherein the procedure of claim 9 is used between a vLAN and one of its stations, one of which is the originator and the other of which is the recipient.

24. A method for improving reliability of communication in a communication system utilizing frame synchronization preamble detection, the method comprising the steps of detecting synchronization in a narrow synchronization window around the expected synchronization preamble to increase the chances of receiving a proper transmission, and providing precise inter-frame gap timing and predictable response size, the precise inter-frame gap allowing a transmitter to trigger its receiver in relationship to the end of its transmission, and the predictable response size allowing the transmitter to time the start of its next transmission in the event that it misses a receiver response.

25. A method for enhancing the reliability of synchronization to a received signal or equalizer adjustment in a communication system using a synchronization preamble to detect synchronization, the method comprising the steps of:

acquiring N samples for each of the first M symbols in the received signal, where N is a multiple of the Nyquist rate and M is the number of symbols in the synchronization preamble;

correlating each group of samples corresponding to a received symbol with the nominal set of symbols, to resolve each sample to a symbol;

determining the bit error rate (BER) between the nominal sequence and resolved sequence for each sample position of the received symbols;

repeating the preceding steps in successive sample positions of the received signal; and

using for one of synchronization and equalizer adjustment purposes, the position of the received signal which yields the lowest BER.

26. A method for optimizing equalizer settings in a receiver for communications system, comprising the steps of:

initially transmitting data symbols in the communications signal at a bit rate which is less than the normal bit rate for the system, permitting the equalizer to converge on an optimum setting; and

as an optimum setting is approached, restoring the signal to its normal bit rate.

27. A method for decreasing interference between receivers in a communications system utilizing a synchronization preamble to synchronize receivers, comprising the step utilizing different preamble sequences for potentially interfering receivers.

28. The method of claim 27 utilized to permit potentially interfering receivers to operate in closer proximity to each other, to achieve more efficient use of bandwidth.

29. The method of claim 27 or 28 wherein the different preamble sequences have low cross-correlation.