Allocation of bit streams for communication over-multi-carrier frequency-division multiplexing (FDM)

• US 20030053493A1
• Filed: 09/17/2002
• Published: 03/20/2003
• Est. Priority Date: 09/18/2001
• Status: Abandoned Application

• Current Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Inventors: Graham Mobley, Joseph, Sorenson, Donald C., West, Lamar E. Jr., Ritchie, John A. Jr., Ao, Jiening
• Application Number:
  US10/245,054
• Publication Number:
  US 20030053493A1
• Time in Patent Office: Days
• US Class Current: 370/538
• CPC Class Codes: H04J 3/0641 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver
• CPC Class Codes: H04L 27/2631 with polyphase implementation
• CPC Class Codes: H04L 27/26524 Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 7/041 using special codes as synchronising signal
• CPC Class Codes: H04N 21/2362 Generation or processing of Service Information [SI]
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence

Abstract

An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Also, the modulation indices of various upstream frequency channels may be different, but a plurality of upstream channels may be used to carry a single data flow generally in parallel. The upstream data flow is fragmented into blocks and formed into superframes to allow transmission over at least one upstream frequency channel. When a plurality of upstream frequency channels are utilized, the superframes facilitate the possibility of having different modulation indices on the plurality of frequency channels. The upstream frequency channels or tones generally use a smaller amount of frequency bandwidth than the amount of frequency bandwidth commonly used to carry television channels on a cable transmission network. The smaller frequency bandwidth generally allows a plurality of the smaller frequency channels to be frequency-division multiplexed into a larger frequency channel capable of carrying television channels on a cable transmission network. Smaller frequency bandwidth channels allow a more efficient allocation of bandwidth to a client device and allows more accurate control over transmission characteristics (such as but not limited to group delay) of the frequency bandwidth. The smaller frequency channels generally can each be assigned to a different client device. Thus, client devices may share one of the large frequency bandwidth channels using frequency-division multiplexing of the smaller frequency bandwidth channels.

Claims

1. A method of communicating data across a plurality of transmission streams that have different bit rates, the method comprising the steps of:

utilizing superframes to group bits from a flow of bits into a plurality of blocks of data, the plurality of blocks of data being a number of data blocks that is at least partially based upon the different bit rates of the plurality of transmission streams;

allocating octets between the flow of bits and the plurality of blocks of data;

allocating the plurality of blocks of data across the plurality of transmission streams based on the ratios of the different bit rates; and

utilizing the plurality of transmission streams in communicating the flows of bits within the plurality of blocks of data.

2. The method of claim 1, wherein the step of utilizing superframes to group bits further comprises the step of forming superframes by dividing the flow of bits into groups of bits that are capable of being communicated in one superframe, wherein the step of allocating octets further comprises the step of further grouping bits into the blocks of data, wherein the step of allocating the plurality of blocks of data further comprises the step of preparing more of the blocks of data for transmission over the transmission streams with higher bit rates and the step of preparing less of the blocks of data for transmission over the transmission streams with lower bit rates, and wherein the step of utilizing the plurality of transmission streams further comprises the step of transmitting the blocks of data that are allocated to the plurality transmission streams.

3. The method of claim 2, wherein the plurality of transmission streams are contemporaneously transmitting information.

4. The method of claim 1, wherein the step of utilizing the superframes to group bits further comprises the step of recovering the flow of bits from the superframes, wherein the step of allocating octets further comprises the step of recovering the octets from the blocks of data and placing the octets into the flow of bits, wherein the step of allocating the plurality of blocks of data further comprises the step of recovering more of the blocks of data from receptions of the transmission streams with higher bit rates and the step of recovering less of the blocks of data from receptions of the transmission streams with lower bit rates, and wherein the step of utilizing the plurality of transmission streams further comprises the step of receiving the blocks of data that are allocated to the plurality of transmission streams.

5. The method of claim 4, wherein the plurality of transmission streams are being used for contemporaneously receiving information.

6. The method of claim 1, wherein the plurality of transmission streams are frequency-division multiplexed into the same communications medium.

7. The method of claim 6, wherein the plurality of transmission streams are frequency-division multiplexed into at least one first frequency channel, and wherein other communication independent of the plurality of transmission streams is frequency-division multiplexed into at least one second frequency channel.

8. The method of claim 7, wherein the at least one first frequency channel and the at least one second frequency channel are frequency channels that are capable of being utilized in cable distribution networks to support television frequency channels.

9. The method of claim 1, wherein the plurality of transmission streams are also frequency-division multiplexed into the same communications medium with a second plurality of transmission streams carrying a second flow of bits.

10. The method of claim 1, wherein the flow of bits and the second flow of bits each provide connection-oriented communications between a first device and a second device.

11. The method of claim 1, wherein the flow of bits provides connection-oriented communication between a first device and a second device, and wherein the second flow of bits provides connection-oriented communication between a first device and a third device.

12. The method of claim 1, wherein the transmission streams operate at the same symbol rate but at least one transmission stream of the plurality of transmission streams operates at a different bit rate than at least one of the other transmission streams based upon a different QAM index.

13. A device of communicating data across a plurality of transmission streams that have different bit rates, the device comprising:

logic configured to utilize superframes to group bits from a flow of bits into a plurality of blocks of data, the plurality of blocks of data being a number of data blocks that is at least partially based upon the different bit rates of the plurality of transmission streams;

logic configured to allocate octets between the flow of bits and the plurality of blocks of data;

logic configured to allocate the plurality of blocks of data across the plurality of transmission streams based on the ratios of the different bit rates; and

logic configured to utilize the plurality of transmission streams in communicating the flows of bits within the plurality of blocks of data.

14. The device of claim 13, wherein the logic configured to utilize the superframes to group bits further comprises logic configured to form superframes by dividing the flow of bits into groups of bits that are capable of being communicated in one superframe, wherein the logic configured to allocate octets further comprises logic configured to further group bits into the blocks of data, wherein the logic configured to allocate the plurality of blocks of data further comprises logic configured to prepare more of the blocks of data for transmission over the transmission streams with higher bit rates and logic configured to prepare less of the blocks of data for transmission over the transmission streams with lower bit rates, and wherein logic configured to utilize the plurality of transmission streams further comprises logic configured to transmit the blocks of data that are allocated to the plurality transmission streams.

15. The device of claim 14, wherein the plurality of transmission streams are contemporaneously transmitting information.

16. The device of claim 13, wherein the logic configured to utilize superframes to group bits further comprises logic configured to recover the flow of bits from the superframes, wherein the logic configured to allocate octets further comprises logic configured to recover the octets from the blocks of data and logic configured to place the octets into the flow of bits, wherein the logic configured to allocate the plurality of blocks of data further comprises logic configured to recover more of the blocks of data from receptions of the transmission streams with higher bit rates and logic configured to recover less of the blocks of data from receptions of the transmission streams with lower bit rates, and wherein the logic configured to utilize the plurality of transmission streams further comprises logic configured to receive the blocks of data that are allocated to the plurality of transmission streams.

17. The device of claim 16, wherein the plurality of transmission streams are being used for contemporaneously receiving information.

18. The device of claim 13, wherein the plurality of transmission streams are frequency-division multiplexed into the same communications medium.

19. The device of claim 18, wherein the plurality of transmission streams are frequency-division multiplexed into at least one first frequency channel, and wherein other communication independent of the plurality of transmission streams is frequency-division multiplexed into at least one second frequency channel.

20. The device of claim 19, wherein the at least one first frequency channel and the at least one second frequency channel are frequency channels that are capable of being utilized in cable distribution networks to support television frequency channels.

21. The device of claim 13, wherein the plurality of transmission streams are also frequency-division multiplexed into the same communications medium with a second plurality of transmission streams carrying a second flow of bits.

22. The device of claim 13, wherein the flow of bits and the second flow of bits each provide connection-oriented communications between a first device and a second device.

23. The device of claim 13, wherein the flow of bits provides connection-oriented communication between a first device and a second device, and wherein the second flow of bits provides connection-oriented communication between a first device and a third device.

24. The device of claim 13, wherein the transmission streams operate at the same symbol rate but at least one transmission stream of the plurality of transmission streams operates at a different bit rate than at least one of the other transmission streams based upon a different QAM index.