Adaptive allocation for variable bandwidth multicarrier communication

• US 6,798,735 B1
• Filed: 10/20/1999
• Issued: 09/28/2004
• Est. Priority Date: 06/12/1996
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Aware Incorporated (Crowley Holdings Preferred LLC)
• Inventors: Tzannes, Marcos, Kechriotis, George, Wu, Pui
• Primary Examiner(s): Duong, Frank
• Application Number:
  US09/421,835
• Time in Patent Office: 1,805 Days
• Field of Search: 370/203, 370/206, 370/207, 370/252, 370/329, 370/341, 370/343, 370/468, 370/480, 370/503, 370/509, 370/512, 455/450, 455/451, 455/452, 455/509, 455/63, 375/222, 375/260, 375/346
• US Class Current: 370/207
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04W 72/04 Wireless resource allocation

Abstract

Data is distributed among the channels of an asymmetric data subscriber loop (ADSL) communications system in accordance with an adaptive algorithm which from time to time measures the signal to noise ratio of the various channels and finds a margin for each channel dependent on achievement (where possible) of a given bit error rate and a desired data transmission rate. The margin distribution is achieved by augmenting the constellation signal to noise ratio to enhance computational efficiency and allow redetermination of bit allocation tables during transmission as necessary. Pairs of bit allocation tables are maintained at the transmitter and receiver and one table of each pair at the transmitter and receiver is updated while the other pair is in use for controlling communication.

Claims

1. In a multicarrier transmission system including two communication units, a method for modulation bits onto subchannels of a communication channel between the two communication units, the method comprising:

allocating bits to subchannels of the communication channel according to a first bit allocation table;

monitoring the communication channel during transmission of the bits allocated to the subchannels according to the first bit allocation table;

developing a second bit allocation table at one of the communication units in response to monitoring the communication channel;

transmitting the second bit allocation table to the other of the communication units over the communication channel; and

storing the first and second bit allocation tables at each of the communication units.

2. The method of claim 1 further comprising switching from the first bit allocation table to the second bit allocation table for allocating bits to the subchannels of the communication channel.

3. The method of claim 2 further comprising modifying the first bit allocation table during transmission of bits allocated to subchannels according to the second bit allocation table.

4. The method of claim 3 further comprising transmitting the modified first bit allocation table from one of the communication units to the other of the communication units.

5. The method of claim 4 further comprising replacing the first bit allocation table at that other of the communication units with the modified first bit allocation table.

6. The method of claim 1 further comprising transmitting a flag over the communication channel to synchronize switching from the first bit allocation table to the second bit allocation table for allocating bits to subchannels.

7. The method of claim 6 further comprising commencing use of the second bit allocation table for allocating bits to subchannels at a designated frame subsequent to transmission of the flag.

8. The method of claim 6 wherein the flag is transmitted over a particular one of the subchannels.

9. The method of claim 1 further comprising receiving a flag over the communication channel to synchronize switching from the first bit allocation table to the second bit allocation table for allocating bits to subchannels.

10. The method of claim 9 further comprising commencing use of the second bit allocating table for allocating bits to subchannels at a designated frame subsequent to receipt of the flag.

11. The method of claim 9 wherein the flag is received over a particular one of the subchannels.

12. In a multicarrier transmission system including two communication units, a method for modulating bits onto subchannels of a communication channel between the two communication units, the method comprising:

transmitting bits allocated to subchannels of the communication channel according to a first bit allocation table;

developing a second bit allocation table at one of the communication units;

transmitting the second bit allocation table to the other of the communication units over the communication channel; and

storing the first and second bit allocation tables at each of the communication units.

13. The method of claim 12 further comprising transmitting a flag over the communication channel to synchronize switching from the first bit allocation table to the second bit allocation table for allocating bits to subchannels.

14. The method of claim 12 further comprising receiving a flag over the communication channel to synchronize switching from the first bit allocation table to the second bit allocation table for allocating bits to subchannels.

15. A transmitter in a multicarrier modulation system, comprising:

a first bit allocation table specifying a first allocation of bits to subchannels used during current communication with a receiver;

a second bit allocation table specifying a different allocation of bits to subchannels than the first bit allocation table; and

a signaler transmitting a flag to synchronize from the first bit allocation table to the second bit allocation table for allocating bits to the subchannels,

wherein the transmitter stores the second bit allocation table for use during subsequent communication with the receiver.

16. A receiver in a multicarrier modulation system, comprising:

a first bit allocation table specifying a first allocation of bits to subchannels used during current communication with a transmitter over a communication channel;

a second bit allocation table specifying a different allocation of bits to subchannels than the first bit allocation table; and

a control unit developing the second bit allocation table,

wherein the receiver stores the second bit allocation table for use during subsequent communication with the transmitter.

17. A receiver in a multicarrier modulation system, comprising:

a first bit allocation table specifying a first allocation of bits to subchannels used during current communication with a transmitter over a communication channel;

a second bit allocation table specifying a different allocation of bits to subchannels than the first bit allocation table; and

a switch unit to receive a flag that synchronizes switching from the first bit allocation table to the second bit allocation table for allocating bits to the subchannels,

wherein the receiver stores the second bit allocation table for use during subsequent communication with the transmitter.

18. A multicarrier transmission system, comprising:

a plurality of communication units in communication with each other over a communications channel having a plurality of subchannels, each communication unit storing a first bit allocation table that specifies a first allocation of bits to the subchannels for use during current communication with each other communication unit over the communication channel; and

a second bit allocation table, stored by each of the communication units, specifying a different allocation of bits to subchannels than the first bit allocation tables, for use during subsequent communication between the communication units,

wherein one of the communication units comprises a transmitter that transmits the second bit allocation table stored by that communication unit to another of the communication units for use during the subsequent communication between the communication units.

19. A multicarrier transmission system, comprising:

a plurality of communication units in communication with each other over a communications channel having a plurality of subchannels, each communication unit storing a first bit allocation table that specifies a first allocation of bits to the subchannels for use during current communication with each other communication unit over the communication channel; and

a second bit allocation table, stored by each of the communication units, specifying a different allocation of bits to subchannels than the first bit allocation tables, for use during subsequent communication between the communication units,

wherein one of the communication units comprises a signaler that transmits a flag to another of the communication units to synchronize switching from the first bit allocation tables to the second bit allocation tables for allocating bits to subchannels.

20. A multicarrier transmission system, comprising:

a plurality of communication units in communication with each other over a communications channel having a plurality of subchannels, each communication unit storing a first bit allocation table that specifies a first allocation of bits to the subchannels for use during current communication with each other communication unit over the communication channel; and

a second bit allocation table, stored by each of the communication units, specifying a different allocation of bits to subchannels than the first bit allocation tables, for use during subsequent communication between the communication units,

wherein one of the communication units comprises a control unit that develops the second bit allocation tables.