Adaptive allocation for variable bandwidth multicarrier communication
View Patent ↗Data is distributed among the channels of an asynchronous 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.
1. A transceiver in a multicarrier modulation system comprising a controller, and wherein the controller is configured to:
select a first allocation of bits to subchannels for first communication with another transceiver;
select a second allocation of bits to subchannels for second communication with the other transceiver;
cause the transceiver to transmit a flag to the other transceiver; and
cause the transceiver to begin transmission to the other transceiver using the second allocation of bits to subchannels after a predetermined number of frames following transmission of the flag.
2. The transceiver of claim 1 , wherein the controller is further configured to receive the different allocation of bits from the other transceiver.
3. The transceiver of claim 1 , wherein the controller is further configured to cause the transceiver to begin transmission to the other transceiver on a next frame immediately following transmission of the flag.
4. A transceiver in a multicarrier modulation system comprising a controller, and wherein the controller is configured to:
select a first allocation of bits to subchannels for first communication with another transceiver over a communication channel;
select, in response to receipt of a flag from the other transceiver, a second allocation of bits to subchannels for second communication with the other transceiver; and
cause the transceiver to begin utilizing the second allocation of bits to subchannels for second communication with the other transceiver after a predetermined number of frames following reception of the flag.
5. The transceiver of claim 4 , wherein the controller is further configured to cause the transceiver to begin transmission to the other transceiver on a next frame immediately following reception of the flag.
6. A method, comprising:
utilizing, by a transceiver, a first allocation of bits to subchannels of a multicarrier modulation system to communicate with another transceiver;
selecting, by the transceiver, a different allocation of bits to subchannels of the multicarrier modulation system;
transmitting, by the transceiver, a flag to the other transceiver; and
utilizing, by the transceiver, the different allocation of bits to communicate with the other transceiver after a predetermined number of frames following transmission of the flag.
7. The method of claim 6 , further comprising receiving the different allocation of bits from the other transceiver.
8. The method of claim 6 , further comprising utilizing, by the transceiver, the different allocation of bits to communicate with the other transceiver on a next frame immediately following transmission of the flag.
9. A method, comprising:
utilizing, by a transceiver, a first allocation of bits to subchannels of a multicarrier modulation system to communicate with another transceiver;
selecting, by the transceiver, a different allocation of bits to subchannels; and
utilizing, by the transceiver upon reception of a flag from the other transceiver, the different allocation of bits to subchannels to communicate with the other transceiver after a predetermined number of frames following the reception of the flag.
10. The method of claim 9 , wherein said selecting a different allocation of bits is in response to monitoring of the multicarrier modulation system.
11. The method of claim 9 , further comprising utilizing, by the transceiver, the different allocation of bits to communicate with the other transceiver on a next frame immediately following transmission of the flag.
12. The method of claim 9 , further comprising transmitting, by the transceiver, the second allocation of bits to the other transceiver based at least on a monitored state of the multicarrier modulation system.