Adaptive allocation for variable bandwidth multicarrier communication

Claim 2

In a multicarrier modulation system having a plurality of channels for transmitting data at varying rates from a transmitter to a receiver dependent on the signal to noise ratio of the respective channels, the improvement comprising: A. means for allocating data to respective ones of said channels in accordance with an initial signal to noise ratio for the corresponding channel, B. means for repetitively calculating trial noise margins across a set of constellation signal to noise ratios used in assigning data to said channels, and C. means for repetitively combining said trial noise margins with the said constellation signal to noise ratios to form modified constellation signal to noise ratios for use in reallocating said data to said channels.

Claim 3

A multicarrier modulation system according to claim 1 in which said margins are added to the constellation signal to noise ratios to form said modified ratios.

Claim 4

A multicarrier modulation system according to claim 2 in which said margins are added to said constellation signal to noise ratios equally.

Claim 5

A multicarrier modulation system according to claim 3 which includes means for defining upper and lower margin thresholds M H and M L , respectively, said trial noise margins being defined as a combination of said thresholds.

Claim 6

A multicarrier modulation system according to claim 4 in which said combination is formed as an average of said upper and lower thresholds.

Claim 7

A multicarrier modulation system according to claim 5 in which at least one of said thresholds is determined as a function of the difference between the amount of data transmissible across said channels in accordance with previously specified signal to noise ratios associated with said channels and the amount of data desired to be transmitted across said channels.

Claim 8

A multicarrier modulation system according to claim 6 in which at least one of said thresholds is set to zero.

Claim 9

A multicarrier modulation system according to claim 6 which includes means for terminating data allocation when the amount of data transmissible across said channels in accordance with previously specified signal to noise ratios associated with said channels equals the amount of data desired to be transmitted across said channels.

Claim 10

A multicarrier modulation system according to claim 6 which includes means for terminating data allocation when said difference diverges.

Claim 11

A multicarrier modulation system according to claim 6 which includes means for terminating data allocation after a defined number of iterations of margin calculations over said constellations.

Claim 12

A multicarrier modulation system according to claim 1 in which said means for calculating trial noise margins comprises: A. means for defining a trial margin that is a function of the difference between the amount of data allocable to said channels in accordance with said initial signal to noise ratios for the respective channels and the amount of data desired to be transmitted, and B. means for repetitively adjusting said trial margin in accordance with the relation between (1) the amount of data transmissible across said channels when the signal to noise ratios of said constellations are augmented by said trial margin and (2) the amount of data transmissible across said channels in accordance with a prior determination of said channel signal to noise ratios.

Claim 13

A multicarrier modulation system according to claim 1 which includes means for periodically transmitting a reference frame from the transmitter to the receiver, and means for measuring the signal to noise ratios of said channels from the transmitted reference frame, said means for repetitively calculating trial noise margins across said constellation signal to noise ratios using the signal to noise ratios determined in the most recently transmitted frame as the initial signal to noise ratios for calculating said margins in the interval between said frame and the next frame.

Claim 14

A multicarrier modulation system according to claim 12 which includes first and second memory register sets at both said transmitter and said receiver for storing channel data allocations in accordance with signal to noise ratios associated therewith, and means for transmitting a flag between the transmitter and the receiver indicating which of the register sets is to be used for subsequently receiving data from said transmitter.

Claim 15

In a multicarrier modulation system having a plurality of channels for transmitting data at varying rates from a transmitter to a receiver dependent on the signal to noise ratio of the respective channels, the improvement comprising: A. means for allocating data to respective ones of said channels in accordance with initial signal to noise ratios measured for the corresponding channels, B. means for calculating a trial noise margin across across a set of constellation signal to noise ratios used in assigning data to said channels, said margin being calculated as a function of said initial signal to noise ratio and the difference between the amount of data transmissible over said channels with said signal to noise ratios and the amount of data desired to be transmitted, C. means for augmenting the constellation signal to noise ratios by the trial noise margin to thereby define augmented signal to noise ratios for use in defining a revised estimate of the amount of data transmissible over said channels, and D. means for repetitively defining successive trial noise margins as a function of the augmented signal to noise ratios and the difference between the amount of data transmissible over said channels with said augmented signal to noise ratios and the amount of data desired to be transmitted until an exit condition is reached.

Claim 16

In a multicarrier modulation system having a plurality of channels for transmitting data at varying rates from a transmitter to a receiver dependent on the signal to noise ratio of the respective channels, the improvement comprising: A. means for allocating data to respective ones of said channels in accordance with initial signal to noise ratios measured for the corresponding channels, B. means for calculating a trial noise margin across across a set of constellation signal to noise ratios used in assigning data to said channels, said margin being calculated as a function of said initial signal to noise ratio and the difference between the amount of data transmissible over said channels with said signal to noise ratios and the amount of data desired to be transmitted, C. means for augmenting the constellation signal to noise ratios by the trial noise margin to thereby define augmented signal to noise ratios for use in defining a revised estimate of the amount of data transmissible over said channels, and D. means for repetitively defining successive trial noise margins as a function of the augmented signal to noise ratios and the difference between the amount of data transmissible over said channels with said augmented signal to noise ratios and the amount of data desired to be transmitted until an exit condition is reached.

Claim 17

A multicarrier modulation system according to claim 14 in which said exit condition comprises equality between the amount of data transmissible over said channels with a particular set of augmented signal to noise ratios and the amount of data desired to be transmitted.

Claim 18

A multicarrier modulation system according to claim 14 in which said exit condition comprises an increase in the difference between the amount of data transmissible over said channels with said augmented signal to noise ratios and the amount of data desired to be transmitted as determined on successive calculations.

Claim 19

A multicarrier modulation system according to claim 14 in which said exit condition comprises determination of a defined number of successive trial noise margins.

Claim 20

A multicarrier modulation system according to claim 14 which includes means for periodically transmitting a reference frame between the transmitter and the receiver, and means for measuring the signal to noise ratios of said channels from the transmitted reference frame, said means for calculating trial noise margins using the signal to noise ratios determined in the most recently transmitted frame as the initial signal to noise ratios for calculating said margins in the interval between said frame and the next frame.

Claim 21

A multicarrier modulation system according to claim 18 which includes first and second memory register sets at both said transmitter and said receiver for storing channel data allocations in accordance with signal to noise ratios associated therewith, and means for transmitting between the transmitter and the receiver a flag indicating which of the register sets is to be used for subsequently receiving data from said transmitter.

Claim 24

A method according to claim 20 in which the step of combining said trial noise margins and said constellation signal to noise ratios comprises adding a calculated trial noise margin to the constellation signal to noise ratios to thereby form augmented signal to noise ratios from which the amount of data transmissible in said channels is determined.

Claim 25

A method according to claim 20 in which the step of repetitively calculating trial noise margins across said constellation comprises the steps of A. repetitively defining a trial margin that is a function of the difference between the amount of data allocable to said channels in accordance with said initial signal to noise ratios for the respective channels and the amount of data desired to be transmitted, and B. repetitively adjusting said trial margin in accordance with the relation between the amount of data transmissible across said channels when the signal to noise ratios of said constellation are augmented by said trial margin and the amount of data transmissible across said channels in accordance with a prior determination of said signal to noise ratios for the respective channels.

Claim 26

A method according to claim 22 which further includes the steps of: A. periodically transmitting a reference frame between the transmitter and the receiver, B. measuring the signal to noise ratios of said channels from the transmitted reference frame and using the signal to noise ratios determined in the most recently transmitted frame as the signal to noise ratios for calculating said margins in the interval between said frame and the next frame.

Claim 27

A method according to claim 23 which includes the steps of providing first and second memory register sets at both said transmitter and said receiver for storing channel data allocations in accordance with signal to noise ratios associated therewith, and transmitting between the transmitter and the receiver a flag indicating which of the register sets is to be used for subsequently receiving data from said transmitter.