Gradient based method and apparatus for OFDM sub-carrier power optimization

Apparatus operable to increase data throughput in an orthogonal frequency division multiplex (OFDM) wireless communications system, comprising at least one data processor operating under control of a stored program, and coupled to OFDM transmission circuitry, to model data throughput as a function of received Signal to Noise Ratio (SNR) with a sigmoid function to produce a throughput curve characterized as having a lower knee region and an upper knee region;

• and to perform a gradient ascent search along the throughput curve by varying the power of a plurality of sub-carriers so as to remove power from any sub-carrier having a received SNR to the left of the lower knee region, and to re-allocate the removed power to sub-carriers having a received SNR to the right of the lower knee region.

A computer readable memory medium storing computer program instructions, the computer program instructions configured to increase data throughput in an orthogonal frequency division multiplex (OFDM) wireless communications system, wherein when the computer program instructions are executed by processing apparatus operations are performed, the operations comprising:

• performing a gradient ascent search along a data throughput curve, where the data throughput curve is modeled using a received Signal to Noise Ratio (SNR) as a sigmoid function to produce the data throughput curve to be characterized as having a lower knee region and an upper knee region, said gradient ascent search operating to vary the power of a plurality of sub-carriers so as to remove power from any sub-carrier having a received SNR to the left of the lower knee region, and to re-allocate the removed power to sub-carriers having a received SNR to the right of the lower knee region.

A computer readable memory medium storing computer program instructions, the computer program instructions configured to increase data throughput in an orthogonal frequency division multiplex (OFDM) wireless communications system, wherein when the computer program instructions are executed by processing apparatus operations are performed, the operations comprising:

• performing a multi-stage gradient ascent search along a data throughput curve, where the data throughput curve is modeled using received Signal to Noise Ratio (SNR) as a sigmoid function to produce the data throughput curve to be characterized as having a lower knee region and an upper knee region, said gradient ascent search operating to vary the power of a plurality of sub-carriers so as to remove power from any sub-carrier having a received SNR to the left of the lower knee region, and to re-allocate the removed power to sub-carriers having a received SNR to the right of the lower knee region, where during a first stage of the gradient ascent search an operation identifies sub-carriers to be disabled, and where during a second stage of the gradient ascent search a further operation allocates power only to retained sub-carriers at the expense of disabled sub-carriers.

Apparatus operable to increase data throughput in an orthogonal frequency division multiplex (OFDM) wireless communications system, comprising data processor means operating under control of a stored program, and coupled to OFDM transmission circuitry, for modeling data throughput as a function of received Signal to Noise Ratio (SNR) with a sigmoid function to produce a throughput curve characterized as having a lower knee region and an upper knee region;

• and for performing a gradient ascent search along the throughput curve by varying the power of a plurality of sub-carriers so as to remove power from any sub-carrier having a received SNR to the left of the lower knee region, and to re-allocate the removed power to sub-carriers having a received SNR to the right of the lower knee region.