Method for peak power reduction in spread spectrum communications systems
AssigneePowerwave Technologies, Inc.
InventorMatthew J. Hunton
Life of this patent
Estimating the term…
Abstract
A system and method for signal peak reduction in a spread spectrum communication system of the type including a filter for limiting signal bandwidth of symbols transmitted from the system. A signal peak reduction unit is provided before the filter that includes a filter predictor that predicts the effect of the filter on input symbols by using filter coefficient values corresponding to the filter impulse response function. Input symbols that are predicted to cause the output signal to exceed a predetermined peak limit value are adjusted. Several examples of suitable algorithms for calculating the necessary peak reduction to be applied to the input symbols are disclosed. The peak reduction unit provides adjusted symbols to the filter for processing and communication system output.
Claims33
A method for adjusting symbol values in a communication system including a filter which provides symbol filtering prior to outputting signals from said system, the method comprising:
- receiving symbols prior to filtering by said filter;
- predicting the effect of said filtering on said symbols;
- and
- adjusting the value of symbols which are predicted to exceed a peak limit value after being subjected to said filtering.
An improved method for spread spectrum communication, comprising:
- providing data symbols corresponding to a plurality of separate data channels combined together;
- providing a filtering operation based on a filter impulse response function;
- and
- performing a peak reduction processing on said data symbols prior to said filtering operation, the peak reduction processing including:
- providing predicted filtered outputs using filter coefficient values corresponding to the filter impulse response function;
- receiving the predicted filtered outputs and a predetermined filter output limit value and determining a peak reduction value based on the amount a predicted filtered output exceeds the limit value;
- and
- combining the peak reduction values and data symbols and providing peak adjusted symbols to be filtered and output by the communication system.
An improved method for spread spectrum communication, comprising:
- receiving data symbols corresponding to a plurality of separate data channels combined together;
- increasing the sampling rate of said symbols and providing up sampled symbols;
- providing a filtering operation based on a filter impulse response function having a plurality of filter coefficients and corresponding to a timing based on said increased sampling rate;
- and
- providing a peak reduction processing prior to said filtering operation employing said data symbols, the peak reduction processing being performed in a plurality of peak reduction stages, each peak reduction processing stage comprising predicting the effect of the filtering operation on the data symbols using filter coefficient values corresponding to a portion of the filter impulse response function to provide predicted filtered outputs and providing a peak reduction processing on predicted filter outputs which exceed a peak limit value, wherein said peak reduction processing provides peak adjusted symbols after said plural stage peak reduction processing to be filtered and output.
A method for reducing peak signal output values adapted for use in a communication method which provides symbol filtering employing a predetermined impulse response function prior to outputting communication signals, comprising:
- receiving symbols prior to filtering and predicting the effect of said filtering on said symbols using filter coefficients corresponding to said impulse response function at a plurality of sample points;
- and
- adjusting the symbols which are predicted to exceed a peak limit value after being subjected to said filtering.
Dependencies are inferred from the claim text.