Method and apparatus for implementing signal quality metrics and antenna diversity switching control

1. A method comprising:

receiving a radio signal including a digital portion modulated by a series of symbols each including a plurality of samples;

computing correlation points between endpoint samples in cyclic-prefix regions of adjacent symbols; and

using the correlation points to produce a digital signal quality metric, wherein the radio signal includes upper and lower sidebands and the step of computing correlation points comprises:

placing the endpoint samples for symbols received on the upper and lower sidebands in vectors;

frequency shifting the sideband vectors to center them at 0 Hz;

lowpass filtering the vectors;

performing a conjugate multiply and fold operation on the vectors to produce correlation vector results for the upper and lower sidebands;

normalizing the correlation results to produce normalized correlation results;

using the correlation vector results and the normalized correlation results to produce a quality value for the upper and lower sidebands; and

using the quality value for the upper and lower sidebands to produce a digital signal quality metric.

2. The method of claim 1 , further comprising:

using the signal quality metric to select one or more antenna elements to be connected to a receiver input.

3. An apparatus comprising:

a radio receiver including an input for receiving a radio signal having a digital portion modulated by a series of symbols, each including a plurality of samples, and a processor for computing correlation points between samples in cyclic-prefix regions of the symbols to produce a digital signal quality metric, wherein the processor places the endpoint samples for symbols received on the upper and lower sidebands in vectors; frequency shifts the sideband vectors to center them at 0 Hz; lowpass filters the vectors; performs a conjugate multiply and fold operation on the vectors to produce correlation vector results for the upper and lower sidebands; normalizes the correlation results to produce normalized correlation results;

uses the correlation vector results and the normalized correlation results to produce a quality value for the upper and lower sidebands; and uses the quality value for the upper and lower sidebands to produce a digital signal quality metric.

4. The apparatus of claim 3 , further comprising:

a plurality of antenna elements for receiving the radio signal; and

a switch for connecting one or more of the antenna elements to the receiver input in response to the digital signal quality metric.