Method and apparatus for estimating a signal fading characteristic
AssigneeMotorola, Inc.
InventorsJohn D. Reed, Frank P. O'Neill, Benjamin T. The
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Abstract
A method and apparatus for measuring a characteristic of a fading signal received using a two or more branch diversity receiver is presented. This fading characteristic is generally proportional to the speed of the user. In a first embodiment the number of times the antenna branches change in a selection diversity process is counted, and the result is scaled for imbalance between the branches. The output of a fading quality estimator, indicative of the fading and generally proportional to the speed, is thereby obtained.
Claims19
A method of determining a characteristic of a fading signal in a communication unit having at least a first diversity branch including a first antenna and a second diversity branch including a second antenna, comprising the steps of:
- (a) determining a first signal quality measure of the fading signal received by the first antenna, a second signal quality measure of the fading signal received by the second antenna, and a count of times that the first signal quality measure becomes greater than the second signal quality measure and that the second signal quality measure becomes greater than the first signal quality measure;
- (b) determining, when the first and second branches are imbalanced, an imbalance measure between the first and second branches;
- and
- (c) determining the characteristic based on the count and, when the first and second branches are imbalanced, the imbalance measure.
A communications unit in a wireless communication system having at least a first branch including a first antenna and a second branch including a second antenna adapted for diversity reception of a signal, comprising:
- a diversity selection switch coupled to the first and second branches;
- a diversity selection counter coupled to the diversity selection switch adapted for counting a number of times the diversity selection switch switches between the first and second branches;
- a branch imbalance estimator, coupled to the first and second branches, adapted for determining an imbalance measure between the first and second branches;
- and
- a fading quality estimator coupled to the branch imbalance estimator adapted for estimating a fading quality measure of the signal, wherein the fading quality estimator is further adapted for estimating the fading quality measure based on the number of times the diversity selection switch switches and the imbalance measure in a predetermined interval.
A method of estimating a speed of a communication unit from a fading signal received by a diversity receiver having at least a first diversity branch including a first antenna and a second diversity branch including a second antenna, comprising the steps of:
- (a) determining a first signal quality measure of the fading signal received by the first antenna, a second signal quality measure of the fading signal received by the second antenna, and a count of times that the first signal quality measure becomes greater than the second signal quality measure and that the second signal quality measure becomes greater than the first signal quality measure;
- (b) determining, when the first and second branches are imbalanced, an imbalance measure between the first and second branches;
- and
- (c) estimating the speed based on the count and, when the first and second branches are imbalanced, the imbalance measure.
Dependencies are inferred from the claim text.