Method and apparatus for estimating a channel parameter

A method of estimating radio channel parameters comprising the steps of:

• obtaining a sample of a radio signal;
• identifying a delay offset, carrier offset frequency, and coherent averaging length from the plurality of possible delay offsets, offset frequencies, and averaging lengths that yields an optimal sample energy metric for a channel propagation path of interest;
• and
• using the identified optimal delay offset, carrier frequency offset, and coherent averaging length to estimate various channel parameters for a channel propagation path of interest on one or more co-located antennas.

An apparatus for estimating a channel metric in a communication system, the communication providing communication services to at least one remote unit operating within the communication system via radio frequency communication signals, the apparatus comprising:

• a receiver arranged to receive radio frequency communication signals from the remote unit and to provide as an output a baseband signal;
• a memory buffer coupled to the receiver and sized to store a sample of the baseband signal;
• a channel circuit coupled to the receiver, the channel circuit operable on the baseband signal to provide decoded information bits;
• a remodulator coupled the channel circuit, the remodulator operable on the information bits to form a reference baseband signal;
• and
• a searcher coupled to the memory buffer and the remodulator, the searcher adapted to coherently average the baseband signal and the reference baseband signal over a plurality delay offsets, a plurality of correlation lengths and a plurality of carrier frequency offsets, and to determine an optimal correlation length.

A computer program embodied on a computer-readable medium for estimating a channel metric in a communication system comprising:

• a first routine that obtains a signal sample and stores the signal samples in a buffer;
• a second routing that sub-groups the signal sample into a plurality of sample sub-groups;
• a third routine that, for each of the sample sub-groups, coherently averages the sample sub-group over a plurality of sample lengths, a plurality of carrier frequency offsets, and a plurality of delay offsets;
• and
• a fourth routine that, for each sample sub-group, identifies a sample length, carrier frequency offset, and delay offset that yields an optimal channel parameter for that sample sub-group.