Method and apparatus for packet acquisition
Certain aspects of the present disclosure relate to a method for acquisition of a received spread spectrum signal transmitted over a wired or wireless medium.
1. A method for acquiring a received signal comprising a spread sync field, the method comprising:
correlating the received signal to produce a filtered signal;
performing differential detection of the filtered signal to produce detector outputs; and
accumulating the detector outputs; and
deriving a frequency offset estimate from an angle of a complex value of one of the accumulated detector outputs having a maximum magnitude at a timing estimate derived based on a storage location of the one of the accumulated detector outputs.
2. The method of claim 1 , wherein correlating comprises employing a function selected from the group consisting of an efficient serial Golay correlation, an efficient parallel Golay correlation, an efficient generalized serial Golay correlation, and an efficient generalized parallel Golay correlation.
3. The method of claim 1 , wherein the sync field comprises a sequence selected from the group consisting of a sequence of ones spread with a spreading sequence, and a sequence of alternating ones and minus-ones spread with a spreading sequence.
4. The method of claim 3 , wherein the spreading sequence comprises a sequence selected from the group consisting of a Golay sequence and a generalized Golay sequence.
5. An apparatus for acquiring a received signal comprising a spread sync field, the apparatus comprising:
a correlator configured to filter the received signal to produce a filtered signal;
a differential detector configured to perform differential detection of the filtered signal to produce detector outputs; and
an accumulator configured to accumulate outputs of the differential detector;
a memory component configured to store the accumulated detector outputs; and
a frequency offset estimator configured to estimate a frequency offset from an angle of a complex value of at least one of the accumulated detector outputs having a maximum magnitude at a timing estimate derived based on a location in the memory component of at least one of the at least one of the accumulated detector outputs.
6. The apparatus of claim 5 , wherein the correlator comprises a correlator selected from the group consisting of an efficient serial Golay correlator, an efficient parallel Golay correlator, an efficient generalized serial Golay correlator, and an efficient generalized parallel Golay correlator.
7. The apparatus of claim 5 , wherein the sync field comprises a sequence selected from the group consisting of a sequence of ones spread with a spreading sequence, and a sequence of alternating ones and minus-ones spread with a spreading sequence.
8. The apparatus of claim 7 , wherein the spreading sequence comprises a sequence selected from the group consisting of a Golay sequence and a generalized Golay sequence.
9. The apparatus of claim 5 , wherein the correlator comprises a matched filter and a mismatched filter.
10. The apparatus of claim 5 , wherein the accumulator comprises an Infinite Impulse Response filter.
11. A non-transitory machine-readable medium having encoded thereon instructions executable to:
correlate the received signal to produce a filtered signal;
perform differential detection of the filtered signal to produce detector outputs; and
accumulate the detector outputs; and
derive a frequency offset estimate from an angle of a complex value of one of the accumulated detector outputs having a maximum magnitude at a timing estimate derived based on a storage location of the one of the accumulated detector outputs.