Method and system for initial signal acquisition in multipath fading channel conditions
An apparatus and method for performing initial signal acquisition in a receiver of a millimeter wave wireless communication system. The apparatus comprises receiving a millimeter-wave signal including complementary sequences at the receiver; cross-correlating the received signal related to the received complementary sequences with respective predefined complementary sequences, wherein the received complementary sequences include a first type of complementary sequences and a second type of complementary sequences; performing a signal sequence detection by auto-correlating the cross-correlated first type of complementary sequences and comparing the auto-correlated results to an energy dependent threshold; and upon detection of the signal sequence, performing a timing synchronization to synchronize a start frame delimiter (SFD), wherein the timing synchronization includes in part a search for a peak in the cross-correlated first type of complementary sequences using a SFD search threshold.
1. A method for performing signal acquisition by an apparatus in a wireless communication system, comprising:
receiving a wireless signal comprising complementary sequences;
cross-correlating the received complementary sequences with respective complementary sequences, wherein the received complementary sequences comprise a first type of complementary sequences and a second type of complementary sequences;
performing a signal sequence detection by auto-correlating the cross-correlated first type of complementary sequences and comparing the auto-correlated results of the auto-correlating to an energy dependent threshold; and
upon detection of the signal sequence, performing a timing synchronization to synchronize a start frame delimiter (SFD) of the received signal, wherein performing the timing synchronization comprises:
searching for a peak in the cross-correlated first type of complementary sequences;
upon identifying a peak sample in the cross-correlated first type of complementary sequences, setting a SFD search threshold relative to an absolute value of the peak sample; and
searching the cross-correlated second type of complementary sequences for a peak exceeding the SFD search threshold, wherein the searching the cross-correlated second type of complementary sequences for the peak exceeding the SFD search threshold is performed for a duration of a search window at different intervals.
2. The method of claim 1 , wherein the received complementary sequences are Golay complementary sequences, wherein the first type is Golay-128 sequences and the second type is Golay-512 sequences.
3. The method of claim 1 , wherein the received complementary sequences are within a preamble of the received signal, and wherein the preamble is defined in an IEEE 802.11ad standard.
4. The method of claim 1 , wherein performing the signal sequence detection further comprises:
applying an averaging window on the auto-correlating results, wherein a size of the averaging window determines a sensitivity of the signal sequence detection.
5. The method of claim 4 , wherein the averaging window is applied only on peak segments of the cross-correlated first type of complementary sequences.
6. The method of claim 1 , wherein the energy dependent threshold is a function of energy of the received wireless signal and a signal detection sensitivity associated with the apparatus.
7. The method of claim 1 , wherein detection of the signal sequence occurs when a sum of the auto-correlating results exceeds the energy dependent threshold.
8. A wireless device, comprising:
at least one antenna; and
a receiver configured to:
receive, via the at least one antenna, a wireless signal, wherein the wireless signal comprises a plurality of complementary sequences;
cross-correlate the received complementary sequences with respective complementary sequences, wherein the received complementary sequences comprise a first type of complementary sequences and a second type of complementary sequences;
perform a signal sequence detection by auto-correlating the cross-correlated first type of complementary sequences and comparing results of the auto-correlating to an energy dependent threshold; and
upon detecting the signal sequence, perform a timing synchronization to synchronize a start frame delimiter (SFD) of the received signal, wherein performing the timing synchronization comprises:
searching for a peak in the cross-correlated first type of complementary sequences;
upon identifying a peak sample in the cross-correlated first type of complementary sequences, setting a SFD search threshold relative to an absolute value of the peak sample; and
searching the cross-correlated second type of complementary sequences for a peak exceeding the SFD search threshold, wherein the searching the cross-correlated second type of complementary sequences for the peak exceeding the SFD search threshold is performed for a duration of a search window at different intervals.
9. An apparatus for performing signal acquisition in a wireless communication system, comprising:
a radio frequency (RF) circuit configured to receive a wireless signal comprising complementary sequences;
a cross-correlator circuit configured to cross-correlate the received complementary sequences with respective complementary sequences, wherein the received complementary sequences comprise a first type of complementary sequences and a second type of complementary sequences;
a signal sequence detection circuit configured to detect a signal sequence in the received signal, wherein the signal sequence detection circuit is configured to auto-correlate the cross-correlated first type of complementary sequences and compare results of the auto-correlating to an energy dependent threshold; and
a timing synchronization circuit configured to perform a timing synchronization to synchronize a start frame delimiter (SFD) of the received signal, wherein performing the timing synchronization comprises:
searching for a peak in the cross-correlated first type of complementary sequences;
upon identifying a peak sample in the cross-correlated first type of complementary sequences, setting a SFD search threshold relative to an absolute value of the peak sample; and
searching the cross-correlated second type of complementary sequences for a peak exceeding the SFD search threshold, wherein the searching the cross-correlated second type of complementary sequences for the peak exceeding the SFD search threshold is performed for a duration of a search window at different intervals.
10. The apparatus of claim 9 , wherein the received complementary sequences are Golay complementary sequences, wherein the first type is Golay-128 sequences and the second type is Golay-512 sequences.
11. The apparatus of claim 9 , wherein the received complementary sequences are within a preamble of the received signal, and wherein the preamble is defined in an IEEE 802.11ad standard.
12. The apparatus of claim 9 , wherein the signal sequence detection circuit is further configured to:
apply an averaging window on the auto-correlating results, wherein a size of the averaging window determines a sensitivity of the signal sequence detection.
13. The apparatus of claim 12 , wherein the averaging window is applied only on peak segments of the cross-correlated first type of complementary sequences.
14. The apparatus of claim 9 , wherein the energy dependent threshold is a function of energy of the received wireless signal and a signal detection sensitivity associated with the apparatus.
15. The apparatus of claim 9 , wherein detection of the signal sequence occurs when a sum of the auto-correlating results exceeds the energy dependent threshold.
16. The apparatus of claim 9 , wherein the timing synchronization circuit is activated upon detection of the signal sequence.