Method and system for using sign based synchronization sequences in a correlation process to reduce correlation complexity in an OFDM system
A mobile device receives a signal, from a base station, comprising a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The received PSS and SSS are used to acquire cell-specific parameters so as to ensure communicates between the mobile device and the base station. The mobile device correlates the received signal in time domain using signs of each of a plurality of correlation reference sequences (reference PSSs). The mobile device generates sign based correlation reference PSSs using signs of the corresponding reference PSSs, which are generated based on a variety of Zadoff-Chu sequences. The received PSS is detected based on the correlation. No multiplication operations are used in the correlation process. Symbol timing is identified according to the detected PSS. The mobile device uses the identified symbol timing to baseband process the received signal. The received signal is an OFDM signal received over a 3GPP LTE/E-UTRA air interface.
1. A method of synchronizing with a base station by a mobile device, comprising:
generating a sign-based first complex correlation reference sequence from a second complex correlation reference sequence, each of the sign-based first complex correlation reference sequence and the second complex correlation reference sequence including a plurality of complex coefficients that each have a real component and an imaginary component, the generating the sign-based first complex correlation reference sequence including:
for components of the second complex correlation reference sequence having a positive value assigning a first value to corresponding components in the sign-based first complex correlation reference sequence; and
for components of the second complex correlation reference sequence having a negative value, assigning a second value to corresponding components in the sign-based first complex correlation reference sequence;
receiving a signal from the base station that includes a Primary Synchronization Signal (PSS); and
correlating the PSS of the received signal with the sign-based first complex correlation reference sequence,
wherein at least one of the above steps is performed by a processor.
2. The method of claim 1 , wherein results of the correlation include a plurality of peaks.
3. The method of claim 2 , further comprising identifying a starting position of the PSS based on a position of a peak having a largest peak magnitude from among the plurality of peaks.
4. The method of claim 2 , further comprising identifying symbol timing of a cell corresponding to the base station based on a position of a peak having a largest peak magnitude from among the plurality of peaks.
5. The method of claim 1 , wherein the generating of the sign-based first complex correlation reference sequence includes generating the second complex correlation reference sequence.
6. The method of claim 5 , wherein the generating of the sign-based first complex correlation reference sequence further includes generating a sequence of complex numbers, from the second complex correlation reference sequence, the real components of the sign-based first complex correlation reference sequence representing only signs of the real components of the second complex correlation reference sequence, and the imaginary components of the sign-based first complex correlation reference sequence representing only signs of the imaginary components of the second complex correlation reference sequence.
7. The method of claim 5 , wherein the generating of the sign-based first complex correlation reference sequence further includes generating a sequence of complex numbers that corresponds to the plurality of complex coefficients of the second complex correlation reference sequence,
wherein, for each positively-valued real component of the second complex correlation reference sequence, setting a value of a corresponding real component of the sign-based first complex correlation reference sequence to +1,
wherein, for each negatively-valued real component of the second complex correlation reference sequence, setting a value of a corresponding real component of the sign-based first complex correlation reference sequence to −1,
wherein, for each positively-valued imaginary component of the second complex correlation reference sequence, setting a value of a corresponding imaginary component of the sign-based first complex correlation reference sequence to +1, and
wherein, for each negatively-valued imaginary component of the second, complex correlation reference sequence, setting a value of a corresponding imaginary component of the sign-based first complex correlation reference sequence to −1.
8. The method according to claim 5 , wherein the second complex correlation reference sequence is generated based on at least one Zadoff-Chu sequence.
9. The method according to claim 1 , wherein the correlation is a real summation process.
10. The method according to claim 1 ,
wherein each of the complex coefficients of the sign-based first complex correlation reference sequence are digitally represented by a single bit.
11. A method of synchronizing with a base station by a mobile device, comprising:
generating a complex correlation reference sequence that includes a plurality of complex correlation coefficients, each of the complex correlation coefficients including a real component and an imaginary component;
receiving a signal from the base station that includes a Primary Synchronization Signal (PSS); and
correlating the PSS of the received signal with a sequence of complex sign coefficients, the sequence of complex sign coefficients including a plurality of complex numbers that each include a real component and an imaginary component, the components having a first value when a corresponding component in the complex correlation reference sequence has a positive value and having a second value when a corresponding component in the complex correlation reference sequence has a negative value,
wherein at least one of the above steps is performed by a processor.
12. The method of claim 11 , wherein the correlation is a real summation process.
13. The method of claim 11 , wherein each of the components of the sequence of complex sign coefficients are digitally represented by a corresponding single bit during the correlation.
14. The method of claim 11 , wherein the complex correlation reference sequence is generated based on at least one Zadoff-Chu sequence.
15. A wireless communication device, comprising:
a sequence generator configured to generate a sign-based first complex correlation reference sequence that includes a plurality of sign-based complex coefficients that each include a real component and an imaginary component, from a second complex correlation reference sequence, the components of the sign-based first complex correlation reference sequence having a first value for corresponding positively-valued components of the second complex correlation reference sequence and having a second value for corresponding negatively-valued components of the second complex correlation reference sequence;
a receiver configured to receive a signal from the base station that includes a Primary Synchronization Signal (PSS); and
a correlator configured to correlate the PSS of the received signal with the sign-based first complex correlation reference sequence.
16. The wireless communication device of claim 15 , wherein the sequence generator is configured to generate the sign-based first complex correlation reference sequence by generating the second complex correlation reference sequence, and
wherein the second complex correlation reference sequence includes complex coefficients that are each represented by a complex number, each complex number having a real component and an imaginary component.
17. The wireless communication device of claim 16 , wherein the sequence generator is configured to generate the sign-based first complex correlation reference sequence by generating a sequence of complex numbers from the second complex correlation reference sequence, the real components of the first complex correlation reference sequence representing only signs of the real components of the real components of the complex coefficients of the second complex correlation reference sequence, and the imaginary components of the first complex correlation reference sequence representing only signs of the imaginary components of the complex coefficients of the second complex coefficient correlation reference sequence.
18. The wireless communication device of claims 16 , wherein the sequence generator is configured to generate the sign-based first complex correlation reference sequence by generating a sequence of complex numbers that corresponds to the plurality of complex coefficients of the second complex correlation reference sequence,
wherein, for each positively-valued real component of the second complex correlation reference sequence, the sequence generator is configured to set a value of a corresponding real component of the sign-based first complex correlation reference sequence to +1,
wherein, for each negatively-valued real component of the second complex correlation reference sequence, the sequence generator is configured to set a value of a corresponding real component of the sign-based first complex correlation reference sequence to −1,
wherein, for each positively-valued valued imaginary component of the second complex correlation reference sequence, the sequence generator is configured to set a value of a corresponding imaginary component of the sign-based first complex correlation reference sequence to +1, and
wherein, for each negatively-valued imaginary component of the second complex correlation reference sequence, the sequence generator is configured to set a value of a corresponding imaginary component of the sign-based first complex correlation reference sequence to −1.
19. The wireless communication device according to claim 15 , wherein the correlation is a real summation process.
20. The wireless communication device according to claim 15 , wherein each of the correlation coefficients are digitally represented by a single bit.
21. A method of synchronizing with a base station by a mobile device, comprising:
generating a sign-based first complex correlation reference sequence corresponding to signs of a second complex correlation reference sequence;
receiving a signal from the base station that includes a Primary Synchronization Signal (PSS); and
correlating the PSS of the received signal with the sign-based first complex correlation reference sequence,
wherein at least one of the above steps is performed by a processor,
wherein the generating of the sign-based first complex correlation reference sequence further includes generating a sequence of complex numbers that corresponds to a plurality of complex coefficients of the second complex correlation reference sequence,
wherein the generating further includes, for each positively-valued real component of the second complex correlation reference sequence, setting a value of a corresponding real component of the sign-based first complex correlation reference sequence to +1, and
wherein the generating further includes, for each negatively-valued real component of the second complex correlation reference sequence, setting a value of a corresponding real component of the sign-based first complex correlation reference sequence to −1.
22. The method of claim 21 , wherein the generating further includes, for each positively-valued imaginary component of the second complex correlation reference sequence, setting a value of a corresponding imaginary component of the sign-based first complex correlation reference sequence to +1, and
wherein the generating further includes, for each negatively-valued imaginary component of the second complex correlation reference sequence, setting a value of a corresponding imaginary component of the sign-based first complex correlation reference sequence to −1.