Synchronization signal optimizations for symbol index detection
Methods, systems, and devices for wireless communication are described. Some examples provide for identifying a primary synchronization signal (PSS) sequence of a synchronization subframe, determining, for the synchronization subframe, an extended synchronization signal (ESS) sequence based at least in part on the PSS sequence and transmitting the synchronization subframe. Other examples provide for generating an ESS sequence for a synchronization subframe to be communicated to a UE, scrambling the ESS sequence based at least in part on cell-specific information associated with the base station and transmitting, to the UE, the scrambled ESS sequence in the synchronization subframe.
1. A method of wireless communication comprising:
receiving, from a base station, an extended synchronization signal sequence for a physical broadcast channel in a synchronization subframe;
receiving cell-specific information associated with the base station;
identifying a pseudo-random sequence based at least in part on the cell-specific information; and
descrambling the extended synchronization signal sequence based at least in part on the pseudo-random sequence and a length associated with the extended synchronization signal sequence.
2. The method of claim 1 , further comprising:
identifying a symbol index of the synchronization subframe based at least in part on the descrambling.
3. The method of claim 1 , further comprising:
verifying cell-specific information associated with the base station based at least in part on the descrambling.
4. The method of claim 1 , wherein the extended synchronization signal sequence is descrambled based at least in part on a sequence
r
(
n
)
=
1
2
(
1
-
2
·
c
(
2
n
)
)
+
j
1
2
(
1
-
2
·
c
(
2
n
+
1
)
)
,
n
=
0
,
1
,
…
,
N
-
1
wherein N represents a length associated with the extended synchronization signal sequence and (c(i), i =0, . . . , 2N+1) represents the identified pseudo-random sequence.
5. The method of claim 1 , wherein the extended synchronization signal sequence is descrambled based at least in part on the synchronization subframe.
6. The method of claim 5 , further comprising:
identifying a synchronization subframe number of the synchronization subframe based at least in part on the descrambling.
7. The method of claim 1 , further comprising:
identifying a subframe index value for the first synchronization subframe based at least in part on the descrambling.
8. The method of claim 1 , wherein the cell-specific information comprises a cell identifier or virtual cell identifier of the base station.
9. The method of claim 1 , further comprising:
receiving, from a second base station, a second scrambled extended synchronization signal sequence; and
determining that an attempt to descramble the second scrambled extended synchronization signal sequence has failed based at least in part on the cell-specific information.
10. The method of claim 1 , further comprising:
decoding a physical broadcast channel message based at least in part on the descrambling.
11. An apparatus for wireless communication comprising:
a processor,
memory in electronic communication with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
receive, from a base station, an extended synchronization signal sequence for a physical broadcast channel in a synchronization subframe;
receive cell-specific information associated with the base station;
identify a pseudo-random sequence based at least in part on the cell-specific information; and
descramble the extended synchronization signal sequence based at least in part on the pseudo-random sequence and a length associated with the extended synchronization signal sequence.
12. The apparatus of claim 11 , wherein the instructions are further executable by the processor to cause the apparatus to:
identify a symbol index of the synchronization subframe based at least in part on the descrambling.
13. The apparatus of claim 11 , wherein the instructions are further executable by the processor to cause the apparatus to:
verify cell-specific information associated with the base station based at least in part on the descrambling.
14. The apparatus of claim 11 , wherein the extended synchronization signal sequence is descrambled based at least in part on a sequence
r
(
n
)
=
1
2
(
1
-
2
·
c
(
2
n
)
)
+
j
1
2
(
1
-
2
·
c
(
2
n
+
1
)
)
,
n
=
0
,
1
,
…
,
N
-
1
wherein N represents a length associated with the extended synchronization signal sequence and (c(i), i =0, . . . , 2N+1) represents the identified pseudo-random sequence.
15. The apparatus of claim 11 , wherein the extended synchronization signal sequence is descrambled based at least in part on the synchronization subframe.
16. The apparatus of claim 15 , wherein the instructions are further executable by the processor to cause the apparatus to:
identify a synchronization subframe number of the synchronization subframe based at least in part on the descrambling.
17. The apparatus of claim 11 , wherein the instructions are further executable by the processor to cause the apparatus to:
identify a subframe index value for the first synchronization subframe based at least in part on the descrambling.
18. The apparatus of claim 11 , wherein the cell-specific information comprises a cell identifier or virtual cell identifier of the base station.
19. The apparatus of claim 11 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive, from a second base station, a second scrambled extended synchronization signal sequence; and
determine that an attempt to descramble the second scrambled extended synchronization signal sequence has failed based at least in part on the cell-specific information.
20. The apparatus of claim 11 , wherein the instructions are further executable by the processor to cause the apparatus to:
decode a physical broadcast channel message based at least in part on the descrambling.
21. A non-transitory computer-readable medium storing code, the code comprising instructions executable by a processor to:
receive, from a base station, an extended synchronization signal sequence for a physical broadcast channel in a synchronization subframe;
receive cell-specific information associated with the base station;
identify a pseudo-random sequence based at least in part on the cell-specific information; and
descramble the extended synchronization signal sequence based at least in part on the pseudo-random sequence and a length associated with the extended synchronization signal sequence.