Method and system for synchronization in communication system
A method can be used for facilitating uplink synchronization between a first transceiver and a second transceiver within a cell in a multi-user cellular communication system. The first transceiver receives a signal for the uplink synchronization from the second transceiver. The signal includes a first signature sequence generated, at least in part, from a sequence with a zero-correlation zone. The first transceiver then performs a correlation of the signal for detection of the first signature sequence.
1. A method for facilitating an uplink synchronization between a first transceiver and a second transceiver within a cell in a multi-user cellular communication system, the method comprising:
receiving, by the first transceiver, a synchronization signal designated for the uplink synchronization, the synchronization signal being sent from the second transceiver over a random access channel, a first signature sequence being used in a preamble portion of the synchronization signal, and the first signature sequence being generated, at least in part, from a sequence with a zero-correlation zone, wherein the sequence with a zero-correlation zone is based on a Zadoff-Chu sequence, the Zadoff-Chu sequence being:
a
(
k
)
=
{
W
N
k
2
/
2
+
qk
,
N
even
W
N
k
(
k
+
1
)
/
2
+
qk
,
N
odd
,
k
=
0
,
1
,
…
,
N
-
1
,
where
W
N
=
exp
(
-
j2
π
r
/
N
)
,
where r, q and N are integers, and r is relatively prime to N; and
performing, by the first transceiver, a correlation of the synchronization signal, the correlation being designated for detection of the first signature sequence.
2. The method of claim 1 , wherein performing the correlation of the synchronization signal comprises correlating one or more predetermined number of delays of the synchronization signal with a second signature sequence.
3. The method of claim 1 , wherein the zero-correlation zone has a length that substantially corresponds to a maximum expected delay of a transmission from the second transceiver to the first transceiver.
4. The method of claim 1 , wherein performing the correlation of the synchronization signal comprises:
correlating one or more predetermined number of delays of the synchronization signal with a second signature sequence in the first transceiver by using a set of matched filters, and
detecting a peak output from the set of matched filters, wherein the peak is used for detection of the first signature sequence.
5. The method of claim 1 , wherein performing the correlation of the synchronization signal comprises:
correlating one or more predetermined number of delays of the synchronization signal with each signature sequence from a set of signature sequences in the first transceiver for calculating one or more amplitudes of aperiodic cross-correlation;
determining a delay corresponding to the maximum amplitude of the one or more amplitudes; and
estimating a time of arrival of the synchronization signal from the second transceiver to the first transceiver by using the delay.
6. The method of claim 1 , further comprising transmitting a reference to the second transceiver, wherein the reference is used by the second transceiver to generate a set of signature sequences comprising the first signature sequence.
7. The method of claim 1 , wherein a downlink synchronization between the first transceiver and the second transceiver is performed prior to the uplink synchronization.
8. The method of claim 1 , further comprising:
estimating, by the first transceiver, a time of arrival of the synchronization signal from the second transceiver to the first transceiver based on the correlation; and
transmitting, by the first transceiver, a command to the second transceiver, wherein the command is based on the time of arrival, and the command being used for adjusting a transmission timing of the second transceiver.
9. The method of claim 1 , wherein the length of the zero-correlation zone being capable of being adapted to the size of the cell.
10. The method of claim 2 , wherein the first signature sequence and the second signature sequence are the same signature sequence.
11. The method of claim 3 , wherein a cell size is used to determine the maximum expected delay.
12. An apparatus, comprising:
a transceiver, configured to receive a synchronization signal being sent from a second transceiver over a random access channel, wherein the synchronization signal is designated for a uplink synchronization between the second transceiver and the apparatus within a cell in a multi-user cellular communication system, a first signature sequence being used in a preamble portion of the synchronization signal, and the first signature sequence being generated, at least in part, from a sequence with a zero-correlation zone, wherein the sequence with a zero-correlation zone is based on a Zadoff-Chu sequence, the Zadoff-Chu sequence being:
a
(
k
)
=
{
W
N
k
2
/
2
+
qk
,
N
even
W
N
k
(
k
+
1
)
/
2
+
qk
,
N
odd
,
k
=
0
,
1
,
…
,
N
-
1
,
where
W
N
=
exp
(
-
j2
π
r
/
N
)
,
where r, q and N are integers, and r is relatively prime to N; and
a processor, configured to perform a correlation of the synchronization signal, the correlation being designated for detection of the first signature sequence.
13. The apparatus of claim 12 , wherein the correlation of the synchronization signal comprises a correlation of one or more predetermined number of delays of the synchronization signal with a second signature sequence.
14. The apparatus of claim 12 , wherein the zero-correlation zone has a length that substantially corresponds to a maximum expected delay of a transmission from the second transceiver to the apparatus.
15. The apparatus of claim 12 , wherein the correlation of the synchronization signal comprises:
a correlation of one or more predetermined number of delays of the synchronization signal with a second signature sequence in the apparatus by using a set of matched filters, and
a detection of a peak output from the set of matched filters, wherein the peak is used for detection of the first signature sequence.
16. The apparatus of claim 12 , wherein the correlation of the synchronization signal comprises:
a correlation of one or more predetermined number of delays of the synchronization signal with each signature sequence from a set of signature sequences in the apparatus for calculating one or more amplitudes of aperiodic cross-correlation; and
a determination of a delay corresponding to the maximum amplitude of the one or more amplitudes, wherein the delay is used for an estimation of a time of arrival of the synchronization signal from the second transceiver to the apparatus.
17. The apparatus of claim 12 , wherein the transceiver is further configured to transmit a reference to the second transceiver, the reference being used by the second transceiver to generate a set of signature sequences comprising the first signature sequence.
18. The apparatus of claim 12 , wherein a downlink synchronization between the apparatus and the second transceiver is performed prior to the uplink synchronization.
19. The apparatus of claim 12 , wherein the correlation is used for estimating a time of arrival of the synchronization signal from the second transceiver to the apparatus.
20. The apparatus of claim 12 , wherein the length of the zero-correlation zone being capable of being adapted to the size of the cell.
21. The apparatus of claim 13 , wherein the first signature sequence and the second signature sequence are the same signature sequence.
22. The apparatus of claim 14 , wherein a cell size is used to determine the maximum expected delay.
23. The apparatus of claim 19 , wherein the transceiver is further configured to transmit a command to the second transceiver, the command being based on the time of arrival, and the command being used for adjusting a transmission timing of the second transceiver.
24. An apparatus, comprising:
a processor, configured to generate a first signature sequence, at least in part, from a sequence with a zero-correlation zone, wherein the sequence with a zero-correlation zone is based on a Zadoff-Chu sequence, the Zadoff-Chu sequence being:
a
(
k
)
=
{
W
N
k
2
/
2
+
qk
,
N
even
W
N
k
(
k
+
1
)
/
2
+
qk
,
N
odd
,
k
=
0
,
1
,
…
,
N
-
1
,
where
W
N
=
exp
(
-
j2
π
r
/
N
)
,
where r, q and N are integers, and r is relatively prime to N; and
a transceiver, configured to transmit a synchronization signal to a receiver over a random access channel, the first signature sequence being used in a preamble portion of the synchronization signal, and the synchronization signal being designated for an uplink synchronization between the apparatus and the receiver within a cell in a multi-user cellular communication system.
25. The apparatus of claim 24 , wherein the transceiver is further configured to receive a command from the receiver, the command corresponding to a time of arrival of the synchronization signal from the apparatus to the receiver, and the command being used for adjusting a transmission timing of the apparatus.
26. The apparatus of claim 24 , wherein the length of the zero-correlation zone being capable of being adapted to the size of the cell.
27. A communication system, comprising a first apparatus in communication with a second apparatus via a cell of the communication system, wherein the first apparatus comprising:
a transceiver, configured to receive a synchronization signal being sent from the second apparatus over a random access channel, the signal being designated for an uplink synchronization between the first apparatus and the second apparatus, a first signature sequence being used in a preamble portion of the synchronization signal, and the first signature sequence being generated, at least in part, from a sequence with a zero-correlation zone, wherein the sequence with a zero-correlation zone is based on a Zadoff-Chu sequence, the Zadoff-Chu sequence being:
a
(
k
)
=
{
W
N
k
2
/
2
+
qk
,
N
even
W
N
k
(
k
+
1
)
/
2
+
qk
,
N
odd
,
k
=
0
,
1
,
…
,
N
-
1
,
where
W
N
=
exp
(
-
j2
π
r
/
N
)
,
where r, q and N are integers, and r is relatively prime to N; and
a processor, configured to perform a correlation of the synchronization signal, the correlation being designated for detection of the first signature sequence.
28. The communication system of claim 27 , wherein the length of the zero-correlation zone being capable of being adapted to the size of the cell.
29. A communication system, comprising a first apparatus in communication with a second apparatus via a cell of the communication system, wherein the first apparatus comprises:
a processor, configured to generate a first signature sequence, at least in part, from a sequence with a zero-correlation zone, wherein the first signature sequence is used in a preamble portion of a synchronization signal, and the sequence with a zero-correlation zone is based on a Zadoff-Chu sequence, the Zadoff-Chu sequence being:
a
(
k
)
=
{
W
N
k
2
/
2
+
qk
,
N
even
W
N
k
(
k
+
1
)
/
2
+
qk
,
N
odd
,
k
=
0
,
1
,
…
,
N
-
1
,
where
W
N
=
exp
(
-
j2
π
r
/
N
)
,
where r, q and N are integers, and r is relatively prime to N; and
a transceiver, configured to transmit the synchronization signal to the second apparatus over a random access channel, wherein the signal comprises the first signature sequence, and the signal is used for a uplink synchronization between the first apparatus and the second apparatus.
30. The communication system of claim 29 , wherein the length of the zero-correlation zone being capable of being adapted to the size of the cell.