Frame synchronization using accumulated summation
A technique for synchronizing a device for communication is based on an accumulated sum of values or absolute values. The absolute value can be of either the sum or difference of a plurality of symbols. In one embodiment, the absolute values of the sum or difference of three symbol pairs are accumulated, and the accumulated total compared to a threshold value to determine whether the symbols are at the end of a predetermined sequence of symbols. When the comparison to the threshold value is positive, the three symbol pairs are the last six symbols in the predetermined sequence. In practice, the invention can be implemented in a number of different environments including, for example, in a WiMedia MBOA network environment. In the WiMedia MBOA environment, the predetermined sequence can comprise the preamble of a WiMedia MBOA packet.
1. A method of synchronization of performed by a network device, comprising:
obtaining a sequence of symbols transmitted according to a predetermined cover sequence, wherein a given symbol of the sequence of symbols comprises a number of samples and wherein the sequence of symbols comprises a sequence of samples;
determining an estimation metric, M sa , by comparing pairs of symbols from the sequence of symbols; and
comparing the estimation metric to a threshold value to determine frame synchronization;
wherein
M
sa
=
∑
l
=
0
l
max
∑
k
=
0
k
max
r
(
k
+
N
s
(
j
·
l
+
m
)
)
±
r
(
k
+
N
s
(
j
·
l
+
m
)
+
n
·
N
s
)
,
where r(i) is the ith sample, where l max is determined according to the number of symbol pairs compared, where k max is determined according the number of samples per symbol, where N s is the number of samples per symbol, and where j, m, and n are determined according to the predetermined cover sequence.
2. The method of claim 1 , wherein the steps of determining the estimation metric and comparing the estimation metric to the threshold value are repeated for sequential values of m; and further comprising transmitting a frame synchronization declaration if the estimation metric is less than the threshold value for a given value of m.
3. The method of claim 2 , wherein the sequence of symbols is further transmitted according to a predetermined frequency band hopping pattern; and wherein j or n is determined such that the symbols of a given compared pair of symbols are transmitted on the same frequency band.
4. The method of claim 2 , wherein n is determined according to the cover sequence such that, if the estimation metric is less than the threshold value, the symbols of at least a predetermined number of the l max compared pairs of symbols are transmitted with different phases.
5. The method of claim 2 , wherein k max comprises the number of samples per symbol excluding zero suffix samples.
6. The method of claim 5 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
l
+
m
)
)
±
r
(
k
+
N
s
(
l
+
m
)
+
3
N
s
)
,
and
m
=
0
,
3
,
6
,
9
,
12
,
15
,
18
,
21
7. The method of claim 5 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
2
l
+
m
)
)
±
r
(
k
+
N
s
(
2
l
+
m
)
+
N
s
)
,
and
m
=
0
,
6
,
12
,
18
8. The method of claim 5 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
l
+
m
)
)
±
r
(
k
+
N
s
(
l
+
m
)
+
3
N
s
)
,
and
m
=
0
,
1
,
2
,
…
9. The method of claim 1 , wherein the sequence of symbols is a preamble of a WiMedia MBOA packet.
10. The method of claim 1 , wherein the network device is WiMedia MBOA-compliant network device.
11. A network device, comprising:
a module configured to obtain a sequence of symbols transmitted according to a predetermined cover sequence, wherein a given symbol of the sequence of symbols comprises a number of samples and wherein the sequence of symbols comprises a sequence of samples;
a module configured to determine an estimation metric, M sa , by comparing pairs of symbols from the sequence of symbols; and
a module configured to compare the estimation metric to a threshold value to determine frame synchronization; wherein
M
sa
=
∑
l
=
0
l
max
∑
k
=
0
k
max
r
(
k
+
N
s
(
j
·
l
+
m
)
)
±
r
(
k
+
N
s
(
j
·
l
+
m
)
+
n
·
N
s
)
,
where r(i) is the ith sample, where l max is determined according to the number of symbol pairs compared, where k max is determined according the number of samples per symbol, where N s is the number of samples per symbol, and where j, m, and n are determined according to the predetermined cover sequence.
12. The network device of claim 11 , wherein the module configured to determine and the module configured to compare are configured to repeat the steps of determining the estimation metric and comparing the estimation metric to the threshold value for sequential values of m; and further comprising a module configured to transmit a frame synchronization declaration if the estimation metric is less than the threshold value for a given value of m.
13. The network device of claim 12 , wherein k max comprises the number of samples per symbol excluding zero suffix samples.
14. The network device of claim 12 , wherein the sequence of symbols is further transmitted according to a predetermined frequency band hopping pattern; and wherein j or n is determined such that the symbols of a given compared pair of symbols are transmitted on the same frequency band.
15. The network device of claim 12 , wherein n is determined according to the cover sequence such that, if the estimation metric is less than the threshold value, the symbols of at least a predetermined number of the l max compared pairs of symbols are transmitted with different phases.
16. The network device of claim 12 , wherein k max comprises the number of samples per symbol excluding zero suffix samples.
17. The network device of claim 16 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
l
+
m
)
)
±
r
(
k
+
N
s
(
l
+
m
)
+
3
N
s
)
,
and
m
=
0
,
3
,
6
,
9
,
12
,
15
,
18
,
21
18. The network device of claim 16 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
2
l
+
m
)
)
±
r
(
k
+
N
s
(
2
l
+
m
)
+
N
s
)
,
and
m
=
0
,
6
,
12
,
18
19. The network device of claim 16 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
l
+
m
)
)
±
r
(
k
+
N
s
(
l
+
m
)
+
3
N
s
)
,
and
m
=
0
,
1
,
2
,
…
20. The network device of claim 11 , wherein the sequence of symbols is a preamble of a WiMedia MBOA packet.
21. The network device of claim 11 , wherein the network device is WiMedia MBOA-compliant network device.
22. A storage media having computer readable program code embodied thereon, the computer readable program code configured to cause a network device to perform a method of synchronization of a network device, the method comprising:
obtaining a sequence of symbols transmitted according to a predetermined cover sequence, wherein a given symbol of the sequence of symbols comprises a number of samples and wherein the sequence of symbols comprises a sequence of samples;
determining an estimation metric, M sa , by comparing pairs of symbols from the sequence of symbols; and
comparing the estimation metric to a threshold value to determine frame synchronization;
wherein
M
sa
=
∑
l
=
0
l
max
∑
k
=
0
k
max
r
(
k
+
N
s
(
j
·
l
+
m
)
)
±
r
(
k
+
N
s
(
j
·
l
+
m
)
+
n
·
N
s
)
,
where r(i) is the ith sample, where l max is determined according to the number of symbol pairs compared, where k max is determined according the number of samples per symbol, where N s is the number of samples per symbol, and where j, m, and n are determined according to the predetermined cover sequence.
23. The storage media of claim 22 , wherein the steps of determining the estimation metric and comparing the estimation metric to the threshold value are repeated for sequential values of m; and further comprising transmitting a frame synchronization declaration if the estimation metric is less than the threshold value for a given value of m.
24. The storage media of claim 23 , wherein the sequence of symbols is further transmitted according to a predetermined frequency band hopping pattern; and wherein j or n is determined such that the symbols of a given compared pair of symbols are transmitted on the same frequency band.
25. The storage media of claim 23 , wherein n is determined according to the cover sequence such that, if the estimation metric is less than the threshold value, the symbols of at least a predetermined number of the l max compared pairs of symbols are transmitted with different phases.
26. The storage media of claim 23 , wherein k max comprises the number of samples per symbol excluding zero suffix samples.
27. The storage media of claim 26 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
l
+
m
)
)
±
r
(
k
+
N
s
(
l
+
m
)
+
3
N
s
)
,
and
m
=
0
,
3
,
6
,
9
,
12
,
15
,
1
8
,
21.
28. The storage media of claim 26 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
2
l
+
m
)
)
±
r
(
k
+
N
s
(
2
l
+
m
)
+
N
s
)
,
and
m
=
0
,
6
,
12
,
1
8.
29. The storage media of claim 26 , wherein
M
sa
=
∑
l
=
0
2
∑
k
=
0
127
r
(
k
+
N
s
(
l
+
m
)
)
±
r
(
k
+
N
s
(
l
+
m
)
+
3
N
s
)
,
and
m
=
0
,
1
,
2
,
…