High-frequency HomePNA
View Patent ↗A network device includes a HomePNA modem and means for synchronizing its clock with clocks of other HomePNA modems in the network in order to communicate at a higher frequency band. In one embodiment, the synchronization is with pilot signals. In another, it is by correcting for clock differences. The upconversions may be via oversampling or via analog mixing. The downconversions may be via subsampling or via analog demixing.
1. A carrier offset estimator to define an estimated offset η, the estimator comprising:
a Hilbert transform operator to transform at least received baseband signals of a periodic preamble; and
an optimizer to optimize a cost function CF(η) for offset η from an output y of said Hilbert transform operator and at least one function of y.
2. A carrier offset estimator to define an estimated offset η, wherein said estimator comprises:
a Hilbert transform operator to transform at least received baseband signals; and
an optimizer to optimize a cost function CF(η) for offset η from an output y of said Hilbert transform operator and at least one function of y, wherein said cost function CF(η) is:
CF
(
η
)
=
y
_
t
+
T
-
(
1
-
j2π
f
c
T
η
2
)
ⅇ
j2π
f
c
T
η
y
_
t
-
η
T
ⅇ
j2π
f
c
T
η
y
t
′
_
_
2
where vector y t+T is the output of said Hilbert transform operator, vector y t is a version of y t+T delayed by a preamble period T, vector y t ′ is a derivative of y t and the linear combination coefficients of said vectors are functions of offset η, said preamble period T and a nominal carrier frequency f c .