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 network device comprising:
a modem to generate HomePNA signals;
transmission means for transmitting said HomePNA signals at shifted baseband frequencies; and
reception means to downconvert signals transmitted from a transmission means of another network device, wherein said reception means comprises an analog demixer.
2. The network device according to claim 1 and wherein said transmission means comprises an analog mixer.
3. The network device according to claim 2 and also comprising a pilot tracking unit providing a carrier signal to said analog mixer.
4. The network device according to claim 2 and also comprising a local clock providing a carrier signal to said analog mixer.
5. The network device according to claim 1 and wherein said transmission means comprises an oversampler.
6. The network device according to claim 5 and wherein said oversampler comprises a digital interpolator to increase a sampling frequency of said HomePNA signals, a digital-to-analog converter to convert an output of said digital interpolator to an analog signal and an upband pass filter to significantly attenuate signals not within said non-baseband frequencies.
7. The network device according to claim 5 and also comprising a pilot tracking unit providing a clock signal to said oversampler.
8. The network device according to claim 5 and also comprising a local clock providing a clock signal to said oversampler.
9. The network device according to claim 1 and also comprising a pilot tracking unit providing a carrier signal to said analog demixer.
10. The network device according to claim 1 and also comprising a local clock providing a carrier signal to said analog demixer and a digital clock compensator using said local clock to compensate for a difference in clock frequency of said local clock and of a local clock which generated said transmitted signals.
11. The network device according to claim 1 and wherein said reception means comprises a subsampler.
12. The network device according to claim 11 and wherein said subsampler comprises an upband pass filter to significantly attenuate signals not within said upband frequencies and an analog-to-digital converter forming part of said reception means and sampling at an operating clock frequency of said reception means.
13. The network device according to claim 11 and also comprising a pilot tracking unit providing a clock signal to said subsampler.
14. The network device according to claim 11 and also comprising a local clock providing a clock signal to said subsampler and a digital clock compensator using said local clock to compensate for a difference in clock frequency of said local clock and of a local clock which generated said transmitted signals.
15. The network device according to claim 10 and wherein said digital clock compensator comprises:
a phasor generator to generate a phasor from an estimated carrier offset {circumflex over (η)}; and
a mixer to mix a baseband signal with said phasor.
16. The network device according to claim 15 and also comprising an offset estimator to determine said estimated carrier offset {circumflex over (η)}.
17. The network device according to claim 16 and wherein said offset estimator comprises a Hilbert transform operator to transform at least received baseband signals.
18. The network device according to claim 16 and wherein said offset estimator comprises an optimizer to optimize a cost function CF(η) of a Hilbert transform y and of at least one function of Hilbert transform y .
19. The network device according to claim 18 and wherein said cost function CF(η) is:
CF
(
η
)
=
y
_
t
+
T
-
(
1
-
j
2
π
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 .
20. The network device according to claim 1 and wherein said non-baseband frequencies are in a frequency range and wherein said frequency range is one of the following ranges: 8-24 MHz, 12-28 MHz, 36-52 MHz, 40-56 MHz and 44-60 MHz.
21. The network device according to claim 1 and wherein said non-baseband frequencies are in a frequency range and wherein said frequency range is selectable.
22. A network device comprising:
a HomePNA modem; and
means for synchronizing a clock of said HomePNA modem with clocks of other HomePNA modems in a network, in order to communicate with HomePNA signals at a shifted baseband_frequency, wherein said means for synchronizing comprises a digital clock compensator.
23. The network device according to claim 22 and wherein said means for synchronizing comprises a phase locked loop.
24. The network device according to claim 22 and wherein said digital clock compensator comprises:
a phasor generator to generate a phasor from an estimated carrier offset {circumflex over (η)}; and
a mixer to mix a baseband signal with said phasor.
25. The network device according to claim 24 and also comprising an offset estimator to determine said estimated carrier offset {circumflex over (η)}.
26. The network device according to claim 25 and wherein said offset estimator comprises a Hilbert transform operator to transform at least received baseband signals.
27. The network device according to claim 25 and wherein said offset estimator comprises an optimizer to optimize a cost function CF(η) of a Hilbert transform y and of at least one function of Hilbert transform y .
28. The network device according to claim 27 and wherein said cost function CF(η) is:
CF
(
η
)
=
y
_
t
+
T
-
(
1
-
j
2
π
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 .
29. The network device according to claim 22 and wherein said shifted basband_frequencies are in a frequency range and wherein said frequency range is one of the following ranges: 8-24 MHz, 12-28 MHz, 36-52 MHz, 40-56 MHz and 44-60 MHz.
30. The network device according to claim 22 and wherein said shifted basband frequencies are in a frequency range and wherein said frequency range is selectable.