Synchronization scheme with adaptive reference frequency correction
View Patent ↗The present invention relates to an apparatus and method for providing synchronization of an output signal to a synchronization information. The synchronization is accomplished by providing coupling of a correction control information that controls a signal generating means, e.g. a phase locked loop arrangement ( 30 ) or a direct digital synthesis arrangement, to its exact frequency to a frequency conversion unit ( 90 ) that converts an uncorrected reference frequency to a correct or exact reference frequency. Thereby, the uncorrected reference frequency for the signal generating means ( 30 ) can be provided by a simple crystal oscillator ( 2 ) without any means for frequency control. The setting of the signal generating means ( 30 ) and the frequency conversion unit ( 90 ) can be done in a predetermined sequence which enables a user equipment to synchronize its reference frequency to the synchronization information emitted by a communication network.
1. A synchronization apparatus for providing synchronization of an output signal to a synchronization information, said apparatus comprising:
a) frequency conversion means for converting a reference frequency into a corrected reference frequency, said reference frequency being used for processing said synchronization information; and
b) control means for generating a correction control information based on a determined synchronization error of said synchronization apparatus with respect to said synchronization information,
c) wherein said control means is arranged to supply said correction control information to said frequency conversion means to correct said reference frequency based on said correction control information.
2. An apparatus according to claim 1 , wherein said synchronization error is determined based on a synchronization error between said output signal and said synchronization information.
3. An apparatus according to claim 1 , wherein said synchronization error is determined based on synchronization error between said reference frequency and said synchronization information.
4. An apparatus according to claim 1 , further comprising signal generating means to which said reference frequency is supplied for generating a conversion signal, wherein said synchronization error is determined based on a synchronization error between said conversion signal and said synchronization information.
5. An apparatus according to claim 4 , wherein said signal generating means is programmed with a channel control information in order to set a predetermined nominal division ratio and wherein said correction control information is supplied to said signal generating means so as to set a frequency correction division ratio for said signal generating means.
6. An apparatus according to claim 4 , wherein said signal generating means comprises a phase locked loop arrangement or a direct digital synthesis arrangement.
7. An apparatus according to claim 1 , further comprising a reference oscillator for generating said reference frequency.
8. An apparatus according to claim 7 , wherein said reference oscillator is a non-controlled fixed-frequency oscillator.
9. An apparatus according to claim 8 , wherein said fixed-frequency oscillator is a crystal oscillator.
10. An apparatus according to claim 8 , wherein said fixed-frequency oscillator is a MEMS oscillator.
11. An apparatus according to claim 1 , wherein said reference frequency is the basis for a channel conversion signal of a receiver, and wherein said nominal division ratio is derived from a ratio between a channel frequency of said channel signal and a nominal reference frequency.
12. An apparatus according to claim 5 , wherein said control means is connected to a programming interface for setting said correction control information and said channel control information.
13. An apparatus according to claim 1 , wherein said correction control information comprises at least one of a frequency correction addend, which is independent from the reception or transmission channel, and an independent conversion factor.
14. An apparatus according to claim 13 , wherein said frequency conversion means comprises a series combination of a multiplier means and a divider means.
15. An apparatus according to claim 14 , wherein said multiplier means is arranged for multiplying said reference frequency by a multiplication factor determined on the basis of said frequency correction addend, which is derived from said correction control information, and an independent conversion factor, and wherein said divider means is arranged for dividing said multiplied reference frequency by a division factor determined on the basis of said independent conversion factor.
16. An apparatus according to claim 1 , wherein said frequency conversion means comprises filter means for limiting the spectral composition of the output signal of the said frequency conversion means.
17. An apparatus according to claim 13 , wherein said control means O is arranged to set said independent conversion factor to obtain an integer value of said multiplication factor.
18. An apparatus according to claim 13 , wherein said control means is arranged to set said independent conversion factor to obtain an integer value of said division factor.
19. An apparatus according to claim 13 , wherein said independent conversion factor is hardwired in said apparatus.
20. An apparatus according to claim 1 , further comprising switching means for supplying either said reference frequency or an output of said frequency conversion means to an output of said synchronization apparatus or to a baseband processing unit.
21. An apparatus according to claim 1 , wherein said output signal is supplied to a baseband processing unit.
22. An apparatus according to claim 20 , wherein said baseband processing unit comprises calculation means for calculating said synchronization error based on a frequency offset.
23. A synchronization method for providing synchronization of an output signal to a synchronization information, said method comprising the steps of:
a) converting a reference frequency into a corrected reference frequency, said reference frequency being used for processing said synchronization information;
b) generating a correction control information based on a determined synchronization error of said synchronization apparatus with respect to said synchronization information; and
c) using said correction control information in said converting step to correct said reference frequency based on said correction control information.
24. A method according to claim 23 , wherein said synchronization error is determined based on a synchronization error between said output signal and said synchronization information.
25. A method according to claim 23 , wherein said synchronization error is determined based on a synchronization error between said reference frequency and said synchronization information.
26. A method according to claim 23 , further comprising an earlier step of supplying said reference frequency to a signal generating means that generates a conversion signal on the basis of said reference frequency, wherein the said conversion signal is based on a channel control information, and a later step in which said conversion signal is based on said channel control information and said correction control information, wherein said correction control information is determined based on a synchronization error between said conversion signal and said synchronization information.
27. A method according to claim 26 , where said signal generating means comprises a phase locked loop arrangement or a direct digital synthesis arrangement, and wherein said channel control information is used in said earlier step to set a predetermined nominal division ratio in said phase locked loop arrangement or said direct digital synthesis.
28. A method according to claim 22 , further comprising the steps of supplying said reference frequency to a baseband processing unit during an initial operating phase of said baseband processing unit, and supplying said output signal to said baseband processing unit after correction of said reference frequency.
29. A receiver device comprising a synchronization apparatus as claimed in claim 1 .
30. A transceiver device comprising a synchronization apparatus as claimed in claim 1 .
31. A wireless electronics device comprising a synchronization apparatus as claimed in claim 1 .
32. A receiver device in which a synchronization method as claimed in claim 23 is used.
33. A transceiver device in which a synchronization method as claimed in claim 23 is used.
34. A wireless electronics device in which a synchronization method as claimed in claim 23 is used.