SYSTEM AND APPARATUS FOR CASCADING AND REDISTRIBUTING HDTV SIGNALS

• US 20090235316A1
• Filed: 12/17/2008
• Published: 09/17/2009
• Est. Priority Date: 03/17/2008
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Wi-LAN Inc.
• Inventors: Collings, Timothy D., Wu, Shiquan, Yee, Jung
• Granted Patent: US 8,155,039 B2
• Time in Patent Office: Days
• US Class Current: 725/81
• CPC Class Codes: H04H 20/02 Arrangements for relaying broadcast information
• CPC Class Codes: H04H 20/33 by plural channels
• CPC Class Codes: H04H 20/42 Arrangements for resource management

Abstract

Redistribution of multimedia signals or the like within a service area is performed by identifying one or more pieces of white space in the VHF/UHF spectrum, selecting a carrier frequency for each piece of white space spectrum, parsing the signal into a like number of components and modulating each component over a carrier frequency. The receiving device performs the reverse operation for reconstructing the signal.

Claims

1. A gateway for redistributing an information signal of a specified bandwidth within a service area, comprising:

a spectrum detector for identifying k pieces of white space sufficient to accommodate the specified bandwidth of the information signal, where k is an integer, k≧

1; and

a transmitter for transmitting the information signal over the identified k pieces of white space.

2. A gateway as claimed in claim 1, further comprising:

a control device for transmitting control messages on a dedicated control channel; and

a control signal detector for detecting the messages transmitted by the control device on the dedicated control channel.

3. A gateway as claimed in claim 2, wherein the dedicated control channel is a bidirectional control channel, and wherein the gateway controls a operation of at least one of the spectrum detector and the transmitter based on the detected messages.

4. A gateway as claimed in claim 1, wherein the gateway controls operation of at least one of the spectrum detector and the transmitter by transmitting in-band control messages.

5. A gateway as claimed in claim 1, wherein the spectrum detector scans a spectrum based on a given current allocation of channels for the service area.

6. A gateway as claimed in claim 1, wherein the spectrum detector is a wavelet spectrum analyzer.

7. A gateway as claimed in claim 1, wherein the spectrum detector comprises:

a tunable RF module for scanning specified spectrum sections and capturing any wireless signal present in the spectrum sections;

an analog to digital converter for converting the captured wireless signal to a digital signal;

a wavelet coefficient calculator for measuring an energy of the digital signal in each of a plurality of frequency-time cells formed within the specified spectrum sections; and

a sorting unit for selecting the k pieces of white space from the frequency-time cells where the energy of the digital signal is under a threshold.

8. A gateway as claimed in claim 7, wherein the spectrum detector selects a size of the frequency-time cells based on the bandwidth of the information signal and the detected current wireless activity at the service area.

9. A gateway as claimed in claim 7, wherein the wavelet coefficient calculator uses a wavelet function ψ

<sub>α

,τ</sub>

(t) providing a concentration of an energy of the frequency-time cells, in both time and frequency within a finite interval, according to this equation;

∫

ψ

<sub>α

,τ</sub>

(t)=0

10. A gateway as claimed in claim 7, wherein the wavelet coefficient calculator is capable of measuring an energy of the digital signal in each frequency-time cell by calculating a wavelet coefficient for the digital signal detected in the respective frequency-time cell.

11. A gateway as claimed in claim 10, wherein the wavelet coefficient calculator is capable of calculating the using shifted variants of a wavelet function ω

<sub>α

,τ</sub>

(t), wherein the wavelet coefficient calculator obtains the shifted variants by performing integer shifts of an energy concentration center of the wavelet function, such that adjacent shifted waveforms {ψ

(t−

τ

)} form an orthogonal basis.

12. A gateway as claimed in claim 1, wherein the transmitter comprises:

a baseband processor for converting the information signal into a baseband signal and parsing the baseband signal into n signal components where n is an integer, nε

[1;

k]; and

a distributor unit with k branches for modulating each carrier frequency corresponding to a respective piece of white space with a signal component, and broadcasting k RF signal components over the respective piece of white space.

13. A gateway as claimed in claim 12, wherein each branch of the distributor unit modulates the baseband signal whenever a 6 MHz piece of spectrum has been identified by the spectrum detector.

14. A gateway as claimed in claim 12, wherein for n=1, all carrier frequencies are modulated with the same baseband signal for obtaining spatial diversity.

15. A gateway as claimed in claim 12, wherein the transmitter further comprises an interface for converting source signals received from a variety of signal sources over a variety of media into the information signal.

21. A method as claimed in claim 15, wherein said identifying k pieces comprises:

scanning specified spectrum sections and capturing any wireless signal (Rx) present in the specified spectrum sections;

converting the captured wireless signal to a digital signal;

measuring an energy of the digital signal in each of a plurality of frequency-time cells formed within the specified spectrum sections; and

selecting the k pieces of white space from the frequency-time cells where the energy of the digital signal is under a threshold.

22. A method as claimed in claim 21, wherein the identifying k pieces of white space includes detecting a current wireless activity at the service area, and wherein the size of the frequency-time cells is selectable based on the bandwidth of the information signal and the current wireless activity detected at the service area.

23. A method as claimed in claim 21, the scanning specified spectrum sections uses a wavelet function ψ

<sub>α

,τ</sub>

(t) selected to concentrate an energy of the frequency-time cell, in both time and frequency within a finite interval, according to this equation;

∫

ψ

<sub>α

,τ</sub>

(t)=0

24. A method as claimed in claim 21, wherein said measuring an energy comprises measuring the energy of the digital signal in each frequency-time cell by calculating a wavelet coefficient for the digital signal detected in the respective frequency-time cell.

25. A method as claimed in claim 24, wherein said calculating a wavelet coefficient uses shifted variants of the wavelet function (ψ

(t−

τ

), and includes obtaining the shifted variants by performing integer shifts of an energy concentration center of the wavelet function, such that adjacent shifted waveforms {ψ

(t−

τ

)} form an orthogonal basis.

16. A method for redistributing an information signal of a specified bandwidth, within a service area, comprising:

identifying k pieces of white space sufficient to accommodate the bandwidth of the information signal, where k is an integer, k≧

1; and

broadcasting the information signal over the identified k pieces of white space.

17. A method as claimed in claim 16, further comprising detecting messages transmitted on a dedicated control channel.

18. A method as claimed in claim 17, wherein the control channel is a bidirectional control channel.

19. A method as claimed in claim 17, wherein the control channel is an uplink control channel, and downlink control messages are transmitted in-band with the data signal.

20. A method as claimed in claim 16, wherein said identifying k pieces comprises scanning a spectrum based on a given current allocation of channels for a TV broadcast at the service area.

26. A method as claimed in claim 16, wherein said broadcasting the information signal comprises:

converting the information signal into a baseband signal;

parsing the baseband signal into n signal components, where n is an integer nε

[1;

k];

selecting a carrier frequency for each of the k pieces of white space;

modulating each of the k carrier frequencies with a signal component, and

broadcasting the n signal components over the respective piece of white space.

27. A method as claimed in claim 26, wherein for n=k, each component signal modulates a carrier frequency.

28. A method as claimed in claim 26, wherein for n=1, all carrier frequencies are modulated with the same baseband signal for obtaining spatial diversity.

29. A method as claimed in claim 26, further comprising converting source signals received from a variety of signal sources over a variety of media into the information signal.

30. A device for receiving an information signal transmitted within a service area, comprising:

an antenna for capturing k RF signal components carried on k frequency carriers, where k is an integer;

a receiver unit having k demodulator branches, each for demodulating a respective RF signal component into an information signal component; and

a combiner for combining the information signal components into the information signal.

31. A device as claimed in claim 30, wherein the receiver unit further comprises an additional branch for demodulating a RF signal into the information signal, for the case when the information signal is carried on a single carrier.