System and apparatus for cascading and redistributing HDTV signals

• US 8,155,039 B2
• Filed: 12/17/2008
• Issued: 04/10/2012
• Est. Priority Date: 03/17/2008
• Status: Expired due to Fees

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Wu, Shiquan, Collings, Timothy D., Yee, Jung
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Ng, Fan
• Application Number:
  US12/337,336
• Publication Number:
  US 20090235316A1
• Time in Patent Office: 1,210 Days
• Field of Search: None
• US Class Current: 370/310
• 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 to a user device within a service area, comprising:

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

1, the spectrum detector comprising

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-frequency-time cells of white space where the energy of the digital signal is under a threshold; and

a transmitter for transmitting the information signal over the identified k frequency-time cells of white space to the user device;

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)dt=0, where α

represents the scaling parameter of the wavelet waveform and τ

represents the shifting parameter of the wavelet waveform.

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 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.

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

identifying k frequency-time cells of white space sufficient to accommodate the bandwidth of the information signal, where k is an integer, k≧

1, the identifying comprising

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 frequency-time cells of white space where the energy of the digital signal is under a threshold; and

broadcasting the information signal over the identified k frequency-time cells of white space to a user device;

wherein 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)dt=0, where α

represents the scaling parameter of the wavelet waveform and τ

represents the shifting parameter of the wavelet waveform.

8. A method as claimed in claim 7, further comprising detecting messages transmitted on a dedicated control channel.

9. A method as claimed in claim 8, wherein the control channel is a bidirectional control channel.

10. A method as claimed in claim 8, wherein the control channel is an uplink control channel, and downlink control messages are transmitted in-band with the data signal.

11. A method as claimed in claim 7, wherein said identifying k frequency-time cells comprises scanning a spectrum based on a given current allocation of channels for a TV broadcast at the service area.

12. A method as claimed in claim 7, wherein identifying k frequency-time cells 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.

13. A method as claimed in claim 7, 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.

14. A method as claimed in claim 7, 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.

15. A gateway for redistributing an information signal of a specified bandwidth to a user device within a service area, comprising:

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

1, the spectrum detector comprising

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 frequency-time cells of white space where the energy of the digital signal is under a threshold; and

a transmitter for transmitting the information signal over the identified k frequency-time cells of white space to the user device;

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 and wherein the wavelet coefficient calculator is capable of calculating the wavelet coefficient using shifted variants of a wavelet function ψ

<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, where α

represents the scaling parameter of the wavelet waveform and τ

represents the shifting parameter of the wavelet waveform.

16. A gateway for redistributing an information signal of a specified bandwidth to a user device within a service area, comprising:

a spectrum detector for identifying k frequency-time cells 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 frequency-time cells of white space to the user device;

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 frequency-time cell of white space with a signal component, and broadcasting k RF signal components over the respective frequency-time cells of white space,

wherein each branch of the distributor unit modulates the baseband signal whenever a 6 MHz frequency-time cell of spectrum has been identified by the spectrum detector.

17. A gateway for redistributing an information signal of a specified bandwidth to a user device within a service area, comprising:

a spectrum detector for identifying k frequency-time cells 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 frequency-time cells of white space to the user device;

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 wherein for n=1, all carrier frequencies are modulated with the same baseband signal for obtaining spatial diversity, and

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

18. A gateway as claimed in claim 17, 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.

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

identifying k frequency-time cells of white space sufficient to accommodate the bandwidth of the information signal, where k is an integer, k≧

1;

broadcasting the information signal over the identified k frequency-time cells of white space to a user device;

wherein broadcasting the information 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 frequency-time cells of white space,

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

broadcasting the n signal components over the respective frequency-time cells of white space; and

wherein for n=1, all carrier frequencies are modulated with the same baseband signal for obtaining spatial diversity.

20. A method as claimed in claim 19, wherein for n=k, each component signal modulates a carrier frequency.

21. A method as claimed in claim 19, further comprising converting source signals received from a variety of signal sources over a variety of media into the information signal.