Methods, apparatus and systems for terrestrial wireless broadcast of digital data to stationary receivers

• US 7,877,064 B2
• Filed: 11/01/2004
• Issued: 01/25/2011
• Est. Priority Date: 11/01/2004
• Status: Active Grant

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Schmidt, Mark S.
• Primary Examiner(s): Kincaid; Lester
• Assistant Examiner(s): Khan; Mehmood B
• Application Number:
  US10/978,602
• Publication Number:
  US 20060092902A1
• Time in Patent Office: 2,276 Days
• Field of Search: 455/427, 455/428, 455/3.02, 455/126, 455/103, 455/101, 455/102, 455/108, 370/347, 375/267, 375/285, 375/299
• US Class Current: 455/103
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0069 Puncturing patterns
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/26524 Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

The present invention provides methods, apparatus and systems for delivery of digital data to stationary receivers over a terrestrial wireless link at a low data rate using a new coded orthogonal frequency division multiplexing (COFDM) scheme. Digital data is encoded and modulated using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream. The data stream is communicated to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%. The COFDM scheme employed by the present invention overcomes the degradation of multipath fading induced by terrestrial channels, such as the Ultra High Frequency (UHF) broadcast channel.

Claims

1. A method for terrestrial broadcast of digital data to stationary receivers, comprising:

encoding and modulating digital data by an encoder and modulator, respectively, using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream; and

communicating said data stream to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%,

wherein the 50% coherence bandwidth is defined as a channel frequency coherence function, φ

_c(Δ

f) for which a magnitude of the channel frequency coherence function is 0.5, the channel frequency coherence function having a multipath intensity profile with the magnitude described by the equation;

2. A method in accordance with claim 1, wherein:

said 50% coherence bandwidth is less than 250 kHz; and

said allocated channel bandwidth is less than 500 kHz.

3. A method in accordance with claim 1, wherein:

said data stream has a data rate of no more than about 1 Mbps.

4. A method in accordance with claim 1, wherein:

said COFDM comprises an 80 tone COFDM scheme.

5. A method in accordance with claim 1, wherein:

said COFDM comprises a COFDM scheme having 4 kHz tone spacing.

6. A method in accordance with claim 1, wherein:

said COFDM comprises a COFDM scheme with an approximately 50 microsecond cyclic prefix guard interval.

7. A method in accordance with claim 1, wherein:

said COFDM scheme comprises a COFDM scheme having a continuous in-frequency pseudo-random pilot symbol for channel estimation and timing.

8. A method in accordance with claim 1, further comprising:

forward error correction coding of said digital data using one of variable rate convolutional coding, low-density parity-check (LDPC) coding, Turbo coding, or concatenated coding of said digital data.

9. A method in accordance with claim 8, wherein:

said forward error correction coding of said digital data comprises rate ½

convolutional coding with a constraint length of K=6.

10. A method in accordance with claim 8, wherein:

said forward error correction coding of said digital data comprises rate ¾

punctured convolutional coding with a constraint length of K=6.

11. A method in accordance with claim 8, further comprising:

block interleaving of said convolutional coded digital data.

12. A method in accordance with claim 11, wherein:

said block interleaving has interleaving parameters (B, M) of B=10 and M=32.

13. A method in accordance with claim 12, further comprising:

modulating said digital data for communication to said stationary receiver using quadrature amplitude modulation (QAM).

14. A method in accordance with claim 13, wherein:

said QAM comprises rate ½

coded 16-QAM; and

a data rate of said data stream is approximately 487 kbps.

15. A method in accordance with claim 13, wherein:

said QAM comprises rate ¾

coded 16-QAM; and

a data rate of said data stream is approximately 740 kbps.

16. A method in accordance with claim 13, further comprising:

Gray coded mapping of interleaved output bits to QAM symbols.

17. A method in accordance with claim 11, wherein:

said block interleaving has interleaving parameters (B, M) of B=15 and M=32.

18. A method in accordance with claim 17, further comprising:

modulating said digital data for communication to said stationary receiver using quadrature amplitude modulation (QAM).

19. A method in accordance with claim 18, wherein:

said QAM comprises rate ¾

coded 64-QAM; and

a data rate of said data stream is approximately 1.12 Mbps.

20. A method in accordance with claim 18, wherein:

said QAM comprises rate ½

coded 64-QAM; and

a data rate of said data stream is approximately 740 kbps.

21. A method in accordance with claim 8, further comprising:

modulating said digital data for communication to said stationary receiver using Quadrature Phase Shift Keying (QPSK) modulation.

22. A method in accordance with claim 1, further comprising:

receiving satellite transmissions containing said digital data at one or more satellite downlink locations;

demodulating and decoding said received digital data prior to said encoding and modulating which produces said data stream for transmission to said stationary receiver via said terrestrial wireless link.

23. A method in accordance with claim 1, further comprising:

receiving said data stream at said stationary receiver;

demodulating and decoding said data stream to recover said digital data for use at said stationary receiver.

24. Apparatus for terrestrial broadcast of digital data to stationary receivers, comprising:

an encoder and modulator for encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream; and

a transmitter for communicating said data stream to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%,

wherein the 50% coherence bandwidth is defined as a channel frequency coherence function, φ

_c(Δ

f) for which a magnitude of the channel frequency coherence function is 0.5, the channel frequency coherence function having a multipath intensity profile with the magnitude described by the equation;

25. A system for terrestrial broadcast of digital data to stationary receivers, comprising:

an encoder and modulator for encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream;

a transmitter for transmitting said data stream;

a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%; and

a stationary receiver for receiving said data stream from said transmitter via said terrestrial wireless link %,

wherein the 50% coherence bandwidth is defined as a channel frequency coherence function, φ

_c(Δ

f) for which a magnitude of the channel frequency coherence function is 0.5, the channel frequency coherence function haying a multipath intensity profile with the magnitude described by the equation;

26. A stationary receiver for receiving a data stream via a terrestrial wireless link, said receiver comprising:

a tuner for receiving a data stream via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%, said data stream produced by encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM);

a demodulator for demodulating said data stream to produce a demodulated data stream; and

a decoder for decoding said demodulated data stream to recover said digital data,

wherein the 50% coherence bandwidth is defined as a channel frequency coherence function, φ

_c(Δ

f) for which a magnitude of the channel frequency coherence function is 0.5, the channel frequency coherence function having a multipath intensity profile with the magnitude described by the equation;

27. A method for receiving a data stream via a terrestrial wireless link, said method comprising:

receiving a data stream via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%, said data stream produced by an encoder and modulator to encode and modulate digital data using coded orthogonal frequency division multiplexing (COFDM);

demodulating said data stream to produce a demodulated data stream;

decoding said demodulated data stream to recover said digital data,

wherein the 50% coherence bandwidth is defined as a channel frequency coherence function, φ

_c(Δ

f) for which a magnitude of the channel frequency coherence function is 0.5, the channel frequency coherence function having a multipath intensity profile with the magnitude described by the equation;