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Timestamp: 2014-11-26 05:48:59
Document Index: 148734933

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 2502924', 'Application No. 2503532', 'Application No. 2515167', 'Application No. 2503530', 'Application No. 2487817', 'Application No. 2484313', 'Application No. 200410100591', 'Application No. 03757359', 'Application No. 04256234', 'Application No. 03742400', 'Application No. 03777694', 'Application No. 03742393', 'Application No. 03774848', 'Application No. 03777627', 'Application No. 02728894', 'Application No. 07075745', 'Application No. 2004', 'art 1', 'Application No. 092129629']

Patent US7483495 - Layered modulation for digital signals - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsSignals, systems and methods for transmitting and receiving layered modulation for digital signals are presented. A layered signal for transmitting data, comprises a first signal layer including a first carrier and first signal symbols for a first digital signal transmission and a second signal layer...http://www.google.com/patents/US7483495?utm_source=gb-gplus-sharePatent US7483495 - Layered modulation for digital signalsAdvanced Patent SearchPublication numberUS7483495 B2Publication typeGrantApplication numberUS 11/653,517Publication dateJan 27, 2009Filing dateJan 16, 2007Priority dateApr 27, 2001Fee statusPaidAlso published asCA2442400A1, CA2442400C, EP1382141A1, EP1382141B1, EP1876705A2, EP1876705A3, EP1876705B1, US7209524, US20020181604, US20070116156, US20090052590, WO2002089371A1, WO2002089371A8, WO2004040924A1Publication number11653517, 653517, US 7483495 B2, US 7483495B2, US-B2-7483495, US7483495 B2, US7483495B2InventorsErnest C. ChenOriginal AssigneeThe Directv Group, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (104), Non-Patent Citations (72), Referenced by (1), Classifications (32), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetLayered modulation for digital signalsUS 7483495 B2Abstract Signals, systems and methods for transmitting and receiving layered modulation for digital signals are presented. A layered signal for transmitting data, comprises a first signal layer including a first carrier and first signal symbols for a first digital signal transmission and a second signal layer including a second carrier and second signal symbols for a second signal transmission disposed on the first signal layer, wherein the layered signal has the first carrier demodulated and first layer decoded to produce the first signal symbols for a first layer transport, the first signal symbols are remodulated and subtracted from the layered signal to produce the second signal layer, and the second signal layer has the second carrier demodulated and decoded to produce the second signal symbols for a second layer transport.
1. A method of transmitting a transmission signal having a legacy upper layer signal and a lower layer signal non-coherently added to the legacy upper layer signal, the method comprising:
transmitting the legacy upper layer signal including a first carrier and first signal symbols; and
transmitting a lower layer signal including a second carrier and second signal symbols;
wherein a plurality of legacy receivers demodulate the legacy upper layer signal to produce the first signal symbols and do not demodulate the lower layer signal to produce the second signal symbols; and
wherein a plurality of layered modulation receivers demodulate the legacy upper layer signal to produce the first signal symbols, remodulate the first signal symbols, and subtract the remodulated first signal symbols from the demodulated legacy upper layer signal to produce the second signal symbols.
2. The method of claim 1, wherein at least one of the legacy upper layer signal and the lower layer signal are quadrature phase shift keyed (QPSK).
10. A receiver system for compatibly receiving a transmission signal having a legacy upper layer signal and a lower layer signal non-coherently added to the legacy upper layer signal, the system comprising:
a plurality of layered modulation receivers, each comprising;
a first demodulator for demodulating the legacy upper layer signal to produce a demodulated signal;
a first layer decoder, coupled to the first layer demodulator, for decoding the demodulated signal to produce legacy upper layer signal symbols;
a remodulator, coupled to the first layer decoder, for remodulating the first signal symbols to produce a remodulated legacy upper layer signal;
a subtracter, coupled to the first demodulator and the remodulator, for subtracting the remodulated legacy upper layer signal from the demodulated signal to produce the lower layer signal;
a second layer demodulator, coupled to the subtracter, the second layer demodulator for demodulating the lower layer signal to produce a second demodulator output; and
a second layer decoder, coupled to the second layer demodulater, the second layer decoder for decoding the second layer demodulated output to produce lower layer signal symbols;
a plurality of legacy receivers, each configured to demodulate the legacy upper layer signal and not the lower layer signal, and each comprising:
a legacy receiver demodulator configured to demodulate the legacy upper layer signal to produce a second demodulated signal; and
a legacy receiver decoder, coupled to the legacy receiver demodulator, configured to decode the second demodulated signal to produce legacy upper layer symbols.
11. The receiver system of claim 10, further comprising a non-linear distortion map for removing non-linear distortion effects from the remodulated legacy upper layer signal.
12. The receiver system of claim 10, wherein the legacy upper layer signal is a boosted legacy signal.
13. The receiver system of claim 10, wherein at least one of the legacy upper layer signal and lower layer signal are quadrature phase shift keyed (QPSK).
14. The receiver system of claim 10, wherein a code rate for at least one of the legacy upper layer signal and lower layer signal is 6/7.
15. The receiver system of claim 10, wherein a code rate for at least one of the legacy upper layer signal and lower layer signal is 2/3.
16. The receiver system of claim 10, wherein a code rate for at least one of the legacy upper layer signal and lower layer signal is 1/2.
17. The receiver system of claim 10, wherein the second signal layer is generated by power boosting the legacy upper layer signal.
18. The receiver system of claim 10, wherein a total code and noise level of the legacy upper layer signal is no greater than a noise foor of the lower layer signal.
19. The receiver system of claim 10, wherein at least one of the legacy upper layer signal and lower layer signal is coded using a turbo code.
20. The receiver system of claim 10, wherein both the legacy upper layer signal and lower layer signal are coded using a single turbo code.
21. The receiver system of claim 10, wherein the legacy upper layer signal and lower layer signal each have a carrier frequency that is substantially similar.
22. The receiver system of claim 10, wherein a carrier frequency of the legacy upper layer signal and a second carrier frequency of the lower layer signal are offset in frequency.
23. The receiver system of claim 10, wherein the first layer decoder comprises a Viterbi decoder.
24. The receiver system of claim 10, wherein the first layer decoder comprises a Reed-Solomon decoder. Description
CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of prior U.S. patent application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� by Ernest C. Chen, filed Apr. 27, 2001 now U.S. Pat. No. 7,209,524, which application is hereby incorporated by reference herein.
application Ser. No. 10/165,710, entitled �SATELLITE TWTA ON-LINE NON-LINEARITY MEASUREMENT,�, filed on Jun. 7, 2002, by Ernest C. Chen, which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/693,135, entitled �LAYERED MODULATION FOR ATSC APPLICATIONS,� filed on Oct. 24, 2003, by Ernest C. Chen, which claims benefit to Provisional Patent Application No. 60/421,327, filed Oct. 25, 2002 and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 11/619,173, entitled �PREPROCESSING SIGNAL LAYERS IN LAYERED MODULATION DIGITAL SIGNAL SYSTEM TO USE LEGACY RECEIVERS,� filed Jan. 2, 2007, which is a continuation of application Ser. No. 10/068,039, entitled �PREPROCESSING SIGNAL LAYERS IN LAYERED MODULATION DIGITAL SIGNAL SYSTEM TO USE. LEGACY RECEIVERS,� filed on Feb. 5, 2002 by Ernest C. Chen, Tiffany S. Furuya, Philip R. Hilmes, and Joseph Santoru now issued as U.S. Pat. No. 7,245,671, which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/693,421, entitled �FAST ACQUISITION OF TIMING AND CARRIER FREQUENCY FROM RECEIVED SIGNAL,� filed on Oct. 24, 2003, by Ernest C. Chen, now issued as U.S. Pat. No. 7,151,807, which claims priority to priority Provisional Patent Application Ser. No. 60/421,292, filed Oct. 25, 2002, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/692,491, entitled �ONLINE OUTPUT MULTIPLEXER FILTER MEASUREMENT,� filed on Oct. 24, 2003, by Ernest C. Chen, which claims priority to Provisional Patent Application No. 60/421,290, filed Oct. 25, 2002, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
appplication Ser. No. 10/691,032, entitled �UNBLIND EQUALIZER ARCHITECTURE FOR DIGITAL COMMUNICATION SYSTEMS,� filed on Oct. 22, 2003, by Weizheng W. Wang, Tung-Sheng Lin, Ernest C. Chen, and William C. Lindsey, which claims priority to Provisional Patent Application Ser. No. 60/421,329, filed Oct. 25, 2002, and which is a continuation-in-part of application Ser. No. 09/844,401 entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/962,346, entitled �COHERENT AVERAGING FOR MEASURING TRAVELING WAVE TUBE AMPLIFIER NONLINEARITY, � filed on Oct. 8, 2004, by Ernest C. Chen, which claims priority to Provisional Patent Application Ser. No. 60/510,368, filed Oct. 10, 2003, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 11/655,001, entitled �AN OPTIMIZATION TECHNIQUE FOR LAYERED MODULATION,� filed on Jan. 18, 2007, by Weizheng W. Wang, Guancai Zhou, Tung-Sheng Lin, Ernest C. Chen, Joseph Santoru, and William Lindsey, which claims priority to Provisional Patent Application No. 60/421,293, filed Oct. 25, 2002, and which is a continuation of application Ser. No. 10/693,140, entitled �OPTIMIZATION TECHNIQUE FOR LAYERED MODULATION,� filed on Oct. 24, 2003, by Weizheng W. Wang, Guancai Zhou, Tung-Sheng Lin, Ernest C. Chen, Joseph Santoru, and William Lindsey, now issued as U.S. Pat. No. 7,184,489, which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 11/656,662, entitled �EQUALIZERS FOR LAYERED MODULATION AND OTHER SIGNALS,� filed on Jan. 22, 2007, by Ernest C. Chen, Tung-Sheng Lin, Weizheng W. Wang, and William C. Lindsey, which claims priority to Provisional Patent Application No. 60/421,241, filed Oct. 25, 2002, and which is a continuation of application Ser. No. 10/691,133 entitled �EQUALIZERS FOR LAYERED MODULATED AND OTHER SIGNALS,� filed on Oct. 22, 2003, by Ernest C. Chen, Tung-Sheng Lin, Weizheng W. Wang, and William C. Lindsey, now issued as U.S. Pat. No. 7,184,473, which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/532,632, entitled �LOWER COMPLEXITY LAYERED MODULATION SIGNAL PROCESSOR,� filed on Apr. 25, 2005, by Ernest C. Chen, Weizheng W. Wang, Tung-Sheng Lin, Guangcai Zhou, and Joe Santoru, which is a National Stage Application of PCT US03/32264, filed Oct. 10, 2003, which claims priority to Provisional Patent Application No. 60/421,331, entitled �LOWER COMPLEXITY LAYERED MODULATION SIGNAL PROCESSOR,� filed Oct. 25, 2002, by Ernest C. Chen, Weizheng W. Wang, Tung-Sheng Lin, Guangcai Zhou, and Joe Santoru, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524
application Ser. No. 10/532,631, entitled �FEEDER LINK CONFIGURATIONS TO SUPPORT LAYERED MODULATION FOR DIGITAL SIGNA,� filed on Apr. 25, 2005, by Paul R. Anderson, Joseph Santoru and Ernest C. Chen, which is a National Phase Application of PCT US03/33255, filed Oct. 20, 2003, which claim priority to Provisional Patent Application No. 60/421,328, entitled �FEEDER LINK CONFIGURATIONS TO SUPPORT LAYERED MODULATION FOR DIGITAL SIGNALS,� filed Oct. 25, 2002, by Paul R. Anderson, Joseph Santoru and Ernest C. Chen, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001,by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/532,619, entitled �MAXIMIZING POWER AND SPECTRAL EFFICIENCIES FOR LAYERED AND CONVENTIONAL MODULATIONS,� filed on Apr. 25, 2005, by Ernest C. Chen, which is a National Phase Application of PCT Application US03/32800, filed Oct. 16, 2003. which claims priority to Provisional Patent Application No. 60/421,288, entitled �MAXIMIZING POWER AND SPECTRAL EFFICIENCIES FOR LAYERED AND CONVENTIONAL MODULATION,� filed Oct. 25, 2002, by Ernest C. Chen and which is a continuation-in-part of application Ser. No. 09/844,401 entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524,
application Ser. No. 10/532,524, entitled �AMPLITUDE AND PHASE MATCHING FOR LAYERED MODULATION RECEPTION,� filed on Apr. 25, 2005, by Ernest C. Chen, Jeng-Hong Chen, Kenneth Shum, and Joungheon Oh, which is a National Phase Application of PCT Application US03/31199, filed Oct. 3, 2003, which claims priority to Provisional Patent Application No. 60/421,332, entitled �AMPLITUDE AND PHASE MATCHING FOR LAYERED MODULATION RECEPTION,� filed Oct. 25, 2002, by Ernest C. Chen, Jeng-Hong Chen, Kenneth Shum, and Joungheon Oh, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524, and also claims priority to;
application Ser. No. 10/532,582, entitled �METHOD AND APPARATUS FOR TAILORING CARRIER POWER REQUIREMENTS ACCORDING TO AVAILABILITY IN LAYERED MODULATION SYSTEMS,� filed on Apr. 25, 2005, by Ernest C. Chen, Paul R. Anderson and Joseph Santoru, now issued as U.S. Pat. No. 7,173,977, which is a National Stage Application of PCT Application US03/32751, filed Oct. 15, 2003, which claims priority to Provisional Patent Application No. 60/421,333, entitled �METHOD AND APPARATUS FOR TAILORING CARRIER POWER REQUIREMENTS ACCORDING TO A AVAILABILITY IN LAYERED MODULATION SYSTEMS,� filed Oct. 25, 2002, by Ernest C. Chen, Paul R. Anderson and Joseph Santoru, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/532,509, entitled �ESTIMATING THE OPERATING POINT ON A NONLINEAR TRAVELING WAVE TUBE AMPLIFIER,� filed on Apr. 25, 2005, by Ernest C. Chen and Shamik Maitra, now issued as U.S. Pat. No. 7,230,480, which is a National Stage Application of PCT Application US03/33130 filed Oct. 17, 2003, and which claims priority to Provisional Patent Application No. 60/421,289, entitled �ESTIMATING THE OPERATING POINT ON A NONLINEAR TRAVELING WAVE TUBE AMPLIFIER,� filed Oct. 25, 2002, by Ernest C. Chen and Shamik Maitra, and which is a continuation-in-part of application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/519,322, entitled �IMPROVING HIERARCHICAL 8PSK PERFORMANCE,� filed on Dec. 23, 2004 by Ernest C. Chen and Joseph Santoru, which is a National Stage Application of PCT US03/020862 filed Jul. 1, 2003, which claims priority to Provisional Patent Application No. 60/392,861, filed Jul. 1, 2002 and Provisional Patent Application No. 60/392,860, filed Jul. 1, 2002, and which is also related to application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524;
application Ser. No. 10/519,375, entitled �METHOD AND APPARATUS FOR LAYERED MODULATION,� filed on Jul. 3, 2003, by Ernest C. Chen and Joseph Santoru, which is a National Stage Application of PCT US03/20847, filed Jul. 3, 2003, which claims priority to Provisional Patent Application No. 60/393,437 filed Jul. 3, 2002, and which is related to application Ser. No. 09/844,401, entitled �LAYERED MODULATION FOR DIGITAL SIGNALS,� filed on Apr. 27, 2001, by Ernest C. Chen, now issued as U.S. Pat. No. 7,209,524
application Ser. No. 10/692,539, entitled �ON-LINE PHASE NOISE MEASUREMENT FOR LAYERED MODULATION�, filed on Oct. 23, 2003, by Ernest C. Chen, which claims priority to Provisional Patent Application No. 60/421,291, filed Oct. 25, 2002.
SUMMARY OF THE INVENTION Signals, systems and methods for transmitting and receiving non-coherent layered modulation for digital signals are presented. For example, a layered signal for transmitting data, comprises a first signal layer including a first carrier and first signal symbols for a first digital signal transmission and a second signal layer including a second carrier and second signal symbols for a second signal transmission disposed on the first signal layer, wherein the layered signal has the first carrier demodulated and first layer decoded to produce the first signal symbols for a first layer transport, the first signal symbols are remodulated and subtracted from the layered signal to produce the second signal layer, and the second signal layer has the second carrier demodulated and decoded to produce the second signal symbols for a second layer transport.
For example, spectral efficiency may be significantly increased while maintaining backward compatibility with pre-existing receivers; if both layers use the same modulation with the same code rate, the spectral efficiency may be doubled. The present invention is more energy efficient and more bandwidth efficient than other backwards-compatible techniques using adapted 8PSK and 16QAM.
While it can achieve at least the spectral efficiency of a 16QAM modulation, the new modulation of the present invention does not require a linear traveling wave tube amplifier (TWTA) as with 16QAM. All layers may use QPSK or 8PSK, which are much more insensitive to TWTA nonlinearity. Also, by using QPSK modulation for all layers in the present invention, there is no additional performance penalty imposed on 8PSK or 16QAM due to carrier phase recovery error.
Overview The present invention provides for the modulation of signals at different power levels and advantageously for the signals to be non-coherent from each layer. In addition, independent modulation and coding of the signals may be performed. Backwards compatibility with legacy receivers, such as a quadrature phase shift keying (QPSK) receiver is enabled and new services are provided to new receivers. A typical new receiver of the present invention uses two demodulators and one remodulator as will be described in detail hereafter.
Layered Signals FIGS. 1A-1C illustrate the basic relationship of signal layers in a layered modulation transmission. FIG. 1A illustrates a first layer signal constellation 100 of a transmission signal showing the signal points or symbols 102. FIG. 1B illustrates the second layer signal constellation of symbols 104 over the first layer signal constellation 100 where the layers are coherent. FIG. 1C illustrates a second signal layer 106 of a second transmission layer over the first layer constellation where the layers may be non-coherent. The second layer 106 rotates about the first layer constellation 102 due to the relative modulating frequencies of the two layers in a non-coherent transmission. Both the first and second layers rotate about the origin due to the first layer modulation frequency as described by path 108.
Hereafter the invention will be described in terms of particular applications which are backwards compatible and non-backwards compatible. �Backwards compatible� in this sense describes supplemental signal layers applied to systems previously implemented. In these applications, the pre-existing system architecture must be accommodated by the architecture of the additional signal layers. �Non-backwards compatible� describes a system architecture which makes use of layered modulation, but there is no pre-existing equipment.
Demodulator and Decoder FIGS. 4A-4B are block diagrams for reception of a layered modulation signal by a typical receiver subsystem 400 of the present invention. FIG. 4A depicts reception where layer subtraction is performed on a signal where the upper carrier has been demodulated. The upper layer of the received combined signal 416, which may contain legacy modulation format, is processed by a demodulator 404 to produce the stable demodulated signal output 420. The demodulated signal is fed to a decoder 402 which FEC decodes the upper layer. The upper layer decoder 402 produces the upper layer symbols which are output to an upper layer transport and also used to generate an idealized upper layer signal. The upper layer symbols may be produced from the decoder 402 after Viterbi decode (BER<10−3 or so) or after Reed-Solomon (RS) decode (BER<10−9 or so), in typical decoding operations known to those skilled in the art. The upper layer symbols from the upper layer decoder 402 are fed to a remodulator 406 which effectively produces an idealized upper layer signal for subtraction from the stable demodulated signal 420.
s UL ⁡ ( t ) = f U ⁡ ( M U ⁢ exp ⁡ ( jω U ⁢ t + θ U ) ⁢ ∑ m = - ∞ ∞ ⁢ S Um ⁢ p ⁡ ( t - mT ) ) + f L ⁡ ( M L ⁢ exp ⁡ ( jω L ⁢ t + θ L ) ⁢ ∑ m = - ∞ ∞ ⁢ S Lm ⁢ p ⁡ ( t - mT + Δ ⁢ ⁢ T m ) ) + n ⁡ ( t ) where, MU is the magnitude of the upper layer QPSK signal and ML is the magnitude of the lower layer QPSK signal and ML<<MU. The signal frequencies and phase for the upper and lower layer signals are respectively ωU, θU and ωU, θU. The symbol timing misalignment between the upper and lower layers is ΔTm. p(t−mT) represents the time shifted version of the pulse shaping filter p(t) 414 employed in signal modulation. QPSK symbols SUm and SLm are elements of
Ignoring fU(�) and fL(�) and noise n(t), the following represents the output of the demodulator 404 to the FEC decoder 402 after removing the upper carrier:
s UL ′ ⁡ ( t ) = M U ⁢ ∑ m = - ∞ ∞ ⁢ S Um ⁢ p ⁡ ( t - mT ) + M L ⁢ exp ⁢ { j ⁡ ( ω L - ω U ) ⁢ t + θ L - θ U } ⁢ ∑ m = - ∞ ∞ ⁢ S Lm ⁢ p ⁡ ( t - mT + Δ ⁢ ⁢ T m ) Because of the magnitude difference between MU and ML, the upper layer decoder 402 disregards the ML component of the s′UL (t).
After subtracting the upper layer from sUL(t) in the subtracter 412, the following remains:
Backward Compatible Applications FIG. 5A depicts the relative power levels 500 of example embodiments of the present invention. FIG. 5A is not a scale drawing. This embodiment doubles the pre-existing rate 6/7 capacity by using a TWTA 6.2 dB above a pre-existing TWTA equivalent isotropic radiated power (EIRP) and second TWTA 2 dB below the pre-existing TWTA power. This embodiment uses upper and lower QPSK layers which are non-coherent. A code rate of 6/7 is also used for both layers. In this embodiment, the signal of the legacy QPSK signal 502 is used to generate the upper layer 504 and a new QPSK layer is the lower layer 510. The CNR of the legacy QPSK signal 502 is approximately 7 dB. In the present invention, the legacy QPSK signal 502 is boosted in power by approximately 6.2 dB bringing the new power level to approximately 13.2 dB as the upper layer 504. The noise floor 506 of the upper layer is approximately 6.2 dB. The new lower QPSK layer 510 has a CNR of approximately 5 dB. The total signal and noise of the lower layer is kept at or below the tolerable noise floor 506 of the upper layer. The power boosted upper layer 504 of the present invention is also very robust, making it resistant to rain fade. It should be noted that the invention may be extended to multiple layers with mixed modulations, coding and code rates.
Non-Backward Compatible Applications As previously discussed the present invention may also be used in �non-backward compatible� applications. In a first example embodiment, two QPSK layers 504, 510 are used each at a code rate of 2/3. The upper QPSK layer 504 has a CNR of approximately 4.1 dB above its noise floor 506 and the lower QPSK layer 510 also has a CNR of approximately 4.1 dB. The total code and noise level of the lower QPSK layer 510 is approximately 5.5 dB. The total CNR for the upper QPSK signal 504 is approximately 9.4 dB, merely 2.4 dB above the legacy QPSK signal rate 6/7. The capacity is approximately 1.74 compared to the legacy rate 6/7.
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Chen, Non-final Communication dated Nov. 15, 2007.72Wolcott, Ted J. et al.; "Uplink-Noise Limited Satellite Channels"; IEEE 1995; pp. 717-721; XP-00580915.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS8804605Aug 31, 2012Aug 12, 2014The Directv Group, Inc.Feeder link configurations to support layered modulation for digital signalsClassifications U.S. Classification375/295, 375/324International ClassificationH03F1/32, H04B7/185, H04B17/00, H04L27/36, H04L27/04, H03F3/58Cooperative ClassificationH04B17/0057, H04L2027/0061, H04H60/07, H04L27/183, H04L27/227, H04L27/366, H03F1/32, H04H20/103, H03F3/58, H04L1/20, H03F2200/393, H04H20/42, H04B7/18515European ClassificationH04H20/42, H04H60/07, H04H20/10A, H04B7/185D4, H04L27/227, H04L1/20, H04B17/00B1R, H04L27/18M, H03F3/58, H03F1/32, H04L27/36GLegal EventsDateCodeEventDescriptionJul 27, 2012FPAYFee paymentYear of fee payment: 4Sep 9, 2011ASAssignmentOwner name: THE DIRECTV GROUP, INC., CALIFORNIAFree format text: CHANGE OF NAME;ASSIGNOR:HUGHES ELECTRONICS CORPORATION;REEL/FRAME:026879/0626Effective date: 20040316RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google