Optimization technique for layered modulation

• US 20070116144A1
• Filed: 01/18/2007
• Published: 05/24/2007
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: Ernest Chen, Guangcai Zhou, Joseph Santoru, Tung-Sheng Lin, Weizheng Wang, William Lindsey
• Original Assignee: Ernest Chen, Guangcai Zhou, Joseph Santoru, Tung-Sheng Lin, Weizheng Wang, William Lindsey
• Inventors: Santoru, Joseph, Lin, Tung-Sheng, Zhou, Guangcai, Chen, Ernest, Wang, Weizheng, Lindsey, William
• Granted Patent: US 7,469,019 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04L 27/183 Multiresolution systems
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

A method and apparatus for optimizing a system for transmitting a layered modulated signal is disclosed. The method comprises the steps of defining the system in terms of a set of system parameters, including an optimal power separation S between a power of a first modulation layer and a power of a second modulation layer and a required system carrier-to-noise ratio (CNR_S), determining an optimal power separation S to minimize the error rate of a lower layer modulated signal BER_L, and selecting the remaining system parameters in the set of system parameters using the determined optimal power separation S.

Claims

1-19. -19. (canceled)

20. A system for transmitting a layered modulation signal characterized by a carrier to noise ratio (CNR) having an upper layer signal and a lower layer signal, wherein a power of the upper layer signal is separated from a power of the lower layer signal by a power separation S, the system defined by performing the steps of:

defining the system in terms of a set of system parameters, including an optimal power separation S between a power of a first modulation layer and a power of a second modulation layer and a required system carrier-to-noise ratio (CNR_s);

determining an optimal power separation S to minimize an error rate of the lower layer signal (BER_L); and

selecting remaining system parameters in the set of system parameters using the determined optimal power separation S, comprising the steps of;

determining a required CNR for the upper layer (CNR_U) and a required CNR for the lower layer (CNR_L) from a relationship between an upper layer coding rate (C_UL) and CNR_U, and a lower level coding rate (C_LL) and CNR_L; and

determining the required system CNR (CNR_s) from CNR_U, CNR_L, and S.

21. The system of claim 20, wherein the required system (CNR_s) is determined at least in part from the relations:

22. The system of claim 20, wherein C_UL=C_LL.

23. The system of claim 20, wherein C_UL≠

C_LL and wherein the step of determining a required system CNR (CNR_s) from CNR_U, CNR_L, and S, comprises the steps of;

selecting a value for CNR_U and a value for CNR_L; and

determining the required system CNR_s from a relationship between CNR_s and CNR_U, CNR_L, and S.

24. The system of claim 23, wherein the required system CNR (CNR_s) is determined at least in part from the relation:

25. A system for transmitting a layered modulation signal characterized by a carrier to noise ratio (CNR) of CNR_s having an upper layer signal and a lower layer signal, wherein a power of the upper layer signal is separated from a power of the lower layer signal by a power separation S, the system defined by performing the steps of:

defining the system in terms of a set of system parameters, including an optimal power separation (S) between a power of a first modulation layer and a power of a second modulation layer and a required system carrier-to-noise ratio (CNR_S);

determining an upper layer CNR compensation (β

) required to produce an upper layer signal error rate (BER_U) defined at least in part by the relationship CNR_U*=CNR_U+β

, wherein CNR_U is the upper layer CNR and CNR_U* is an increased upper layer CNR required to achieve a BER_U defined by BER_U=γ

BER_L, wherein BER_L is a bit error rate of the lower layer signal and γ

<

1;

determining an optimal power separation S to minimize BER_L; and

selecting remaining system parameters in the set of system parameters using the determined optimal power separation S, comprising the step of determining the required system CNR (CNR_s) at least in part from the determined optimal power separation, S, and a relation

$10<br><br>\text{\hspace{1em}<br><br>}<br><br>{\log }_{10}<br><br>\frac{{10}^{\left({\mathrm{CNR}}_S+S\right)/10}}{1+{10}^{S/10}+{10}^{{\mathrm{CNR}}_S/10}}=10<br><br>\text{\hspace{1em}<br><br>}<br><br>{\log }_{10}<br><br>\frac{{10}^{{\mathrm{CNR}}_S/10}}{1+{10}^{S/10}}+\mathrm{\beta <br><br>},$

wherein CNR_S and S are expressed in decibels.

26. The system of claim 25, wherein the upper layer CNR compensation β

is determined at least in part from a relationship between β and

parameters including CNR_U and γ

.

27. The system of claim 26, wherein β

is determined at least in part from a relationship between β and

parameters further including a coding rate of the upper layer (C_UL).