Section division operating point determination method for multicarrier communication systems
First Claim
1. A method for allocating transmission performance quantities among discrete multicarrier modulation communication channels, the method comprising steps of:
- determining and storing a set of Lagrange multiplier λ
data correlating bit rate to allocated power for a plurality of subchannels;
choosing a starting value of λ
, and high and low values surrounding λ
;
evaluating λ
to determine its performance based upon stored allocated performance quantity data;
updating λ
with a section search that alters one of the high and low values to converge toward λ
;
repeating said steps of updating and evaluating until one of the following conditions is demonstrated by said step of evaluating, (a) a newly chosen λ
meets a performance quantity budget indicated by said performance quantity data;
(b) a newly chosen λ
equals a previous high or low value for λ
, or (c) a predetermined number of updates have been conducted; and
allocating a performance quantity based upon the λ
meeting a condition defined in said step of repeating.
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Abstract
Optimum bit rates and power levels are determined for subchannels in multicarrier communication systems. A tangent of the rate-power curve has a slope λ. The slope is defined by the quotient difference between high/low power and high/low rate. A particular λ is evaluated to find its corresponding total power followed by an update of λ, in the form of an increase or decrease, to get closer to the optimal solution. Each λ is evaluated to find the optimal operating point for each subchannel on the rate-power curve by summing the power allocated to the subchannels, and comparing the result to the power budget. Look-up tables are stored for individual channels, but similarity between channels permits joint use of look-up tables by multiple channels. The tables are used to determine the rate-power characteristics at each iteration. An optimal solution is found when either a newly chosen power allocation meets the power budget exactly or a newly chosen power budget equals the high or low power of a previous iteration.
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Citations
19 Claims
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1. A method for allocating transmission performance quantities among discrete multicarrier modulation communication channels, the method comprising steps of:
-
determining and storing a set of Lagrange multiplier λ
data correlating bit rate to allocated power for a plurality of subchannels;
choosing a starting value of λ
, and high and low values surrounding λ
;
evaluating λ
to determine its performance based upon stored allocated performance quantity data;
updating λ
with a section search that alters one of the high and low values to converge toward λ
;
repeating said steps of updating and evaluating until one of the following conditions is demonstrated by said step of evaluating, (a) a newly chosen λ
meets a performance quantity budget indicated by said performance quantity data;
(b) a newly chosen λ
equals a previous high or low value for λ
, or(c) a predetermined number of updates have been conducted; and
allocating a performance quantity based upon the λ
meeting a condition defined in said step of repeating.- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for allocating power among discrete multicarrier modulation communication channels, the method comprising steps of:
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defining a look-up table having parameters defining an optimal operating points on bit rate versus signal-to-noise ratio curves for a plurality of subchannels; and
finding a line for given slope λ
tangent to any one signal to noise ratio curve to allocate power to an associated subchannel for a predetermined power budget by,(a) selecting predetermined high and low slopes above and below the power budget; and
(b) performing an iterative section search between high and low slopes to determine an optimal power allocation. - View Dependent Claims (9)
computing a new slope which bisects the predetermined high and low slopes;
comparing to find whether the new slope is above or below the power budget;
thenupdating the high slope with the new slope if the new slope exceeds the power budget;
updating the low slope with the new slope if the new slope is less than the power budget; and
repeating said computing, comparing and said updating until the new slope equals either the high slope, the low slope or a power budget, or a predetermined number of iterations have been conducted.
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10. A method for allocating bit rate among discrete multicarrier modulation communication channels, the method comprising steps of:
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defining a look-up table having parameters defining optimal operating points on bit rate versus signal-to-noise ratio curves for a plurality of subchannels; and
finding a slope tangent to any one signal to noise ratio curve to allocate bit rate to an associated subchannel for a predetermined power by, (a) selecting predetermined high and low slopes above and below rate-power characteristics for the slope;
(b) evaluating bit rate from the look-up table for the slope; and
(c) performing an iterative section search to converge between high and low slopes to determine an optimal bit rate. - View Dependent Claims (11)
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12. A method for allocating bit rate among discrete multicarrier modulation communication channels, the method comprising steps of:
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(a) obtaining initial values of λ
low and λ
high,(b) calculate the following equations;
(c) verify that Rlow,≦
Rtarget≦
Rhigh;
if it is, go to (d);
if not, go back to (b) with new estimates of λ
low and λ
high;
(d) calculating λ
new, where(e) determining a lookup parameter β
i for i=1, . . . N from stored data and obtaining rate-power characteristics {overscore (P)}newi and Rnewi from a stored look-up table using the lookup parameter β
i, where(f) computing the total rate for λ
new and comparing it to Rlow, Rhigh, and Rtarget;
if Rnew equals Rtarget, then go to step (g), else, if Rnew<
Rtarget, then set {overscore (P)}low={overscore (P)}new and Rlow=Rnew and go to step (d), else, set {overscore (P)}high={overscore (P)}new, and Rhigh=Rnew and go to step (d); and
(g) completing rate allocation by assigning Rnewi to the ith subchannel, allocating power and computing the optimal performance margin γ
m (dB) as- View Dependent Claims (13, 14, 15)
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16. A method for allocating power among discrete multicarrier modulation communication channels, the method comprising steps of:
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(a) obtaining initial values of λ
low and λ
high;
(b) calculate the following equations;
(c) verify that Plow≦
Pbudget≦
Phigh;
if it is, go to (d);
if not, go back to (b) with new estimates of λ
low and λ
high;
(d) calculating a λ
new, where(e) determining a lookup parameter β
i for i=1, . . . N from stored data and obtaining rate-power characteristics Pnewi and Rnewi from a stored look-up table using the lookup parameter β
i, where(f) computing the total power allocation for λ
new and comparing it to Plow, Phigh, or Ptarget, as follows;
if Pnew equals either Plow, Phigh, or Pbudget then go to step (g), else, if Pnew<
Pbudget, then set Plow=Pnew and Rlow=Rnew, store Plowi and Rlowi and go to step (d), else, set Phigh=Pnew, and Rhigh=Rnew and go to step (d); and
(g) assigning Pnewi and Rnewi to the ith subchannel if Pnew=Pbudget, otherwise assigning Plowi and Rlowi to the ith subchannel. - View Dependent Claims (17, 18, 19)
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Specification