1. A method for channel estimation, comprising:
receiving an error signal returned by a terminal, wherein the error signal is an error signal of at least two tones in a downlink frequency band;
obtaining channels of the at least two tones according to the error signal; and
interpolating the channels of the at least two tones, and obtaining channels of remaining tones in the downlink frequency band.
2. The method for channel estimation according to claim 1, wherein the interpolating the channels of the at least two tones comprises: respectively interpolating amplitudes and phases of the channels of the at least two tones.
3. The method for channel estimation according to claim 1, wherein the interpolating comprises interpolating by using a linear interpolation function or a Gaussian interpolation function.
4. The method for channel estimation according to claim 1, wherein the obtaining the channels of the at least two tones comprises acquiring the channels of the tones by using an orthogonal sequence based method.
5. An apparatus for channel estimation, comprising:
a receiving unit, configured to receive an error signal returned by a terminal, wherein the error signal is an error signal of at least two tones in a downlink frequency band;
a first channel acquisition unit, configured to obtain channels of the at least two tones according to the error signal received by the receiving unit; and
a second channel acquisition unit, configured to interpolate the channels of the at least two tones, and obtain channels of remaining tones in the downlink frequency band.
6. The apparatus for channel estimation according to claim 5, wherein the second channel acquisition unit comprises:
an interpolation unit, configured to interpolate the channels of the at least two tones obtained by the first channel acquisition unit; and
an acquisition unit, configured to obtain the channels of the remaining tones in the downlink frequency band according to interpolation results of the interpolation unit.
7. The apparatus for channel estimation according to claim 6, wherein the interpolation unit comprises:
a first interpolation unit, configured to interpolate amplitudes of the channels of the at least two tones obtained by the first channel acquisition unit; and
a second interpolation unit, configured to interpolate phases of the channels of the at least two tones obtained by the first channel acquisition unit.
8. The apparatus for channel estimation according to claim 7, wherein the acquisition unit is configured to obtain the channels of the remaining tones in the downlink frequency band according to amplitude values obtained by the first interpolation unit and phase values obtained by the second interpolation unit.
9. The apparatus for channel estimation according to claim 5, wherein the apparatus is integrated in a digital subscriber line access multiplexer (DSLAM).
10. The apparatus for channel estimation according to claim 8, wherein the apparatus is integrated in a digital subscriber line access multiplexer (DSLAM).
11. A digital subscriber line (DSL) system, comprising:
a terminal, configured to return an error signal to an access device, wherein the error signal is an error signal of at least two tones in a downlink frequency band; and
an access device, configured to receive the error signal returned by the terminal, obtain channels of the at least two tones according to the received error signal, interpolate the channels of the at least two tones, and obtain channels of remaining tones in the downlink frequency band.
12. The DSL system according to claim 11, wherein the access device comprises:
a receiving unit, configured to receive the error signal returned by the terminal;
a first channel acquisition unit, configured to obtain the channels of the at least two tones according to the error signal received by the receiving unit; and
a second channel acquisition unit, configured to interpolate the channels of the at least two tones, and obtain the channels of the remaining tones in the downlink frequency band.
13. The DSL system according to claim 12, wherein the second channel acquisition unit comprises:
an interpolation unit, configured to interpolate the channels of the at least two tones obtained by the first channel acquisition unit; and
an acquisition unit, configured to obtain the channels of the remaining tones in the downlink frequency band according to interpolation results of the interpolation unit.
14. The DSL system according to claim 13, wherein the interpolation unit comprises:
a first interpolation unit, configured to interpolate amplitudes of the channels of the at least two tones obtained by the first channel acquisition unit; and
a second interpolation unit, configured to interpolate phases of the channels of the at least two tones obtained by the first channel acquisition unit.
15. The DSL system according to claim 14, wherein the acquisition unit is configured to obtain the channels of the remaining tones in the downlink frequency band according to amplitude values obtained by the first interpolation unit and phase values obtained by the second interpolation unit.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A golf ball, comprising:
a) dual core comprising an inner and outer core layer, the inner core having an outer surface and geometric center and the outer core layer having an outer surface and inner surface; the inner core comprising a rubber composition and the outer core layer consisting essentially of a polyamide non-ionomeric composition, the polyamide composition consisting essentially of:
i) about 40 to about 98% by weight polyamide;
ii) about 1 to about 60% by weight of an acid anhydride-modified polyolefin; and
iii) about 1 to about 60% by weight of a fatty acid additive selected from the group consisting of fatty acid salts, fatty acid amides, and mixtures thereof, wherein the center of the inner core and surface of the outer core layer each has a hardness, and the surface hardness of the outer core layer is greater than the center hardness of the inner core; and
b) a cover having at least one layer disposed about the core, and wherein the acid anhydride-modified polyolefin is an ethylene-vinyl acetate copolymer.
2. The golf ball of claim 1, wherein the polyamide is selected from the group consisting of polyamide 6; polyamide 6,6; polyamide 6,10; polyamide 6,12; polyamide 11; polyamide 12; polyamide 6,9; and polyamide 4,6, and copolymers and blends thereof.
3. The golf ball of claim 1, wherein the acid anhydride used to modify the ethylene-based copolymer is selected from the group consisting of maleic, fumaric, nadic, itaconic, and clorendic acid anhydrides, and substituted derivatives thereof.
4. The golf ball of claim 1, wherein the fatty acid additive is a fatty acid salt and the fatty acid is selected from the group consisting of stearic acid, behenic acid, erucic acid, linoleic acid, oleic acid, palmitic acid, and dimerized derivatives, and mixtures thereof.
5. The golf ball of claim 4, wherein the metal cation of the fatty acid salt is selected from the group consisting of Zn, Na, Li, K, Ca, Mg, Ni, Ba, Mn, Cu, Ti, and Al, and mixtures thereof.
6. The golf ball of claim 1, wherein the fatty acid additive is a fatty acid amide selected from the group consisting of primary monoamides, substituted monoamides, and bisamides.
7. The golf ball of claim 1, wherein the rubber composition has a flex modulus of 1,000 to 60,000 psi and the polyamide composition has a flex modulus of 20,000 psi to 150,000 psi, the flex modulus of the rubber composition being less than the flex modulus of the polyamide composition.
8. The golf ball of claim 1, wherein the center hardness of the inner core is about 15 Shore D or greater and the surface hardness of the outer core is about 40 Shore D or greater, the center hardness of the inner core being less than the surface hardness of the outer core layer.
9. The golf ball of claim 1, wherein the cover is a single layer having a thickness of about 0.015 to about 0.090 inches and is formed from a thermoplastic or thermoset material.
10. The golf ball of claim 9, wherein the cover consists essentially of about 40 to about 99% by weight polyamide; about 1 to about 60% by weight of an acid anhydride-modified polyolefin; and about 1 to about 60% by weight of a fatty acid additive selected from the group consisting of fatty acid salts, fatty acid amides, and mixtures thereof.
11. The golf ball of claim 1, wherein the cover comprises two or more layers and has an overall thickness of about 0.020 to about 0.160 inches and wherein each cover layer is formed from a thermoplastic or thermoset material.
12. The golf ball of claim 11, wherein at least one of the cover layers consists essentially of a polyamide non-ionomeric composition, the polyamide composition consisting essentially of: i) about 40 to about 98% by weight polyamide; ii) about 1 to about 60% by weight of an acid anhydride-modified polyolefin; and iii) about 1 to about 60% by weight of a fatty acid additive selected from the group consisting of fatty acid salts, fatty acid amides, and mixtures thereof.
13. A golf ball, comprising:
a) a dual core having an inner core and outer core layer, the inner core having an outer surface and geometric center and the outer core layer having an outer surface and inner surface; the outer core comprising a rubber composition; and the inner core consisting essentially of a polyamide non-ionomeric composition, the polyamide composition consisting essentially of:
i) about 40 to about 98% by weight polyamide;
ii) about 1 to about 60% by weight of an acid anhydride-modified polyolefin; and
iii) about 1 to about 60% by weight of a fatty acid additive selected from the group consisting of fatty acid salts, fatty acid amides, and mixtures thereof, wherein the center of the inner core and surface of the outer core layer each has a hardness, and the surface hardness of the outer core layer is greater than the center hardness of the inner core; and
b) a cover having at least one layer disposed about the dual core, and wherein the acid anhydride-modified polyolefin is an ethylene-vinyl acetate copolymer.