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US 8,135,056 B2Granted
Noise and channel estimation using low spreading factors
AssigneeQUALCOMM Incorporated
InventorsDa-shan Shiu, Durga Prasad Malladi, Srikrishna Bhashyam
Life of this patent
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Abstract
Noise measurements are made within a fraction of a single symbol period of a longest orthogonal code symbol. A control processor identifies an unoccupied code having a spreading factor that is less than a longest spreading factor for the system. A despreader measures symbol energy based on the unoccupied code and a noise estimator generates noise estimations based on the measured symbol energies. The subscriber station uses similar techniques in order to perform channel estimations within a period that is a fraction of a symbol period of a longest-spreading-factor code.
Claims49
A noise measurement method comprising:
- determining that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor of an occupied longest-spreading-factor code associated with a longest-spreading factor time period;
- measuring a first symbol energy, during a first short time period, based on the short-spreading-factor code to provide a first measured symbol energy;
- measuring a second symbol energy, during a second short time period, based on the short-spreading-factor code to provide a second measured symbol energy, wherein the first and second short time periods occupy different time periods within the longest-spreading-factor time period, wherein the first symbol energy corresponds to an energy associated with a symbol having a first symbol type and the second symbol energy corresponds to an energy associated with a symbol having the first symbol type;
- and
- generating a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
2 more elements
An apparatus comprising:
- means for determining that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor of an occupied longest-spreading-factor code associated with a longest-spreading factor time period;
- means for measuring a first symbol energy, during a first short time period, based on the short-spreading-factor code to provide a first measured symbol energy;
- means for measuring a second symbol energy, during a second short time period, based on the short-spreading-factor code to provide a second measured symbol energy, wherein the first and second short time periods occupy different time periods within the longest-spreading-factor time period, wherein the first symbol energy corresponds to an energy associated with a symbol having a first symbol type and the second symbol energy corresponds to an energy associated with a symbol having the first symbol type;
- and
- means for generating a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
2 more elements
An apparatus comprising:
- a control processor configured to determine that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor of an occupied longest-spreading-factor code associated with a longest-spreading factor time period;
- a despreader configured to measure a first symbol energy, during a first short time period, based on the short-spreading-factor code to provide a first measured symbol energy, and to measure a second symbol energy, during a second short time period, based on the short-spreading-factor code to provide a second measured symbol energy, wherein the first and second short time periods occupy different time periods within the longest-spreading-factor time period, wherein the first symbol energy corresponds to an energy associated with a symbol having a first symbol type and the second symbol energy corresponds to an energy associated with a symbol having the first symbol type;
- and
- a noise estimator configured to generate a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
1 more element
A computer-readable medium embodying instructions which, when executed by a processor, cause said processor to perform a noise measurement method comprising:
- determining that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor of an occupied longest-spreading-factor code associated with a longest-spreading factor time period;
- providing a control signal to a despreader to cause the despreader to measure a first symbol energy, during a first short time period, based on the short-spreading-factor code to provide a first measured symbol energy, and to measure a second symbol energy, during a second short time period, based on the short-spreading-factor code to provide a second measured symbol energy, wherein the first symbol energy corresponds to an energy associated with a symbol having a first symbol type and the second symbol energy corresponds to an energy associated with a symbol having the first symbol type;
- and
- providing a control signal to a noise estimator to cause the noise estimator to generate a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
1 more element
A noise measurement method, comprising:
- determining that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor;
- measuring a first symbol energy based on a parent code of the short-spreading-factor code to provide a first measured symbol energy, the first symbol energy being measured in a first parent code symbol period;
- measuring a second symbol energy based on the parent code of the short-spreading-factor code to provide a second measured symbol energy, the second symbol energy being measured in a second parent code symbol period, wherein data in any occupied child codes of the parent code of the short-spreading-factor code is the same in the first parent code symbol period and the second parent code symbol period;
- and
- generating a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
2 more elements
A computer-readable medium embodying instructions which, when executed by a processor, cause said processor to:
- determine that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor;
- measure a first symbol energy based on the parent code of the short-spreading-factor code to provide a first measured symbol energy, the first symbol energy being measured in a first parent code symbol period;
- measure a second symbol energy based on a parent code of the short-spreading-factor code to provide a second measured symbol energy, the second symbol energy being measured in a second parent code symbol period, wherein data in any occupied child codes of the parent code of the short-spreading-factor code is the same in the first parent code symbol period and the second parent code symbol period;
- and
- generate a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
2 more elements
An apparatus, comprising:
- means for determining that a short-spreading-factor code is unoccupied, wherein the short-spreading-factor code has a short spreading factor that is less than a longest spreading factor;
- means for measuring a first symbol energy based on a parent code of the short-spreading factor code to provide a first measured symbol energy, the first symbol energy being measured in a first parent code symbol period;
- means for measuring a second symbol energy based on the parent code of the short spreading-factor code to provide a second measured symbol energy, the second symbol energy being measured in a second parent code symbol period, wherein data in any occupied child codes of the parent code of the short-spreading-factor code is the same in the first parent code symbol period and the second parent code symbol period;
- and
- means for generating a first noise estimate based on a difference between the first measured symbol energy and the second measured symbol energy.
2 more elements
Dependencies are inferred from the claim text.