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US 7,889,799 B2Granted
Method and apparatus for OFDM channel estimation
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsJiann-Ching Guey, Havish Koorapaty
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AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsJiann-Ching Guey, Havish Koorapaty
Estimating the term…
According to methods and apparatus taught herein, an Orthogonal Frequency Division Multiplexed (OFDM) transmitter increases pilot density in the edge regions of an OFDM signal, such as by using additional pilot sub carriers in the edge regions. For example, the OFDM signal includes first pilot sub carriers uniformly distributed across the frequency band of the OFDM signal, and second pilot sub carriers distributed within the edge regions. A corresponding OFDM receiver circuit uses the increased pilot density to improve channel estimation. For example, the receiver circuit uses the first pilot sub carriers in a Maximum Likelihood (ML) estimation process to obtain first channel estimates, and uses the results of ML estimation along with the second pilot sub carriers in a Minimum Mean Square Error (MMSE) estimation process to obtain second channel estimates. The receiver forms the improved channel estimates using the first and second channel estimates.
A method of channel estimation for an Orthogonal Frequency Division Multiplexed (OFDM) signal, the method comprising:
A receiver circuit configured for channel estimation for a received Orthogonal Frequency Division Multiplexed (OFDM) signal having an increased pilot density within one or both edge regions of a frequency band spanned by the OFDM signal, relative to a middle region of the frequency band, the receiver circuit comprising one or more processing circuits configured to use the increased pilot density to improve channel estimation for the OFDM signal within the one or both edge regions, wherein the OFDM signal includes first pilot symbols in first pilot sub carriers that are uniformly distributed across the frequency band and second pilot symbols in second pilot sub carriers that are distributed in the one or both edge regions, and wherein the one or more processing circuits are configured to use the increased pilot density to improve channel estimation for the OFDM signal within the one or both edge regions by generating first channel estimates using a Maximum Likelihood (ML) estimation process based on the first pilot symbols, and generating second channel estimates for the one or both edge regions using a Minimum Mean Square Error (MMSE) estimation process based on the second pilot symbols and channel statistics determined from the ML estimation process.
A method of channel estimation in a receiver configured to receive an Orthogonal Frequency Division Multiplexed (OFDM) signal, the method comprising:
Dependencies are inferred from the claim text.