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AssigneeApple Inc.
InventorsJianglei Ma, Ming Jia, Hua Xu, Wen Tong, Peiying Zhu, Dong-Sheng Yu, Hang Zhang
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A method and apparatus for improving channel estimation within an OFDM communication system. Channel estimation in OFDM is usually performed with the aid of pilot symbols. The pilot symbols are typically spaced in time and frequency. The set of frequencies and times at which pilot symbols are inserted is referred to as a pilot pattern. In some cases, the pilot pattern is a diagonal-shaped lattice, either regular or irregular. The method first interpolates in the direction of larger coherence (time or frequency). Using these measurements, the density of pilot symbols in the direction of faster change will be increased thereby improving channel estimation without increasing overhead. As such, the results of the first interpolating step can then be used to assist the interpolation in the dimension of smaller coherence (time or frequency).
A method of inserting pilot symbols in orthogonal frequency division multiplexing (OFDM) frames for transmission by a plurality of antennas, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols, the method comprising, for at least a first frame:
A non-transitory, computer accessible memory medium storing program instructions for inserting pilot symbols into orthogonal frequency division multiplexing (OFDM) frames for transmission by a plurality of antennas, the OFDM frames having a time domain and a frequency domain, each OFDM sub-frame comprising a plurality of OFDM symbols, wherein the program instructions are executable by one or more processors to, for at least a first frame:
An orthogonal frequency division multiplexing (OFDM) transmitter adapted to insert pilot symbols into OFDM frames, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols, comprising:
Dependencies are inferred from the claim text.