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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 comprising:
An OFDM receiver comprising:
A method of interpolation using a set of four pilot symbols in a scattered pilot pattern in time-frequency wherein the set of four pilot symbols comprise first and second pilot symbols on a common sub-carrier frequency, spaced in time, and third and fourth pilot symbols transmitted on different sub-carriers on a common OFDM symbol period, the method comprising:
A method of inserting pilot symbols into OFDM sub-frames for transmission by a plurality of transmitting antenna, the OFDM sub-frames having a time domain and a frequency domain, each OFDM sub-frame comprising a plurality of OFDM symbols, the method comprising:
Dependencies are inferred from the claim text.