Scattered pilot pattern and channel estimation method for MIMO-OFDM systems
First Claim
1. A method of inserting pilot symbols into Orthogonal Frequency Division Multiplexing, OFDM, frames at an OFDM transmitter having at least two transmitting antennas, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain, the method comprising the steps of:
- for a first antenna of the OFDM transmitter, inserting scattered pilot symbols in a scattered pattern in time-frequency by inserting a first set of pilot symbols in a first pattern in time-frequency and inserting a second set of pilot symbols in a second pattern in time-frequency at the same frequencies as the first pattern, offset by one OFDM symbol in the time domain; and
for a second antenna of the OFDM transmitter, inserting scattered pilot symbols using the same scattered pattern.
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Accused Products
Abstract
A method and apparatus are provided for reducing the number of pilot symbols within a MIMO-OFDM communication system, and for improving channel estimation within such a system. For each transmitting antenna in an OFDM transmitter, pilot symbols are encoded so as to be unique to the transmitting antenna. The encoded pilot symbols are then inserted into an OFDM frame to form a diamond lattice, the diamond lattices for the different transmitting antennae using the same frequencies but being offset from each other by a single symbol in the time domain. At the OFDM receiver, a channel response is estimated for a symbol central to each diamond of the diamond lattice using a two-dimensional interpolation. The estimated channel responses are smoothed in the frequency domain. The channel responses of remaining symbols are then estimated by interpolation in the frequency domain.
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Citations
25 Claims
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1. A method of inserting pilot symbols into Orthogonal Frequency Division Multiplexing, OFDM, frames at an OFDM transmitter having at least two transmitting antennas, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain, the method comprising the steps of:
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for a first antenna of the OFDM transmitter, inserting scattered pilot symbols in a scattered pattern in time-frequency by inserting a first set of pilot symbols in a first pattern in time-frequency and inserting a second set of pilot symbols in a second pattern in time-frequency at the same frequencies as the first pattern, offset by one OFDM symbol in the time domain; and for a second antenna of the OFDM transmitter, inserting scattered pilot symbols using the same scattered pattern. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus, comprising:
an Orthogonal Frequency Division Multiplexing, OFDM, transmitter having at least two transmit antennas, the OFDM transmitter being adapted to insert pilot symbols into OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain, and configured to; insert, using a first antenna of the OFDM transmitter, scattered pilot symbols in a scattered pattern in time-frequency by inserting a first set of pilot symbols in a first pattern in time-frequency and inserting a second set of pilot symbols in a second pattern in time-frequency at the same frequencies as the first pattern, offset by one OFDM symbol in the time domain; and insert, using a second antenna of the OFDM transmitter, scattered pilot symbols using the same scattered pattern. - View Dependent Claims (8, 9, 10)
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11. A User Equipment (UE), comprising:
one or more processors configured to; receive, from a first antenna of an OFDM transmitter, scattered pilot symbols in a scattered pattern in time-frequency, wherein the scattered pattern includes a first set of pilot symbols in a first pattern in time-frequency and a second set of pilot symbols in a second pattern in time-frequency at the same frequencies as the first pattern, offset by one OFDM symbol in the time domain; and receive, from a second antenna of the OFDM transmitter, scattered pilot symbols using the same scattered pattern. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method, comprising:
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receiving, from a first antenna of an OFDM transmitter, scattered pilot symbols in a scattered pattern in time-frequency, wherein the scattered pattern includes a first set of pilot symbols in a first pattern in time-frequency and a second set of pilot symbols in a second pattern in time-frequency at the same frequencies as the first pattern, offset by one OFDM symbol in the time domain; and receiving, from a second antenna of the OFDM transmitter, scattered pilot symbols using the same scattered pattern. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A method of inserting pilot symbols into Orthogonal Frequency Division Multiplexing, OFDM, frames at an OFDM transmitter having at least two transmitting antennas, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain, the method comprising the steps of:
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for a first antenna of the OFDM transmitter, inserting scattered pilot symbols in a scattered pattern in time-frequency by inserting pilot symbols corresponding to the first antenna in a first pattern in time-frequency; and for a second antenna of the OFDM transmitter, inserting scattered pilot symbols using the scattered pattern by inserting pilot symbols corresponding to the second antenna, wherein the pilot symbols for the first antenna correspond to a first code and the pilot symbols for the second antenna correspond to a second code.
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24. A device for inserting pilot symbols into Orthogonal Frequency Division Multiplexing, OFDM, frames at an OFDM transmitter having at least two transmitting antennas, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain, comprising:
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a first antenna of the OFDM transmitter; a second antenna of the OFDM transmitter; and one or more processors configured to; for a first antenna of the OFDM transmitter, insert scattered pilot symbols in a scattered pattern in time-frequency by inserting pilot symbols corresponding to the first antenna in a first pattern in time-frequency; and for a second antenna of the OFDM transmitter, insert scattered pilot symbols using the scattered pattern by inserting pilot symbols corresponding to the second antenna, wherein the pilot symbols for the first antenna correspond to a first code and the pilot symbols for the second antenna correspond to a second code.
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25. A non-transitory computer readable medium for inserting pilot symbols into Orthogonal Frequency Division Multiplexing, OFDM, frames at an OFDM transmitter having at least two transmitting antennas, the OFDM frames having a time domain and a frequency domain, each OFDM frame comprising a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain, the computer readable medium storing instructions to cause a processor to perform operations comprising:
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for a first antenna of the OFDM transmitter, inserting scattered pilot symbols in a scattered pattern in time-frequency by inserting pilot symbols corresponding to the first antenna in a first pattern in time-frequency; and for a second antenna of the OFDM transmitter, inserting scattered pilot symbols using the scattered pattern by inserting pilot symbols corresponding to the second antenna, wherein the pilot symbols for the first antenna correspond to a first code and the pilot symbols for the second antenna correspond to a second code.
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Specification