Liu Awarded Patent for Data Communication with Embedded Pilot InformationProfessor K. J. Ray Liu has been awarded U.S. Patent 7,848,443, issued on December 7, 2010, for his invention, titled "Data Communication with Embedded Pilot Information for Timely Channel Estimation." The co-inventors are Chaiyod Pirak and Jane Z. Wang.
The invention involves embedding pilot information into data at a transmitter for obtaining channel state information at a receiver.
Multiple-input multiple-output (MIMO) communication systems beneficially provide high capacity data communication with greater reliability than their single channel counterparts. Space-time (ST) coding has engendered transmit diversity so as to significantly improve the bit error rate (BER) of data transmission without an increase in transmission power. However, a major challenge in realizing such systems lies in providing the coherent detector with channel state information, which is a measure of the effects of the channel on the propagation of the signal.
Pilot-embedding, also referred to as the pilot-superimposed technique, adds a sequence of pilot signals directly to the data stream. Channel estimation and data detection are accomplished at the receiver through a soft-decoding procedure. This technique achieves better bandwidth efficiency since no time slots are sacrificed for pilot signal use. The pilot-embedding technique does, however, involve higher computational costs in the decoder and a longer delay in the channel estimation process.
The need exists in the field of data communication for channel state information acquisition, which is computationally affordable and able to track channels states in fast-fading channels.
In one aspect of the invention, a method is provided for data communication in which data symbols are first provided at a transmitter. Pilot data are added to each of the data symbols to form pilot-embedded data symbols, at least one of which is transmitted from a transmitting antenna defining one end of a data channel. At least one of the pilot-embedded data symbols is received at a receiving antenna defining an opposite end of the data channel. The data symbols are recovered from the received pilot-embedded data symbols using the estimated channel state coefficient.
In another aspect of the invention, a method for data communication is provided which forms a block codeword from a sequence of data symbols. The codeword is modulated with a plurality of data bearing coefficients and a value from a plurality of pilot values is added thereto to form a pilot-embedded codeword. The pilot-embedded codeword is transmitted and subsequently received at a receiver. At least one channel state coefficient indicative of a characteristic of a corresponding data channel is estimated from the received codeword and the sequence of data symbols is recovered from the received pilot-embedded codeword using the estimated channel state coefficient.
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Published December 19, 2010