Joint I/Q Imbalance Compensation and Channel Equalization for STBC MISO/MIMO OFDM Systems, and FPGA Design
Date Issued
2010
Date
2010
Author(s)
Lin, Yi-Hung
Abstract
In this thesis, the joint I/Q imbalance compensation and channel equalization and
the start up self-calibration algorithm of I/Q imbalance are proposed. The IEEE 802.11n
MISO/MIMO OFDM transceiver is adopted as a test vehicle to demonstrate the presented
algorithm. The self-calibration algorithm is performed at transceiver start-up to
estimate the end user I/Q imbalance parameter, including phase and gain mismatch.
Therefore, the Tx/Rx I/Q imbalance of end user can be alleviated by self calibration
and compensation. In addition, the start-up self calibration and compensation can make
conventional CFO estimation and compensation more reliable under end user Rx I/Q
imbalance impairment. Although Rx I/Q imbalance self compensation and CFO have
been compensated, the remote Tx I/Q imbalance and quasi-static channel variation
degrade the system performance. Therefore, based on MMSE criteria, the joint I/Q imbalance
compensation and channel equalization is presented to minimize the remote Tx
I/Q imbalance and quasi-static channel variation during the physical data transmission.
Consequently, the performance improvement is 2-dB compared with LS algorithm.
On the other hand, the cost-e cient architecture of joint I/Q imbalance compensation
and channel equalization is proposed to reduce hardware complexity based on
strength-reduced transformation. The cost e cient architecture of joint I/Q imbalance
and channel equalization contains three parts: MIMO detection, updating process and
channel estimation. The overall architecture obtains the 35% reduction e ciency in
multiplication. Furthermore, The uncoded SER of this design is the same as the direct
implementation.
Finally, the joint I/Q imbalance compensation and channel equalization is realized by
FPGA board EP1S80 at 40MHz and the system evaluations are measured by Tektronix TLA715 pattern generator and logic analyzer.
Subjects
I/Q imbalance
I/Q mismatch
Type
thesis
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