Paper Info
Title
Low-Complexity EM-based Joint CFO and IQ imbalance Acquisition
Abstract
New air interfaces are currently being developed to meet the high spectral efficiency requirements of the emerging wireless communication systems. In this context, OFDM is considered as a promising air interface candidate for both indoor and outdoor communications. Besides spectral efficiency and power consumption, the production cost of the transceiver should also be optimized. Direct-conversion radio frequency receivers are appealing because they avoid costly intermediate frequency hardware. However, they imply analog IQ separation, introducing a phase and amplitude mismatch between the I and Q branches. A communication system based on OFDM is sensitive to synchronization errors, such as CFO, and to front-end non-idealities, such as IQ imbalance. The goal of this paper is to use the iterative EM algorithm to acquire jointly the CFO and the IQ imbalance. The solution relies on a repetitive preamble and does not require the knowledge of the propagation channel. Based on a second order approximation of the likelihood function, the complexity of the EM algorithm is significantly reduced. The algorithm is shown to perform extremely well: the estimates of the CFO and of the IQ imbalance converge to their ML estimate after less than 3 iterations. While the CFO estimate is robust against variations of the SNR, the IQ imbalance estimate accuracy is reduced at values of the SNR below 10 dB and above 35 dB.
Year
DOI
Venue
2007
10.1109/ICC.2007.477
Glasgow
Keywords
Field
DocType
OFDM modulation,channel estimation,expectation-maximisation algorithm,IQ imbalance acquisition,iterative EM algorithm,low-complexity EM-based joint CFO,power consumption,second order approximation,spectral efficiency,wireless communication systems
Synchronization,Intermediate frequency,Computer science,Expectation–maximization algorithm,Communications system,Communication channel,Real-time computing,Spectral efficiency,Air interface,Orthogonal frequency-division multiplexing
Conference
ISSN
ISBN
Citations 
1550-3607
1-4244-0353-7
14
PageRank 
References 
Authors
1.04
10
4
Name
Order
Citations
PageRank
Horlin François135144.46
A. Bourdoux2596.93
Eduardo Lopez-estraviz3928.68
Liesbet Van Der Perre41013108.24