Method for estimating and compensating carrier frequency offset and I/Q imbalance

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(11)

EP 1 793 551 A8

(12)	CORRECTED EUROPEAN PATENT APPLICATION
	Note: Bibliography reflects the latest situation

(15)	Correction information:
	Corrected version no 1 (W1 A2)

(48)	Corrigendum issued on:
	17.10.2007 Bulletin 2007/42

(43)	Date of publication:
	06.06.2007 Bulletin 2007/23

(21)	Application number: 06125251.6

(22)	Date of filing: 01.12.2006

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International Patent Classification (IPC):

H04L 27/26^(2006.01)

H04L 27/38^(2006.01)

(84)	Designated Contracting States:
	AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR
	Designated Extension States:
	AL BA HR MK YU

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Priority:

02.12.2005 EP 05111627

(71)	Applicants:
	INTERUNIVERSITAIR MICROELEKTRONICA CENTRUM VZW 3001 Leuven (BE) Samsung Electronics Co., Ltd Suwon-si 442-743, Gyeonggi-do (KR)

(72)	Inventor:
	De Rore, Stefaan 3061, Leefdaal (BE)

(74)	Representative: Sarlet, Steven Renaat Irène et al
	Gevers & Vander Haeghen, Holidaystraat, 5 1831 Diegem 1831 Diegem (BE)

(54)	Method for estimating and compensating carrier frequency offset and I/Q imbalance

(57) A method for estimating and compensating carrier frequency offset (CFO) and I/Q imbalance introduced on an RF multicarrier signal received via a transmission channel on a direct downconversion analog receiver. The method comprises the steps of:
(a) rough CFO estimation by
- using a preamble comprising at least a first set of training symbols in 3 equal groups of length I and a second set of training symbols built by taking the first set and applying an artificial CFO on it, and
- measuring the angle rotation between the repeated training symbols and
- weighting the angle measurements;
(b) fine CFO estimation whereby a CFO-with -IQ algorithm is applied for high SNRs and a standard ML algorithm is applied for low SNRs. The CFO-with-IQ algorithm is based on weighted estimates of cosφ and sinφ based on the first and the second set of training symbols;
(c) combining the rough and fine CFO estimates to obtain a correct CFO estimate.