APPARATUS AND METHOD FOR CANCELING DC OFFSET IN BROADBAND WIRELESS ACCESS COMMUNICATION SYSTEM

• US 20090129494A1
• Filed: 11/21/2008
• Published: 05/21/2009
• Est. Priority Date: 11/21/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: LEE, Dong-Woo, Choi, Hee-Chan, Shin, Yong-Won
• Granted Patent: US 8,249,194 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 25/061 providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset removal of dc offset in coupling arrangements H04L25/029, H04L25/0296
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation

Abstract

An apparatus and method for canceling a Direct Current (DC) offset in a Broadband Wireless Access (BWA) communication system are provided. The method includes canceling a DC offset by performing self-calibration in a modulator/demodulator (modem), attempting initial synchronization acquisition in the modem, and if the initial synchronization acquisition succeeds, canceling a DC offset by performing DC offset trace and cancellation.

Claims

1. A method for canceling a Direct Current (DC) offset in a receiver having a modem and a Radio Frequency (RF) unit of a Broadband Wireless Access (BWA) communication system, the method comprising:

canceling, by a modem, a DC offset by performing self calibration;

performing, by the modem, an initial synchronization acquisition; and

canceling, by the modem, the DC offset by performing a DC offset trace and cancellation process if the initial synchronization acquisition succeeds.

2. The method of claim 1, before the step of canceling, by a modem, a DC offset by performing self calibration, further comprising:

determining, by the modem, a gain index for the initial synchronization acquisition in a coarse frame synchronization step and applying the gain index to a Radio Frequency (RF) unit.

3. The method of claim 1, wherein the step of canceling, by a modem, a DC offset by performing self calibration, comprises:

measuring the DC offset, by the modem, with no signal input to a RF unit;

determining whether the measured DC offset is more than a reference value; and

performing an inverse calibration for the RF unit by a magnitude of difference between the measured DC offset and the reference value when the measured DC offset is more than the reference value.

4. The method of claim 1, wherein canceling, by the modem, the DC offset by performing a DC offset trace and cancellation process, comprises:

determining whether a measured DC offset is more than a reference value, when the modem senses occurrence of a frame interrupt;

measuring a current gain index value when the measured DC offset is more than the reference value; and

performing an inverse calibration for the RF unit by storing a calibration value

in a DC offset correction end of an RF unit depending on the current gain index value.

5. An apparatus for canceling a Direct Current (DC) offset in a receiver of a Broadband Wireless Access (BWA) communication system, the apparatus comprising:

a modem for canceling a DC offset by performing a self calibration, performing a initial synchronization acquisition, and canceling the DC offset by performing a DC offset trace and cancellation process when the initial synchronization acquisition succeeds.

6. The apparatus of claim 5, further comprises a Radio Frequency (RF) unit, used by the modem, for determining a gain index for the initial synchronization acquisition in a coarse frame synchronization step and applying a set value for the gain index.

7. The apparatus of claim 5, wherein the modem measures the DC offset with no signal input to the RF unit, determines whether the measured DC offset is more than a reference value and performs an inverse calibration for the RF unit by a magnitude of difference between the measured DC offset and the reference value when the measured DC offset is more than the reference value.

8. The apparatus of claim 5, wherein the modem determines whether a measured DC offset is more than a reference value when the modem senses occurrence of a frame interrupt, measures a current gain index value when the measured DC offset is more than the reference value and performs an inverse calibration for the RF unit by storing a calibration value in a DC offset correction end of an RF unit depending on the current gain index value.