Apparatus and method for canceling direct current (DC) offset in broadband wireless access communication system

• US 8,249,194 B2
• Filed: 11/21/2008
• Issued: 08/21/2012
• 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, Shin, Yong-Won, Choi, Hee-Chan
• Primary Examiner(s): Torres, Juan A
• Application Number:
  US12/275,308
• Publication Number:
  US 20090129494A1
• Time in Patent Office: 1,369 Days
• Field of Search: 375/316
• US Class Current: 375/316
• 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 Integrated Circuit (RFIC) 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;

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

outputting by the modem a control signal to the RFIC unit comprising a calibration value of the DC offset that is stored in the RFIC unit for controlling calibrating a DC offset by the RFIC unit.

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 an RF unit by storing a calibration value in a DC offset correction end of the 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 modern comprising an Automatic Gain Controller (AGC) for setting a gain of a receiving end of an Radio Frequency Integrated Circuit (RFIC), said modem being configured for canceling a received DC offset by performing a self-calibration of the modem, performing an initial synchronization acquisition, and canceling the DC offset by performing a DC offset trace and cancellation process when the initial synchronization acquisition succeeds; and

a receiver coupled to the modem, said receiver comprising the RFIC, said RFIC being configured for controlling reception/transmission switching and for performing an initialization process and a self-calibration of the RFIC under the control of the modem by receiving a control signal output from the modem including a DC offset value for self-calibrating the RFIC.

6. The apparatus of claim 5, wherein the RFIC includes means 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 that is used by the modem.

7. The apparatus of claim 5, wherein the modem includes means for measuring the DC offset without a signal being input to the RFIC, and means for comparing whether the measured DC offset is greater than a reference value and controls an inverse calibration by the RFIC unit according to a magnitude of difference between the measured DC offset and the reference value, when the measured DC offset is greater 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 RFIC by storing a calibration value in a DC offset correction end of an RF unit depending on the current gain index value.