Apparatus and method for adjusting offset in a wireless communication system

1. A method for controlling an offset adjustment for a Mobile Station (MS) by a Base Station (BS) of a wireless communication system, the method comprising:

if UpLink (UL) data received from the MS does not exist, determining an offset mean value of the MS using a previously estimated offset of the MS;

determining whether to transmit an unsolicited ranging response message (Unsolicited RNG-RSP) using the offset mean value of the MS; and

if it is determined to transmit the Unsolicited RNG-RSP, transmitting to the MS the Unsolicited RNG-RSP,

wherein the Unsolicited RNG-RSP includes an offset adjustment value for the MS.

2. The method of claim 1 , wherein the offset of the MS includes at least one of a timing offset and frequency offset of the MS, and

wherein the offset mean value of the MS includes at least one of a timing offset mean value and frequency offset mean value of the MS.

3. The method of claim 1 , further comprising, before determining the offset mean value of the MS, identifying the number of times of continuously transmitting an Unsolicited RNG-RSP using an offset mean value of the MS determined in a state of non-existence of UL data,

whereby, if the number of times of continuously transmitting the Unsolicited RNG-RSP does not exceed the reference number of times, determining the offset mean value of the MS.

4. The method of claim 1 , wherein the determining of the offset mean value of the MS comprises determining the offset mean value of the MS through an Infinite Impulse Response (IIR) operation that applies the latest estimated offset of the MS.

5. The method of claim 1 , further comprising, after transmitting the Unsolicited RNG-RSP, initializing the offset mean value of the MS.

6. The method of claim 1 , further comprising, after transmitting the Unsolicited RNG-RSP, reactivating a timer driven during a reference time, and not determining an offset mean value of the MS until driving of the timer terminates.

7. The method of claim 1 , further comprising: if the UL data received from the MS exists,

estimating an offset of the MS using the UL data; and

determining an offset mean value of the MS using the offset of the MS,

whereby determining whether to transmit an Unsolicited RNG-RSP using the offset mean value of the MS.

8. The method of claim 1 , further comprising, if the UL data received from the MS does not exist, comparing the number of times of continuous non-existence of UL data with the reference number of times,

wherein, if the number of times of continuous non-existence of UL data is less than the reference number of times, determining the offset mean value of the MS using the previously estimated offset of the MS.

9. The method of claim 8 , further comprising: if the number of times of continuous non-existence of UL data is equal to or is greater than the reference number of times,

setting an offset of the MS to ‘0’; and

determining an offset mean value of the MS using the offset of the MS set to ‘0’, and

whereby determining whether to transmit the Unsolicited RNG-RSP using the determined offset mean value of the MS.

10. The method of claim 9 , wherein the determining of the offset mean value of the MS comprises determining the offset mean value of the MS through an IIR operation that applies the offset of the MS set to ‘0’.

11. An apparatus for use in a Base Station (BS) of a wireless communication system, the apparatus capable of controlling an offset adjustment for a Mobile Station (MS), the apparatus comprising:

a receive apparatus configured to receive a signal from the MS;

an offset determiner configured to determine an offset mean value of the MS using a previously estimated offset of the MS, if UpLink (UL) data received from the MS does not exist;

a controller configured to determine whether to transmit an unsolicited ranging response message (Unsolicited RNG-RSP) using the offset mean value of the MS; and

a transmit apparatus configured to send the MS the Unsolicited RNG-RSP, if transmitting the Unsolicited RNG-RSP,

wherein the Unsolicited RNG-RSP includes an offset adjustment value for the MS.

12. The apparatus of claim 11 , wherein the offset of the MS includes at least one of a timing offset and frequency offset of the MS, and

wherein the offset mean value of the MS includes at least one of a timing offset mean value and frequency offset mean value of the MS.

13. The apparatus of claim 11 , wherein the offset determiner comprises:

an offset estimator configured to estimate an offset of the MS using the UL data, if UL data exists;

an offset setter configured to transmit the offset of the MS estimated in the offset estimator to an offset mean value determiner, if the UL data exists and transmit the latest offset of the MS estimated in the offset estimator to the offset mean value determiner, if the UL data does not exist; and

the offset mean value determiner configured to determine the offset mean value of the MS through an Infinite Impulse Response (IIR) operation that applies the offset of the MS received from the offset setter.

14. The apparatus of claim 11 , wherein, if the number of times of continuously transmitting an Unsolicited RNG-RSP using an offset mean value of the MS determined in a state of non-existence of UL data does not exceed the reference number of times, the controller is configured to control to determine the offset mean value of the MS.

15. The apparatus of claim 11 , wherein, after transmitting the Unsolicited RNG-RSP,

the controller is configured to initialize the offset mean value of the MS and reactivate a timer driven during a reference time, and not determine an offset mean value of the MS until a driving of the timer terminates.

16. The apparatus of claim 11 , wherein, if the number of times of continuous non-existence of UL data is less than the reference number of times, the offset determiner is configured to determine the offset mean value of the MS using the previously estimated offset of the MS.

17. The apparatus of claim 11 , wherein, if the number of times of continuous non-existence of UL data is equal to or is greater than the reference number of times, the offset determiner is configured to determine an offset mean value of the MS using an offset of the MS set to ‘0’.

18. The apparatus of claim 17 , wherein the offset determiner comprises:

an offset estimator configured to, if UL data exists, estimate an offset of the MS using the UL data;

an offset setter configured to, if the UL data exists, transmit the offset of the MS estimated in the offset estimator to an offset mean value determiner and, if the UL data does not exist, transmit the offset of the MS set to ‘0’ to the offset mean value determiner; and

the offset mean value determiner configured to determine the offset mean value of the MS through an IIR operation that applies the offset of the MS received from the offset setter.

19. A Base Station (BS) capable of controlling an offset adjustment for a Mobile Station (MS), the BS comprising:

a receiver configured to receive a signal from the MS;

an offset determiner configured to determine an offset mean value of the MS using a previously estimated offset of the MS, if UpLink (UL) data received from the MS does not exist;

a controller configured to determine whether to transmit an unsolicited ranging response message (Unsolicited RNG-RSP) using the offset mean value of the MS; and

a transmitter configured to send the MS the Unsolicited RNG-RSP, if transmitting the Unsolicited RNG-RSP,

wherein the Unsolicited RNG-RSP includes an offset adjustment value for the MS.

20. The BS of claim 19 , wherein the offset of the MS includes at least one of a timing offset and frequency offset of the MS, and

wherein the offset mean value of the MS includes at least one of a timing offset mean value and frequency offset mean value of the MS.