Apparatus and method for adaptively changing uplink power control scheme according to mobile status in a TDD mobile communication system

• US 20060040619A1
• Filed: 08/19/2005
• Published: 02/23/2006
• Est. Priority Date: 08/20/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kwon, Young-Hoon, Sung, Sang-Hoon, Yang, Jang-Hoon, Hwang, In-Seok, Yoon, Soon-Young, Cho, Jae-Hee, Huh, Hoon
• Granted Patent: US 7,558,535 B2
• Time in Patent Office: Days
• US Class Current: 455/69
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/28 using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission

Abstract

An apparatus and method for changing an uplink power control scheme according to mobile status in a TDD mobile communication system are provided. A subscriber station transmits to a base station a power control change request message including information about a requested power control scheme. Upon receipt of the power control change request message, the base station selects a power control scheme for the uplink of the subscriber station and transmits to the subscriber station a power control change command message including information about the selected power control scheme. The subscriber station extracts, upon receipt of the power control change command message from the base station, the power control scheme information from the power control change command message and selects a power control scheme according to the extracted information.

Claims

1. A base station device in a mobile communication system supporting at least two uplink power control schemes, comprising:

a mobility estimator for generating a mobility index by estimating the velocity of a subscriber station; and

a power controller for selecting a power control scheme for the uplink of a subscriber station from among the at least two power control schemes by comparing the mobility index with a threshold.

2. The base station device of claim 1, wherein the power controller selects an open-loop power control scheme if the mobility index is greater than the threshold, and selects a closed-loop power control scheme if the mobility index is less than the threshold.

3. The base station device of claim 1, further comprising a medium access control (MAC) entity for generating a power control change command message to be transmitted to the subscriber station, if the selected power control scheme is different from a previous power control scheme.

4. The base station device of claim 3, wherein the power control change command message includes a Power control mode change field indicating a requested power control scheme, a Start Frame field indicating the start time of applying the indicated power control scheme, a Power adjust field indicating a power control command about the transmit power of the subscriber station if the indicated power control scheme is the closed-loop power control scheme, and an Offset_perSS field indicating a margin which is set taking into account the different between a point in time when the transmit power of the subscriber station is calculated and an actual uplink transmission point in time if the indicated power control scheme is the open-loop power control scheme.

5. The base station device of claim 1, wherein the power controller selects a power control scheme periodically or upon receipt of a power control change request message from the subscriber station.

6. The base station device of claim 5, wherein the power control change request message includes a Power control mode change field indicating a power control scheme requested by the subscriber station, and a UL Tx Power field indicating the transmit power of an uplink burst that carries the power control change request message.

7. The base station device of claim 1, wherein the mobile communication system is orthogonal frequency division multiplexing/orthogonal frequency division multiple access-time division duplex (OFDM/OFDMA-TDD) communication system.

8. A subscriber station device in a mobile communication system supporting at least two power control schemes, comprising:

a medium access control (MAC) entity for, upon receipt of a power control change command message from a base station, extracting information about a power control scheme requested by the base station from the power control change command message; and

a power controller for selecting a power control scheme according to the extracted information received from the MAC entity and determining the transmit power of an uplink burst according to the selected power control scheme.

9. The subscriber station device of claim 8, wherein the power control change command message includes a Power control mode change field indicating the power control scheme requested by the base station, a Start Frame field indicating the start time of applying the indicated power control scheme, a Power adjust field indicating a power control command about the transmit power of a subscriber station if the indicated power control scheme is a closed-loop power control scheme, and an Offset_perSS field indicating a margin which is set taking into account the different between a point in time when the transmit power of the subscriber station is calculated and an actual uplink transmission point in time if the indicated power control scheme is an open-loop power control scheme.

10. The subscriber station device of claim 8, further comprising a mobility estimator for generating a mobility index by estimating the velocity of the subscriber station,

wherein the power controller selects the open-loop power control scheme if the mobility index is greater than a threshold, and selects the closed-loop power control scheme if the mobility index is less than the threshold, and

wherein the MAC entity generates a power control change request message to be transmitted to the base station, if the selected power control scheme is different from a previous power control scheme.

11. The subscriber station device of claim 10, wherein the power control change request message includes a Power control mode change field indicating a power control scheme requested by the subscriber station, and a UL Tx Power field indicating the transmit power of an uplink burst that carries the power control change request message.

12. The subscriber station device of claim 8, wherein if the subscriber station requests a bandwidth to the base station, the MAC entity generates a bandwidth request message including information about transmit power.

13. The subscriber station device of claim 12, wherein the bandwidth request message includes a Bandwidth Request (BR) field indicating the amount of uplink data to be transmitted and a UL Tx Power field indicating the transmit power of an uplink burst that carries the bandwidth request message.

14. The subscriber station device of claim 8, wherein the mobile communication system is orthogonal frequency division multiplexing/orthogonal frequency division multiple access-time division duplex (OFDM/OFDMA-TDD) communication system.

15. A method of adaptively determining an uplink power control scheme in a mobile communication system supporting at least two uplink power control schemes, comprising the steps of:

(1) deciding by a base station a power control scheme for the uplink of a subscriber station according to the status of the subscriber station;

(2) transmitting to the subscriber station by the base station a power control change command message including information about the selected power control scheme; and

(3) extracting by the subscriber station, upon receipt of the power control change command message from the base station, the power control scheme information from the power control change command message and selecting by the subscriber station a power control scheme according to the extracted information.

16. The method of claim 15, wherein step (1) is performed periodically.

17. The method of claim 15, wherein step (1) comprises the step of selecting the power control scheme for the uplink of the subscriber station by comparing a mobility index indicating the velocity of the subscriber station with a threshold.

18. The method of claim 15, wherein step (2) comprises the steps of:

comparing the selected power control scheme with a previous power control scheme; and

transmitting to the subscriber station the power control command message with the power control scheme information, if the selected power control scheme is different from the previous power control scheme.

19. The method of claim 15, wherein the power control change command message includes a Power control mode change field indicating the power control scheme requested by the base station, a Start Frame field indicating the start time of applying the indicated power control scheme, a Power adjust field indicating a power control command about the transmit power of the subscriber station if the indicated power control scheme is a closed-loop power control scheme, and an Offset_perSS field indicating a margin which is set taking into account the different between a point in time when the transmit power of the subscriber station is calculated and an actual uplink transmission point in time if the indicated power control scheme is an open-loop power control scheme.

20. A method of adaptively determining an uplink power control scheme in a mobile communication system supporting at least two uplink power control schemes, comprising the steps of:

(a) transmitting to a base station by a subscriber station a power control change request message including information about a requested power control scheme;

(b) deciding by the base station, upon receipt of the power control change request message, a power control scheme for the uplink of the subscriber station;

(c) transmitting to the subscriber station by the base station a power control change command message including information about the selected power control scheme; and

(d) extracting by the subscriber station, upon receipt of the power control change command message from the base station, the power control scheme information from the power control change command message and selecting by the subscriber station a power control scheme according to the extracted information.

21. The method of claim 20, further comprising the step of determining by the subscriber station whether to change a power control scheme based on the velocity of the subscriber station.

22. The method of claim 20, wherein step (b) comprises the step of selecting the power control scheme for the uplink of the subscriber station by comparing a mobility index indicating the velocity of the subscriber station with a threshold.

23. The method of claim 20, wherein step (c) comprises the steps of:

comparing the selected power control scheme with a previous power control scheme; and

transmitting to the subscriber station the power control command message with the power control scheme information, if the selected power control scheme is different from the previous power control scheme.

24. The method of claim 20, wherein the power control change request message includes a Power control mode change field indicating a power control scheme requested by the subscriber station, and a UL Tx Power field indicating the transmit power of an uplink burst that carries the power control change request message.

25. The method of claim 20, wherein the power control change command message includes a Power control mode change field indicating the power control scheme requested by the base station, a Start Frame field indicating the start time of applying the indicated power control scheme, a Power adjust field indicating a power control command about the transmit power of the subscriber station if the indicated power control scheme is a closed-loop power control scheme, and an Offset_perSS field indicating a margin which is set taking into account the different between a point in time when the transmit power of the subscriber station is calculated and an actual uplink transmission point in time if the indicated power control scheme is an open-loop power control scheme.

26. A method of determining an uplink power control scheme in a base station in a mobile communication system supporting at least two uplink power control schemes, comprising the steps of:

generating a mobility index by estimating the velocity of a subscriber station;

deciding a power control scheme for the uplink of a subscriber station according to the mobility index; and

transmitting to the subscriber station a power control change command message including information about the selected power control scheme, if the selected power control scheme is different from a previous power control scheme.

27. The method of claim 26, wherein the power control scheme selecting step is performed periodically or upon request from the subscriber station.

28. The method of claim 26, wherein the power control change command message includes a Power control mode change field indicating the power control scheme requested by the base station, a Start Frame field indicating the start time of applying the indicated power control scheme, a Power adjust field indicating a power control command about the transmit power of the subscriber station if the indicated power control scheme is a closed-loop power control scheme, and an Offset_perSS field indicating a margin which is set taking into account the different between a point in time when the transmit power of the subscriber station is calculated and an actual uplink transmission point in time if the indicated power control scheme is an open-loop power control scheme.

29. A method of determining an uplink power control scheme in a subscriber station in a mobile communication system supporting at least two power control schemes, comprising the steps of:

extracting, upon receipt of a power control change command message from a base station, information about a power control scheme requested by the base station from the power control change command message;

deciding a power control scheme according to the extracted information; and

determining the transmit power of an uplink burst according to the selected power control scheme.

30. The method of claim 29, wherein the power control change command message includes a Power control mode change field indicating the power control scheme requested by the base station, a Start Frame field indicating the start time of applying the indicated power control scheme, a Power adjust field indicating a power control command about the transmit power of a subscriber station if the indicated power control scheme is a closed-loop power control scheme, and an Offset_perSS field indicating a margin which is set taking into account the different between a point in time when the transmit power of the subscriber station is calculated and an actual uplink transmission point in time if the indicated power control scheme is an open-loop power control scheme.

31. The method of claim 29, further comprising the steps of:

determining the uplink power control scheme according to the status of the subscriber station; and

transmitting to the base station a power control change request message, if the determined power control scheme is different from a previous power control scheme.

32. The method of claim 31, wherein the power control change request message includes a Power control mode change field indicating the power control scheme requested by the subscriber station, and a UL Tx Power field indicating the transmit power of an uplink burst that carries the power control change request message.

33. A method of determining an uplink power control mode in a broadband wireless communication system supporting an open loop power control and a closed loop power control, comprising the steps of:

transmitting a power control change request message from a subscriber station (SS) to base station (BS) to change the power control mode;

deciding by the BS of the change of the power control mode between the open loop power control and closed loop power control; and

transmitting a power control change response message from the BS to the SS including the decided power control mode.