TDMA communication system having enhanced power control

• US 20030207695A1
• Filed: 02/16/2001
• Published: 11/06/2003
• Est. Priority Date: 06/13/2000
• Status: Active Grant

• Current Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Original Assignee: Cingular Wireless II LLC (AT&T, Inc.)
• Inventors: Chuang, Justin Chi-I, Chang, Li Fung, Kostic, Zoran, Sollenberger, Nelson Ray, Qiu, Xiaoxin, Chawla, Kapil K., Timiri, Shailender B.
• Granted Patent: US 6,754,506 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets

Abstract

A TDMA wireless communication system adjusts the power control target and transmission power based upon link quality to enhance voice capacity. The power can be adjusted in response to the average SNIR and number of decoding errors in a link quality reporting period. The power control target can be increased and decreased in discrete intervals after evaluating the number of decoding errors in the reporting period. The transmission power can be adjusted towards the new power control target based upon the average SNIR.

Claims

1. A method for controlling power in a wireless TDMA system, comprising:

receiving a decoding error signal from a receiver indicative of a number of data decoding errors detected by a receiver for a decoding error reporting period;

receiving a link quality measurement value from the receiver for a link quality reporting period;

increasing a power control target by an up step interval or decreasing the power control target by a down step interval based upon the decoding error signal; and

adjusting a signal transmission power based upon the link quality measurement.

2. The method according to claim 1, wherein the decoding error signal includes a frame error indicator that is set to a predetermined value if the number of data decoding errors in a given decoding error reporting period is greater than a predetermined threshold.

3. The method according to claim 1, wherein the decoding error reporting period corresponds to a predetermined number of frames.

4. The method according to claim 1, wherein the up and down step interval sizes correspond to an average decoding error probability.

5. The method according to claim 1, wherein the link quality measurement is selected from the group consisting of SINR, BER, and BLER.

6. The method according to claim 1, wherein the link quality measurement includes an average SINR value.

7. The method according to claim 1, further including increasing the signal transmission power if the link quality measurement is less than a predetermined target level.

8. The method according to claim 7, further including decreasing the signal transmission power if the link quality measurement level is greater than a predetermined target level.

9. The method according to claim 1, wherein the link quality reporting period corresponds to a predetermined number of frames.

10. The method according to claim 1, further including adjusting the signal transmission power according to P(n+1)=P(n)+β

(Γ

(n+1)−

{overscore (γ

)}(n)), where, P(n) is the transmission power of the nth link quality reporting period, Γ

(n+1) is the power control target in the (n+1) link quality reporting period, {overscore (γ

)}(n) is the average SINR in the nth link quality reporting period, and β

is a damping factor.

11. A method for controlling power in an EGPRS system, comprising:

providing a first loop for adjusting a signal transmission power based upon a link quality measure received from a receiver for each link quality reporting period; and

providing a second loop for adjusting a power control target based upon a decoding error signal received from the receiver for each decoding error reporting period.

12. The method according to claim 11, wherein the link quality measure corresponds to an average SINR for the link quality reporting period.

13. The method according to claim 11, wherein the link quality reporting period corresponds to a predetermined number of frames.

14. The method according to claim 11, wherein the decoding error signal has a first value corresponding to a number of decoding errors greater than a predetermined threshold.

15. The method according to claim 14, wherein the decoding error corresponds to a frame error indicator.

16. The method according to claim 11, further including adjusting the power control target by respective up and down step sizes.

17. The method according to claim 16, wherein the up and down step sizes are determined by