User equipment method employing a time division duplex technique

• US 6,597,724 B2
• Filed: 02/22/2002
• Issued: 07/22/2003
• Est. Priority Date: 03/22/2000
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Dick, Steven G., Shin, Sung-Hyuk, Zeira, Ariela
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US10/080,482
• Publication Number:
  US 20020080764A1
• Time in Patent Office: 515 Days
• Field of Search: 375/130, 375/140, 370/347, 370/318, 370/342, 455/522, 455/69
• US Class Current: 375/130
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters

Abstract

An outer loop/weighted open loop power control method controls transmission power levels in a spread spectrum time division duplex communication user equipment (UE). The user equipment receives a communication including an transmitted power level and measures its received power level. Based in part on the measured power level and the transmitted power level, a path loss estimate is determined. A quality of the path loss estimate is also determined. The transmission power level for a communication from the user equipment is based on in part weighting the path loss estimate in response to the estimate'"'"'s quality.

Claims

1. An outer loop/weighted open loop method for controlling transmission power levels at a user equipment employing a spread spectrum time division duplex technique having frames with time slots, comprising:

a) receiving, during a first time slot, a communication including a power level;

b) measuring a power level of said received communication;

c) determining a path loss estimate based in part on the measured power level and the received power level; and

d) setting a transmission power level for transmission during a second time slot based in part on the path loss estimate weighted by a first factor and a long term path loss estimate weighted by a second factor, wherein the first and second factors are a function of a time separation of the first and second time slots; and

e) determining a quality, α

, of the path loss estimate based in part on a number of time slots, D, between the first and second time slot; and

wherein the first factor is α and

the second factor is 1−

α

.

2. The method of claim 1 further comprising:

determining the long term path loss estimate based at least in part upon an average of path loss estimates of received communications.

3. The method of claim 1 wherein a maximum time slot delay is D_max and the determined quality, α

, is determined by;

4. The method of claim 1 wherein a maximum allowed time slot delay is D_max-allowed and the determined quality, α

, is determined by;

5. A method for controlling transmission power levels at a user equipment employing a spread spectrum time division duplex technique having frames with time slots for communication, comprising:

a) receiving, during a first time slot, a first communication target adjustment and a first communication;

b) measuring a power level of the first communication;

c) determining a path loss estimate based in part on power level obtained at step (b); and

d) setting a transmission power level for a transmission of a second communication during a second time slot based in part on the path loss estimate weighted by a first factor, a long term path loss estimate weighted by a second factor, and a target level adjusted by the target adjustment, wherein the first and second factors are a function of a time separation of the first and second time slots; and

e) determining a quality, α

, of the path loss estimate based in part on a number of time slots, D, between the first and second time slot; and

wherein the first factor α and

the second factor is 1−

α

.

6. The method of claim 5 wherein the target level is a signal to interference ratio.

7. The method of claim 6 wherein an adjustment to the signal to interference ratio lies within a maximum and minimum value limits.

8. The method of claim 6 wherein each target adjustment is in a range of approximately 0.25 decibels to 4 decibels.

9. A method for controlling transmission power levels at a user equipment employing a spread spectrum time division duplex technique having frames with time slots for communication, comprising:

a) receiving a first communication;

b) determining an error rate of the communication received at step (a);

c) producing target adjustments as needed based in part on the error rate; and

d) transmitting a second communication having a transmission power level in a first time slot and the target adjustments; and

wherein;

a target adjustment increasing the target signal interference ratio is SIR_INC;

a target adjustment decreasing the target signal interference ratio is SIR_DEC;

a target block error rate is BLER_TARGET; and

SIR_DEC is determined by

SIR_DEC=SIR_INC×

BLER_TARGET/(1−

BLER_TARGET).

10. The method of claim 9 wherein the BLER_TARGET is in the range of approximately 1% to 10%.