METHOD FOR UPLINK POWER CONTROL IN OFDMA TDD SYSTEM

• US 20110261731A1
• Filed: 12/30/2009
• Published: 10/27/2011
• Est. Priority Date: 12/31/2008
• Status: Active Grant

• Current Assignee: Wireless Alliance, LLC (Intellectual Discovery Co., Ltd.)
• Original Assignee: SeAH Networks Co., Ltd. (SEAH Holdings Corporation)
• Inventors: Lee, Dong-Kwan
• Granted Patent: US 8,717,969 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/245 taking into account received signal strength

Abstract

The present invention relates to a method for uplink power control in an OFDMA TDD system. The method for uplink power control according to the present invention comprises: calculating an RSSI average by using RSSI measured from a downlink signal; and carrying out an uplink power control based on the RSSI average, with the RSSI average being calculated by using a weight that is determined depending on a channel variation rate and link symmetry.

Claims

1. A method for uplink power control in OFDMA (Orthogonal Frequency Division Multiple Access) TDD (Time Division Duplex) system, the method comprising:

calculating an RSSI (Received Signal Strength Indicator) average by using RSSIs measured from downlink signals; and

carrying out an uplink power control based on the RSSI average,

wherein the RSSI average is calculated by using a weight that is determined according to a channel variation rate and a link symmetry.

2. The method of claim 1, wherein the channel variation rate is determined by an estimated value of the Doppler frequency.

3. The method of claim 2, wherein the estimated value of the Doppler frequency is calculated by using pilots.

4. The method of claim 1, wherein the weight is determined high if the channel variation rate is lower than a reference value.

5. The method of claim 1, wherein the RSSI is calculated by using the main path signals if multiple reception antennas are applied.

6. The method of claim 1, wherein the RSSI is calculated by using preambles if space-frequency diversity is applied.

7. The method of claim 1, wherein the RSSI is calculated by using pilots if MIMO (Multiple Input Multiple Output) system is applied.

8. A method for uplink power control in OFDMA (Orthogonal Frequency Division Multiple Access) TDD (Time Division Duplex) system, the method comprising:

calculating an CINR (Carrier to Interference and Noise Ratio) average by using CINRs measured from uplink signals; and

carrying out an uplink power control based on the CINR average,

wherein the CINR average is calculated by using a weight that is determined according to a channel variation rate and link symmetry.

9. The method of claim 8, wherein the link symmetry is determined by the number of reception antennas.

10. The method of claim 8, wherein the channel variation rate is determined by an estimated value of the Doppler frequency.

11. The method of claim 10, wherein the first weight that is set when an estimated value of the Doppler frequency is smaller than a reference value, is smaller than the second weight that is set when the estimated value of the Doppler frequency is larger than the reference value.