Method for controlling signal power level to control contention beween mobile terminals, and signal power level controller in orthogonal frequency division multiplexing system

• US 8,134,957 B2
• Filed: 12/04/2006
• Issued: 03/13/2012
• Est. Priority Date: 12/08/2005
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Jin-Up, Kim, Dae-Sik, Kim, Hyung-Jin, Cho, Seong-Chul, Jo, Gweon-Do
• Primary Examiner(s): MEW, KEVIN D
• Application Number:
  US12/086,251
• Publication Number:
  US 20090168705A1
• Time in Patent Office: 1,926 Days
• Field of Search: 370/204, 370206-208, 370328-329, 370342-343, 370/345, 370441-442, 370/465, 455/127.1, 455/522
• US Class Current: 370/328
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• 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
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

The present invention relates to a device for controlling a power level to control contention between mobile terminals in an uplink contention period in an orthogonal frequency division multiplexing access (OFDMA) system, and a method thereof. In the method, cell broadcasting information broadcasted from the base station is received by the mobile terminal, the transmission power information of the base station is obtained from the cell broadcasting information by the mobile terminal, a received power level of the received cell broadcasting information is obtained by the mobile terminal, transmission power of a signal transmitted to the base station is determined based on the transmission power information and the received power level, and the signal is transmitted to a contention period based on the determined transmission power.

Claims

1. A signal power level controlling method of a mobile terminal accessed to a base station in an orthogonal frequency division multiplexing access system, the signal power level controlling method comprising:

a) the mobile terminal receiving cell broadcasting information from the base station wherein the cell broadcasting information includes transmission power information;

b) the mobile terminal obtaining the transmission power information of the base station from the cell broadcasting information;

c) the mobile terminal obtaining a received power level of the received cell broadcasting information; and

d) determining transmission power of a signal to be transmitted to the base station based on the transmission power information and the received power level, and transmitting the signal to the base station in a contention period based on the determined transmission power.

2. The signal power level controlling method of claim 1, further comprising, after c), d) receiving a signal having the greatest signal power level among a plurality of received mobile terminal signals in the contention period.

3. The signal power level controlling method of claim 2, wherein, in d), the signal having the greatest signal power level among the plurality of mobile terminal signals has a signal to noise ratio (SNR) that is higher than that of a signal having a low signal power level.

4. The signal power level controlling method of claim 1, wherein, in d), a level of the transmission power of the signal transmitted to the base station is randomly determined by the mobile terminal, and it is set to be higher than the lowest threshold value for receiving the signal by the base station.

5. The signal power level controlling method of claim 4, wherein the signal is transmitted from the mobile terminal to the base station with the transmission power obtained by adding the transmission power determined by the mobile terminal to a difference between the base station transmission power information and the received power level.

6. A mobile terminal accessed to a base station in an orthogonal frequency division multiplexing access system, the mobile terminal comprising:

a signal power level controller device, the signal power level controller comprising;

a received power obtaining unit for obtaining a received power level of received cell broadcasting information when the mobile terminal receives the cell broadcasting information from the base station;

a transmission power information obtaining unit for obtaining base station transmission power information included in the cell broadcasting information wherein the transmission power information is power information of the cell broadcasting information when the cell broadcasting information is transmitted from the base station to the mobile terminal; and

a transmission power determining unit for determining a power level applied to transmit a signal from the mobile terminal to the base station, based on the obtained received power level and the base station transmission power information.

7. The signal power level controller of claim 6, wherein the transmission power determining unit determines the transmission power by adding the transmission power of the signal to be transmitted from the mobile terminal to the base station to a difference between the base station transmission power and the received power level.