Global channel power control to minimize spillover in a wireless communication environment

• US 6,181,919 B1
• Filed: 11/20/1998
• Issued: 01/30/2001
• Est. Priority Date: 02/12/1997
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Ozluturk, Fatih M.
• Primary Examiner(s): Nguyen, Lee
• Assistant Examiner(s): Nguyen, Simon
• Application Number:
  US09/196,808
• Time in Patent Office: 802 Days
• Field of Search: 455/515, 455/69, 455/70, 455/522, 455/126, 455/561, 455/127, 370/335
• US Class Current: 455/69
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/32 TPC of broadcast or control channels
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels

Abstract

A system which dynamically adjusts the power of signals transmitted from a wireless base station over global channels to minimize spillover to other communication cells monitors the total transmit power of the base station and dynamically adjusts the global channel transmit power as a function of the total transmit power of the base station as measured at the base station.

Claims

1. A base station comprising:

means for transmitting at an output power level a plurality of assigned channels and at least one global channel;

means for monitoring said output power level;

closed-loop forward power control means for individually controlling power levels of said assigned channels; and

means for controlling a transmission power level of said global channel independently of the assigned channels'"'"' power levels based on in part said output power level, such that when said output power level increases, the global channel power level increases and when said output power level decreases, the global channel power level decreases.

2. The base station of claim 1 wherein said global channel power control means further comprises a processor, responsive to said monitoring means, which calculates a desired power level for said global channel and adjusts the power of said global channel in response thereto.

3. The base station of claim 2 wherein said desired power level P_G at a distance r_i from the base station is calculated using the following formula:

$P_G=\frac{N}{N+\mathrm{\gamma <br><br>}}<br><br>a<br><br>\left(r_i\right)+\frac{\mathrm{\gamma <br><br>}}{N+\mathrm{\gamma <br><br>}}<br><br>P_T$

wherein γ

is the desired signal to noise ratio, N is the processing gain and P_T is said output power level.

4. The base station of claim 2 wherein said desired power level P_G is calculated using the following formula:

$P_G=\frac{\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}+N}<br><br>\frac{N_0<br><br>W}{\mathrm{\alpha <br><br>}}<br><br>R^2+\frac{\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}+N}<br><br>P_T$

wherein α

=(λ

²)/(4π

)², γ

is the desired signal to noise ratio, N is the processing gain, N_O is the white noise power density, P_T is said output power level, W is the transmit bandwidth, R is the maximum operating range and λ

is the wavelength of the carrier frequency.

5. The base station of claim 4 wherein said transmitting means further comprises:

means for combining said assigned channels and said global channel to provide a transmit information signal;

means for upconverting said transmit information signal prior to transmission; and

antenna means for transmitting said upconverted signal.

6. The base station of claim 5 wherein said output power level is monitored at said combining means.

7. The base station of claim 5 wherein the power level of each said assigned channel and said global channel is separately monitored by said monitoring means to provide said output power level.

8. The base station of claim 5 further including second antenna means for detecting said output power level;

wherein said monitoring means is responsive to said second antenna means.

9. The base station of claim 2 wherein a free space propagation model is used in said desired power level calculation.

10. The base station of claim 2 wherein a Hata propagation model is used in said desired power level calculation.

11. The base station of claim 2 wherein a breakpoint propagation model is used in said desired power level calculation.

12. The base station of claim 1 wherein said transmitting means further includes means for transmitting a plurality of global channels.

13. A method for controlling the power of global channels transmitted from a base station comprising:

transmitting at an output power level a plurality of assigned channels and at least one global channel;

monitoring said output power level;

individually controlling power levels of said assigned channels using closed-loop forward power control; and

controlling a transmission power level of said global channel independently of the assigned channels'"'"' power levels based on in part said output power level, such that when said output power level increases, the global channel power level increases and when said output power level decreases, the global channel power level decreases.

14. The method of claim 13 further comprising:

calculating a desired power level, based upon said monitoring step, for said global channel; and

adjusting the power of said global channel in response thereto.

15. The method of claim 14 wherein said desired power level P_G is calculated using the following formula:

$P_G=\frac{\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}+N}<br><br>\frac{N_0<br><br>W}{\mathrm{\alpha <br><br>}}<br><br>R^2+\frac{\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}+N}<br><br>P_T$

wherein α

=(λ

²)/(4π

)², γ

is the desired signal to noise ratio, N is the processing gain, N_O is the white noise power density, P_T is said output power level, W is the transmit bandwidth, R is the maximum operating range and λ

is the wavelength of the carrier frequency.

16. The method of claim 15 wherein said transmitting step further comprises:

combining said assigned channels and said global channel to provide a transmit information signal;

upconverting said transmit information signal prior to transmission; and

transmitting said upconverted signal.

17. The method of claim 16 further comprising monitoring said output power level prior to said combining step.

18. The method of claim 15 further comprising separately monitoring the power level of each said assigned channel and said global channel to provide said output power level.

19. The method of claim 15 further including detecting said output power level using a co-located antenna.

20. The method of claim 13 further including transmitting a plurality of global channels.