Automatic Transmit Power Control - ATPC

Proprietary and Confidential

Agenda

2

• Why ATPC?

• How does ATPC works?

• ATPC Vs. MTPC

• ATPC Configuration

Proprietary and Confidential

ATPC – Automatic Transmit Power Control

3

The quality of radio communication between low Power devices varies

significantly with time and environment.

This phenomenon indicates that static transmission power, transmission range,

and link quality, might not be effective in the physical world.

• Static transmission set to max. may reduce lifetime of Transmitter

• Side-lobes may affect nearby Receivers (image)

Main Lobe

Side Lobe

Proprietary and Confidential

ATPC – Automatic Transmit Power Control

1. Enable ATPC on both sites

2. Set Input reference level (min. possible RSL to maintain the radio link)

3. ATPC on both ends establish a Feedback Channel through the radio link (1byte)

4. Transmitters will reduce Output power to the min. possible level

5. Power reduction stops when RSL in remote receiver reaches Ref. input level

6. ATPC is strongly recommended with XPIC configuration

ATPC module

Radio Transceiver

Radio Receiver

Radio Receiver

Signal Quality Check

-

Site A Site B

TSL Adjustments

Radio

Feedback

Ref. RSL

Monitored RSL

RSL

required

change

4

Proprietary and Confidential

ATPC – Example when ATPC is OFF

MTPC

TSL A = 30dBm

RSL A = ?

MTPC

TSL B = 30dBm

RSL B = ?

RSL A = -30dBm (TSL B + FSL) RSL B = -30dBm (TSL A + FSL)

FSL= -60 dB Site A Site B

5

Proprietary and Confidential

ATPC – Example when ATPC is ON (One site ATPC, second site MTPC)

ATPC

IRLB (Input Ref. level on Site B) = -50dBm

TSL A = ?

RSL A = ?

MTPC

TSL B = 30dBm

RSL B =?

RSL A = -30dBm (TSL B + FSL)

RSL B = -50dBm (TSL A + FSL) TSL A = 10dBm (IRLB-FSL)

You want -50dBm on Site B, so what is TXA in Site A?

FSL= -60 dB Site A Site B

6

Proprietary and Confidential

ATPC – Example when ATPC is ON (ATPC on both sites)

ATPC

IRLB (Input Ref. level on Site B) = -50dBm

TSL A = ?

RSL A = ?

RSL A = -50dBm (TSLB + FSL) RSL B = -50dBm (TSL A + FSL)

TSL A = 10dBm (IRLB - FSL)

ATPC

IRLA (Input Ref. level on Site A) = -50dBm

TSL B = ?

RSL B = ?

TSL B = 10dBm (IRLA-FSL)

FSL= -60 dB Site A Site B

7

Proprietary and Confidential

ATPC – Example when ATPC is ON (ATPC on both sites), ATPC range

FSL= -60 dB Site A Site B

ATPC

IRLB (Input Ref. level on Site B) = -60dBm

TSL A = ?

RSL A = ?

RSL A = -50dBm (TSL B + FSL) RSL B = -50dBm (TSL A + FSL)

TSL A = 10dBm (IRLB-FSL)

ATPC

IRLA (Input Ref. level on Site A) = -50dBm

TSL B = ?

RSL B = ?

TSL B = 10dBm (IRLA - FSL)

RSL B is -50dBm because typical ATPC range for TX level is 20dB (depend on RFU type)!!!

It means that TSL A can’t be 0dBm because possible min is 10dBm (Max is 30dBm)

8

Max TSL is 30dBm

ATPC range is 20dB Max TSL is 30dBm

ATPC range is 20dB

Proprietary and Confidential

ATPC Configuration

9

Thank You

10