Bluetooth Low Energy

Information for this guide was taken from the following PDF.

Bluetooth Specification Guide

Overview

• Uses frequency hopping transceiver to combat interference
• Data Rate = 1Mb/s
• Multiple Access Schemes Used
  • FDMA (Frequency Division Multiple Access)
  • TDMA (Time Division Multiple Access)
• Channels
  • 40 - 2MHz channels (3 advertising, 37 data)
  • f = 2402+2k MHz (k=0,...,39)

Transmitter Specifications

Modulation Characteristics

GFSK Definition

• GFSK (Gaussian Frequency Shift Keying)
• Bandwidth-Bit Period Product = 0.5
• Modulation Index 0.45 to 0.55
• ‘1’ = Positive Frequency Shift
• ‘0’ = Negative Frequency Shift
• Symbol Timing < <math>\pm</math> 50ppm
• Minimum Frequency Deviation > 185kHz

Frequency Tolerance

• Initial Center Frequency <math> \pm </math> 150 kHz
• Maximum Drift (during packet) <math> \pm </math> 50 kHz
• Maximum Drift Rate 400 Hz/us

Spectral Mask

BLE Spectral Mask

Frequency Offset	Spurious Power
2 MHz (|M-N| = 2)	-20 dBm
3 MHz (|M-N|<math>\geq</math>3)	-30 dBm

Receiver Specifications

Actual Sensitivity Level

• Defined as the receiver input level for which a BER (bit error ratio) of 0.1% is achieved
• < -70 dBm (from any transmitter that meets specifications)

Interference Performance

• Measured with a wanted signal 3dB over the reference sensitivity level
• Measurement resolution is 1MHz
• BER should be < 0.1% for all ratios listed in the table

Frequency of Interference	Ratio
Co-Channel Interference	21 dB
Adjacent (1 MHz) Interference	15 dB
Adjacent (2 MHz) Interference	-17 dB
Adjacent (<math>\geq</math>3 MHz) Interference	-27 dB
Image Frequency Interference	-9 dB
Adjacent (1 MHz) Interference to In-Band Image Frequency	-15 dB

• 5 Spurious Response RF Channels (that don't meet the requirements) are allowed <math>\geq</math>2 MHz from the wanted signal (excluding the image frequency and image frequency <math>\pm</math>1 MHz. On these spurious response RF channels, a relaxed interference requirement of -17dB shall be met.

Out-of-Band Blocking

• Measured with a wanted signal 3dB over the reference sensitivity level
• Interfering signal shall be a continuous wave signal
• Desired signal has be a reference signal (defined below)
• BER should be < 0.1%

Interfering Signal Frequency	Interfering Signal Power Level	Measurement Resolution
30 - 2000 MHz	-30 dBm	10 MHz
2003 - 2399 MHz	-35 dBm	3 MHz
2484 - 2997 MHz	-35 dBm	3 MHz
3 - 12.75 GHz	-30 dBm	25 MHz

• Up to 10 exceptions are permitted (which are depending on the given RF channel and are centered at a frequency which is an integer multiple of 1 MHz)
  • For at least 7 of these spurious response frequencies, a reduced interference level of at least -50dBm is allowed
  • for a maximum of 3 of these spurious response frequencies, the interference level may be lower

Intermodulation Characteristics

A BER <math>\leq</math>0.1% shall be met under the following conditions

• The wanted signal (at frequency = <math>f_0</math>) has a power level 6 dB over the reference sensitivity level. The wanted signal shall be the reference signal (defined below)
• A static sine wave signal (at frequency = <math>f_1</math>) has a power level of -50 dBm
• An interfering signal (at frequency <math>f_2</math>) has a power level of -50 dBm. The interfering signal shall be the reference signal (defined below).

<math>f_0 = 2f_1 - f_2 \,</math>

<math>|f_2-f_1|=n \, </math> where n=3,4,or 5

Maximum Usable Level

• Must be greater than -10dBm with BER < 0.1%

Reference Signal

• Modulation = GFSK
• Modulation Index = 0.5 <math>\pm</math>1%
• BT = 0.5 <math>\pm</math>1%
• Bit Rate = 1 Mbps <math>\pm</math>1ppm
• Modulating Data for Wanted Signal = PRBS9
• Modulating Data for Interfering Signal = PRBS15
• Frequency Accuracy Better than <math>\pm</math>1ppm