19. Wireless Interference

Question 1

What is BLE and what is its power and range?

Answer 1

Bluetooth Low Energy
20dBm transmit power
100 meter range

Question 2

Bluetooth devices are grouped into 3 groups. What are the 3 classes power designation and range?

Answer 2

Class 1 (industrial) - max 100 mW - 100 meter range
Class 2 - max 2.5 mW - 10 meter range
Class 3 - max 1 mW - 1 meter range

Question 3

With Bluetooth, devices can be linked together with one acting as master and up to how slave devices? Also what is the cell called?

Answer 3

1 master and 7 slave devices in a PAN

piconets

Question 4

BLE uses how many channels and in what band?

Answer 4

40 channels in the 2.4GHz

Question 5

What band does ZigBee use and how many channels?

Answer 5

2.4GHz

16 channels 5MHz wide

Question 6

What is ZigBee commonly used for and what IEEE number defines it?

Answer 6

Energy management and home and building automation applications
IEEE 802.15.4

Question 7

ZigBee uses low power but can ramp up to what mW?

Answer 7

60mW

Question 8

The Digital Enhanced Cordless Telecommunications (DECT) standard was developed by whom?

Answer 8

ETSI

Question 9

What version of DECT is used in the US and what band does it operate on?

Answer 9

Version 6.0

1.9GHz

Question 10

DECT phones shouldn’t cause interference in the 2.4GHz or 5GHz. Are there cordless phones that do operate in those bands?

Answer 10

Yes and their transmit power could easily overpower an AP.

Question 11

What IEEE number defines the standard for Worldwide Interoperability for Microwave Access (WiMAX)?

Answer 11

IEEE 802.16

Question 12

What are some types of devices that can cause interference?

Answer 12

Canopy—A fixed wireless broadband technology
Continuous transmitter
Jammer
SuperAG—A proprietary set of extensions developed by Atheros
Wireless video camera that use analog or non-802.11
Wi-Fi invalid channel
Wi-Fi inverted
Xbox controllers (2.4GHz)

Question 13

Can the AirMagnet Spectrum XT connect to Cisco SE?

Answer 13

No

Question 14

How do access the Cisco Meraki RF Spectrum feature from the portal?

Answer 14

Wireless > RF Spectrum

Question 15

What is the name of the chip set that lets Cicso CleanAir scan for interference?

Answer 15

Spectrum Analysis Engine (SAgE) chipset

Question 16

By default, is Cisco CleanAir enabled or disabled?

Answer 16

Disabled

Question 17

In order to generate interference reports from an AP, what modes does it have to be set to?

Answer 17

Local and monitor

SE-Connect will not generate interference reports

Question 18

Interference severity is calculated by RSSI and duty cycle. What is the range of the severity index and which is high and which is low?

Answer 18

0 (low severity)

100 (high severity)

Question 19

What is the range of the air-quality index (AQI)?

Answer 19

0 (channel unusable)

100 (channel perfect)

Question 20

What are the 3 thresholds that ED-RRM (event-driven RRM) can be set to (include AQI)?

Answer 20

Low (AQI 35)
Medium (AQI 50)
High (AQI 60)

Question 21

What does a cluster ID designation look like?

Answer 21

It’s a pseudo-MAC address