L11 Flashcards
What hop systems does the bluetooth standard support? How many unique frequencies are in each?
79 (32 unique) and 23 (16 unique)
True or False
Every Bluetooth unit has a free-running internal clock.
True
- Used for timing and frequency regulation of each transceiver
How is security in bluetooth supported?
48-bit unique BD_ADDR
128-bit authentication key
8-128 bit encryption key
128-bit random number
What band is supported by bluetooth and wifi?
2.4 Ghz both
Which has a higher one of the following properties, wifi or bluetooth?
A. Battery life
B. Power consumption
C. Area coverage
A. Bluetooth
B. Wifi
C. Wifi
What is CRC? What are the two implementations of CRC?
CRC (Cyclic Redundancy Check): an efficient method to detect errors in communication and other test procedures
Table-driven
Loop-driven
What is the use of IEEE 802.15.2?
It facilitates coexistence of IEEE 802.15 WPAN devices with other wireless appliances operating in unlicensed frequence bands. It does this through coexistence mechanisms (collaborative and non-collaborative).
What affects cochannel (bluetooth and wifi) interference?
Distance between the mutually interfering networks
The traffic generated by both channels
Power level
Data rates of the WLAN
Type of data transferred
What is the relationship between Bluetooth throughput and distance between it and the WLAN master?
Bluetooth slave throughput increases as the distance between it and the WLAN master device increases
What is the difference between collaborative and non collaboratavie co-existence mechansisms for wifi and bluetooth?
Collaborative: when there is a communication link between the WLAN and WPAN networks (such as being directly embedded on the same device)
Non-collaborative: do not require any communication link between the WLAN and WPAN networks
What is a collaborative mechanism for co-existence?
Alternating Wireless Medium Access (AWMA): use some of time interval (TB) between successive Beacon frames for WPAN transmission
What are 4 non-collaborative mechanisms
Adaptive interference suppression of devices
Adaptive packet selection and scheduling
Adaptive frequency hopping (AFH): classify good and bad frequency channels then modify their hop patterns
Packet scheduling for ACL links
Explain Adaptive packet selection and scheduling (non-collaborative mechanism).
Selection: select the 802.15.1 packets for transmission based on the existing traffic and channel conditions
Scheduling: channel classification listens to the traffic to determine the interference level. Based on the classification, the master applies a delay policy
Explain Adaptive Frequency Hopping
Adaptive frequency hopping (AFH): classify good and bad frequency channels then modify their hop patterns
What is Packet Traffic Arbitration (PTA)?
Packet Traffic Arbitration (PTA) dynamically coordinates sharing of radio resources between two coexisting wireless systems. The priority schemes: fixed and randomised.
