30 Questions
What is the shortest fixed interframe space called?
SIFS
Which type of interframe spacing is used by Access Points to transition the network from DCF to PCF?
PIFS
Which interframe spacing has the highest priority among SIFS, PIFS, and DIFS?
SIFS
What does DIFS stand for in the context of interframe spacing?
Distributed-coordination Interframe Spacing
In which mode does the AP control which stations may transmit data?
Point coordination mode
Which interframe space is neither the shortest nor the longest, getting priority between SIFS and DIFS?
PIFS
What type of contention method is used by IEEE 802.3 / Ethernet networks?
CSMA/CD
Which type of network uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)?
IEEE 802.11 networks
In CSMA/CD, what happens if a collision is detected while a node is transmitting?
The node temporarily stops transmitting
Why do wireless stations using CSMA/CA not detect collisions?
They cannot transmit and receive at the same time
What does Interframe Spacing (IFS) ensure before a station can transmit a frame?
No other station is transmitting
How does Interframe Spacing (IFS) provide priority access to certain frames?
By preceding certain frames with a shorter IFS
What is the Distributed Coordination Function (DCF) in wireless LAN?
An access method that allows all stations to maintain access on the shared transmission medium using CSMA/CA protocol.
Why can't ad hoc networks utilize Point Coordination Function (PCF)?
Ad hoc networks have no access points available to perform polling.
What is the primary advantage of Point Coordination Function (PCF) in wireless LAN?
Guarantees a known amount of latency for applications requiring Quality of Service (QoS).
In the Point Coordination Function process, what happens when a wireless station tells the AP that it is capable of answering a poll?
The AP begins polling each wireless station to check if they need to send data frames.
Which type of network can use the Distributed Coordination Function (DCF) mode in wireless LAN?
BSS, ESS, and IBSS networks
What is the main function of Access Points (APs) in wireless LAN with regard to data transmission?
To transmit data and act similarly to wired hubs.
What is modulation coding?
Adding data to a carrier by altering the amplitude, frequency, or phase of the carrier
Which modulation techniques are used in 802.11 and 802.11b?
DBPSK, DQPSK, GFCK
What is orthogonal frequency division multiplexing (OFDM)?
A technique that alters the carrier signal for data transmission
How do more complex signal encoding methods affect data rate and susceptibility to corruption?
Increase data rate and susceptibility to corruption
Which spreading codes are used in 802.11 and 802.11b?
Barker Code, CCK
How do higher transmission speeds impact modulation techniques?
Modulation techniques change to provide higher data throughput
What is the purpose of the virtual carrier sense control message described in the text?
Performing Network Allocation Vector (NAV) distribution
Which process involves a 4-way handshake and is illustrated in the text?
RTS/CTS
What happens to the data rate of a transmitting unit when distance increases between the AP and a station?
It drops to the next lower specified data rate
Which data rates are used for 802.11g OFDM according to the text?
6, 12, 18, 24, 36 Mbps
Why does a wireless LAN system never drop from 11 Mbps to 10 Mbps according to the text?
10 Mbps is not a specified data rate
What triggers a wireless LAN client to drop its data rate according to the text?
Signal strength decrease below a threshold
Test your knowledge on wireless LAN communication methods including Distributed Coordination Function (DCF), Point Coordination Function (PCF), CSMA/CA vs. CSMA/CD, Interframe Spacing, RTS/CTS, Dynamic Rate Shifting/Selection, and modulation coding. Explore how stations on a wireless LAN access the shared transmission medium.
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