Ch. 7 - Wireless & Mobile Networks Flashcards
Mobility Challenge
Managing users changing network attachment points.
4G LTE vs. 5G Speed
4G LTE = 54 Mbps; 5G = 10 Gbps
Ad Hoc Mode
Nodes transmit directly without base stations.
Handoff
Mobile changes base station during active connection.
Single Hop Network
Direct connection from host to base station.
Multiple Hops Network
Host relays through several nodes to connect.
Wireless Network Taxonomy
Classifies networks by infrastructure and connectivity.
MANET
Mobile Ad hoc Network; self-configuring network of mobile devices.
VANET
Vehicular Ad hoc Network; network for vehicle communication.
Signal Attenuation
Reduction in signal strength as it travels.
Multipath Propagation
Signal reflection causing multiple arrival times.
Modulation Scheme Examples
QAM256/QAM16: Quadrature Amplitude Modulation with 256 or 16 levels; BPSK: Binary Phase Shift Keying; simplest modulation scheme.
Hidden Terminal Problem
Communication issue where nodes can’t detect each other.
CDMA
Code Division Multiple Access; multiple users share frequency.
Chipping Sequence
Unique code for each user in CDMA.
Inner Product
Mathematical operation used in encoding and decoding.
CSMA/CA
Carrier Sense Multiple Access with Collision Avoidance. Protocol to avoid collisions in wireless networks.
Access Point (AP)
Device allowing wireless devices to connect to a network.
Basic Service Set (BSS)
Group of wireless devices connected to an AP.
SSID
Service Set Identifier, name of a wireless network.
2 Methods for Discovering APs
Active Scanning: Host sends probe requests
Passive Scanning: Host listens for beacon frames
Collision Avoidance
Preventing simultaneous transmissions to avoid data loss.
Collision Detection
Difficulty sensing collisions due to signal fading.
RTS-CTS Exchange
Mechanism to prevent collisions during data transmission.
DIFS
Distributed Inter-Frame Space before transmission.
SIFS
Short Inter-Frame Space for ACK transmission.
Backoff Interval
Random time before retransmitting after collision.
Beacon Frame
Frame indicating AP presence and waiting messages.
Power Management
Node sleeps until next beacon frame arrives.
SNR
Signal-to-Noise Ratio affecting transmission quality.
BER
Bit Error Rate indicating transmission reliability.
Ad Hoc Network
Network without fixed infrastructure.
Bluetooth
Personal area network technology for short-range (11-30m indoors) communication.
Frame Control
Field indicating frame type in 802.11.
Piconet
A small network of Bluetooth devices.
Parked Mode
Clients conserve battery by sleeping.