Transcript CSC 322 Final Summary

CSC 322 Review
A slide to a chapter summary of the
material covered
(based on the 8/e book)
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C1. Data Communications and
Networking Overview
• The 3 (or 5) entity general communication model
• Actual data communications is more complicated
– Transmission system utilization, interface, signal
generation, synchronization, exchange management,
error detection and correction, flow control, addressing,
routing, recovery, message formatting, security,
network management
• Networking
– LANs (one organisation, smaller area, faster speeds)
– WANs (larger areas, crossing public rights of way,
common carrier circuits)
• circuit switching,
• packet switching
– frame relay, cell relay (ATM)
– MANs (middle ground)
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C2. Protocol Architecture
• A simple (quite general) protocol architecture
– Protocols: syntax, timing, semantics
• Layering combats complexity
– Peer layered architecture
– Information flow (down  across  up)
• Open System Interconnection (OSI)
– 7 layers
– Standardisation framework
– Service Primitives, and Parameters
• The TCP/IP protocol architecture
– 5 layers
– The “industry/world” standard
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C3. Data transmission
• Terminology
– Frequency, spectrum, bandwidth, effective bandwidth, etc
• Any signal can be expressed as an infinite number of sine
waves (frequency components).
– Remember it is only the odd ones (f, 3f, 5f, 7f….)
• Relationship between data rate and bandwidth
– The higher the data rate the higher the required bandwidth
– The higher the bandwidth the greater data rate can be achieved
• Transmission impairments
– attenuation, delay distortion, noise (4 types)
• Channel capacity
– Nyquist (error & noise free, f(B, channels))
– Shannon (error free, f(B, SNR))
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C4. Transmission Media
• Guided media
– Twisted pair (2 versions), coaxial, optical fibre
– Description, characteristics, categories
• Wireless transmission technologies
– Dish antenna, Antenna gain
– Microwave (earth & satellite), broadcast radio, infrared
• Wireless propagation
– Skywave, line-of-sight, groundwave
• Wireless (line-of-sight) impairments
– Free space loss, refraction, atmospheric absorption, mutlipath
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C5. Signal Encoding Techniques
• Digital(=D) & Analogue(=A) Data
– to Digital & Analogue Signals
• D-data  A-signal
– Frequency/Phase/Amplitude shift keying
• D-data  D-signal
– NRZ, Multilevel, Biphase
– Scrambling
• A-data  D-signal
– Delta, Pulse code
• A-data  A-signal(3)
– AM, FM
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C6. Digital Data Communication
Techniques
• Transmission approaches
– Synchronous
– Asynchronous
• Errors, types
– Single bit, Burst errors
• Error detection
– Check bits
• Error correction
– FEC, Redudancy, hamming distance
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C7. Data Link Control Protocols
• Flow control (S&W, SW)
• Error control
– 4 Mechanisms of ARQ
– 3 version of ARQ
• HDLC protocol
– Basics
• types of stations (3)
• Configuration (2)
• modes (3)
– Frame types and structure (I / S / U)
– Operation (3 phase type)
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C8. Multiplexing
• Utilising a single line to relay multiple connections
• Frequency Division MUXing
• Time Division MUXing
– MUXed line has at least the data rate of the sum of lines
– Slots are fixed and allocated
• Statistical Time Division (relies on non frequent use)
– Slots are allocated on demand
– MUXed line has less than the sum of lines being MUXed
• ADSL
– Separates the 1MHz in 3 regions (POTS, Upstream, Downstream)
– FDM within upload and download
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C14. Cellular Wireless Networks
• Not covered fully (first 14 slides)
• Cellular network organisation
– Cells
– Frequency reuse
– Increasing the capacity
• Operation of a cellular systems
– Base station
– Cells
– MTSO
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C17. Wireless Networks
• Single and multi cell LANs
• Applications (nomadic, adhoc, cross
building, lan extension)
• Technologies (just the names)
– IR, Spread spectrum, Narrow band microwave
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C15. LAN Overview
• LAN applications (high speed, backbone, storage area
networks, personal, backend)
• Topologies (ring, star, bus, tree)
• IEEE 802 reference model
– LLC and MAC
• Medium Acces Control
– Central vs distributed
– Synchronous vs asynchronous
• Asynhronous
– Round robin, reservation, contention
• Bridges, Switches, Hub, Layer 2 & 3 (hardware switches)
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