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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)