Level 3
Unit No:
Guided learning hours:
42 hours


This unit explores data communication, transmission methods and protocols that enable connectivity and transmission of data, including signal theory. Learners will learn why particular transmission methods are chosen for particular situations and be able to compare the effectiveness of these different methods. Learners will also be able to apply knowledge and understanding by connecting communication devices between users.

Unit Learning Outcomes


Understand the principles of data communications.

Communication devices: wired devices e.g. data terminal equipment (DTE), data circuit-terminating equipment (DCE), wireless devices, GPRS, mobile phones, laptops, netbooks, tablets.

Computer networks: types e.g. LAN, WAN, wireless, network topologies e.g. star, mesh, bus, tree (or hierarchical), ring, network services eg packet switched, ISDN, multiplexed, ATM, WAP, broadband, network software e.g. network operating system, network connection software, access methods e.g. CSMA/CD, CSMA/CA, token passing.

Network components: servers, workstation, network cards e.g. Ethernet, wireless, token ring Interconnection devices: e.g. switches, routers, bridges, wireless access points, mobile base stations Models: e.g. open system interconnection (OSI) model, TCP/IP model Protocols: e.g. Bluetooth, Wi-Fi, IrDa, cellular radio, GSM/UMTS, WAP, WML, 802.11 standards, TCP/IP, wireless security protocols.

Assessment Criteria

  • 1.1

    Explain the use and features of different types of communication devices.

  • 1.2

    Explain how networks communicate.

  • 1.3

    Explain how different communication protocols are used to govern and control data transmission.


Understand the features of data communications systems.

Elements: communication devices, data elements, electronic communication methods, transmission media and methods.

Signal theory: digital signalling methods, representing data electronically (bits, bytes, packet structures), synchronous transmission, asynchronous transmission, error detection, error correction, bandwidth limitation, bandwidth noise, channel types eg telephone, high frequency (HF) radio, microwave, satellite, other issues e.g. bandwidth, data compression.

Data elements: checksum e.g. cyclic redundancy check (CRC), encapsulation e.g. frames, packets, datagrams, addresses, sequence numbers.

Electronic communication: methods e.g. simplex, duplex, half-duplex communication, parallel, universal serial bus, serial, infra red, Bluetooth, WiFi, 3G, 4G, 5G etc.

Transmission: methods e.g. coaxial, optical fibre, unshielded twisted pair (UTP), shielded twisted pair (STP), infrared, radio, microwave, satellite.

Assessment Criteria

  • 2.1

    Describe the main elements of data communication systems

  • 2.2

    Explain the principles of signal theory.

  • 2.3

    Compare the effectiveness of different transmission methods.


Be able to implement different forms of network communications

Internet communication: terminology e.g. HTTP, HTTPS, FTP, SMTP, uniform resource locator, worldwide web, other e.g. blogs, wikis, video conferencing, vlogs, social networking.

System requirements: wired or mobile systems, communication services e.g. email, video, internet, software, configuration.

Direct communication: e.g. instant messaging, video communication, email, web phone, social networking, web conferencing, desktop sharing.

Interconnection devices: e.g. switches, routers, bridges, wireless access points, mobile base stations

Assessment Criteria

  • 3.1

    Create direct network communication between two users.

  • 3.2

    Set up interconnection devices for direct communication.