CWNA – Chapter 1 Summary & Exam Essentials

Overview of Wireless Standards, Organisations and Fundamentals.

4 Key organisations involved with wireless networking industry

– FCC and other regulatory domains (ITU-R (ACMA (Australia)) (ARIB(Japan)) – FCC regulates communication from/to/within US. Both licensed and unlicensed communications are typically regulated in the following 5 areas 

– Frequency, Bandwidth, Maximum power of the intentional radiator (IR),  Maximum equivalent isotropically radiated power (EIRP), Use (indoor and/or outdoor), Spectrum sharing rules.

– IEEE – 802.11 working group is responsible for creating WLAN standard.

– IETF – International community of people whose goal is to make the internet work better. 

– Wi-Fi Alliance – Global, non-profit organisation of more than 550 member companies devoted in making the wireless communication better. Its main task is to ensure interoperability of WLAN products by providing certification testing.

ISO – international Organisation for Standardisation. 

OSI model – Open Systems Interconnection (APSTNDP)

Application Layer 7- WWW browsers, NFS, SNMP, Telnet, HTTP, FTP
Presentation Layer 6 – Include encryption, ASCII, TIFF, GIF, JPEG, MPEG, etc..
Session Layer 5 –  NFS, NetBIOS names, RPC, SQL
Transport Layer 4 – TCP, UDP 
Network Layer 3 – Provides switching and routing technologies, creates logical paths, known as virtual circuits.
Data Link Layer 2 -The MAC layer and the Logical link control (LLC) layer. IEEE 802.3, ATM, Frame Relay.
Physical Layer 1 – Cables, Ethernet, Fibre, etc.

The 802.11-2016 standard defines communication mechanism only at the Physical and the MAC sublayer of the Data-Link layer of the OSI model. 

Communications Terminology 

Simplex – Device is either capable of transmitting or receiving.
Half-Duplex- Capable of transmitting and receiving but not at the same time. Only 1 device can transmit at a time.
Full- Duplex – Capable of transmitting and receiving at the same time.

Radio Frequency Fundamentals 

1. Amplitude – Height, force, or the power of the wave. 
2. Wavelength – Distance between similar points on two back to back waves.

Frequency – Describes a behaviour of waves. How fast the wave travels, or more specifically how many waves are generated over a period of time, is known as frequency.

Phase – is a relative term. It is the relationship between 2 waves with the same frequency

Keying Methods – Some more explanation here.

1. Amplitude-Shift Keying
2. Frequency-Shift Keying
3. Phase-Shift Keying.

EXAM ESSENTIALS 

1. Know the 4 Industry Organisations
2. Understand core, distribution and access layer
3. Explain the difference between simplex, half-duplex, and full duplex.
4. Understand Wavelength, Frequency, Amplitude & Phase.
5. Keying Methods.

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