Certified Wireless Network Administrator (CWNA)

Discover how the IETF uses the RFC process to turn ideas into standards and best practices. See how protocol standards and IP addressing concepts guide network design and internet operation.

Explore how frequency describes the behavior of waves by counting how many waves occur per second from an antenna, and how the distance between peaks defines transmission frequency.

Explore keying methods used in wireless signaling, including amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying schemes, and learn how receivers detect ones and zeros.

Explore wireless history and standards, from FCC, ITU-R, and IETF to OSI model’s access, distribution, and core layers. Understand how carrier signals carry ones and zeros from transmitter to receiver.

Demonstrate how wavelength relates to frequency through the speed of light, using lambda = c / f and c = 300,000,000 m/s, so higher frequency means a smaller wavelength.

Signals reflect off surfaces larger than the wave, creating multipath through delayed copies, including AM radio skywave and microwave reflections.

Explore how diffraction bends wireless signals around objects, unlike refraction through a medium, and examine practical implications for signal propagation around obstacles.

Explore multipath propagation in wifi networks and antenna spacing. See why early access points used two antennas about 4.2 inches apart to receive signals from reflections at different times.

Increase antenna power output by generating more transmitter power or by focusing the radiated signal; a focused beam boosts brightness, like a flashlight.

Explain how wifi rf power is measured in milliwatts, a thousandth of a watt, and note indoor 802.11 equipment typically transmits between 1 mW and 100 mW.

Apply rule of three and ten to power, showing how a 3 dBi gain doubles 100 mW to 200 mW, while a 3 dB loss halves it to 50 mW.

Explain the rules of tens and threes for dbm and milliwatts using a conversion table, illustrating doubling and halving, then apply to a wireless bridge with loss and gain.

Trace how to convert 50 mW to dB, apply a -1 dB loss and a +5 dB gain, and determine the resulting power to understand transmitter gains and coverage area.

Explore the components of RF communications, understand units of power, and apply RF mathematics using the rule of tens and threes to get you in the ballpark.

Measure antenna beam width by locating the strongest point on a 360-degree chart and tracing to where the signal drops by minus 3 dB, yielding the beam width angle.

Explore how planar antennas provide targeted coverage for long hallways and rows of offices, using semi directional beams and appropriate beam width to optimize access points.

Discover the Yagi antenna for short to medium distance point-to-point links up to about two miles, with high gain, and how tilting it on a wall targets coverage between buildings.

Explore dynamic beam forming by steering RF energy with a center tower and multiple antennas, focusing the radiation pattern in shape and direction frame by frame to follow moving receivers.

Explore antennas, coverage concepts, and beamforming, including azimuth and elevation charts, and examine antenna arrays, Mimo, and transmit beamforming for multi-radio frequencies.

The lecture surveys the original IEEE 802.11 standards, detailing the physical layer and MAC sublayer, and contrasts infrared as a light-based medium with FHSS and DSS spread spectrum methods.

Explore 802.11a’s high-speed 5 GHz unlicensed operation, compare it with 2.4 GHz, and explain 100 MHz channel sizing and OFDM to boost data rates and adoption choices.

Explore 802.11i part2’s robust security network, emphasizing authentication, integrity, and confidentiality. See how access points and radius servers verify credentials and issue different encryption keys to different users under WPA.

Enables robust management frames in 802.11w, a task group w standard, to protect association and disassociation frames.

The 900 mhz ism band provides multiple 26 mhz channels from 902 to 928 mhz; GSM use in Europe limits it, while the United States used it for cordless phones.

Explore 60 GHz wireless technology as a high-throughput, unlicensed-band solution with physical and mac layer enhancements, delivering up to seven gigabits per second for short indoor connections.

Compare narrow band and spread spectrum to understand how bandwidth shapes channel design and interference prevention, with FCC guidelines ensuring space between frequencies.

Explore how five gigahertz channels support 802.11a/n/ac, and how guard bands separate uni one and uni two, with 30 MHz spacing from band edges and 20 MHz in uni three.

Explore adjacent, nonadjacent, and overlapping channels in a wireless LAN. Design roaming-friendly cell coverage by using non-overlapping frequencies, such as channels 1, 6, and 11.

Explain how throughput relates to bandwidth and frequency band, distinguishing physical bandwidth from data bandwidth, and show how modulation and coding affect data rates, including Ofdm advantages.

Explore the four major wireless topologies: wireless wide area network, wireless metropolitan area network, wireless personal area network, and wireless local area network, alongside other technologies like cellular, Bluetooth, and Zigbee.

Explore wireless local area networks (WLANs) that use access points to extend range and support multiple clients, ideal for home or office deployments with high throughput.

The distribution service channels data from the access point to its destination within basic or extended service sets. In deployments, the distribution system medium, DSM, is typically Ethernet.

Understand the basic service set (BSS), the simplest wireless topology with a single access point that connects multiple clients to a wired Ethernet network. Moving out of range disrupts connectivity.

Explore extended service sets that link two or more basic service sets via a distribution system medium, uniting access points and client stations; roaming can interrupt connections.

Ensure seamless roaming with a wireless LAN controller managing handoffs between access points, supported by overlapping coverage in the extended service set.

Explore how roaming between access points with co-location affects a user’s connection, requiring re-association and causing brief service disruption, including voice over IP calls.

Explore the two client station modes in CWNA: infrastructure mode, where a computer connects to an access point, and ad hoc (independent service set) mode, enabling direct device-to-device data exchange.

Review wireless networking topologies, covering eight to eleven options, and examine the configuration modes for different access points.

Compare collision avoidance and collision detection in wireless and wired networks, highlighting half duplex limits and how CSMA/CA and CSMA/CD use media access control to manage access.

The distributed coordination function is the fundamental and mandatory access method for 802.11 communications, with optional methods like PCF and the hybrid coordination function (HCF).

Explore the distributed coordination function components, including carrier sense, physical and virtual listening, duration/ID fields, interframe spaces, backoff timers, and sifs/difs to minimize collisions on a half duplex medium.

Explain interframe space and its six types, highlighting reduced interframe space for QoS, SIFS, PCF interframe space, DIFS, arbitration interframe space, and extended interframe space for corrupted frames.

Explain how the duration id field signals the time in microseconds required for a unicast frame exchange (0 to 32,767 μs), during which other radios defer and hear the transmission.

Explore block acknowledgement requests that allow aggregating acknowledgements for multiple frames, improving efficiency, with immediate block acks for low latency traffic and delayed block acks for file transfers.

Explore the data link layer and its two sublayers: the logical link control (LLC) that interfaces with layer three, and the MAC address sublayer that handles media access.

Explore how control frames within 802.11 manage power saver signaling, clear to send, and block acknowledgments, while contrasting DCF, PCF, and HCF for contention-free, QoS-enabled frames.

Examine data frame subtypes, including data, null data, acknowledgments, and polls, plus PCF control frames, and how quality of service boosts efficiency and access-point preference.

Analyze beacon frames to understand time synchronization via the timestamp, supported data rates (basic and mandatory), channel, SSID, TIM for power saving, and security plus vendor-specific beacon fields.

Learn how authentication and association enable devices to connect to an access point and begin sending traffic to the wired network.