This was session 361, part of the Wireless LAN Professional Wi-Fi Design Class, where Ferney covered the complete lifecycle of a Wi-Fi project. The session focused extensively on the definition phase, explaining that proper project definition goes far beyond simply installing Wi-Fi everywhere – it requires understanding client requirements, device types and capabilities, cabling infrastructure, budget constraints, vendor selection, power requirements, and physical mounting considerations. Ferney emphasized that Wi-Fi professionals should be involved in all stages of the project lifecycle rather than just being called in for post-deployment surveys when problems arise. The discussion included detailed explanations of design tools like Ekahau, Hamina, and Wavelify, and the importance of pre-deployment validation using “AP on a stick” testing to ensure designs work in real-world conditions. Ferney also clarified the difference between design (predictive simulation) and survey (on-site measurement), and addressed common pitfalls like the “one AP per classroom” approach that often leads to inadequate coverage.

The session focused on the concept of cell overlap in Wi-Fi network design, specifically addressing the fallacy of quantifying cell overlap as a percentage. Ferney explained that the idea of requiring a certain percentage of cell overlap, such as 30%, is not measurable or practical due to the irregular shapes of real-world Wi-Fi coverage areas. He demonstrated using design tools like Ekahau and Hamina to show how secondary coverage, which provides multiple signals for redundancy and roaming, is achieved by adding more access points rather than targeting a specific overlap percentage. The discussion highlighted the need to educate customers and peers to remove such unverifiable requirements from RFPs and contracts. The session also briefly touched on the life cycle of a project, which was postponed for a future discussion.

This was session 359 of Ferney’s free Wi-Fi design class, focusing on Wi-Fi interference terminology and concepts. Ferney explained key Wi-Fi terms including Basic Service Set (BSS), Basic Service Set Identifier (BSSID), Service Set Identifier (SSID), and Extended Service Set (ESS), demonstrating how different access points announce the same SSID using different BSSIDs. The session covered various types of Wi-Fi interference such as Co-Channel Interference (CCI), Adjacent Channel Interference, and Overlapping Basic Service Sets (OBSS), along with protection mechanisms like RTS/CTS. Ferney discussed how most Wi-Fi interference comes from other Wi-Fi networks rather than external sources, and showed examples using Wi-Fi Explorer Pro to analyze interference patterns in real networks. The class included participants from around the world including Australia, France, Sweden, Italy, Chile, Canada, and the United States, with Ferney emphasizing that all session recordings would be made available for free to help train Wi-Fi professionals worldwide.

This was Session 358 of Ferney’s free Wireless LAN Professionals Wi-Fi Design class, focused on the association process in Wi-Fi networks. Ferney explained how devices discover Wi-Fi networks through passive scanning (beacons sent 10 times per second, per radio, per SSID) and active scanning (probe requests sent by clients and probe responses sent by APs), emphasizing that too many networks increase airtime utilization and overhead. The class covered the complete association process from WLAN discovery through open system authentication, association request/response frames, and finally IP address acquisition via DHCP, with Ferney demonstrating real packet captures using Wireshark to show the entire process taking 1.9 seconds. Ferney stressed the importance of keeping the number of SSIDs low to reduce beacon overhead and discussed different authentication methods including PSK and 802.1X, noting that PSK is less secure due to its vulnerability to brute force attacks when passwords are shared among multiple users.

Hello, good morning, afternoon, or evening to everyone around the world! Welcome to Session 356 of Tesos en Wi-Fi, part of the free Wireless LAN Professionals Wi-Fi Design Class. Today, on Saturday, July 25th, I decided to celebrate my birthday doing what I love most: sharing Wi-Fi knowledge with all of you 100% free!. The Frame Types Burden: Why most airtime isn’t actually carrying data, but small management and control frames. OFDM Subcarriers & Channel Bonding: How 20 MHz channels divide into 64 subcarriers, and the price we pay in spectrum congestion when bonding into 40, 80, or 160 MHz wide channels. Interference Realities: The technical differences between Co-Channel Interference (CCI), Adjacent Channel Interference (ACI), and Overlapping Basic Service Sets (OBSS). DFS & AFC Rules: How Dynamic Frequency Selection protects radar systems, and how Automatic Frequency Coordination manages standard-power 6 GHz APs. Wi-Fi 6 OFDMA Mechanics: How Resource Units allow up to 9 client devices to transmit simultaneously, shifting Wi-Fi from single-device contention to efficient spectrum scheduling.

In this session of the Wireless LAN Professionals Wi-Fi Design Class 345a, we explore the foundational physics and practical applications of RF power measurements, focusing on dB Math and Free Space Path Loss. We strip away complex logarithmic formulas to introduce simple mental shortcuts that every wireless engineer must master for field calculations and certification exams. The Rules of Tens and Threes, the Inverse Square Law & Guacamole Analogy: We discuss how RF waves naturally dissipate over free space. We also analyze a real-world multi-device case study from a past WLPC Berlin presentation highlighting how easily RSSI fluctuates based on device orientation or user hand positioning. Why We Design in dBm Instead of Milliwatts: We visualize why enterprise Wi-Fi is mapped in dBm rather than raw power.

In this session of the Wireless LAN Professionals Wi-Fi Design Class 344a, we delve into the technical core of wireless data transmission: Modulation and Coding Schemes and MIMO Multiple Input Multiple Output engineering. We break down the complex variables that determine real-world data rates and explore how modern Wi-Fi devices negotiate speeds based on environmental conditions. We analyze the efficiency vs. redundancy trade-offs between the classic baseline coding rates: 1/2, 2/3, 3/4, and 5/6. We explain how a 1/2 coding rate delivers high redundancy sending 2 bits to net 1, while a 5/6 coding rate prioritizes maximum data efficiency sending 6 bits to net 5. Spatial Streams & MIMO Deep Dive: Using practical, everyday analogies, we clarify how spatial streams function as separate physical data flows. We dissect standard data sheet notations (e.g., 4×4:4), mapping out how the first digit represents transmit chains, the second represents receive chains, and the final digit represents active spatial streams. Access Point vs. Client Discrepancies: We explore the design benefits of deploying high-order 4×4:4 APs even when enterprise clients are mostly 2×2:2 or low-power 1×1:1 devices.

In this session of the Wireless LAN Professionals Class (Session 343), we tackle the core mechanics of how Wi-Fi devices share the air: Contention and the medium access protocols that prevent networks from collapsing into chaos. Since Wi-Fi is a shared, half-duplex medium, understanding these rules is critical for any wireless engineer. Key technical topics covered in this session include: Distributed Coordination Function (DCF): We break down the classic 802.11 baseline mechanism for resource sharing using Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). Clear Channel Assessment (CCA): We dissect how a station physically and virtually listens to the channel before transmitting: Physical Layer Carrier Sensing: Preamble Detection (PD/SD) checks for valid 802.11 signals at or above -82 dBm, while Energy Detection (ED) flags any raw RF noise at or above -62 dBm.Virtual Layer Carrier Sensing: How stations use the Network Allocation Vector (NAV) timer inside headers to virtually count down microsecond durations before attempting access. Inter-frame Spaces (IFS): We map out the quiet periods mandatory between transmissions, highlighting the timing gap priority structure including Short Inter-frame Space (SIFS) and Distributed Coordination Function Inter-frame Space (DIFS). The Random Backoff procedure is also explained. The Game is the name that Mr. Keith Parsons has given this process and has been used in the industry for a long time. The Game is the process in which devices pick a random number and countdown to zero. After all conditions meet, devices can send waves.

In this session, which is part of the Wireless LAN Professionals Wi-Fi Design Class, we dive deep into the fundamental operations of Network Interface Controllers (NICs) and how they interpret the wireless environment. We explore the critical process of converting electromagnetic waves into digital ones and zeros, highlighting the complexities that arise from hardware variations. Anatomy of Ethernet vs. Wi-Fi Frames: We break down the structure of frames, including the preamble for synchronization, expanded headers containing up to four MAC addresses in Wi-Fi, and the Frame Check Sequence (FCS) used to verify data integrity. RadioTap Header and Metadata: We explain how the receiving NIC adds essential information not found in the air, such as timestamps, channel stamps, and RSSI readings from its own perspective. Noise, SNR, and MCS: We discuss the challenges NICs face when estimating the noise floor and how the Signal-to-Noise Ratio (SNR) dictates which modulation schemes (MCS) the chipset chooses for data transmission. Survey Methodology and Speed: We address common questions regarding walk speed during site surveys and how scanning multiple channels across 2.4 GHz, 5 GHz, and 6 GHz affects data accuracy and interpolation.

During this session, part of the Wireless LAN Professionals Wi-Fi Design class we covered fundamentals of radio frequencies [RF] and characteristics of waves such as amplitude [measured in Watts, mW, and dBm], frequency [measured in Hertz], wavelength [measured in centimeters or inches] and phase. We finished the second part of this session learning about antennas. This beautiful devices.