Posts

It was absolutely wonderful to return to San Diego for Cisco Live this year, especially since it had been nearly 10 years since my last attendance. The experience was incredibly nostalgic and in my opinion is one of the best location for the conference. The weather was beautiful and the Gaslight district has so much to offer. I am looking forward to the new WiFi7 CW9179F access point for large venues. It is 6 pounds lighter than the C9104 Marlin and has some really cool new features, including a back facing antenna. ...

My CWNE Journey Overview In this future post I will share my experience going through the CWNE Application process. Comming Soon - fingers crossed

What is Airtime Airtime is a critical metric in wireless design. It determines how much time a device occupies the channel to transmit or receive data. When multiple clients share the same radio, excessive airtime consumption leads to poor performance. This simplified calculation helps estimate how many AP radios are needed to support a given number of clients with specific application requirements. Key Assumptions Application throughput per client: 1 Mbps (e.g., basic web/email) 1 AP with 2 radios (2.4 & 5 GHz) Wi-Fi 6 (802.11ax) clients using typical MCS data rates Goal: keep total airtime per radio under 80% utilization Airtime Calculation Steps Determine Data Rate Based on MCS index, spatial streams (SS), modulation, and channel width. Data rate = MCS 5 + 2SS + 80 MHz ...

Overview This is a collection of important notes and information that I have collected over the years through my studies to act as a quick reference/refresher for myself. Important WiFi Metrics RSSI SNR MCS Data Rate Security Congestion Responsiveness Scans Selection Decisions Roaming Scans CAPWAP Ports 5246 – Control (DTLS) 5247 – Data RF Design Guidelines AP Spacing ~44–70 ft apart (~20% overlap) Avoid straight lines; stagger placement AP per Area Data only: 1 AP per 5,000 sq ft Voice: 1 AP per 3,000 sq ft High density: 1 AP per 11–120 sq ft Cisco: 1 AP per 2,000 sq ft Install Height 10–15 ft above ground Avoid HVAC, lights, beams AP Separation 10 ft between APs 3 ft from obstructions Design Tips Design at half power Model actual AP characteristics Signal Strength Targets Cell Edge (RSSI) -67 dBm for data -65 dBm for voice -75 dBm for location accuracy Roaming Target -70 dBm as roaming edge Voice latency: ≤100ms Client Tx Power Avg: 14 dBm (match AP when possible) SNR Minimum: >20 dB More critical than RSSI Channel Planning Unique Channels 2.4 GHz: 3 5 GHz: ~25 6 GHz PSC: 15 primary (every 4th) Interference Types CCI: Co-Channel Interference (same channel) ACI: Adjacent Channel Interference Channel Bonding Adds 3 dB noise OBSS = Overlapping bonded channels Performance Metrics Retries: <5% Packet Loss: <1% for voice <3% for data Latency: <150ms Jitter: <20ms Channel Utilization: Voice: <50% Video: <30% Carrier Sense Threshold: <-82 dBm Energy Detect: ~-62 to -72 dBm Power & Attenuation Same Channel Separation: >19 dB (e.g., -67 dBm edge, next AP < -86 dBm) Distance Rule: Every 6 dB drop ≈ 2× distance Attenuation Test: Place AP 12–16 ft from wall Measure both sides Client Handling Clients per AP: Typical: 30–50 High-density: 20–30 RTLS Requirements: Min 4 APs ≥3 APs at -62 dBm Outdoor Antennas Vertical Separation: 3–12 m (2.4/5 GHz) Horizontal Separation: 5 GHz: 7.5–15 m 2.4 GHz: 1–5 m Max Cable Length: 30 ft (10 m) Protocol & Behavior CAPWAP Heartbeat: 30s default SSID Limit: 3–4 recommended Management Frames: Lowest basic rate Multicast Frames: Highest basic rate Neighbor Ads: Sent at max AP Tx power 6 GHz Specifics Probing ...

Overview In this post I will outline some lessons learned about my journey designing for and deploying the Cisco C9104 Marlin access point in our stadium. Installation One of the many challenges of deploying wireless in a stadium is where to best mount the access points. There are many opinions on this matter with different preferences from wireless engineers depending on the design, layout, and mounting options. In our final design, we chose to use the catwalk to mount the access points facing the stands, but one thing I hadn’t previously considered was the catwalk’s weight capacity. The last thing I wanted weighing on my conscience,no pun intended, was the catwalk collapsing under the added load during an event. ...

First things first—it’s pronounced “FRAY-NEL Zone,” not “FRES-NEL Zone”. The term comes from physicist Augustin-Jean Fresnel, who made major contributions to the field of wave optics. When brainstorming a name for this blog, I wanted something that would resonate with the wireless community—something technical, but also memorable. Much like the Clear to Send podcast, I aimed for a name that symbolizes communication between two endpoints: the creator (me) and the reader (you). The Fresnel Zone felt like the perfect fit—an essential concept in wireless communication that also represents the space where our ideas and conversations intersect. ...

I recently attended an Ekahau webinar focused on Wi-Fi networking in higher education but after reflecting on the session, I realized I didn’t quite capture the full scope of challenges that make university environments so unique. Having worked in both public and private sectors, I thought it would be valuable to share some personal insights from my experience in higher ed. Working for a university is a distinct experience. It offers tremendous opportunities to learn but this is often out of necessity due to limited staff, competing priorities, and tight budgets. Yet, it’s this very challenge that forces creativity and growth. ...

Left to Righ: Me, Rowell, Dale, Mac, Matt A quick word about meeting your heros I have been fortunate enough to have met some of my social media heros who have helped motivate me through online videos & podcasts and have had a significant impact on my career, even though I myself am a complete stranger. I was very cautious and intimidated about meeting them, considering the stigma around meeting your heros, but I was pleasantly surprised. ...

This is what I hope will become a relevant blog about 802.11 WiFi topics. My name is Larry and I am a network engineer working for a university with a passion for all things wireless. I did not start out as wireless network engineer but have benefited greatly from the wifi community. My hope is to give back and share snippits of codes and/or general thoughts to help the next generation of wireless engineers. ...

Hello World This is my first post, please be gentle.