There will be 100 concurrent users streaming video to their laptops. A 30/70 split between 2.4 Ghz and 5 Ghz will be used. Roughly how many APs (rounded to the nearest whole number) are needed based on client count?

The number of required Access Points (APs) is determined by the client capacity per radio, which is heavily influenced by the application type. For high-throughput, real-time applications like video streaming, a conservative client count per radio is essential to ensure performance and manage airtime contention.
1. Client Distribution: 5 GHz clients: 100 users 70% = 70 clients 2.4 GHz clients: 100 users 30% = 30 clients
2. Capacity per Radio: For high-density deployments with demanding applications like video, a conservative design parameter of 20-25 clients per radio is a standard best practice. Using a value of 20 clients per radio ensures sufficient airtime for each stream.
3. AP Calculation (per band): 5 GHz APs needed: 70 clients / 20 clients per radio = 3.5. This must be rounded up to 4 APs. 2.4 GHz APs needed: 30 clients / 20 clients per radio = 1.5. This must be rounded up to 2 APs. The final AP count must satisfy the band with the highest demand, which is 5 GHz. Therefore, 4 APs are required.

A. 2: This assumes a client density of 35 per 5 GHz radio (70/2), which is far too high for reliable concurrent video streaming and would result in severe performance degradation.
B. 3: This assumes a client density of approximately 24 per 5 GHz radio (70/3). While better, this is still not conservative enough for a large-scale concurrent video deployment.
D. 5: This assumes a client density of only 14 per 5 GHz radio (70/5), which is overly conservative and would lead to unnecessary hardware costs and potential co-channel interference.

1. Cisco Enterprise Mobility 8.5 Design Guide: In the chapter on "WLAN RF Design Considerations," under the "Client Density" section, the guide states, "The maximum number of clients that can associate to a radio is 200, but this is not a practical number for a good user experience... A more practical number is 20 to 30 clients for a typical enterprise deployment." For a high-demand video application, using the most conservative end of this practical range (20 clients) is the appropriate design choice.

2. High Density Wi-Fi Design Guide (Cisco Validated Design): This guide emphasizes that capacity is a function of airtime, not just client count. It states, "Applications such as video streaming... consume a significant amount of airtime... In environments with these types of applications, the number of clients per AP must be reduced to ensure a good user experience." This principle directly supports using a lower client-per-AP value (like 20) for the calculation in this scenario. (Reference: Section: "Capacity and Coverage," Subsection: "Application Impact on Capacity").

3. Stanford University, CS244e: Advanced Topics in Networking, Lecture Notes on 802.11 Design: Course materials on wireless network design frequently highlight that for real-time traffic like VoIP or video, the number of active clients per AP should be kept low, often recommending between 15-25, to minimize jitter and packet loss caused by media contention. This academic principle aligns with the calculation used.