Wi-Fi Roaming Performance in MDUs: Navigating Seamless Connectivity

Introduction: The Quest for Uninterrupted Connectivity

At 802.11 Networks Corp, we’re driven by a passion for Enterprise Wireless. We believe in demystifying complex topics, diving deep into the technical intricacies, and presenting our findings in a way that sparks conversation and propels industry-wide improvements. Today, we’re focusing on a critical aspect of modern living: Wi-Fi roaming in Multi-Dwelling Units (MDUs).

Think bustling apartment complexes, vibrant student housing, comfortable senior living facilities, and modern condominiums. Why this focus?

• Ubiquity of MDU Living: A significant portion of the population resides in MDUs. In the US, estimates range from 30% to 42%, highlighting the sheer scale of this living arrangement.
• The Promise of Managed Wi-Fi: MDUs offer a unique opportunity for property-wide, managed Wi-Fi solutions. When implemented effectively, these systems deliver substantial technical and economic advantages to residents.

A cornerstone of a successful managed Wi-Fi deployment is seamless roaming. Residents expect their connected devices to transition smoothly between access points (APs) as they move throughout the property. This eliminates frustrating disconnections and ensures a consistent user experience.

In this post, we’ll dissect common MDU deployment architectures, exploring their strengths and weaknesses. We’ll start by differentiating between managed and non-managed environments, then delve into four specific client authentication and roaming scenarios. Our goal is not to declare a “winner” but to foster a constructive dialogue that enhances human connectivity.

Understanding MDU Wi-Fi Architectures

To fully understand the results of the performance test, we must first understand the architectures that are being tested.

1. Traditional Residential Deployments: The “Home Router” Approach

• Each apartment operates its own dedicated home router.
• These networks typically feature:
  • A private SSID secured with WPA2-Personal for individual residents.
  • A universal SSID, often utilizing Passpoint with pre-installed profiles, enabling limited roaming across the complex.
• Technical Characteristics:
  • NAT (Network Address Translation) is standard, isolating each apartment’s network.
  • 802.11r (Fast Transition) is generally absent.
  • Some APs may implement key caching to expedite re-authentication for returning devices.
• Limitations:
  • Limited roaming performance.
  • Interference between many routers.
  • Difficult to manage as a whole.

2. Managed MDU Deployments: Centralized Control

• A professionally designed RF network covers the entire property.
• APs are strategically placed based on a thorough RF survey, ensuring optimal coverage.
• A single, unified SSID is broadcast throughout the property.
• Technical Characteristics:
  • VLANs (Virtual Local Area Networks) are employed to segregate resident traffic, ensuring privacy and security.
  • Authentication options include:
    • Passpoint-like systems with pre-installed profiles (ideal for smartphones and laptops).
    • Multi-PSK (MPSK) solutions with RADIUS authentication (offering a balance of security and ease of use, and better IoT compatibility).
• Key Points:
  • Allows 802.11r to be implemented
  • Centralized management and troubleshooting.
  • Enhanced security and privacy relative to using a single, shared PSK.
  • Ability to fine tune the network.

Quantifying Roaming Performance: The Test Bed

To objectively assess roaming performance, we constructed a test bed that replicated the scenarios described above. We distilled the myriad of possible configurations into four representative cases:

1. WPA2-Enterprise (TLS) + Bridged + 802.11r:
   • Represents a managed MDU with Passpoint or similar pre-installed profiles.
   • Bridged network: Clients retain their IP address during roaming.
   • 802.11r: Rapid authentication using R1 keys distributed via the Distribution System (DS).
2. WPA2-Enterprise (TLS) + NAT’d + Key-Caching:
   • Mirrors the universal roaming SSID in traditional residential deployments (e.g., Xfinity Mobile Hotspot).
   • NAT’d network: DHCP lease renewal and Layer 3 (L3) connection break during roaming.
   • Key caching: Speeds up re-authentication for returning clients, but no 802.11r.
3. MPSK-RADIUS + Bridged + 802.11r (or Key-Caching):
   • Represents a managed MDU with MPSK and RADIUS authentication.
   • Bridged network: Maintains L3 connection.
   • 802.11r availability based on capabilities of backend MPSK solution used
   • Each resident gets a unique PSK tied to a VLAN.
4. MPSK-RADIUS + NAT’d + Key-Caching:
   • While less common, it was tested to provide a complete view.
   • NAT’d network.
   • Key Caching.

The Test Setup: Precision and Control

• Two Enterprise OpenWiFi APs broadcasted the four SSIDs, each corresponding to a test case.
• The APs were connected to a Linux-based router (providing DHCP, RADIUS, and NAT) via a switch.
• FreeRADIUS was used for RADIUS authentication.
• All tests were conducted in RF isolation chambers to ensure accuracy.
• Roaming events were manually triggered for consistent results.

Test Architecture Diagram:

Test Execution: Measuring Roaming Dynamics

• Each test began with a pre-authenticated client connected to AP1.
• A continuous ping to 8.8.8.8 (Google DNS) was executed with a 1-second interval.
• Four manual roaming events were triggered during the 100-ping test.
• Latency and packet loss were recorded for each scenario.

Results: A Clear Picture of Performance

• WPA2-Enterprise (TLS) + Bridged + 802.11r:
  • Packet Loss: 4%
  • Average Latency: 16.98 ms
• WPA2-Enterprise (TLS) + NAT’d + Key-Caching:
  • Packet Loss: 12%
  • Average Latency: 19.91 ms
• MPSK-RADIUS + Bridged + 802.11r:
  • Packet Loss: 1%
  • Average Latency: 18.20 ms
• MPSK-RADIUS + NAT’d + Key-Caching:
  • Packet Loss: 9%
  • Average Latency: 18.07 ms

Analysis and Conclusion: Optimizing MDU Wi-Fi

Why Roaming Matters: Seamless roaming is essential for a positive user experience in MDUs. Disruptions lead to frustration and decreased productivity.

Best Solutions:

• Managed MDUs:
  • Regardless of the authentication method (MPSK/WPA2-Enterprise), Bridged networks with 802.11r offer excellent performance.
  • MPSK-RADIUS with VLANs adds user-friendlinesss for IoT devices
• Traditional Residential:
  • NAT’d networks with key caching are common, but less ideal.
  • Requires separate, universal SSID for Roaming across property.

Client Considerations:

• Passpoint benefits devices with pre-installed profiles.
• MPSK-RADIUS accommodates IoT and other devices with limited capabilities.

Comparison Matrix:

Key Takeaway: By understanding these technical nuances, Professional WLAN experts, like 802.11 Networks Corp, can help ISPs & MDU Network Operators to deliver exceptional roaming experiences.