CWDP 305 - Chapter 2 Defining Specifications for the WLAN

This chapter is a lot, with lots of terminology and important specifications to remember. I'll try to get to the point and log all the essentials in order to summarise the chapter for study purposes. I'm still new to this, so bear with me.

Regulatory compliance refers to rules set by external authorities—such as governments or parent companies—that determine how technologies like WLANs can be deployed. In the U.S., WLANs must follow FCC regulations, which outline frequency bands, limit EIRP (Effective Isotropic Radiated Power), and require features like DFS (Dynamic Frequency Selection) and DCA (Dynamic Channel Assignment) to prevent radar interference. FAA rules also apply near airports. With the introduction of Wi-Fi 6E (802.11ax), access to the 6 GHz band was expanded, allowing up to seven 160 MHz-wide channels indoors at 30 dBm EIRP, and four channels outdoors at 36 dBm.

Reading and studying with the official study book the US Regulatory compliance, Because I live in the Netherlands I will discuss the EU regulations as well. In Europe, WLANs must comply with the Radio Equipment Directive (RED) and ETSI standards, but spectrum access is more restricted. Only the three lowest 160 MHz channels in the 6 GHz band are available, providing a total of five 160 MHz channels, compared to ten in the U.S.

The Business Analysis Process defines the problem or opportunity, the solution environment, and possible solution options. Business requirements involve identifying and documenting organizational needs early in development to guide system design.

• The project charter: A document that gives official recognition of a project and gives a project manager written approval to begin working on the named project.
• The project purpose: The project purpose is the reason an organization or business
• establishes a project and the primary objective for the project to achieve once completed.
• The project vision statement: A document that provides the project owner(s) witha well‐written description of the project outcome that will result in positive changes in the business.
• A Scope of Work (SoW) or Statement of Work: A written statement listing the work to be performed under a contract to complete a project.

Gathering, Defining, and Implementing Technical Requirements

Location Services - Unlike typical voice and data setups, access points (APs) should be strategically positioned in corners and along walls to improve the accuracy of device location. In smaller buildings, placing APs along walls may not be necessary, depending on RF propagation characteristics. It's essential to have at least three to four APs capable of detecting signals at -75 dBm or higher for precise location tracking. Techniques such as Received Signal Strength (RSS), Time of Arrival (ToA), and Angle of Arrival (AoA) are used to enhance location accuracy, while Bluetooth Low Energy (BLE) beacons can further improve tracking capabilities across different environments.

Latency is the delay between the input time of a packet and the time that packet reaches its destination, or it is the round‐trip‐time (RTT) for a higher layer communication to reach the destination and the acknowledgement to be received by the original transmitter. Controlling latency within a WLAN depends heavily on several things within the network like for example routing and switching, applications and devices used, cabling and fiber infrastructure and WLAN design. Voice and video applications are most commonly affected by latency. For voice applications, it is best to have latency at or below 150ms from mouth to ear and less than 1% packet loss.

Signal Strength Requirements: In WLANs, signal strength is the measured power of a transmitted signal at a distance, often called RSSI (though its 802.11 definition differs). Measured in dBm (e.g., –67 dBm), it’s shown as a negative number. Another key factor is the noise floor, which consists of interfering signals and background radiation on the channel. SNR (signal to noise ratio) is a measure used to quantify the level of a desired signal relative to the level of background noise. It is typically expressed in decibels (dB). A higher SNR indicates a clearer and more reliable signal, as it means that the signal strength is much greater than the noise level.

Coverage Requirements: To effectively plan WLAN coverage, start by using a floor plan to identify areas that need access. Make sure you get the most accurate floorpan as possible! Nothing is more daunting than crappy floorpans. During the design phase, ensure there’s sufficient coverage for your services and applications. Understanding the facility is crucial. Building materials can impact signal strength—thick concrete walls may require more access points (APs), while metal structures can hinder signal penetration. Additionally, as distance from the AP increases, signal strength decreases due to free space path loss. By considering these factors, you can optimize AP placement and ensure your network meets both coverage and capacity requirements. To meet capacity requirements:

• Co-existing APs: Deploy multiple APs on different channels to increase throughput.
• Smaller coverage cells: Use more APs with lower power to reduce congestion and improve data rates.
• Higher throughput protocols: Upgrade to 802.11ac APs for better performance, even with 802.11n clients.

When planning for capacity requirements, it's essential to start with a spectrum analysis of the environment. This helps identify and address potential sources of interference that could impact WLAN performance in key areas. By doing this, you can either eliminate these interferences or design your network to work around them effectively.

Security is critical in WLAN design, balancing performance and threat prevention. Key considerations include fast secure roaming, network monitoring, BYOD/MDM, and guest access. In CWSP a whole entire course is dedicated to the wireless security, which I'll be studying next.

Authentication & Encryption

• Hard Requirements: Enforced via NAC, often required in high-security environments (e.g., government, healthcare). Examples:
  • EAP-TLS
  • WPA2-Enterprise
  • FIPS-140 encryption
• Client Support: Security adapts to device capabilities (e.g., WPA-Personal with strong passphrases).

Secure authentication prevents unauthorized access. Best practices:

• Use WPA2/WPA3 Enterprise (802.1X) with RADIUS for strong security.
• Avoid weak passwords, which are vulnerable to attacks (brute force, phishing, keyloggers).
• 802.1X Authentication Process:
  • Supplicant: Client device requesting access.
  • Authenticator: AP or WLAN controller verifying credentials.
  • Authentication Server: RADIUS server handling authentication.

WPA3 Enterprise offers a 192-bit encryption and EASY CONNECT for simpler onboarding while maintaining WPA2 compatibility.

Fast Secure Roaming - Essential for VoIP and mobile applications. Methods include:

• OKC (proprietary, limited compatibility) refers to a method used in the 802.11 protocol for improving the efficiency of key management in secure communications.
• 802.11r/k (standards-based, growing adoption) are amendments to the IEEE 802.11 wireless networking standard that enhance the performance and efficiency of Wi-Fi networks, particularly in environments with mobile devices.
• WPA-Personal/WPA2-Personal (widely supported but higher management overhead)
• PPSK (unique per-device keys for added security) To enhance the management and security of Wi-Fi access.

Layer 2 roaming is generally suitable for most applications since it maintains network connections at higher layers. In contrast, Layer 3 roaming can lead to issues, as it changes the IP address, which may cause applications to fail or require a reset due to lost connections at higher layers.

Wireless Intrusion Prevention Systems (WIPS) help mitigate common attacks through centralized servers and distributed sensors for WLAN monitoring. There are integrated WIPS (built into the WLAN controller) and overlay WIPS (standalone). When designing a WLAN, consider WIPS options and ensure customers understand their differences. Existing WIPS may need upgrades for modern detection capabilities.

BYOD (Bring Your Own Device) lets employees bring their favourite own gadgets to work, boosting productivity, cutting down on hardware costs, and keeping everyone happy with the devices they love. MDM (Mobile Device Management) steps in to ensure everything runs smoothly and securely, managing both personal and company devices. It uses techniques like containerization to keep enterprise data safe and MDM controls to approve and monitor devices. Plus, with BYOA (Bring Your Own Application), employees can use their personal software licenses, making it even more budget-friendly. But when rolling out BYOD, make sure your MDM can handle all the device types, security settings, and infrastructure needs to keep everything in check!

Network Access Control (NAC) checks devices for compliance before granting access. Non-compliant devices may be denied or quarantined for updates. Guest Access uses VLANs to separate guest and corporate traffic. Options include: Open access (public hotspot), Captive portal (terms agreement) and Secured access (WPA-Personal, Web auth, or registration) For security, guest VLAN traffic can be routed through a DMZ with firewalls. Just make sure employees know how to use the right Wi-Fi, not to have them use the guest network or even worse personal hotspots on their phones!

Wireless Roaming - Proper WLAN design ensures smooth roaming. Key factors:

• Cell Overlap: 20–30% RF overlap for seamless handoff.
• RF Profiles: Set minimum signal and data rates for optimal connections.
• Fast Secure Roaming: Use 802.11r, 802.11k, and OKC for faster transitions.
• Layer 3 Roaming:
  A Mobile Node (MN) is a roaming device that maintains connectivity while moving between networks. The Home Agent (HA) routes packets to the MN, while the Foreign Agent (FA) updates the HA on the MN’s current location. The Care-of Address (CoA) manages packet delivery to ensure seamless communication. Using Mobile IP, devices can stay connected across subnets, which is essential for uninterrupted VoIP calls. In a Mobile IP-enabled network, the home agent and foreign agent work together to facilitate Layer 3 roaming, allowing devices to move across VLANs without changing their IP addresses, which is critical for VoIP functionality.

Wireless Network Monitoring - Monitoring WLAN ensures performance and security. Common issues like Rogue APs which are unauthorized devices and can cause interference and security risks. WIPS can detect and mitigate them. It also detects neighboring networks, nearby WLANs may interfere. Auto-channel selection helps avoid conflicts. New interference sources are devices like microwaves and cameras and can disrupt Wi-Fi. Regular spectrum analysis is essential.

Wireless Bridge Links - Wireless bridges connect buildings without wired links, often for cost savings or redundancy. They can be: Point-to-Point (one-to-one) & Point-to-Multipoint (one-to-many) Key Considerations:

• Configuration: Bridges use a root (parent) and non-root (child) setup.
• Building Count: Single connection uses point-to-point, multiple uses point-to-multipoint.
• Distance: Omni-directional antennas for short-range, directional high-gain antennas for long-range.
• The Fresnel zone cannot be obstructed more than 40% without causing serious degradation of the signal.

Documentation is key!

Effective WLAN design begins with thorough requirements analysis and comprehensive documentation. Following standards like IEEE 29148-2018 ensures requirement statements are clear and valid, supporting quality system development. Before starting a new WLAN project or upgrading an existing one, gather and review existing documentation, including:

• Network infrastructure: Check switch compatibility, available ports, PoE capacity, network closet locations, fiber availability, and VLAN size.
• Cabling: Identify and document available network drops that could reduce costs and installation time.
• Network services: Understand current DNS, DHCP, NTP, and authentication setups to guide WLAN security and IP planning.
• IP addressing: Evaluate DHCP setup and subnet capacity to ensure sufficient IPs for WLAN devices.
• Floor plans: Use updated and validated floor plans to mark cable drops, AP locations, and spectrum analysis data. This will save you from a lot of potential headaches down the line.
• Existing WLAN systems: Document and make photographs of the AP locations and gather historical survey data for reuse and compatibility assessment.

The main point to remember is to prioritize thorough documentation over minimal documentation. This helps prevent unexpected issues and ensures a seamless design and deployment process.

Environmental Factors Documentation (for WLAN Design)

When designing a WLAN, it's critical to document environmental factors early—some during requirements gathering and others before design begins. 

Wireless Enviroment scans include spectrum analyses which identifies RF noise and interference, often mapped to floor plans. Packet captures to reveal existing devices, channels, and PHYs in use. Tools like Acrylic or Wi-Fi Explorer can show active networks and clients.

Site Details

•   Accurate floor plans with AP placements.
•   Locations of switches, PoE availability, and cable drops.
•   Existing WLAN infrastructure (if upgrading or expanding).
•   Photos of equipment and planned install areas.
•   Heat maps from surveys.
•   A full materials list (APs, antennas, switches, licenses, etc.).
•   Detailed design description showing how it meets customer needs.
•   Building material attenuation factors and ceiling heights for accurate modeling.

Project Management involves setting clear expectations early on and maintaining strong communication and documentation for a successful implementation.

Requirements Engineering (per IEEE 29148-2018)

Requirement Categories

• Functional/Performance: What the system does (e.g., maintain connectivity).
• Interface: Internal/external system interactions.
• Process: Legal, contractual, and organizational requirements.
• Quality (Non-Functional): Attributes like reliability, security, maintainability.
• Usability/Quality-in-Use: User experience and satisfaction.
• Human Factors: Safety, health, and human efficiency in system use.

Functional vs. Non-Functional Requirements

• Functional requirements define what the system must do, including features needed for user goals (e.g., AP availability, seamless roaming).
• Non-functional requirements focus on performance and quality aspects that support these functions without detailing them (e.g., uptime guarantees, monitoring tools).

Each requirement should be written acording to the IEEE Guidelines. These are: necessary, appropriate, unambiguous, complete, singular, feasible, verifiable, correct, and conforming to style. And these sets should be complete, consistent, feasible, clear, and verifiable.

Language Guidelines : Use "shall" for mandatory statements. Avoid vague verbs like "must" or passive voice. Prefer positive, active statements. Avoid phrases like “shall be able to.”

Recommended Template : [Condition][Subject][Action][Object][Constraint of Action]

Example:  When a device seeks to join the corporate network [Condition], a wireless access point [Subject] must be operational [Action] to establish a connection [Object] throughout the entire office building [Constraint of Action].

That was chapter 2!

In this chapter, I learned about the importance of requirements engineering, including IEEE 29148-2018 and related standards. Explored key concepts in requirements engineering and the considerations necessary for WLAN projects. With proper requirements analysis, you have the right foundation to build an effective WLAN design. Without this analysis, it becomes nearly impossible to implement solutions that meet the organization’s needs.

I really liked how this chapter emphasized the importance of thorough analysis for successful projects. There was a lot to take in, but the insights are super helpful for proper defining a WLAN. Working with half the information and crappy drawn floor plans is definitely not a fun way to kick off a project! In the next chapter, we’ll dive into a specific part of requirements engineering that focuses on wireless networks, including both Wi-Fi and non-Wi-Fi IoT networks, called requirement areas.

Until next time, keep the signal strong!

Source(s):

Carpenter, T., et al. (2024). CWDP-305: Certified Wireless Design Professional Study Guide (1st ed.). Durham NC, USA: Certitrek Publishing