Frequencies

This section discusses the frequency bands used in wireless communication and their significance.

2.4GHz

2.4GHz is a widely-used frequency band that provides longer range wireless communication at the cost of slower speeds and more interference.

Uses:

• Home WiFi networks
• Bluetooth devices
• Wireless peripherals
• IoT devices

Examples:

• 802.11b/g/n networks
• Microwave ovens
• Baby monitors
• Wireless keyboards/mice

Key Points:

• Channel Width: 20MHz standard width
• Non-overlapping channels: Only channels 1, 6, 11 don’t overlap
• Signal penetration: Higher ability to pass through walls vs 5GHz
• Interference: More common due to crowded frequency space
• Range: Longer range than 5GHz
• Speed: Slower maximum speeds (typically up to 450Mbps)

5GHz

5GHz is a higher frequency band offering faster speeds and less interference but with shorter range and less ability to penetrate walls.

Uses:

• High-speed WiFi
• Video streaming
• Gaming
• Large file transfers

Examples:

• 802.11ac networks
• WiFi 6 devices
• Modern smart TVs
• Gaming consoles

Key Points:

• Channel Width: Multiple options – 20/40/80/160MHz
• Signal penetration: Lower ability to pass through walls vs 2.4GHz
• Interference: Less common due to more available channels
• Range: Shorter range than 2.4GHz
• Speed: Faster maximum speeds (up to several Gbps)
• DFS: Required to avoid radar interference

Frequency Selection

Frequency selection is the process of choosing between 2.4GHz and 5GHz bands based on specific use case requirements.

Uses:

• Network planning
• Device placement
• Performance optimization

Examples:

• Dual-band routers
• Band steering
• Auto-channel selection

Key Points:

• Band selection: Choose based on distance and speed needs
• Signal strength: Decreases with distance and obstacles
• Network congestion: More likely on 2.4GHz
• Device compatibility: Older devices may only support 2.4GHz

Channels

Channels are subdivisions of frequency bands used to carry wireless signals. Proper channel selection helps minimize interference and optimize network performance.

Channel Configuration

Channel configuration is the process of selecting and setting up specific frequency channels for wireless communication.

Uses:

• Network optimization
• Interference reduction
• Coverage planning
• Multi-AP deployments

Examples:

• Auto-channel selection
• Manual channel planning
• Channel width adjustment
• DFS channel usage

Key Points:

• 2.4GHz Channels: Only 3 non-overlapping channels (1, 6, 11)
• 5GHz Channels: More available channels, less overlap
• Channel Width: Wider channels = higher speed but more interference
• Co-Channel Interference: Occurs when APs use same channel nearby
• Adjacent Channel Interference: Happens with overlapping channels

Regulations

Channel regulations are rules set by governing bodies that control which channels can be used in different regions.

Uses:

• Compliance management
• Interference prevention
• Spectrum management
• International compatibility

Examples:

• FCC regulations (US)
• ETSI standards (Europe)
• DFS requirements
• Power limits by region

Key Points:

• Regional Differences: Available channels vary by country
• DFS Channels: Required radar detection in 5GHz
• Power Limits: Maximum power varies by region and frequency
• Indoor vs Outdoor: Different rules for indoor/outdoor use
• Certification: Equipment must meet regional standards

Channel Planning

Channel planning is the strategic process of assigning channels to minimize interference in multi-AP environments.

Uses:

• Enterprise WiFi deployment
• Public venue coverage
• Campus networks
• High-density environments

Examples:

• Heat mapping tools
• Site surveys
• Channel reuse patterns
• Capacity planning

Key Points:

• Channel Separation: Maintain distance between same channels
• Coverage Overlap: 15-20% overlap recommended for roaming
• Signal Strength: -67dBm minimum for voice/video
• Noise Floor: Background interference level affects planning
• Client Density: Affects channel width selection

WiFi Standards (802.11)

WiFi standards define the capabilities and specifications for wireless networking, with each generation offering improvements in speed, capacity, and features.

802.11a/b/g (Legacy)

The original WiFi standards that laid the foundation for wireless networking.

Uses:

• Basic internet connectivity
• Email and web browsing
• Legacy device support

Examples:

• Original WiFi routers
• Older IoT devices
• Legacy printers

802.11n (WiFi 4)

WiFi 4 introduced MIMO technology and significant speed improvements over previous standards.

Uses:

• HD video streaming
• Online gaming
• Home networking

Examples:

• Dual-band routers
• Smart home devices
• Gaming consoles

802.11ac (WiFi 5)

WiFi 5 brought major improvements in speed and capacity, focusing on 5GHz operation.

Uses:

• 4K video streaming
• Cloud gaming
• Large file transfers
• Business networks

Examples:

• Modern smartphones
• Smart TVs
• Enterprise APs

802.11ax (WiFi 6/6E)

The latest WiFi standard focuses on efficiency and performance in crowded environments.

Uses:

• High-density deployments
• VR/AR applications
• Smart cities
• Industrial IoT

Examples:

• Latest smartphones
• WiFi 6 routers
• Modern laptops
• IoT devices

WiFi Standards Comparison

Feature	802.11a/b/g	802.11n	802.11ac	802.11ax
Max Speed	54 Mbps	600 Mbps	3.5 Gbps	9.6 Gbps
Frequency Bands	2.4/5 GHz	2.4/5 GHz	5 GHz	2.4/5/6 GHz
MIMO Support	✖	✔	✔	✔
Beamforming	✖	✖	✔	✔
Channel Width	20 MHz	20/40 MHz	20/40/80/160 MHz	20/40/80/160 MHz
MU-MIMO	✖	✖	✔	✔
OFDMA	✖	✖	✖	✔
Year Released	1999-2003	2009	2014	2019

Short-Range Wireless Technologies

This section covers various short-range wireless communication technologies used for device-to-device communication and identification.

Bluetooth

Bluetooth is a wireless technology standard for exchanging data between devices over short distances using UHF radio waves.

Uses:

• Wireless audio streaming
• Device pairing (keyboards, mice)
• File transfer between devices
• IoT device communication

Examples:

• Wireless headphones
• Car audio systems
• Fitness trackers
• Smart home sensors

Near Field Communication (NFC)

NFC is a very short-range wireless technology that enables simple and secure communication between electronic devices.

Uses:

• Contactless payments
• Access control
• Transit cards
• Device pairing

Examples:

• Mobile payment systems
• Hotel key cards
• ID badges
• Smart posters

Radio-Frequency Identification (RFID)

RFID uses electromagnetic fields to automatically identify and track tags attached to objects.

Uses:

• Inventory tracking
• Asset management
• Supply chain monitoring
• Access control

Examples:

• Warehouse management
• Pet microchips
• Anti-theft tags
• Toll collection systems

Technology Comparison

Feature	Bluetooth	NFC	RFID
Range	Up to 100m	Up to 4cm	Few cm to 100m
Frequency	2.4 GHz	13.56 MHz	125 KHz – 2.4 GHz
Data Rate	Up to 2 Mbps	424 Kbps	Up to 640 Kbps
Power Requirement	Low-High	Very Low	None-Low
Pairing Required	✔	✖	✖
Security Level	High	Very High	Low-Medium
Battery Life Impact	Medium	Very Low	None

Long-Range Fixed Wireless

Long-range fixed wireless technologies provide broadband connectivity over extended distances without wired infrastructure, commonly used in rural areas and point-to-point connections.

Licensing

Wireless frequencies can be either licensed or unlicensed, each serving different purposes and requirements.

Uses:

• Licensed bands for critical communications
• Unlicensed bands for public access
• Point-to-point connections

Examples of Licensed Band Usage:

• Public safety networks
• Cellular backhaul systems
• Military communications
• Broadcasting services

Examples of Unlicensed Band Usage:

• Wireless Internet Service Providers (WISPs)
• Campus networks
• Municipal wireless networks
• Community broadband

Power

Transmission power levels determine the range and reliability of wireless connections while adhering to regulatory limits.

Uses:

• Long-distance links
• Rural broadband
• Backhaul connections
• Point-to-multipoint distribution

Regulatory Requirements

Government regulations control the use of wireless frequencies and power levels to prevent interference and ensure proper spectrum usage.

Uses:

• Frequency coordination
• Power limit compliance
• Equipment certification

Examples of Regulatory Requirements:

• FCC regulations – Controls frequency usage and power limits in the US
• EIRP limits – Maximum allowed power output including antenna gain
• Equipment standards – Required certifications for wireless devices
• RF exposure limits – Safety requirements for human exposure
• Site registration – Required documentation for tower installations
• International compliance – ITU and local country regulations

Feature	Licensed	Unlicensed
Frequency Access	Exclusive	Shared
Cost	High	Low
Power Limits	Higher	Lower
Interference Protection	✔	✖
Typical Range	50+ km	5-25 km
Application Process	Required	None