11.5.3 Wireless Networking Facts

Wireless Networking Basics

• Wireless networks use radio waves to transmit data through the air.
• Unbounded medium: Radio waves are not confined to a cable like wired networks, allowing signals to reach areas inaccessible to wired connections.
• FCC regulation: Wireless networks operate within specific radio frequency ranges regulated by the Federal Communications Commission (FCC).
• Common frequencies: The most common frequencies used by wireless networks are 2.4 GHz and 5 GHz.
• 2.4 GHz: Wider, shorter range signals, allowing for longer distances, but slower data transmission.
• 5 GHz: Thinner, taller signals, offering shorter range, but faster data transfer.
• Unlicensed frequencies: Both frequency ranges are unlicensed, meaning no special permission is required to use them, but other devices can also use these frequencies.
• Channel conflicts: Multiple devices using the same frequency in a single area can lead to signal collisions and dropped connections.
• Channel adjustment: To avoid conflicts, you can adjust the wireless channel, slightly shifting the frequency.
• Channel width: Each channel is approximately 20 MHz wide, leading to slight overlap between channels.
• Non-overlapping channels: 2.4 GHz has three non-overlapping channels, while 5 GHz offers 24 non-overlapping channels.

Wireless Standards

• IEEE 802.11 standards: Wireless networks are defined by these standards, which specify ways to increase bandwidth and reduce interference during data transmission.
• 802.11 designation: Standards are labeled with 802.11 followed by letters indicating updates.

Wireless Standards Comparison

Wireless Network Performance Factors

• Theoretical speed: Maximum advertised speeds are often theoretical, and actual speeds are achieved only under optimal conditions.
• Transmission speed impacts: Speed is affected by distance, obstructions (like walls), and interference.
• Signal distance: Maximum signal distance is influenced by obstructions, antenna strength, and interference.
• Real-world distance: Typical environments with one or two walls might reduce the maximum distance by half.
• Speed vs. distance trade-off: Higher speeds usually come at the expense of shorter range.

Technologies for Enhanced Performance

• Multiple-Input, Multiple-Output (MIMO): Increases bandwidth by using multiple antennas for both transmission and reception.
  • Antenna configuration: 802.11n can support up to four sending and receiving antennas.
  • Beamforming: Improves speed by focusing the signal towards a specific receiving device, enhancing signal quality.
• Multi-User MIMO (MU-MIMO): An advancement of MIMO that allows multiple users to share the same channel.
  • Increased MIMO streams: 802.11ac doubled MIMO radio streams from four to eight alongside MU-MIMO implementation.
• Channel bonding: Combines two non-overlapping 20 MHz channels into a single 40 MHz channel, effectively more than doubling bandwidth.
  • Practicality: Channel bonding is generally more feasible in 5 GHz with its greater non-overlapping channel capacity.
  • Limited 2.4 GHz bonding: 2.4 GHz only allows for a maximum of one non-overlapping bonded channel due to its limited channel count.

Long-Range Wireless Networks

• Connecting buildings: Long-range wireless networks are commonly used to connect buildings on the same network.
• Solutions based on distance: Different solutions exist depending on the distance between network locations.
• Short distances: High-end access points with specialized antennas can be used for close proximity connections.
• Longer distances: Specialized equipment and licensed frequency ranges (900 MHz or 3.65 GHz) are required.
• Power increases: Increasing access point power can extend transmission range, but can lead to overheating and instability.
• FCC compliance: Consult FCC guidance regarding power increases to avoid interfering with other wireless devices.