FOA Guide to Fiber Optics


WiFi - IEEE 802.11 Wireless

WiFi
WiFi in a conference center and a city park

Wi-Fi, an abbreviation of "Wireless Fidelity," allows you to connect to the Internet from your couch at home, in restaurants, airports, hotel rooms or a conference room at work without wires. Wi-Fi is a wireless technology like a cell phone, but optimized for data and Internet connections. Wi-Fi enabled computers send and receive data anywhere within the range of a local wireless antenna
(access point) connected to a Ethernet network or directly to the Internet through a cable modem, DSL modem or FTTH (fiber to the home)  ONT (optical network terminal) connection.

WiFi originally referred only to the IEEE 802.11b version of the wireless standard, but to reduce confusion, it was expanded to include all versions of 802.11.
WiFi is the version of wireless networks most users are familiar with. Most laptops, tablets, smart phones and other mobile devices now support WiFi connections and all offices have installed WiFi access points. Metropolitan WiFi networks are outside plant installations connecting access points around the city over a municipal Ethernet network over singlemode fiber.

There are numerous versions of 802.11 developed over time to be faster, more reliable, secure and wide-ranging and many versions but not all are backward compatible

802.11: was the first version of this wireless LAN and provided 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS). 802.11 as well as version a and b are effectively obsolete.
 
802.11a: an extension to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.

802.11b (also referred to as 802.11 High Rate or Wi-Fi): an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1 Mbps) in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.

802.11g: applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.

802.11n: uses multiple channels and frequencies to transmit data at higher rates (~100 Mb/s) while still offering compatibility to previous 802.11 versions.

802.11ac: uses multiple channels and frequencies to transmit data at still higher rates (up to ~500 Mb/s throughput) while still offering compatibility to previous versions. Sometimes referred to as 5G WiFi.

802.11ad "WiGig" is a tri-band Wi-Fi using 60 GHz, that can achieve a theoretical maximum throughput of up to 7 Gbit/s.

Which WiFi version should be chosen? The latest, of course! WiFi wireless standards are developed by the IEEE 802.11 committee, and standards are already up to version “n” (802.11n) and version "ac" coming soon. Many current networks use 802.11g or n which offer adequate bandwidth for most users and enough channels (frequencies) to accommodate multiple access points for good coverage.  The higher bandwidth version now more commonly used, called “ac” trades channel selection for bandwdth by transmitting part of the signal over one of several frequencies, similar to GbE which uses all 4 UTP pairs simultaneously. It is important to note that the b, g and n versions are interoperable.

There are several other wireless networks that may also be used either with or in place of WiFi.

Bluetooth  (IEEE 802.15)
Bluetooth is a limited distance network for consumer devices. It has been used to connect a wireless printer or mouse to a PC, wireless headsets to cell phones and stereos, cell phones to cars for hands-free operation, digital cameras to printers, etc. 802.15 is a communications specification that was approved in early 2002 by the Institute of Electrical and Electronics Engineers Standards Association (IEEE) for wireless personal area networks (WPANs). The initial version, 802.15.1, was adapted from the Bluetooth specification and is fully compatible with Bluetooth 1.1.
In terms of installation, Bluetooth is built-in to many devices and plugged into USB ports or added as cards to PCs, not installed as access points like WiFi, so it is not generally of interest for cabling installers.

WIMAX  (IEEE 802.16)
WiMAX is a further development of wireless network technology that expands the data capacity of wireless to ~ 100 Mb/s and it’s distance capability to several miles. WiMAX is still in the development stage, where WiFi is well established. Unlike WiFi which was primarily a short distance network aimed at private networks, WiMAX appears aimed at communications carriers who could use it in place of landline networks, substituting WiMAX, for example, for Fiber To The Home, in areas needing upgrades of their networks or using it to allow notebook PC or PDA roaming in a metropolitan area.

Like all networks, WIMAX needs a lot of standards work, here under the IEEE 802.16 committee. Products are already available, but many users are awaiting final standards and interoperability before committing to the technology. WiMax networks will look more like cellular networks, built into the local geography like cellular phone infrastructure, requiring negotiating frequency allocations and antenna locations.

WIMAX installations will primarily be outside plant installations connecting over singlemode fiber. WiMax has not been widely used.

"Super WiFi"
Bringing broadband to the rural areas of the US or any large country with sparse population can be very expensive. The US has a plan, however, that may make it more affordable. "Super WiFi" is not your usual WiFi. It is using WiFi protocols but broadcasting on frequencies of unused TV channels, called "white space." The FCC is ready to open up new frequencies to broadband to allow delivering broadband Internet and phone to rural areas where cabling is too expensive.

Super WiFi works at a lower frequency than either regular WiFi or cellular systems so it has more reach into areas that are too rugged for most wireless systems. Usage in more urban areas may be a problem however, if there are too many broadcast TV stations which can interfere with Super WiFi signals (and vice versa.) These antennas will also require fiber to connect into the network.


Wireless In Premises Networks
Wireless in the corporate premises network is WiFi (IEEE 802.11), the common network built into most laptop or netbook computers, tablets, VoIP phones, many cellular phones and other portable devices. The wireless “antenna” in the network, called an "access point," is a lot more than that. It’s a radio transceiver and network adapter that connects to your laptop to allow access to the network, with some logic that implements part of the network protocols allowing access to the network. The transceiver in the antenna has limited power as does the transceiver in the portable device, so the distance from the antenna to your laptop is limited. Connection between devices and antennas can be affected by metal in a building that reflects or attenuates signals. Signals can even be absorbed by people in the building. A typical office building may need 4-8 antennas per floor to get consistent connections throughout the area. 

WIreless LAN architecture


The antenna is connected to the network just like a PC, using UTP or fiber optic cable to a local switch which connects it into the network backbone. Not only does the wireless antenna require a network cable to connect to the network, but it needs power – uninterruptible power, just like any network hub or switch – to operate. Many, if not most, WiFi APs operate using Power over Etherent (PoE) over the UTP cabling connecting them to the network or special fiber optic cables with power conductors.


DAS with structured cabling

The architecture of the cabling for a wireless cellular distributed antenna system (DAS) is no different from an Ethernet LAN or standardized structured cabling. In some cases, DAS systems can be monitored by network management software used for LANs.
 
More on wireless in premises systems including wireless network standards
.  

Metropolitan Wireless

Metropolitan wireless systems offer WiFi coverage over a larger, city-wide area with access points placed around the city on street lights, traffic signal poles, utility poles or buildings. Initially, they were proposed as an inexpensive way of offering broadband to everyone, but providing support and competitive issues with other broadband suppliers ended most of these early trials. Now cities often install WiFi for public service use and free Internet access in parks and plazas, like these examples. The distances these access points are from the network connections require fiber, usually SM fiber available in the metro fiber network used for other communications.

Metro WiFi in Santa Monica


Downtown Santa Monica California, where you can see two separate systems, one public, one private for city services, on one pole.


Istanbul Tureky WiFi


Istanbul, Turkey installed metro WiFi for visitors as the European City of the Year.



Line-Of-Sight WiFi

LOS
(San Diego Broadband)

Several services have offered metro WiFi wireless using line of sight WiFi connections instead of running fiber between buildings. This is possible using both licensed and unlicensed frequencies. The access point or antenna needs an Internet feed which is going to be fiber in most cases. Google bought Webpass for their work in this area. The ISP finds a fiber connected building and negotiates using their connections and rooftop to serve other buildings.


Rural WiFi

Rural wireless works the same way as line of sight metro WiFi. The wireless Internet service provider runs fiber to a location where antennas can service as many users as possible with line of sight connections. The ISP is often in a small town that has good Internet connections and a building tall enough for line of sight to local users. Rural WiFi is widely used in rural areas in California.


Rural WiFi

Rural WiFi antenna on home. (San Diego Broadband)



Proposed But Not Widely Accepted Wireless Systems
Two wireless standards have been proposed but have not been widely adopted, WiMAX and Super WiFi.

WiMAX 
WiMAX is a further development of wireless network technology that expands the data capacity of wireless to ~ 100 Mb/s and it’s distance capability to several miles. Unlike WiFi which was primarily a short distance network aimed at private networks, WiMAX appears aimed at communications carriers who could use it in place of landline networks, substituting WiMAX, for example, for Fiber To The Home, in areas needing upgrades of their networks or using it to allow notebook PC or PDA roaming in a metropolitan area.

"Super WiFi" On Fiber

Bringing broadband to the rural areas of the US or any large country with sparse population can be very expensive. The US has a plan, however, that may make it more affordable. "Super WiFi" is not your usual WiFi. It is using WiFi protocols but broadcasting on frequencies of unused TV channels, called "white space." The FCC is ready to open up new frequencies to broadband to allow delivering broadband Internet and phone to rural areas where cabling is too expensive.

Super WiFi
 An example of a super Wi-Fi antenna: Altai

Super WiFi works at a lower frequency than either regular WiFi or cellular systems so it has more reach into areas that are too rugged for most wireless systems. Usage in more urban areas may be a problem however, if there are too many broadcast TV stations which can interfere with Super WiFi signals (and vice versa.) These antennas will also require fiber to connect into the network.
More in MIT Technology Review
 And the US Government Announcement.



More On Fiber For Wireless
FTTA- Fiber To The Antenna  
Testing FTTA Fiber  
DAS - Distributed Antenna Systems  
Small Cells  
WiFi - Premises Wireless  

FOA Guide Table of Contents.


 


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