WiFi
- IEEE 802.11 Wireless
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.
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.
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.
Downtown Santa Monica California, where you can see two
separate systems, one public, one private for city
services, on one pole.
Istanbul, Turkey installed metro WiFi for visitors as the
European City of the Year.
Line-Of-Sight WiFi
(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 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.
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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