deploying wi-fi wireless networks

8/8/2019 Deploying Wi-Fi Wireless Networks

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Deploying WiDeploying Wi--Fi Wireless NetworksFi Wireless Networks

Service ProvisioningService Provisioning



Status of Wi-Fi in India

Healthy Installations in Hotels.Most Premium Hotels are covered [Kanyakumari toKashmir, more or less]. Growing all the time.

Early stages Installations in Airports, but we can expect

most airports to be covered within a year

Coffee Shops, quite a few ± Café Coffee Day is a primeexample

Nascent adoption in enterprises, one can expect healthy

growth

Nascent adoption in homes, one can expect healthygrowth

Laptops growing at a rate of about 150%



How does Wi-Fi Work?

User Selects

the Network

User associates with Access

Point

Access Point is

Connected to a Wired

Network Switch

User is able to connect to

computers on the wired network



Glossary of Wi-Fi terms

802.11b The most common of the three wireless

networking specifications included in the Wi-Fi

certification mark. 802.11b uses the 2.4 GHz band and

runs at 11 Mbps.

802.11g The newest of the three Wi-Fi specifications.802.11g is backward compatible with 802.11b, thanks in

part to its use of the 2.4 GHz band, and it runs at the 54

Mbps speed of 802.11a. Most new equipment uses

802.11g.

802.11

a One of three wireless networking specificationsunder the Wi-Fi rubric. 802.11a uses the 5 GHz band and

runs at 54 Mbps. 802.11a is little used outside specific

business situations.




802.11n Is a standard in the works, which is aims to boost raw

speed upto 600Mbps, while maintaining backward compatibility

with 802.11b/g. The main technology for achieving this

throughput is multipath reflection which enables data to be sent

in multiple streams802.11i, also known as WPA2, specifyies security mechanisms

for Wi-Fi. This supersedes the previous security specification,

Wired Equivalent Privacy (WEP), which was shown to have

severe security weaknesses. Wi-Fi Protected Access (WPA) had

previously been introduced by the Wi-Fi Alliance as an

intermediate solution to WEP insecurities. WPA implemented a

subset of 802.11i. The Wi-Fi Alliance refers to their approved,

interoperable implementation of the full 802.11i as WPA2 .

802.11i makes use of the Advanced Encryption Standard (AES)

block cipher;




IEEE 802.11e as of late 2005 has been approved as a standard

that defines a set of Quality of Service enhancements for LAN

applications, in particular the 802.11 WiFi standard. The

standard is considered of critical importance for delay-sensitive

applications, such as Voice over Wireless IP and StreamingMultimedia. The protocol enhances the IEEE 802.11 Media

Access Control (MAC) layer.



R egulation in India

2.4 GHz [802.11b/g] is delicensed for in door and out door use

1W Transmit Power and 4 W EIRP

5 GHz [802.11a] is delicensed for in door use [100mw Transmit

Power, 200 mw EIRP]



Both 802.11b and 802.11g operate in the 2.4 GHz frequency band, specificallybetween 2.400 GHz (2400 MHz), and 2.484 GHz (2484 MHz). Each Channel is

of 22 Mhz. The picture below shows the number of channels in the frequency

band. As can be seen adjacent channels over lap and there are 3 over lapping

channels, viz. 1, 6 and 11.

802.11b and 802.11g

802.11b Spectrum Coverage

CHANNELS



As shown below, Channels 1, 6, and 11 are "non-overlapping," meaning they

can all be used in the same area without causing "co-channel interference"

(CCI). In this way, users can be load balanced across three channels, each

providing up to 11Mbps of throughput, thereby effectively providing up to 33

Mbps of aggregate bandwidth. Therefore, larger scale WLAN deployments

utilize these three channels in a "geographic space" overlapping fashion tomaximize coverage area while preventing channel interference.

CHANNELS



Non-overlap Channel Placement

CHANNELS



Important Specificationsof Access Points

Transmit Power [30 mw, 100 mw, 200 mw, 500 mw, 1 W]

Automatic/Manual Power Control

Provision for Connecting External Antenna

Multiple SSIDs/VLANs

Security WPA/WPA-2[802.11i] and Security Configurationper SSID

QOS support

Rogue Access Point detection

Manageability [SNMP]



Important Specificationsof Access Points

WDS [Wireless Distribution System]

Single Radio/Dual Radio

Mesh Networking

Client Isolation or Intra Cell Blocking

POE [Power Over Ethernet]

Radius Authentication and Accounting Support

Automatic Configuration

Auto Channel Selection



Antenna Basics

An antenna propagates and receives RF signals from the air and

makes them available to the receiver

Frequency ± Antennas should be tuned to either 2.4 GHz (802.11 b/g)

or 5 GHz (802.11a)

Power - Antennas can handle specific amounts of power put out by thetransmitter. Antennas are generally rated >1W

Radiation pattern ± Defines the radio wave propagation of the

antenna. An isotropic pattern means the AP transmits radio waves in

all directions equally (beach ball pattern)

Gain ± Represents how well the antenna increases effective signalpower, with decibels as unit of measure. For instance, AP transmitting

at 100mw with 3 dB gain produces 200mw effective output. dBi is the

gain relative to an isotropic source.



Antenna Basics

SNR (Signal to Noise Ratio) ± Ratio of amplitude of radio signal to

amplitude of noise in a transmission channel. The greater the ratio, the

better the transmission.

Receiver sensitivity ± A measurement of the weakest signal a receiver

can receive and still correctly translate it into data. Omni-directional antennas ± Propagate RF signals in all

directions(360-degree) equally in the horizontal plane, but limit range

on the vertical plane. Radiation pattern resembles a doughnut with

the antenna at the center of the hole.

Directional antenna - Transmits and receives RF energy more in one

direction than others. Radiation pattern is similar to a flashlight or

spotlight. The higher gain antennas have a narrower beam width,

which limits coverage on the sides of the antennas.



To determine the best possible external antenna for your wireless LAN-to-LAN Bridge,

please refer to the table below that outlines the relationship between antenna gains

(dBi) and distances:

UNDERSTAND YOUR ANTENNA

Gain(Send

er)

Gain (Receiver)

18dBi 14dBi 8dBi 6dBi 5dBi

18dBi 3.4 miles 2.5 miles 1 mile1100

yards656 yards

14dBi 1.5 miles 1.5 miles 1 mile 874yards 656 yards

8dBi1100

yards1100

yards1100

yards874 yards 656 yards

6dBi 874 yards 874 yards 874 yards 874 yards 656 yards

5dBi 656 yards 656 yards 656 yards 656 yards 656 yards



Antennas direct RF power into the air over a coverage area. An antenna gives the

wireless system three fundamental properties²gain, direction, and polarization. Gain is a

measure of increase in power while direction is the shape of the transmission pattern.

Polarization is typically described as vertical or horizontal, which usually corresponds to

the antenna alignment. Most access point antennas are designed to operate in a vertical

position, resulting in a horizontal coverage plane (polarization). Re-orienting the antenna

to a horizontal position will result in a vertical plane as shown below.

Antenna Polarization




Omni-directional antennas have a 360-degree coverage pattern on a horizontal

plane. The coverage pattern is shaped like a doughnut with the access point in the

center. These antennas are ideal for square or somewhat square areas. Most

diagrams of omni-directional antennas show only a two-dimensional view with the

antenna represented as a hole in the center of a series of concentric rings.

Omni-direction 2D Propagation Pattern

Omni-directional





Directional antennas focus data transmission in one direction. This will produce a

conical-shaped coverage pattern, similar to that of a flashlight. The antenna

directionality is specified by the angle of the beam width. Beam width angles vary

from 90 degrees (somewhat directional), to 20 degrees (very directional). The

focused beam allows for longer, narrower coverage patterns, which can be ideal for

elongated areas, around corners, and outdoor applications such as inter-building

communications in a multi-building network. As with omni-directional, mostdirectional antennas are represented in two dimensions. however, the actual

propagation pattern is more accurately represented in three dimensions Directional

3D, depicts the RF pattern of a three-dimensional directional antenna

Directional Antenna



B ASIC SITE SURVEY - WIFI

Obtain a facility diagram. Before getting too far with the site survey, locate a set of buildingblueprints. If none are available, prepare a floor plan drawing that depicts the location of walls,walkways.

Visually inspect the facility. Be sure to walk through the facility before performing any tests toverify the accuracy of the facility diagram. This is a good time to note any potential barriers thatmay affect the propagation of RF signals. For example, a visual inspection will uncover obstacles

to RF such as metal racks and partitions, items that blueprints generally don't show.

Identify user areas. On the facility diagram, mark the areas of fixed and mobile users. In additionto illustrating where mobile users may roam, indicate where they will not go. You might get by withfewer access points if you can limit the roaming areas.

Determine preliminary access point locations. By considering the location of wireless users

and range estimations of the wireless LAN products you're using, approximate the locations of access points that will provide adequate coverage throughout the user areas. Plan for somepropagation overlap among adjacent access points, but keep in mind that channel assignmentsfor access points will need to be far enough apart to avoid inter-access point interference.

Be certain to consider mounting locations, which could be vertical posts or metal supports aboveceiling tiles. Be sure to recognize suitable locations for installing the access point, antenna, datacable, and power line. Also think about different antenna types when deciding where to positionaccess points. An access point mounted near an outside wall, for example, could be a goodlocation if you use a patch antenna with relatively high gain oriented within the facility.



B ASIC SITE SURVEY - WIFI

Verify access point locations. This is when the real testing begins. Many wireless LAN vendors,provide free RF site survey tools that identifies the associated access point, data rate, signalstrength, and signal quality. You can load this software on a laptop or Pocket Pc and test thecoverage of each preliminary access point location.

Install an access point at each preliminary location, and monitor the site survey software readingsby walking varying distances away from the access point. There's no need to connect the access

point to the distribution system because the tests merely ping the access point; however, you'llneed AC power. So be sure to take along an extension cord, and learn where AC outlets exist.

Take note of data rates and signal readings at different points as you move to the outer bounds of the access point coverage. In a multi-floor facility, perform tests on the floor above and below theaccess point. Keep in mind that a poor signal quality reading likely indicates that RF interferenceis affecting the wireless LAN. This would warrant the use of a spectrum analyzer to characterizethe interference, especially if there are no other indications of its source. Based on the results of the testing, you might need to reconsider the location of some access points and redo the affectedtests.

Document findings. Once you're satisfied that the planned location of access points will provideadequate coverage, identify on the facility diagrams recommended mounting locations. Of coursethe installers will need this information. Also, provide a log of signal readings and supported datarates near the outer propagation boundary of each access point as a basis for future redesignefforts.



Approximate Construction Material Attenuation Values

Found in most locations, common obstacles such as doors, windows,

and walls offer fairly known levels of attenuation. These values represent

attenuation in addition to the general signal strength loss over distance.

The following is a general example of the attenuation values of

common office construction:



Security ± Client Configuration



Infrastructure Required for Wi-Fi

Security

Client Access Point Radius

Server

Certificate

Server



Considerations forEnterprise Wi-Fi

Access Point must support multiple SSIDs/VLANs

Must support 802.1x and WPA, WPA-2 to provide securityto internal users and internal networks

Must support Rogue Access Point Detection

QOS support for future applications such as VOWIFI andVideo applications

Manageability [SNMP]

Convenient Mechanism to provide Internet Access toVisitors and Guests



Considerations for PublicHot Spots

Plug and play service. The user should not have the

need to change IP address settings or Proxy settings

Simple and easy to use login mechanism to the guest,

which includes authentication and billing. This would

include Radius based authentication as well as PMS[Property Management Systems] integration in the case

of hotels

Complete support for VPN applications

Seamless switch over from wired to wi-fi networks and

vice versa. For example a guest who has purchased a 24hour account by connecting to the wired port in the room

should be able to use it from the Wi-Fi network as well,

say in the Coffee Shop or Lobby or elsewhere,

automatically

Provision for Bandwidth on Demand



Provision for Public IPs for User Laptop

Support for both Open/Unsecure Connections andSecure Connections

Roaming between hotspots and between differentservice Providers

Branding on Portal Pages

Network Management system to provide Performanceand Configuration Management as well as FaultMonitoring and Notifications

There should be provision for both historical reports as

well as online live reports, guest wise, date wise, periodwise, Plan wise, fault wise, usage wise and so on

Automatic redirection to welcome page when user triesto access the Internet

Considerations for PublicHot Spots



Metro WI-FI is a technology which attempts to WI-FIwhole areas of cities

Many cities have taken the initiative for setting up suchWI-FI networks to benefit their citizens

A metro Wi-Fi network uses a mesh architecture toachieve its objectives. Access Points placed atop roof tops, towers, lamp posts are connected to each other wirelessly [in contrast to typical installations where APsare connected to a wired network]

The back haul is also through wireless, typically 5 GHz

bandThere has been a lot of debate on whether providingsuch a server is a city or municipality¶s job or whether itshould be left to the traditional Service Providers andTelcos

What does the future hold for Metro Wi-Fi networks?

Metro WI-FI



Metro WI-FI ± Typical Architecture



Hotels

Airports

Coffee Shops

Hospitals

Residential complexesCommercial Complexes

Exhibition Sites

Locations



Premium Hotels provide good revenue

4 star and 3 star hotels are promising

Wi-Fi in Public areas does not require high investmentand may be a good starting point in 3 star hotels

Long term contracts provide control over location

Hotels



Important Location for Wi-Fi service

Non remunerative Flat fee structure is an obstacle

There is a need for negotiation with IAAI at highestlevel.

Privatisation of airports needs to be factored in

Airports



High end chains are promising

Need for large number of hotspots

Need for culture of easy availabilty and common usage

Coffee Shops



Public areas and high end rooms

Health Tourism

Hospitals



New Luxury Apartments

Offer to set up infrastructure and provide all services for residents. Telephony, Broadband, Wi-Fi, VOIP

R esidential Complexes



Offer to set up infrastructure and provide all services.Telephony, Leased Lines, Broadband, Wi-Fi, Wi-Max,VOIP

Commercial Complexes



Plain Vanilla Internet Access

Roaming, Wholesale roaming

Leveraging customer base to increase revenue. Single Account Multiple Services

Wi-Fi PhonesThe promise of smart phones and PDAs

R evenue Streams



Need to set up large number of hotspots

Critical mass of hotspots so that wi-fi access is a way of life and common

Have relatively higher tariff for spot accounts andattractive pricing for monthly, yearly subscriptions

Leveraging customer base to increase revenue. Single Account Multiple Services

R evenue Streams ±Internet Access



Need to set up large number of hotspots

Critical mass of hotspots so that wi-fi access is a way of life and common

More usage per hot spot, more revenue

Subscribers use in other service provider locations,nationally and internationally, and thus increaserevenue

R evenue Streams ±R oaming



Cellular subscribers

Broadband subscribers

Dial-Up Internet subscribers

Very Important for revenue generation

R evenue Streams ±Leveraging existingcustomer base



New service

Lots of interest in the world

Initial application is expected to be in the Enterprises

Gains in importance in Metro Wi-Fi scenario

R evenue Streams ± Wi-FiPhones



Thank You

Thank you very much

Questions are Welcome

deploying wi-fi wireless networks

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