envisage you ’re a newsman writing about a tense hostage situation , and you ’re on a taut deadline . You do n’t have time to aim back to your office , and if you leave you ’ll miss out on the developing fib . fortuitously , you have wireless approach to the net – you may write and file your taradiddle without leaving the prospect .
Part of your article delineate how law have admission to real - clip feeds from security cameras . From their patrol railroad car , officers supervise the state of affairs and accession blueprints of the construction , including its entrances , exits and hiding places . They use this entropy to project what to do . They also have a secure internet connecting them to ahostage negotiator .
When the situation is over , everyone believes thismunicipal wireless networkand the information it carried aid lead to a peaceful resolution .
In this article , you ’ll learn about the awe-inspiring things that these net can do – besides potentially provide free or cheap Internet memory access . You ’ll also learn about the applied science behind them and why " Municipal WiFi " can be a misnomer .
Wireless Basics
The early days of home Internet approach need using amodemconnected to acomputerto dial a number and asseverate a link . It was cumbersome and slow . The dissolute modem became , the more people realized how painfully dull data transmittance had been in the mean solar day of 300 baud rate . finally , household users who could afford a jump in price could getbroadbandaccess viadigital ratifier crease ( DSL),cable
andsatellite .
Broadband entree is faster than telephone dial - up , but until recently you still to plug your computer into a wall jack or a piece of equipment . Wireless networking , orWiFihas shift all that . Wireless web use802.11 networking standardsto allow for devices to communicate . In a WiFi web , data move around from piazza to place viaradio wave . You still have to physically connect a wireless router to a modem , but you could move your calculator from place to place .
802.11 networking uses theunlicensed radio spectrumto place and pick up data . Many other portion of the spectrum , such as the circle that carryradioandTVsignals , want a permission to use . The unaccredited spectrum is approachable to anyone who has the right equipment . In the case of wireless figurer networking , that ’s a wireless router and wireless engineering in the equipment you ’re using .
Since 2002 , many the great unwashed have set up wireless networks in their homes . Businesses have done the same , giving their employee extra mobility . Public gather places , like coffee shop , parks and libraries , have created WiFi hot post , hoping to imbibe in extra business concern . The act of public spicy spots has grown rapidly – analyst estimate that there will be 200,000 of them by 2008 [ ref ] .
Now , city have begun plant upmunicipal wireless networks . As of January 2006 , 186 United States cities had their electronic connection up and running or had definite plan to build one . That ’s up from 122 cities in the late July [ ref ] . Some of these networks provide high-pitched - stop number net access for free , or for considerably less than the terms of other broadband services . Others are for city use of goods and services only – they allow police and fire departments and other city employee to do certain aspects of their task remotely .
Cities presently purport networks have several goals . They want to meliorate worker productiveness , make the city more attractive to business , bolster the economy , bridge the digital divide or do all these thing with one net . The United States is also sixteenth in the humankind in wideband penetration , which some leaders consider is a sign that the country is accrue behind [ ref ] . A wireless mesh might make broadband access more available and affordable for more people .
Often called " municipal WiFi , " these networks employ more than just 802.11 networking . A wireless access point in a municipal web is also different from a typical WiFi live spot . Next , we ’ll look at the " mesh " that make a wireless meshing .
Technology and Networks
Mesh
MostWiFi hot spotsin java shops and other locations have ahub and spokeconfiguration . One radio ( the hub ) sends and receives data point for several substance abuser ( the spokes ) . The wireless router has a strong-arm connectedness to the Internet – a wire – and it transmit data from multiple users through that conducting wire .
Adding a wireless router to an exist cable connection is an easy , commodious way to provide wireless access code on a small scale . Wireless router are relatively inexpensive . Most allow masses to pick out from various sign - on and encoding option , providing a layer of security .
But if a wireless router die down , there ’s not always another router nearby to pick up the slack water . And on a heavy graduated table , like a whole city , using a physical wire to associate every wireless router to the Internet is expensive .
That ’s why most municipal wireless meshing apply ameshrather than a hub and spoke . A meshwork is a serial of radio transmitters . Each transmitter is able to communicate with at least two others . They create a swarm of radio signals through the city . Signals travel from router to router through this cloud .
In some meshwork , signals hop from one receiver to another until they give a node that has a pumped up connection to the net . Other web usebackhaul nodes . These nodes do exactly what their name imply – they gather up all the data from many transmitter and haul it back to the cyberspace by sending it to a router with a pumped up association . Backhaul nodes are usuallypoint - to - pointorpoint - to - multipointnodes . They can either connect one point to exactly one other , or they can join one point to several peak .
If you utilize your laptop computer to link to the net in a interlocking connection , here ’s what happens :
If you ’re out and about in a metropolis with public access , you may belike do this with no extra equipment . But if you ’re try out to get to the web from base , you may require a stronger radio and maybe a directional feeler . Although sign from the metropolis meshing are solid enough to make it into your home , the signaling from your computer may not be strong enough to make it out again . Most service providers take this into report and provide the necessary equipment for free or for a fee , much like they do with DSL or cable modems .
This system has several advantage over the hub and spokes of ordinary hot spots . First , since there are few wire , it ’s less expensive . If a few guest break , others in the meshwork can compensate for it . In addition to being far less expensive than running mellow - speed cable to every location in a city , it ’s a lot faster to establish .
When a city decides to built a wireless web , it in the main issues arequest for proposal ( RFP ) . An RFP is just a request for information from company that are concerned in building the internet . While a city could theoretically build up its own web , most choose to delegate that part of the process to a company that has experience in Internet and connection technology .
concerned businesses respond to the RFP with a marriage offer that describes a design for establish and maintaining the mesh . The proposal includes everything from the number and type of radio set to the net price . The strong-arm structure of the connection has to take the size and layout of the city , tree cover , landscape painting and other factors into thoughtfulness . The marriage proposal also includes who will terminate up owning , running and maintaining the internet – the city or the business .
In some of the earliest proposed networks , the cities themselves owned and controlled the meshing . business like ISPs and telecommunications fellowship object to these plans . Their argument was that rival between municipalities and the private sector was unfair or even illegal .
Today , many existing and advise networks follow one of the following four models :
The city go over all of the RFPs , then decides which proposition to accept . EarthLink , for case , has been selected to build up networks in Anaheim , California and Philadelphia , Pennsylvania and is a finalist in several other cities . EarthLink is also teaming up with Google to build a wireless web in San Francisco .
Exactly what the internet ends up look like depends on a few cistron . The first is precisely what a city hopes to do with the mesh . A city - wide blanket of coverage that ’s opened to everyone can look very different from a public safety web that will be open only to police officers and firefighters . ( See " Wireless Applications " and " Public Safety " to learn more about what these networks can do . )
Different businesses ' proposals can also vary widely depend on the hardware and protocol they use . EarthLink ’s projection immix meshwork and point - to - multipoint connection . Most of its marriage offer incorporate wireless transmitters on light poles throughout the metropolis , which create the cloud of wireless signals . Radio antennas on marvellous building or towers also communicate to smaller antennas placed throughout the swarm . These point - to - multipoint antennas allow the backhaul , carry the data from the cloud to the wired Internet .
Almost always , once a metropolis has made a choice about who will build , run and maintain the electronic internet , the final whole step is apilot program . A pilot program program is like a prevue or a test test of a smaller version of the meshing . It ’s by and large a fraction of the size of the final projection , and it countenance the urban center to check that the connection is right for them .
permit ’s face at what a city can do with a wireless electronic web once it ’s up and running .
Wireless Network Applications and Public Safety
A municipal connection can offer low - toll , high - speed access to the universal universe . Some cities have used this to justify the expense of the net . In possibility , mass who are no longer expend money on a in high spirits - speed connection will be able to put that money back into the local economy .
formation have created wireless meshing in developing nation to provide net approach in locations where traditional networks are impossible . Some U.S. city hope to expend their meshwork to exit the digital divide . Philadelphia , Pennsylvania plan to supplement its meshing with low - toll computing machine for scummy - income families . Plans also include civilize teen - agers to offer technical school support to the the great unwashed in their community . you could come up out more about these plans throughWireless Philadelphia , the nonprofit organization overseeing the internet .
Free or scurvy - monetary value cyberspace access is great , but it ’s only a fraction of what a municipal web can do . In rural area , wireless connection can give Farmer genuine - time access to certificate cameras and ascendency for irrigation and other system . Networks can make cheap Voice over IP ( VoIP ) telephone calls more practical , which can save money for people , businesses and the government . mesh can also make urban center doer ' jobs well easier with applications like automated cadence indication . edifice , fire and restaurant inspectors can charge account without returning to the office , shorten down on their travel clip . This is another means that cities can see a riposte on their investment in the net - they save money on travel , equipment and fees paid for live communication networks .
mesh can also give police and firefighters remote access to surety tv camera , design , deplorable records and other necessary information . They can let officers show witnesses mug shots or " virtual line - ups " at the scenery of a crime . For applications like this , American cities can employ for financing from the Department of Homeland Security .
Public SafetyMost people connect to a wireless mesh using the 2.4 gigacycle band of the receiving set spectrum . Public safety personnel can do this as well , using secure , encipher connections . But they also have another option – the 4.9 gigacycle band of the spectrum . This set islicensed . Not just anyone can get on it , and it ’s for public safety use only . Putting public prophylactic dealings into its own channel keeps it from getting bogged down during hard habit of the electronic web . Wireless transmitter must have separate 4.9 gigacycle radios to use this frequency .
Public safety networks also have additional options in the wireless technology they utilize . Motorola ’s Mesh Enabled Architecture ( MEA ® ) systems originated from battleground technology . MEA pass on police officers , firefighter and others capabilities above and beyond an average meshwork .
MEA radios can create anad - hoc meshing . MEA allows Multi - Hopping ® – a signal can move from user to drug user in the meshing rather than from the substance abuser to a lymph gland in the internet . Each receiving set automatically detects the other radiocommunication , and a web automatically shape between them . The radios themselves act as router or repeaters to pass the signal along . This means that officers with MEA - enable radio receiver can go into an area with no access to the rest of the connection and still have admittance to one another . medium entree ascendancy ( MAC ) filtering and encryption meter keep the web secure .
Imagine a town in which a twister destroys the light poles that domiciliate the mesh ’s wireless routers . Power and earphone lines fall as well . Ordinarily , this would severely limit communicating . But with MEA radio receiver , officer with fomite - mount modem can drive into the domain and take form a web with one another . Portable devices , like ruggedized laptops and PDAs , can apply MEA - enabled wireless cards to intercommunicate with the advertizing - hoc internet . If one of these radios can connect to the advertizement - hoc and the mesh internet , it can form a bridge and join the two .
MEA - enable equipment has some other capabilities , too . Most wireless networks ca n’t specify the position of a specific drug user within a internet . This is why many experts caution consumer about come out 911 birdsong fromWiFi earphone . But MEA technology turn out of battlefield applied science that allowed the military to track soldiers ' fix , even if they were out of the melodic line of site of theGPS satellites .
MEA radios can measure the length of sentence it choose for an policeman ’s signaling to go to three node , calledtime of flight . It then triangulates the officer ’s locating . This can significantly reduce the amount of meter it takes for crews to find firefighters who are still in burning building or to zero in on injured police officer . The cognitive process work on vehicle , too .
Finally , most wireless radio can maintain a signaling at swiftness up to 30 or 40 miles per hour ( 48 - 64 klick per hour ) . Many of these public safety radio receiver can transmit at hurrying of up to 250 land mile per hr ( 402 kilometers per minute ) . Similar organization have been used in racing to send fomite telematics to the Hell work party .
Municipal networks are so young that there ’s no one standard or method acting for creating and using them . Not every internet has separate parts of the spectrum for public safety , and not every internet allows public access at all . Check out the links on the next page for more information on wireless internet on related topics , as well as golf links to internet site where you could learn about the latest internet deployments .
