4757444 wireless training site survey

8/14/2019 4757444 Wireless Training Site Survey

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Many people think that there is a science behindinstalling a Wireless LAN (WLAN). While there iscertainly a lot of science behind the technology,performing a site survey may be thought of more asan art. Scientists are traditionally thought of asstringent and unable to operate "outside the box."Artists are bold and creative.

??As a WLAN site survey engineer, you will have to be

knowledgeable on both the wireless equipment youare installing, as well as the wired equipment withwhich you may be interfacing. You will often have tobe creative in the design and implementation of theWLAN equipment. A good site survey engineer will beable to think "outside the box," allowing him toovercome limitations presented by the facility as wellas the equipment.


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A site survey will help the customer determine howmany access points (APs) will be needed throughout thefacility to provide the desired coverage. It will alsodetermine the placement of those APs as well as detailthe necessary information for installation.

A site survey will also determine the feasibility of thedesired coverage in the face of obstacles such as wired

connectivity limitations, radio hazards, and applicationrequirements. This will allow the customer to properlyinstall the WLAN and have consistent, reliable wirelessaccess.

In this class we will provide you with all of thenecessary tools and knowledge needed to perform a sitesurvey. While this is certainly the place to start, it must


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be combined with experience. The more experienced andknowledgeable the site survey engineer, the better thesurvey.

In this class we will educate you on the processes ofperforming a site survey. We will show the tools and howto configure and use them. We will give you an idea of themany different industries where you may be required toperform site surveys.

You will be given a list of recommended equipment for asite survey kit that should get you through almost anysite survey.

We will discuss techniques for performing a site survey.And we will try and make you aware of many of the"gotcha's," pointing out some of the concerns that youmay not even think to consider when performing a site


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survey.

In short, we will try to share our many years' ofexperience in the field performing site surveys and

installations.

The Open Systems Interconnection (OSI) referencemodel provides a useful structure for defining anddescribing the various processes in open systemsnetworking. The OSI model may be thought of as ablueprint for developers to use when designing protocolimplementations.

There are seven layers to the OSI model, each dealingwith a portion of the communication processes. Although we will explain the function of each level, our primaryconcern will be the lower two levels of the model. Cisco's


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Aironet APs operate at these levels. An AP is referred toas a "Layer 2 Device".

The seven layers of the OSI model are:

Application, Presentation, Session, Transport, Network,Data Link, and Physical

The Physical layer deals with issues concerningtransmitting and receiving data across a network,regardless of the media type used. This layer is

specifically concerned with the physical structure of thenetwork (or topology), bit transmission and timing, andspecifications for interfacing with the media.


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The Data Link layer is actually divided into two sub-layers, the Media Access Control (MAC) layer, and theLogical Link Control (LLC) layer. The primary focus of theData Link layer is the conversion of bits into packets (orpackets into bits).

The MAC sub-layer provides addressing information fornetwork device communication as well as informationallowing multiple devices to share the same media.

The LLC sub-layer is responsible for establishingand maintaining links between network devices.


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The MAC layer is particularly important because wireless devices require their own MAC layer. They arenot communicating via cables and, therefore, cannot use

the MAC layer developed for cabled media. Cisco's Aironetproducts were first to market with the MAC layer for thehigh speed products, and first with an 802.11 bcompliant MAC layer.

The Network layer deals with network addresses,addressing and delivering packets, and communicationbetween devices on different logical networks.

The Transport layer interacts with the networklayer to provide quality control and someconnection services.


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The Session layer is responsible for communicationdialogs (simplex, half duplex, full duplex) between twodevices. This includes the establishment, management,and termination of the dialogs.

The Presentation layer handles data encryption, datacompression, and converting system data to a machineindependent common format.


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The Application layer provides services on the network.Some of these are file, print, e-mail, and databaseservices. This layer provides the interface to the networkfor applications. However, this layer is not the actualapplication.


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The Institute of Electrical and Electronics Engineers(IEEE) is one of the largest and most influential bodies inthe world for setting global standards. The IEEE is madeof committees. We will only be concerned with the 802committee, which develops standards that govern lower-layer protocols and interactions with transmissionmedias.

we will specifically be concerned with the 802.11standards. Many of you may be familiar with the 802.3standard or the 802.5 standard. Just as these standardsdefine characteristics related to Ethernet or Token-Ringnetworks, 802.11 defines characteristics ofWLANs.


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802.11 is a standard that ensures interoperabilitybetween WLAN equipment from different manufacturers. The standard specifies three different methods fortransmission -Infrared (IR), Frequency Hopping SpreadSpectrum (FHSS) or Direct Sequence Spread Spectrum(DSSS). Cisco's Aironet 340 series equipment uses DSSS.

Two of the subsets of the 802.11 standard are 802.11 aand 802.11b. 802.11a covers equipment in the 5GHzrange, while 802.11 b covers higher speeds (currently upto 11 Mbps) in the 2.4GHz range. Cisco's Aironet 340series of products adhere to the 802.11 b standard.


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Under the 802.11 standard you should be able to useany 802.11 wireless client with any 802.11 wirelessbackbone. This is possible because 802.11 covers thetransmission between the client and the AP, associationprocesses, and modulation schemes. However the 802.11standard does not cover communication between APsacross the wired backbone, roaming, wireless links over 1mile, load balancing, wireless repeaters, etc. Furthercooperation from the WLAN vendors will be required

before many of these features can be implemented intothe standard.


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You need to be aware of these standards, as well as thelimitations of 802.11 while designing a WLAN. Because

the standard does not cover communication between APsacross the wired backbone, it is recommended that theWLAN backbone consist of a single manufacturer'sproduct. Cisco's Aironet products offer superior roaming,load balancing, wireless repeaters, throughput and 11Mbps (among other functionality above and beyond802.11). This makes the 340 series an ideal choice for theWLAN backbone.

If the customer desires to use a specific client cardadapter, or a data collection terminal (some of which arenot equipped with Cisco 340 series radios), it is possibleto install an all-Cisco WLAN backbone that willcommunicate with a number of non-Cisco products.

This will allow the customer a robust, reliable WLANconnection while still remaining 802.11 compliant.


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Just as with wired networks, the topology of your WLANmay take many forms. But in reference to a WLAN, theterm "topology" does not refer to architectures such asbus or ring. Instead it refers to the BSA (Basic ServiceArea) which is comprised of"microcells.

Each AP has an area of coverage referred to as a"microcell, or "cell." In an installation comprised of asingle AP this is a very simple concept. When multiple

APs are installed, the cells must overlap so that the wireless connection is never interrupted while roamingfrom AP-to-AP.

This is the main purpose of a site survey - to place APsand survey the cells to allow for proper overlap. Toomuch or too little overlap can cause disruption of thewireless connection to the client.


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Sometimes the topology of the WLAN will be dictated bythe layout of the wired LAN to which the WLAN will beconnected. If wired connectivity is only available alongone side of a 100,000 sq. ft. warehouse, for example, thedistance limitations of a Cat 5 cable run (328') may notbe sufficient to reach the recommended location of theAP.

This is where the site survey engineer will have to becreative. There are many possible solutions - a wirelesshop using a repeater talking back to a wired AP, arepeater or a hub to extend the Cat 5 cable run, orinstalling a fiber link to provide connectivity on the otherside of the warehouse.

As a site survey engineer you are responsible for not


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only finding the best locations for the APs, but alsofinding ways to connect the APs to the wired network.

It is therefore crucial that the engineer have anunderstanding of wired networks. This understandingshould cover wired LAN topologies, standards, andcomponents.

The understanding of components must includefunctionality of repeaters, hubs, switches, and routers.Attaching an AP to a hub has very different implicationsthan attaching an AP to a switch, for example.

By understanding the components, you will be able todesign a WLAN that meets all specifications for theexisting wired LAN topology. You must also be aware of


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the media being installed and be sure that the WLAN youdesign will meet all requirements for that media type aswell as state and local building codes.


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As wireless technology continues to evolve, data ratesand interference immunity are improving. Theseimprovements make wireless a viable technology for usein most applications. As the acceptance of wirelesstechnologies continues to grow, the advantages of amobile workforce and a flexible network become moreand more clear to network managers.


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As a site survey engineer you need to be aware ofspecific issues that surround many of the variousindustries you may come into contact with.

Often IT mangers, upper management, or boardmembers may want to discuss the implementation ofwireless equipment in their facility.

All site survey engineers expect that these issueshave been worked through with a salesman or SE priorto his arrival. But this is not always the case.

You need to be aware of the many issues so that youcan appear intelligent and informed while meeting withthese individuals. If you appear incompetent ormisinformed they may cancel the site survey or the


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implementation altogether.

The customer wants to know that the WLANinstallation will provide a reliable link to the network for

the wireless clients.

Early adopters of wireless technology were in verticalmarkets.

These users were more concerned with mobility than ^standards or throughput.

Users today are moving into more horizontal markets where mobility may be less of a concern thaninteroperability and throughput.

With the Cisco Aironet 340 series of products, we do Ihave to sacrifice mobility and roaming to gain through


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and interoperability.

One of the early adopters of wireless technology was theretail industry.

Data collection devices are extremely valuable tools forchecking stock, receiving, and point of sale.

Wireless data collection devices offer the retail industryreal time updates to their databases and the ability toplace registers and printers throughout the store forspecial events (such as a sidewalk or tent sale) without


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having to worry about cabling.

Retail implementations often involve a large number ofusers sending data very frequently. Stores are likely to dotheir inventorying at night. This can mean that there will

be a limited number of users during the normal storehours, which does not tax the WLAN.

But when the inventory crew comes in at night, thecustomer expects that the WLAN will be able to handlethe demand. You need to work with the store manager todetermine how often they do inventory, how many data


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collection devices will be used, and what therequirements are for their particular application.

Also ask if they will require coverage on the loading

docks or inside the trucks at the loading docks.Depending on the WLAN design there may be enough RFcoverage bleeding through to the outside of the buildingsto accommodate this, but you should not depend uponthis unless you have factored it into your design.

Other concerns within the retail industry include theclose proximity of the store to other RF devices. Somestores may stock and demo RF devices in their store.

These may include satellite systems, baby monitors, orcordless phones. Many of these may be 900MHz, but

some ^ may also be2.4GHz. In any case, it is notrecommended that you install Aps next to this type ofequipment.


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Typically these devices have a higher output than theAps. Also be aware that many stores use internal cordlessphone systems. Encourage them to use a system thatoperates on a different frequency (900MHz). It is far less

expensive to replace a few cordless phones than to tryand design a WLAN around an existing phone systemthat interferes.

Retail stores may also be located in malls or strip malls where there may be other users operating 2.4GHzequipment. Examine this possibility before starting thesite survey. Talk with surrounding store managers abouttheir systems. If there are other systems in the area you

will have to try and separate the stores by channel,ESSID, etc.

Warehouse implementations present many of the sameproblems as we discussed in the retail market. There maybe a limited number of users during the day, but when ashipment comes in, or if multiple shipments come in atthe same time, many or all users may be operating at thesame time.


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Stock levels in warehouses can vary on a monthly,weekly, or daily business.

Talk with the warehouse manager about when stock

levels are at their highest and try to perform your sitesurvey during this period.

If this is not possible, do your best to compensate forthe potential increase in stock or put a statement into your documentation that indemnifies you if the physicallayout of the site changes, to include stock levels.

Always try to talk with the people who work in the warehouse. A forklift driver may actually have a moreaccurate opinion of current stock levels and when stocklevels may be at their high or low points, as well as whenstock levels will be at their highest. Do not assume thatjust because people do not work directly with the network


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that they do not have information that may be relevant toyour survey.

Talking to a single individual may lead you down the

wrong path. Making inquiries of numerous people willhopefully give you more accurate detail. Talk with asmany people as you can throughout the warehouse andinquire about stock levels and periods of high usage.

Warehouses or distribution centers are typically dirtyand have maximum exposure to the elements. Here are afew questions to keep in mind while performing thesurvey:

-Will the APs need to mounted in sealed boxes?


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-Are there freezer areas (which are difficult to coverand hard on electrical equipment)?-Do you need heated enclosures? Is there extremehumidity?

-How much clearance do you have above theshelving? Will it be sufficient to mount an antenna?Or will the antenna be crushed by a forklift or theinventory that the forklift is loading onto the topshelf? .

Healthcare site surveys are some of the most restricting,time consuming, and difficult site surveys you will everperform.


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The primary reason for this is that almost every hospitalis a multi-story building with numerous small rooms.

Beyond this there are a number of devices that may

interfere with your AP, or vice-versa. Hospitals are also prime candidates for wanting to "grill"the engineer before he can start surveying.

The hospital staff will have many questions regardingthe equipment, the frequencies used, the potentialinterference, and whether testing that has been done


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with the products.

Never forget - hospitals are full of people whose livesdepend upon the machines that are helping them

survive.

Cisco's equipment has been tested with numerouspieces of hospital equipment. Contact your Ciscorepresentative to obtain a list of the equipment.

In the event that it has not been tested against aspecific piece of equipment, offer to test the AP with theequipment.

DO NOT TEST THE EQUIPMENT WHILE IT ISSERVICING A PATIENT!

Hospitals will expect to see a competent individual who


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is appropriately dressed in their facility. They are not veryaccepting of an individual in jeans and workboots. Tohelp ease these concerns, many engineers even go so faras to wear a shirt and tie while surveying a hospital.

Remember, you may be required to enter many of thepatient's rooms. There are large numbers of elderlypeople in hospitals who are concerned or even scared ofyour equipment.

The engineer will need to have excellent customerservice skills, patience, and even kindness in order to putthese people at ease. Some of these patients may havebeen restricted to their beds for a number of weeks oreven months. They will be eager to talk to anyone whoenters the room. And often the engineer in a tie ismistaken for a doctor.

Hospital surveys also require engineers with a certain


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amount of mettle. It is not unheard of to have to surveythe Intensive Care Units, Infant Intensive Care Units,Birthing Units, Surgery Units, Burn Victim Units,Morgues, Emergency Room and Trauma Units. The sight

of patients in this condition sometimes has a veryprofound effect on individuals. The engineer needs to beable to handle all of this with grace. More than oneengineer has been caught in the Trauma Unit when acritically injured patient is being wheeled in.

Most hospitals can not afford to have an individualescort the engineer all day while he surveys. Mostengineers are given a visitor badge and a "25 cent" tour,

where they are shown specific areas where they will notbe allowed without an escort, if at all. In the surgery areaof hospital the engineer may be required to gown up tosurvey the area. And almost no engineers are allowed inthe psychiatric ward or the criminal ward without asecurity escort.

Because of the multi-floor configuration of hospitals,the survey must be thought of as a three dimensional


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survey. While marking site maps (which are twodimensional) many engineers start to think of the surveyas two dimensional. But the RF signal needs to bethought of as three dimensional, covering not only the

floor the AP is mounted on but the floors above and belowas well.

A hospital is a good example of a 3-D site survey, but 3-D site surveys are not specific to hospitals.

Every multi-floor survey needs to be thought of as threedimensional, but this is especially the case in hospitalsas they typically require a large number of APs. Because

there are only three non-overlapping channels, specialcare needs to be taken when locating APs so youeliminate interference from other APs as much aspossible. Take advantage of the non-overlapping channelswhen you can.

Watch out for trauma and x-ray areas where the wallsmay be lead-lined. Locate elevator shafts, which areusually co-located in hospitals and may be detrimental to

your RF signal.


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Hospitals are also very concerned with aesthetics. Largeantennae hanging from the ceiling tiles generally are nota good idea.

Patch antennae are a good choice for hospitals. Theyare strong antennae with good coverage patterns,allowing for fewer APs. They can be inconspicuouslymounted and can even be painted (DO NOT USE A LEADBASED PAINT!) to make them even less obvious.

Ground plane antennae are also an excellent choice.APs are usually mounted above the ceiling tiles.


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Watch out for the many devices in hospitals that can bedetrimental to your signal.

Some hospitals use Spectral-ink phone systems. Mostof these are 900MHz but that technology is changing.

They may also have existing WLAN equipment.

Telemetry equipment is often an excellent source ofinterference. (Should you have to survey near telemetryequipment, consider leaving the wallet behind. Creditcards seem to be adversely affected by the equipment).

There are many, many sources of interference inhospitals. Learn to locate and work around them.


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Hotels are much like hospitals in their buildingconstruction and configuration (multi-floor with manyrooms).

Hotels have started using the WLANs to support data

collection devices for taking inventory of things such asmini-bars. But with the popularity of the Internet and thedemand for Internet connectivity, WLANs are beinginstalled into more and more hotels to provide Internetconnectivity to hotel guests.

Beyond requiring the engineer to look at the surveythree dimensionally, datarates/throughput, and security

are some of the issues presented by a hotelimplementation.

Hotels want to offer their guests fast, reliable internetaccess . This means fewer users per AP .


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Most business travelers will want to know that the datathey are sending is secure and the hotel will want toknow that not just anyone with an 802.11 card canaccess their network.

One possible solution is WEP encryption.

The overhead WEP adds is minimal.

Depending on the age of the hotel, buildingconstruction may become a factor. Newer hotels will havedrop tile ceilings. Older hotels will often have "hard cap"ceilings. These are ceilings that are poured concrete.

There is no real, effective way to run cable across a hardcap ceiling. Keep this in mind when you are decidingwhere to mount APs. Older hotels may also have walls ofpoured concrete instead of sheetrock. This presents thesame problems as hard cap ceilings.

Hotels will also have many of the same concerns ashospitals do regarding aesthetics.


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The primary concern when implementing a WLAN in aneducational facility is the persons that are beingeducated.

More and more WLANs are being installed in grade

schools, middle schools, and high schools. Students atthis age have a tendency to be curious and sometimesdestructive.

An antenna mounted to the ceiling in a hallway willlikely not stay mounted for long.

APs have flashing lights that seem to draw incurious children.

Educational facilities, more so than any otherimplementation, MUST have the equipment installed inthe most inconspicuous manner possible. This is the onlyway to insure that the equipment will be safe.


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Another problem facing the education market isthat numerous schools still utilize Apple computers.

Cisco does not have a driver for the Macintosh at thispoint in time.

Schools with Macintosh computers may require creativesolutions like the Workgroup Bridge (WGB), which allowsMacs to access the network via a hub connected to theWGB.

The challenge with these solutions is that theassociated cabling and/or the Workgroup Bridge may stillbe exposed.


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The Wireless Office presents a tremendous opportunitytoday.

t

On the average, large offices change configurations atleast twice a year. This may involve new additions orexpansions, or it may involve relocating individuals orentire departments. In either case, a WLAN makes thesetypes of moves much easier. Whether the employee isusing a desktop or a laptop, all that needs to be done isto move the PC and ensure that it is within a WLANcoverage area.

This ease of use means countless hours saved for the ITdepartment, and dollars saved on cabling or re-cablingexpenses.


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Rail yards can be difficult to survey and install for manyreasons. The cars themselves are very large and may beconstructed of wood or metal.

Cars may be filled with a variety of materials which can

limit your signal. These may include livestock, wood,metals, or perishable materials in wooden or cardboardboxes.

Inside the yard the tall cars on parallel tracks formsnarrow pathways for the signal. Yagi antennae mountedon poles above the cars at either end of the yard often arethe best solution, allowing you to shoot down the narrowpathways.


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Airports tend be very large single story structures. Thismakes the survey simpler for the engineer because thesurvey becomes two-dimensional. The long, openpathways also make for easy coverage.

One difficulty in covering airports is when coverage isneeded outside the facility; in the baggage areas, forexample. Much like warehouse installations, these APsmay be subjected to extreme weather conditions and mayrequire weatherproof enclosures.


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Another difficulty in surveying airports is the hightraffic and security in airports.

While people are certainly used to seeing work crews

roaming throughout an airport, it does not mean thatthey will be cautious around you while you are surveying.Take care not to leave materials lying about that may bestolen or may injure people running from gate to gate. Amisplaced cable that a traveler trips over could result in acrippling lawsuit.

Airports are also very security conscious. Aps andbattery packs, with their flashing lights and wires wrapped around them, can easily be mistaken for abomb. This is certainly not a situation that any engineerwants to find himself in.


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Like airports, government facilities are secure facilities.Being in the wrong place at the wrong time withsomething that may be mistaken for a bomb could resultin a spread eagle position, nose to the asphalt with an M-16 pointed at the back of your head.

You may be required to obtain security clearances ormay require escorts. Your vehicle may be subject tosearch as you enter and/or leave the facility. You may berequired to submit an equipment list and have yourequipment checked on a daily basis.

Beyond the security issues you will find facilities of

every type at government locations, particularly militaryfacilities. Many military bases may have one of everyfacility we have discussed here and you may be requiredto survey them.


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The single fastest growing market is the ISP market.ISPs are finding new and more effective ways toimplement WLAN technology and are helping to drivesome of the technology developments. Unfortunately,ISPs have unique needs that cannot always be met by the

equipment.

The difficulty with ISPs is that they are trying to useequipment that is intended to be used in a LAN in aMetropolitan Area Network (MAN) environment, andsometimes even a WAN environment. They see thistechnology as a cheap replacement for Telco service ormicrowave technology.

Far too often a misinformed ISP thinks that installing asingle AP on a mountaintop with a powerful omniantenna is sufficient to provide coverage for the entirecity located in the valley below.


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ISPs tend to be in a hurry to install the equipment andstart providing service without doing the proper research.They try to link clients and APs at distances over a mile(this requires a bridge, not an AP). They are not aware ofthe implications of installing an 802.11 compliant AP.

They do not understand that certain parameters need tobe changed to avoid having anyone with an 802.11 clientattach to their AP and access their service.

You may be required to give the ISP a "dose of reality"and make recommendations on which equipment to use,how to implement the technology, and the limitations ofthe technology. It may not be what they want to hear, butbetter they know upfront than after they have promisedservice that they can not deliver.


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What we have presented here are some of the concerns you may face while surveying certain types of facilities.We have tried to make you aware of some of the pitfallsassociated with each of these. We hope that challengesthat we have listed will help to prepare you for others

that you may encounter.


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One of the factors affecting your WLAN design shouldbe the particular type of client that the customer will beusing.

Some may choose to use PC cards in laptops to providemobility to their internal staff and easy connectivity forremote users when they are in the facility.

Some may want to use PCI cards, giving users thefreedom to occasionally move desktop PCs without havingto worry about installing cable.

Some may use a repeater or a workgroup bridge to

provide connectivity to remote users without usingstandard leased lines or having to worry aboutattempting to run fiber. Others may want to use datacollection terminals.

And some may use a combination of these options.


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In an environment where the PCs will remain stationarymost of the time, providing wireless connectivity is afairly easy task. For installations of this type, users

typically need "pools" of 11 Mbps coverage and will not beoverly concerned with their link speed while moving.

Many customers do not fully understand the equipmentthat will be installed or what to expect. Some peoplebelieve that it will be a full 11 Mbps link for every user.Some question the reliability of the RF link and intend touse the wireless link on a limited basis. The truth is thatmost users will fall somewhere between these two.


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Remember, 11 Mbps of throughput does not meanan 11 Mbps data rate.

There are many factors that limit the link speed.Overhead, operating system, and number of users are

examples.

There is more overhead associated with the RF linkthan there is on the wired link. Realistically, themaximum link speed will be around 7Mbps.

The Operating System will be part of this limitation aswell. File transfer soeeds for a Microsoft ooeratina systemare about 5.5 Mbps. Linux speeds are closer to 7 Mbps.

The 11Mbps wireless link can be thought of as a 10 Mbps wired Ethernet segment when deciding how many usersit can handle.


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Let's consider a typical wireless office. Most users will havean office, desk, or cube where they spend most of their day. They may have to occasionally attend a meeting,conference, or class.

For this type of application, APs need to be placed toprovide 11 Mbps coverage at the desks or in the conferenceroom. Link speeds as low as 2Mb may be sufficienteverywhere else.

It is not uncommon for the user to tell you he wants 11Mbps coverage everywhere. But after he has seen how manyAPs this will require, he may change his mind, at whichtime you may need to redo your survey. Avoid this by

talking with your customer up front and addressing theissues. Find out where he thinks he needs 11 Mbpscoverage and why.

Chances are that the user needs coverage at his desk, orin a conference room, but will not likely be trying to surf theweb or check e-mail while he is walking between the two.


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You will need to ask the customer exactly where he needsthe 11 Mbps coverage.

In the example above, the customer may think he needsAPs in the corners of the office. If you do this, a large

percentage of the coverage cells will be covering outside thebuilding.

He may have a single user who he feels needs to have 11Mbps coverage (maybe a V.P. or director). But if he has alarge number of users on a lOOMbps backbone with a T-1connection, the V.P. or director never sees 11 Mb via thewired connection anyway. So he is not gaining anything byyour providing him with an 11 Mbps wireless connection. A

better focus for the 11 Mbps coverage would be an areawith a larger number of wireless users.

A better solution might be to move the two APs to thecenter of the building. This provides 11 Mbps coverage forhigh usage areas like the conference room and the users in"cubicle land," and provides for load balancing. Usersaround the perimeter get 5.5 Mbps coverage.


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Be aware of the applications that users may by utilizing.Someone who performs the occasional file transfer andchecks e-mail has very different needs from someone usinga CAD application across the network.

Most offices today use a client/server model withfrequently used applications loaded on each terminal.

Some companies are moving to thin clients and may havemuch greater bandwidth requirements. This type of setuprequires a very reliable connection to the network, as aninterruption of network service renders the user helpless.


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There will be "pools" of coverage at each data rate.

If the customer wants to provide certain area with coverage ata specific data rate, you may have to perform multiple sitesurveys.

You may have to survey at each data rate and find out wherethe coverage pool is for each data rate. The Cisco Site SurveyUtility surveys at a given rate and does not rate shift.

You will need to map out the higher data rate cells so they canbe shifted to the proper areas. You will need to map out thelower data rate coverage cells with an eye on the overlap ofthese cells and on frequency selection. This can be timeconsuming but may well be necessary, depending on your

customer's needs.

Finding out ahead of time how much throughput the users will require should be something you do before you startsurveying. This will be one of the factors that will help youdetermine where you need to place the APs.


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Copper installations can still provide higher data rates,but price is no longer a factor. A WLAN can be installed forroughly the same price as a copper-based network, andprovides many benefits over a wired network.

As prices continue to come down on wireless productsand throughput speeds continue to increase, wireless willcontinue to increase in popularity.

This may also be a factor in your design. If the customer wants to start by using a few wireless clients, and thenincrease the number once he is sure of the reliability, you will need to design his WLAN to accommodate this futureexpansion.


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If the customer intends to use data collection devicesexclusively, this will change the way you perform yoursurvey.

Most data collection devices today operate at 2MbpsMost data collection devices do not require 11 Mbps.

If the customer is using a 2Mbps data collection devicewith no intention of adding other wireless clients that mayoperate at 11 Mpbs, then perform the site survey at2Mbps.

Make sure that all areas where the data collection

devices will be used have a 2Mbps link. Some data collection devices have the ability to rate shiftDiscuss the devices that your customer will be using, whatabilities these devices have, and how your customerintends to use them.


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As we discussed earlier, retail or warehousing sites mayhave areas where large numbers of very busy users will belocated. A receiving area may be one such area. Asequipment is unloaded off trailers, it is unboxed and barcodes are scanned in rapid succession. The bandwidth

needs are again going to be determined by the application.A screen scraping emulation sends large packets containinga lot of data, for example. If there are 20-30 users scanningbarcodes and entering keystrokes in rapid succession, asingle AP may not be enough.

If, for example, all of the data collection devices aretalking at 2Mbps, realistically the AP is only operating at2Mbps. This is not to say that the AP is limited to 2Mbps,

but all clients are communicating at with the AP at 2Mbps.While the 11 Mbps connection might be sufficient to handlethe 20-30 users, the 2Mbps may not. You will have toexamine the packet size of the application and the numberof users to determine if you will need extra AP's in this area.


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Data collection users are also highly mobile users. That isthe advantage of the wireless data collection device. Itenables the end user to freely roam throughout the facilityand scan items instead of having to carry the item to a

scanner which is attached to a fixed terminal.

Coverage must not have holes and must have enoughoverlap between APs to offer truly transparent roaming.


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Some data collection devices are mounted to forklifts,which can move throughout the facility very quickly.

A driver may scan a barcode and then enter the quantity

as he is driving away. Take into consideration that theforklift driver does not understand the technology, andusually doesn't want to. He simply wants a system thatworks. It is your job to provide him with this system.

Part of this will be the application's ability to handle amobile user and the occasionally dropped packets that goalong with that mobile user. But by providing the mostseamless coverage possible, you will ensure that the

application will have fewer problems and work successfully.


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What we have presented are two of the most commonimplementations of WLAN's, the Wireless office and DataCollection. The principles involved center around whether

the user will be stationary most of the time and occasionallymobile, or a highly mobile user who is constantly on the go.

Understanding how the customer intends to use theWLAN is very important to understanding how you will needto survey.

Some of this information can be obtained through the pre-site survey form. But a good site survey engineer realizesthat the best way to understand what the customer needsis to interface with the customer.


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A survey kit should contain at least one of each type ofPCMCIA card.

Survey with the card that the client intends on using. Ifthe client is planning on mounting a terminal inside of a

crane and attaching it via an LM card with a 5.2 dBiomni, you do not want to survey using the attached endcap antenna on the PC Card.

Make sure that your kit includes the adapters for theLM card (MMCX RP-TNC). This way you will be able toattach a variety of antennae to the LM card and emulateyour clients desired installation.


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It is always a good idea to carry more than one AP.

Many are the engineers who have had a mishap withtheir only AP (AP's do not usually perform very well afterbeing dropped form a lift or ladder).

An extra AP allows the survey to continue withouthaving to wait for a spare to be shipped.


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AP's require power to operate. There will not always bepower available nearby while performing a site survey. Agood battery pack will last for at least 8 hours, allowingthe engineer to survey all day without having to recharge.

Also recommended is a fast charger for the site surveytool. If a laptop is used, spare battery packs that can becharged separate from the laptop are alwaysrecommended. Wireless PC Cards require a constantsource of power while surveying and may reduce batterylife to less than two hours. Li-on batteries power the unitlonger, charge more efficiently, and are lightweight.


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There is no single antenna that is perfect for all

applications. A variety of antennae are offered becausethey are needed. Antenna choice and placement is, inmany cases, dictated by the customer. A customer maynot want the antenna to be visible, or it may be located in

a high traffic area. By carrying a variety of antennae you will be prepared for any situation. The minimum

collection of antennae should include (but is not limitedto):

2.2 dBi "Rubber Duckies" 5.2 dBi Ceiling Mount5.2 dBi Mast Mount 5.2 dBi Ground Plane6.0 dBi Patch 8.5 dBi Patch13.5 dBi Yagi 5.2 dBi Diversity Pillar Mount

If you will be performing site surveys where you areaware that you will be using an antenna that is not in you kit, carry that antenna as well. Always survey withthe antenna you intend to use. Do not use a differentantenna and attempt to "guesstimate" the coverage.

You are performing the site survey to take the guesswork


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out of the installation.


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You should always carry an AP mounting bracket (whenavailable). The kit should also contain various mountingsolutions for the bracket (beam clamps, C-clamps) as wellas mounting brackets for each antenna (when available).Beyond this you must again be creative. Zip ties, duct

tape, bailing wire, electrical tape, two sided tape, velcroand paper clips are common components in a goodengineer's kit.

During a survey there is no bad mounting solutionexcept the solution that does not properly secure the AP,battery pack, and antenna. Not only might you damage your equipment, but you risk injuring yourself or others when the equipment comes crashing down. (This also

fails to instill any measure of confidence in the customeras he watches the "trained professional's" expensiveequipment shatter to pieces on his warehouse floor).


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Once the AP placement is determined, it will benecessary to mark the location.

Location markers should be very bright and resistant todust, grease, and water.

Surveyor's tape works very well and comes in a varietyof bright colors.

Brightly colored signs allow you to not only mark thelocation of an AP, but give some detail as to how the AP isto be configured and mounted, and can give a point ofreference to anyone reading the site survey report.

Markers should be sturdy but temporary.


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In order to provide the customer with the details neededto bid for the installation, you will have to provide manymeasurements in the site survey report. And thesemeasurements need to be as accurate as possible.

If you guess the Cat 5 run to be 300' and it turns out tobe 380', the customer will be very unsatisfied.

Your kit should include a measuring wheel (formeasuring cable distances). Many people include moreadvanced equipment, such as laser measuring devicesand range finders. These are all viable options, but ameasuring wheel will get you what you need. Formeasuring vertical distances, a rope marked in 10'

increments will allow you to accurately judge distancesfloor to ceiling.

Counting floor tiles and/or ceiling tiles is not a goodmeasurement of distance!


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Surveys should always be performed using theequipment that will eventually be installed.

This can sometimes be difficult with splitters, lightningarresters, and extension cables.

Instead of carrying one of every length of cable,lightning arresters, splitters, and other accessories, some

engineers outfit the site survey kit with an antennaattenuator. The antenna attenuator allows you to injectvarying amounts of loss without needing the actualaccessories.


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The most important part of a site survey is the sitesurvey kit. No matter how talented the engineer may be,it is impossible to perform a site survey without theproper tools.

It is recommended that a site survey kit be a portableunit. For ease of use, a hard plastic case that rolls andcan be checked as luggage is the best and most commonpackage.

Often site surveys are requested on very short notice,and the ability to carry the carry the case in the trunk orbackseat of a car, or check it as luggage allows theengineer to travel with his equipment and solves the

problem of the kit being lost or detained when shipped. Italso allows for quick deployment of an engineer.


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Today's IT professionals are generally alreadyoverworked, and do not want any project that mayincrease their workload.

They want a site survey that provides in detail wherethe AP's are to be located, how they will be mounted, howthey will be connected to the network, and where anycabling or power may need to be installed.

By providing the customer with a detailed site surveyreport, the IT manager can turn the necessary portionsover to a local contractor who can install the cabling thatmay be needed to provide the WLAN connectivity to the

network. At the same time, preparations can be made onthe customer's network for the upcoming installation.

The IT manager's part is limited to turning over thework to a trusted local contractor. You have saved him alot of work. He will remember this in the future when heneeds another site survey.


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In order to generate a detailed site survey report, you willneed to get to know your customer's wired network. We willlist some of the areas of the network you should investigate. The customer wants to be confident that the SE is capableand knowledgeable.

LAN Infrastructure

You will need to work with someone in the customer's ITdepartment to discover the layout of the customer's network.Generally, it is a good idea to start with a discovery of theLAN topology. It will be helpful if they can provide you withlogical drawings of the network.

Know your topologies - There are many differenttopologies but most companies today use some sort of startopology for their network. It may be a clustered ordistributed star. Understand where the components of thenetwork are located. Have the IT representative show youwhere the servers are located, where the connectivity pointsare (cabling closets with hubs, switches, routers, etc.), andwhere the cabling is run throughout the building.


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Look into the media types that make up the network. The customer will most likely use some type of copperUTP cabling for most of the runs. Copper can be run to amaximum distance of 328 feet without a repeater or hub.Fiber can be run for miles if necessary.

Some facilities use fiber cabling. Most of these sites usea combination of fiber and copper, with the fiber actingas the main backbone of the network and copper runs tothe desktop.

In the event that the facility uses fiber cablingthroughout, make sure to advise the customer that the

AP's only provide RJ-45 connections and that a mediatransceiver will be needed for each of the AP's. This canbe a significant cost.


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Ask the IT representative about the operating systemsfor the clients and servers and ask which protocols arebeing used on the network.

Ask specifically which protocols will be sent over the

WLAN. You may need to filter out all protocols that willnot be used on the WLAN to cut down on unnecessarywireless traffic.

Make sure that the customer is aware that not alloperating systems are supported (drivers are notavailable from Cisco for Linux or Macintosh systems yet).


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Once you understand the topology and the media, lookinto the network components.

Hubs may be 10Mbps, lOOMbps, or 10/100 hubs. TheCisco AironetAP's have 10/100 auto-sensing ports, and

will work on either port, but whenever possible youshould try and connect via a lOOMbps capable port.


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If the customer uses switches you will need to find outhow these switches are set up.

Switches have the ability for each port to represent a"virtual LAN" (VLAN). Ports may be grouped together to

form VLANs.

Many people today are not aware of these abilities andtry and use switches just as they would hubs. They thinkthat all devices plugged into the switch will be able tocommunicate.

This may or may not be the case depending on thedefault settings of the switch.

Switches can stop broadcast packets.


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Switches are designed for wired networks withstationary users. Switches are not set up to handlemobile users.

If the switch sees each port as a VLAN and there are AP's on

each port, the switch is not set up to handle users moving fromone VLAN to another.

Cisco Aironet AP's are set up to get around the shortcomings ofa switch. When a client roams from AP1 to AP2, AP2 sends adirected packet to AP1 letting it know that the client is nowregistered to AP2. AP1 can then forward any packets that it hasfor the client to AP2.

You may also want to consider the need for a design using a

single VLAN spanning multiple switches as your roaming area with multiple APs. This allows the best continuum ofuninterrupted connectivity to allow almost all applications to

work seamlessly. This requires that you be careful about theoverall amount of ambient broadcast/multicast traffic in thesame area, and the effect this may have on all nodes.

Another solution is to use MobilelP. This allows the VLAN sizesto be smaller as Mobile IP will take care of maintainingconnectivity as the node(s) cross IP subnet boundaries.


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The customer's application may not be set up to handleanon-contiguous broadcast domain, i.e. one separated byIP routers.


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One potential solution to this problem is to group theports with AP's connected to them and the port the hostis using into a single VLAN. This may or may not work for your customer, depending on many factors such as

topology and application needs.


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Another potential solution is to network all of the AP'sto the same hub that the host uses. Cable distancelimitations may make this difficult.

Still another solution may be to network all of the AP's

together via hubs and have them connect to same hubthe host uses. This is not a viable option if the host isremote.

Note: This solution may present problems for somepeople. Under the 802.3 standard, when using aswitch, you should not extend beyond two hops.(Remember, the wireless link between client and APis not considered a hop.) This would be three hops.

You may be required to remind (or explain) to yourcustomer how his switch works and inquire if thiswill present a problem for his WLAN.

These problems are seen most frequentl y ininstallation using data collection terminals, where auser may scan a bar code while standing in one cell andthen wander into another cell while keying in the


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quantity and pressing Enter.


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Sometimes problems arise with switches because of thetables they build.

Some switches drop addresses from their tables after aperiod of inactivity. When the client tries to connect, the AP isno longer in the switch tables and can not pass traffic to thenetwork.

Typically, this is not a concern. AP's are generally notinstalled and used infrequently enough for this problem toappear. But in some installations, an AP may be installed ina back corner of a warehouse or retail store and only usedduring certain times of the year. In this case, it may benecessary to lengthen the timeout values on the switch oradd a static entry.

If the customer decides to use DHCP the switch will have beset to handle the DHCP requests. DHCP requests are a typeof broadcast packet and can be stopped by the switch. If theswitch is not configured properly, the clients will be unable toobtain an IP address.


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Routers present internetworking considerations similarto switches. Like switches, routers do not pass broadcastpackets. Again, this may present a problem for theapplication or for clients trying to use DHCP.

A router may also indicate that they intend to use aremote host. If this is the case, it may be necessary toenter a static route in the router.


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Bridges can also present challenges because of theirtables. Most bridges used today build dynamic tables.

Some facilities may need to build their tables manually,sometimes by choice or sometimes because they are

using older bridges.

Most IT personnel are not eager to have to work withthese tables. It may be necessary in order for the WLANapplication to work properly, especially if they will beaccessing a remote host.

Most modern day bridges support dynamic learning with support for static filtering. If the customer is still

using equipment that requires the manual building oftables, it may be time for him to consider upgrading theequipment.


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Try to identify potential problems up front and discusshow these issues will be handled. This will potentiallysave the customer a lot of time and trouble during theinstallation.

If the customer is aware of these issues, they can behandled before the installation. These are not issues thecustomer wants to find during the installation, or duringthe "go live" period.

By addressing potential problems and being proactiveinstead of reactive, you and your survey appear as thestrong, reliable source during installation, instead of theweak link.

Your firm's reputation for site surveys is one of yourstrongest assets and should always be protected. Onebad site survey can hurt your business for months oryears to come.


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As you are surveying a facility and deciding on locationfor the APs, you should also be looking for ways toconnect the APs to the network.

By now you should be aware of the network layout and

components and have a good idea of where and how youcan interface with the network.

Most SEs are not experts on cabling. Your job is toperform the survey and make recommendations. Theserecommendations need to cover the cable associated withthe APs.

Because of this, you will have to have some knowledge

of cabling. Here we will address some of the issuessurrounding cabling and make you aware of the itemsyou should be concerned with during the survey.


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The most frequently used cable for today's networks isCategory 5 (Cat 5) unshielded twisted pair (UTP).

Cat 5 cable consists of eight strands of copper, groupedin pairs. Each pair is twisted to help avoid cross-talk. The

four pairs of wires are housed in a PVC sheath.

Most networks use two of the four pair of wires. All fourpairs are punched down onto the connector, but only twoare actually used.

UTP means that there is no additional shielding for thepair of wires inside the PVC sheath. Cat 5 UTP cable canbe run a maximum distance of 328 feet or 100 meters.


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Cat 5 is also available in Shielded Twisted Pair (STP).

This cable has an extra layer of shielding inside thesheath, The reason that Cat 5 UTP cable cannot be runover 328' is because of attenuation (signal on the wire

becomes weak or distorted). Part of the reason for thedistortion is interference. By using a shielded cable, thereis less interference and less attenuation, allowing you torun longer distances.

STP is generally not as widely used as the UTP. Instead,Cat 5 UTP cable is run to its maximum distance and thenplugged into a repeater, hub, or switch, where the signalis then rebroadcast down the next length of Cat 5 UTP.

Another option is to use Fiber Optic cabling fordistances that exceed 328'.


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Cat 5 cable is available in plenum and non-plenum. Buildingconstruction, as well as local and state building codes, willdetermine which type of cabling must be used.

The plenum is the space between the drop tile ceiling and thetrue ceiling.

In a plenum environment, this space is used for air return. Inthe event of a fire, the PVC sheath can melt and give off toxicfumes.

Since network cables are traditionally run in the plenum, toxicfumes will then be circulated throughout the building. Therefore,plenum cable must be used in these facilities. All otherequipment installed (APs) must also be plenum rated. CurrentlyCisco's 340 series APs are not plenum rated.

Plenum cables have a different sheath that will not melt aseasily and will not give off toxic fumes. Plenum cable is easilyidentified.

The sheath of plenum cable is much stiffer and harder to workwith than standard Cat 5 cable. The cable will also be marked with a code (CMP, for example, indicates a plenum rated,unshielded cable).


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Some easy ways to identify a plenum environment are"egg crate" ceiling tiles, a lack of insulation above theceiling tiles, and firewalls. Some local and state buildingcodes require plenum cable regardless of theenvironment.

A non-plenum environment is one where the air returnis ducted. When the air return is ducted there is verylittle chance that the toxic fumes could spread in theevent of a fire.

In this type of environment it may be suitable to usea general purpose (PVC) type cabling.

Some indications of a non-plenum environment are anabundance of duct work above the ceiling tiles, a lack offirewalls, and insulation above the ceiling tiles.

These cables will also have identifying codes (CM,for example, indicates a non-plenum unshieldedcable).


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Firewalls are usually easily identified.

They will be concrete, cinderblock, or brick structuresthat extend the full width of a room or passageway, andextend from floor to ceiling.

There are no breaks in firewalls. Firewalls are designedto contain a fire to a specific area by acting as a barrier.

It may sometimes be necessary to go through a firewall.In this event there are procedures for penetrating the wall. These procedures must be compliant with theNational Electrical Code. You can obtain a copy of theNEC from local electrical suppliers.

For this reason you should make a note in your surveyreport of any area where your design will have topenetrate a firewall.


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Another reason to make note of firewalls is that theywill affect your RF signal.

Many facilities have firewalls with doorways. The doorsare specially constructed and sealed to withstand a fire.

Other than their heavy construction, these doors are noteasily identified.

If you think that a set of doors may be part of a firewall,check and make sure. If they are, survey with the doorsclosed.

Closing the doors will have an effect on your coverage. Just because the doors are open when you are in the

facility, do not assume they will always be left open.


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Risers are often referred to as "wiring closets".

Risers are areas of the building where cabling, conduits,and plumbing may be run from floor-to-floor.

Most often, risers are stacked on top of one another,making it easy to run the height of the building.

All four walls of a riser act as firewalls, as well as thefloor and ceiling. And like firewalls, there are standardsfor penetration.

Make a note of risers for the same reasons that you

would firewalls. It will require penetrations that meetNEC standards and will require plenum-rated equipment.


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Always design and measure cable runs in straight

paths.

If a cable running north-south needs to be run in adifferent d^recjion, make a 90 degree turn. Do not run

the cable at an

Never measure the distance from the point ofnetwork connectivity to the AP as "the crow flies".

If you do and the customer gives your report to a localcontractor for an estimate, the estimate could be wrong.

Also, the cable run may be too long and require a

different type of cabling.


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Always calculate for a "service loop" on either end of thecable run. Service loops are usually 10 feet.

This gives the contractor some "play" in the cable incase the cable has to run around some unforeseen object,

or in case the cable has to be terminated numeroustimes.

Runs that are measured at anything over 300 feetshould be carefully examined. From the floor, it isdifficult to judge the exact distance.

Also calculate a "fudge factor." Different SEs have adifferent percentage that they use here. Adding 15% is

usually enough to insure that there will be enough cableto get around unforeseen objects.

Make a note of your estimated "fudge factor" percentagein your report. Otherwise, the contractor may add hisown and decide the run will be out of specification.


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The number one rule when designing the cable portionof your WLAN is to avoid fire hazards and to avoidcreating a fire hazard.

Design your cable runs properly. If the customer

chooses to ignore your recommendations, that is hisprerogative. This is why accurate documentation isnecessary. In the future you may have to prove that theinstalled cabling is not what you recommended. Withoutproper documentation, this will be very hard to do.

But if you design a faulty system and he installsaccording to your recommendations, you could findyourself in a lot of hot water.

We have given you a very brief idea of some of thequestions and concerns you should have in your mindwhile performing a site survey. By keeping these things inmind while you survey, you will be able to design a WLANthat will not only be reliable, but also easy to install as well. A few extra minutes as you are doing your surveycan save your customer hours of work.


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When you have decided where the APs will be mounted, you will then have to decide how the APs will bemounted.

Much like mounting the AP for a site survey, there are

an infinite number of ways to hang the AP using avariety of resources.

Here we will look at some of the most common methodsfor mounting Aps and some of the general concernsassociated with mounting an AP and the antenna.


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Cisco 340 series APs do not ship with a mountingbracket.

The APs have two slide-mount holes for mounting.

These holes can be used for any surface where it ispossible to mount two mounting screws.

Screws drilled into concrete will be fairly stable andshould provide a secure mount for the AP if doneproperly. Drywall or wood may be less secure.

It is recommended that all APs be mounted with extrameasures to ensure the safety and continued operation ofthe AP.

A proper mount for the AP means less chance of downtime. Loss of connectivity means lost time to the workers.


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Mounting brackets are available from third parties.

A simpler, but less secure solution, is to fashion somesort of mount. This can be done using many of the sameitems you carry in your site survey kit. Here are some

ideas:

When mounted on a pole or column, the AP can be ziptied to the pole or column. Use heavy-duty zip ties.Heavy-duty zip ties can be as wide as half an inch. Ifusing these zip-ties, make sure not to cover up theindicator lights on the AP.

In the diagram above, the AP is mounted in whatappears to be an upside-down position. This positionallows the indicator lights for the Ethernet port to be seenfrom the floor.

Whenever possible, Aps should be labeled with theName, IP address, Channel and SSID. The letters need tobe easily readable from the floor in the event that the AP


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requires troubleshooting.


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If the column is too large for zip-ties, another option is tomount a piece of a 2x4 to the column.

This can be done by using screws or bolt to attach the wood

to the column. Another option is to use a silicone or glue tomount the board to the column, like Liquid Nails. DO NOTUSE THE LIQUID NAILS TO MOUNT THE AP DIRECTLY TOTHE COLUMNI In the event that the AP needs to be removedor replaced, it will typically be destroyed.

The AP is then mounted to the wood using screws andsecured using zip-ties. If the piece of wood extends beyondthe width of the column, the zip ties can be wrapped around

the ends of the wood and across the face of the AP.

Otherwise it may be necessary to attach a mounting basefor the zip tie on the board. If you use the mounting bases, besure to secure them to the board using a screw. Do notdepend on the sticky tape on the bottom of the mount. TheAP will probably outlast the sticky tape.

The use of a piece of 2x4 is also good for concrete ceilings


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and walls.


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When mounting to a rafter or beam, the AP may be zip tiedto the rafter or beam.

In some cases, it is not possible to wrap a zip tie around therafter or beam. If this is the case, you may use the piece of2x4, secured to the beam with beam clamps.

You may also use a beam clamp to secure a mounting plateto the beam and then attach the AP to the mounting plate.

Always make sure that the 2x4 is securely mounted to thestructure before mounting the AP.

If surveying with the "rubber ducky" antennae, make sure tosurvey with them in the position they will be mounted. In the

examples shown on this page and the prior two pages, theantennae would be pointing straight down. There are differentcoverage patterns above and below the antenna. If you survey

with the antenna in one position and mount it in anotherposition, your coverage may be different than what you


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expect.


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Every AP will have an antenna attached to it.

Most antennae are either shipped with a mountingbracket or a mounting bracket is available as an option. The challenge is that most antennae are designed to be

mounted in a certain way.

A 5.2 dBi mast mount antenna is designed to mounted to amast and is shipped with the hardware to mount the antenna to amast.

In order to mount the antenna to an I-beam, you may needsome ingenuity. Standoffbrackets are available, but these are notdesigned to be mounted to an I-beam, either. Some installers usezip ties, beam clamps, or bolts to attach the standoffbrackets to

I-beams and then mount the antenna to the bracket.

If you intend to use a mast mount antenna indoors, make sureit is mounted as shown above. The antenna is intended foroutdoor use and designed to be mounted with the metal sleeve onthe bottom. For indoor use, invert the antenna.

Be creative. Modified brackets can be used for a variety ofantennae.


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Just as with the APs, always make sure that yourantenna has a secure, solid mount.

Make sure that the antenna will hang properly whenmounted to the base. If you surveyed with the antenna in

a vertical orientation and it is mounted to an insecurebase, it may hang at a 45 angle, changing the coveragepattern.

Do not hang antennae by their cables. The cable is notdesigned for this and may eventually break or sufferinternal damage that cannot be seen.

Another reason not to hang antennae by cables is thatthis would change the coverage cell. Also, the antennaemay sway when the air conditioning comes on, providinga moving coverage cell.


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Sometimes antennae may be used or mounted in anunusual way.

In some circumstances, a Yagi or Patch antennamounted very high and pointed straight down at the floor

is the best solution.

If you intend for the antenna to be mounted in anunusual way, make a note of it in your report. Theinstaller may not understand your intent and mount theantenna per its specifications, changing the coveragepattern.


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All APs require power to operate. You should providedetails in your report about how and where the APs willtap into the electrical system.

APs should be powered from a 24 hour, input power

source breaker. This may be shared, but a dedicatedsource is preferred.


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Familiarize yourself with various types and brands ofelectrical equipment. You do not need to be an expert onthese, but should be able to identify them. This will allow you to be very specific in your report when detailing where the AP will get it's power from. For example, you

report may state that "AP #4 will receive power from theSquare D box on the North wall of the Shipping Area.Distance from the Square D box to the AP was estimatedat 145 feet."

By defining the location and brand of the breaker box,the electrician will be able to easily identify the box andinstall the associated wiring.

Also be familiar enough with the breaker panels toidentify if there are available breakers or if the breaker isfull. If you specify a specific box to be used and there areno available breakers, this could present a problem,especially if your report is used to generate a quote forthe electrical work.


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Electrical workboxes should be mounted face up suchthat the weight of the AP transformer can rest on thefaceplate. The transformer should then be secured to thefaceplate orworkbox using zip ties.

Do not mount equipment to electrical conduit,plumbing, or ceiling supports. This is usually a codeviolation.

There could also be a leak in the plumbing, orextreme temperatures in the pipe.

Conduit could become electrified in the event of an

electrical short, and the electrical wiring in the conduit isa good source ofEMF.

Mount the equipment as far away from these aspossible.


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Sometimes APs may be located in areas where they are subject to extrememoisture, temperatures, dust and particles. These APs may need to bemounted inside a sealed enclosure. These enclosure are generally referred toas "NEMA enclosures". NEMA stands for National Electronics ManufacturersAssociation. NEMA has a rating system for these enclosures. The ratings areas follows:

Type 1 - Intended for

indoor use primarily to


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provide a degree of

protection against (hand)contact with enclosedequipment. Usually, alow cost enclosure but

suitable for clean and dryenvironments. Type 2 - Intended for

indoor use primarily toprovide a degree ofprotection against limited

amounts of falling dirt

and water. Type 3 - Intended for

outdoor use primarily to


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provide a degree of

protection against windblown dust, rain,and sleet; undamaged byice which forms on the

enclosure. Type 3R - Intended foroutdoor use primarily to

provide a degree ofprotection against fallingrain and sleet;

undamaged by ice which

forms on the enclosure. Type 4 - Intended for

indoor use primarily to


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provide a degree of

protection againstwindblown dust and rain,splashing water, andhose directed water;

undamaged by ice which forms on theenclosure.

Type 4X - Intended forindoor or outdoor useprimarily to provide a

degree of protection

against corrosion,windblown dust and rain,

splashing water, and


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hose directed water;

undamaged by ice whichforms on the enclosure.


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Type 6 - Intended for indoor or outdoors which occasionaltemporary submersion is enclosed.

Type 6P - Intended for indoor or outdoors which

occasional prolonged submersion is encountered.Corrosion protection.

Type 12 - Intended for indoor use to provide a degree ofprotection against dust, falling dirt, and dripping non-corrosiveliquids.Type 13 - Intended for indoor use primarily to provide a degreeof protection dust, spraying of water, oil, and non-corrosivecoolant.

The NEMA enclosures most often used for wireless


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networking products are Type 2, 4, and 4X. Some specificrequirements might require Type 12 or 13.

These types of enclosures can be purchased through

local hardware and electrical supply stores.Unfortunately, when purchased through these type ofsupply stores, the NEMA enclosure is little more than asealed box. There are no external antenna connectors, nointernal mounting standoffs, and no internal powersupply.


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Almost no NEMA enclosure is available off the shelfwith an internal power supply. Mounting for the AP inside the enclosure can befashioned just as you would when mounting an APwithout an enclosure.

Power will have to run to the enclosure and an electricalworkbox (plug) installed inside the enclosure. In order to attach an external antenna (an antennamounted inside the box is not very effective), a bulkheadextender will need to be installed. This is a simpleconnector that connects to the AP inside the enclosureand provides an antenna connector on the outside of theenclosure. Make sure that any holes drilled into the box are sealed.

If even one hole is left unsealed then the integrity of theenclosure has been compromised. Antenna connectorsshould be mounted to the bottom of the enclosure toprovide as much protection from dripping condensationas possible. It is also a good idea to seal the antennaconnection with a product like Coax Seal.


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Pre-fabricated NEMA enclosures with antennaconnectors, standoff brackets, and surge protectors areavailable from third parties. They are more expensivethan a standard NEMA enclosure, but provide betterprotection for the AP and can save either you, your

customer, or the installer a great deal of time andtrouble.

Special NEMA enclosures are also available that aretemperature controlled and make use of solar panels topower the equipment. Make sure that if you use a NEMA enclosure it issecurely mounted. A NEMA enclosure that measures twocubic feet can weigh as much as thirty pounds. If the

enclosure is not properly secured it could fall, injuringsomeone, damaging equipment, or destroying theconnected conduit for the power. Exposing the wiringcreates a potential fire hazard.


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In this section we have made you aware of some of theissues surrounding mounting and powering the APs.

You are not expected to be an electrician or to know allof the local, state, or federal codes. You do need to be

aware of the ones that appl y to you and can affect yoursurvey.

Keep all of these issues in mind as you survey. It willsave both you and the customer time in the long run. Youwill make better decisions when surveying the first time,instead of having to re-survey because you were notpaying attention to potential mounting or powerproblems.


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Sometimes you may not be able to mount an antenna tothe AP using the existing connecting cable.

Use of these extension cables will result in signal loss.You suffer a loss of about .5dB for every connection.

For example, an antenna extension cable will have to beconnected to the AP (.5dB loss) and to the antenna (.5dBloss). This results in 1dB of loss without even consideringthe cable itself.

Current extension cables available from Cisco haveapproximately 4.7dB of loss per 100 feet.

These cables are 9913 style, and the total loss for a 100foot extension cable is estimated at 6.7dB, includingcable loss and connector loss.


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Keep this loss in mind if you are considering usingan extension cable.

It is not recommended that you use the 100 footextension cable with the 340 series products. The reason

is that there are virtually no antennae that would be usedindoors that could suffer this amount of loss and still beeffective. Any antennae with less than 7dB of gain wouldbe completely ineffective if used with the 100 foot cable.

A better idea is to run the Cat 5 cable to the antennalocation and mount the AP as close to the antenna aspossible. In the event that you must use an antennaextension cable, use only as much extension cable as youneed.

The cables are available in 25, 50, 75, and 100 footlengths. These cables fit most needs.


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If you need a specific size cable you can ordercustom made cables from cable manufacturers.

For very long distances (in excess of 75 feet), you may

want to consider a different type of cable with a lowerloss. One such cable would be LMR600. This has a muchlower loss than the 9913 (4.2 dB vs. 6.7dB) and can stilluse the 9913 style connectors available through Cisco.

Cisco does not offer an LMR600 extension cable (yet).


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Cisco offers the RPTNC connectors for 9913 and RG-58cables. Do not attempt to use RG-58 cable for anextension cable. The amount of loss in this type of cablesrenders it useless as an extension cable.

The RG-58 connectors are available in case the originalconnector on an antenna is damaged and needs to bereplaced. Most Cisco antenna connection cables are RG-58.

Some installers try to substitute extension cables withan N-style connector. These are widely available. An RG-58 "jumper" is used to connect to the AP and antenna.

Although the extension cables with the N-styleconnectors are more widely available, and possibly lessexpensive, this solution would not be worthwhile in thelong run.

The jumper cables will have an RPTNC connector onone end and an N-style connector on the other. One jumper is needed for connection to the AP, and another


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for the antenna. This results in a loss of as much as3.5dB or more.


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Earlier we discussed the use of a splitter for certainapplications.

Splitters certainly have their place and can be very useful ifinstalled properly. But you need to understand theramifications of installing a splitter.

Most splitters use N-style connectors. This is because veryfew splitters are designed for WLAN equipment.

Most splitters available today are for use with broadbandequipment, much of which uses N-style connectors.

N-style splitters are implemented with WLAN equipment bymaking use of jumper cables. These jumper cables are9913,notRG-58.

Three jumpers are used with the splitter. A three foot jumper connects the AP to the splitter. Then two longer jumpers (usually 15-20 foot) are used to connect the


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antennae to the splitter.


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The splitter will add about 4db of loss.

If you manufacture your own cables and they are longerthan the supplied cables, then the loss will increase(depending on what type of cable you use).

We mention 4dB loss as a general guideline whendeciding if the use of a splitter will be appropriate. Seethe technical specifications of your specific splitter forexact measurements.

Each antenna connected to the splitter suffers the 4dBloss. This means that while the use of a splitter and a

second antenna may allow you to cover more area, it willnot double your coverage area.


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Once the customer has decided to have a site surveydone, you will need to have him fill out a pre-site surveyform.

The pre-site survey form will help you determine what

type of survey you will be conducting, how many days it will take, what equipment you will need to bring, and what questions you will need to ask during yourwalkthrough.

A pre-site survey form is your introduction to thecustomer's facility, so make sure that you gather all ofthe information you need in the form. This is a generalinformation gathering form.

We have provided you with a sample form. You will haveto create a form unique to your company that fits yourneeds.


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The product that you will be producing is the sitesurvey report.

All of the work that y

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