As Wireless technologies are maturing, there has been lots of stress given to the proper positioning of users and assets accessing WLAN. WLAN site survey provide indispensible method towards designing the WLAN network to properly and efficiently support WLAN and providing reliability of the network and alienating various obstructions and interferences which may hinder proper reception of RF signals from the wireless access points and hence making the network inefficient and unreliable.
WLAN site survey is often required and is often regarded as the first major step towards the deployment of Wireless Network and allows the customers to have consistent, reliable wireless access.
The basic purpose of any site survey is to determine how many access points will be needed in a facility to provide the requisite coverage and placements of those access points to provide efficient reception of RF signals.
It has been found that with the increasing demand of public access and close proximity of Wi-Fi "Hot Spots" there is increased potential of interference which WLAN site survey can address to and provides efficient placements of these "Hot Spots" so that they have minimum overlap regions and minimum interferences.
Similarly, WLAN site survey finds its use in various other locations which we had explored and studied. For example, conducting a site survey in a hospital is essential because often hospital complex are very large and have require lots of access points and hence care need to be taken that there is minimal interference from other access points. Also various facilities like Trauma centre and X-Ray centre walls are lead lined which may be detrimental to the RF signals. Also the RF signals might affect various other wireless equipments of the hospitals and hence there proper placement is very essential.
Any WLAN site survey involves steps which include Access Point selections and finding potential areas which may cause issues like Multipath distortion, which is caused by radio reflection, which might be detrimental to the RF signal quality and reception. Site survey also provides assistance in the type of antennas to be used and in drawing the overall WLAN topology.
Establishing a Wireless Network within a premises or otherwise is not always an easy task, especially for the network service provider, because wireless network or WLAN are deployed where there are no wires involved between the inter-networking of the computers and hence the reliability of the connection becomes very important for the service provider. This is important because the reliability of the connection depends on how better the transmission signal transmitted is perceived in the wireless networks.
For any wireless network, the reliability of the network is much dependent on how well the Access point from where the other devices can perceive the signal is placed. This is very important because unknowingly many times, even the presence of walls, file cabinets, any electrical equipment nearby the Access point may affect the quality of the WLAN network. To counter this problem, one need to perform a site survey before establishing the WLAN network in the premises. This shall not only help in giving the best out of the capability of the WLAN but also shall provide other benefits like securing the network from intruders etc.
The project report shall discuss the various aspects of all the process which are involved in the provision of establishing a WLAN network.
Aims and Objectives
Having presented the basic idea of the need to have a wireless site survey before installing any WLAN network, we shall now establish the AIMS and OBJECTIVES which this project report proposes to establish.
- To gain a broad understanding of commercial equipment used in Wireless Network hardware provisioning
- Demonstrating troubleshooting skills by suggesting solutions to problems identified by the site surveying activity
To gain a broad understanding of commercial equipment used in Wireless Network hardware provisioning
- Investigation on all aspects of the processes involved in the provision of establishing a WLAN based on a clear survey of the companies premises. This includes multipath mitigation, reflection absorption and radio wave interference. - This Aim is meant to establish an understanding of the steps and why the site survey is so important to establish any WLAN network and also to analyses what to expect in the end from the completion of the site survey
- Identification of obstacles and equipment selection to a successful deployment - The Objective of this aim is to identify the equipments in order to perform the site survey and other equipments that may be required for WLAN selection and identification of various obstacles which may need to be addressed
Demonstrating troubleshooting skills by suggesting solutions to problems identified by the site surveying activity
- WLAN network design based on a scenario to show the problems identified and provides solutions. - This aim is directed towards the objective of demonstrating how a site survey may often help in troubleshooting various problems like network congestion, bad signal reception with the help of site survey.
Objectives achieved through this project
- To appreciate the importance, grasp an understanding of performing a WLAN site survey correctly in order to ensure a successfully deployment of Wireless Network
- To have a theoretical understanding of SNR
- To conduct a site survey and to analyse findings
- To reflect on the role of SNR affecting Wireless Networks, multipath mitigation, reflection, absorption and radio wave interference
- To suggest viable solutions to problems identified given a WLAN network design scenario and to suggest areas of further research.
Approach and Methodology
As this project is a research and practical based project which highlights the need to conduct a site survey where the WLAN is proposed to be established so as to achieve the aim and objectives as mentioned in the previous section, the following methodology was adopted:
Understanding of the need to have a WLAN site survey: This was done through research and readings done so as to find out the concepts of the WLAN.
Firstly the research was done to find how to determine the best location for the wireless access point, then as an experimentation part, a wireless adaptor was installed on a desktop and then a secure WLAN network was configured.
This activity helped in getting the overall knowledge of not only the benefits of the site survey of the proposed WLAN but also of the overall WLAN concepts including its installation.
As a result of this research, the need of the WLAN site survey was discovered because even though, a WLAN has been established successfully, walls, file cabinets and other un-noticeable objects may often tend to hinder and obscure the RF signals. For instance, presence of electrical equipment near an Access Point may often tend to interfere the RF signals of the Access Point or presence of neighbors Access Point may overlap with your access point and may provide undesirable behavior.
This is because RF are radio waves and as per the physics law, they may get interfered by the presence of nearby electrical signal or for instance a metallic object. As a result of this, often the user may face intermittent or no signal or weak signal. Hence when installing a WLAN in a building or office premises, site survey helps in finding the best location for the placement of the Wireless Access Point.
After deciding upon the placement of the WLAN Access Point, the next step of the experimentation was to install a Wireless Adapter on the Laptop so as to configure a Wireless LAN. The Wireless Adapter sniffs the RF signal relayed by the Access Point and after the connection is established, starts the communication with the other networked device via. the Access Point.
There are various type of WLAN Adapters which includes:
- PCI Card Wireless Adapter
- USB Wireless Adapter
- CardBus Wireless Adapter
The next step in the experimentation is to connect and configure the Access Point.
Once the Access point and the Wireless Adapter is configured, the system can be used for internetworking.
Determining the equipment for conduction WLAN site survey :
The next step in the practical was to determine the equipment for conducting the site survey and how to use them. For this purpose, CISCO 802.11 wireless access point was used. Some of the salient features from the research of the site survey are as follows :
AP location for site survey : Ideally all the site survey should be performed as close as the actual Access Point Location. Also in most of the cases, AP should be mounted on a ceiling or at some height because in that case, the RF signal will be least obstructed by the interferences.
Performing the Actual Site Survey: Two ways was identified which can be followed for performing the site survey to establish the WLAN network. They are Manual site Survey and the other one is Assisted Site Survey.
Manual Site Survey
In this type of site survey, normally the AP is placed at the temporary identified location and then the wi-fi enabled PDA or other computing device is then taken to various location of the site manually to record the reading and perform the analysis. There are various tools available which can help to provide the data. Most often the Wireless Adapters provider vendors themselves provide tools to record the reading. With the CISCO 802.11 adapter used for the experimentation, it provides a CISCO Aironet Desktop utility which provides a site survey tool component. Figure below provides a snapshot of the tool. It provides statistics such as data rate, signal quality and other information.
While conducting the site survey, various issues are to be taken care of like :
- When conducting the site survey, the doors and other office doors should be closed as it shall simulate the real time scenario.
- Also all the metal casing in the nearby area of the Access Point must be closed.
Assisted Site Survey
Some Access Point Provider provide assisted site survey tools which helps to simulate the optimal radio transmit power and channel selection in an existing WLAN by allowing to conduct the site survey without the need to walk all the over the premises.
Conducting Site Surveys and exploring potential problems in real scenarios
The major problem encountered during the site survey for establishing the WLAN network is to find the correct spot for the placement of the Access Point. These problems were identified by actually conducting a WLAN site survey at real sites which included a Hospital, an educational building and an office complex.
As a part of the research following guidelines can be adopted to fix on the spot to place the Access Point.
- One of the most preferred spot for the placement of the Access Point is the wall at some height. This provides a good RF coverage and also bypasses any obstacles like file cabinet, wardrobe and other furniture.
- One other spot is placing the Access Point on top of the furniture if one wants to avoid the AP to be mounted on the wall.
- Another rule of thumb would be that the Access Point should be placed in the centre of the area which is supposed to be covered by the Access Point.
- In case the site is a multistory building, then one should keep in mind that the weakest point is the position above and below the Access Point. Hence the Access Point in that case can be placed outside the building or should be supported with the antenna.
- The antenna of the Access Point should be kept vertical.
- One should avoid placing the Access Point near metal casing as it shall result in the interference and reflection of the RF signals and hence resulting in the intermittent signal being received.
- One should also avoid placing the Access Point near Microwave or any other wave emitting devices like cordless phone unit or mobile station etc.
- To avoid the problem of reflection of the RF signals which results in the loss of signals, one should avoid placing the Access Point near water tanks or other water bodies.
As discussed in the introduction of this project proposal, a Wireless LAN site survey is the first step to be performed towards establishing a wireless Network. This section shall detail out what the major steps are performed during the site survey, various equipments required to complete the survey and other details which may establish the importance of WLAN and the need of conducting a WLAN site survey.
What is a WLAN site survey?
A WLAN site survey is the first major step towards the deployment of Wireless Network and is often regarded as one of the most major step towards ensuring that the WLAN installed is reliable and do not provide any interrupts during the internetworking of the computers.
WLAN works on by receiving the Radio Frequencies (RF) transmitted from the Access Points. The purpose of the site survey is to study the RF behavior, what is the coverage of the Radio Frequencies so that most of the receiving devices can perceive the signals from a single Access Point and determine the obstacles which may produce any interference to the transmission of RF and can provide interruption in the intercommunication between the two internetworked devices.
Since the reliability of the WLAN network depends entirely on how well the RF is perceived by the internetworked devices, the site survey ensures that the Access Point should be placed at a place which provide :
- Maximum RF Coverage
- Is hindered by minimal interferences
What is the need for WLAN site Survey and the outcome of the WLAN site survey?
With WLAN, often issues like RF signal interferences may arise which interrupts the intercommunication of the networked devices. Other issues such as Mulitpath Distortion and Hidden Node problem may also arise which may affect the quality and reliability of the WLAN. Hence in order to counter these problems a site survey is essential. A site survey defines the contours of the RF coverage, determines the region where the problem of multipath distortion may occur, areas where RF interferences are high and then finds the solutions to eliminate the problem. It also helps in providing assistance in determining the network devices which a client need to acquire in order to establish a WLAN network.
To bring the crux of the overall requirement of having a WLAN site survey is to:
- Provide a High Availability of the RF to the networked devices
- Provide Scalability in terms of the number of devices which may connect with the access point
- Provide Manageability of the overall WLAN network to be established and determining the devices to be procured etc.
- Provide Interoperability within the devices connected to each other.
Hence the outcome of any WLAN site survey is to propose the RF coverage, positioning of the Access Point and placing of other equipments for better RF coverage, power Consideration and other electrical requirements such as wiring etc. and the overall installation guideline of the WLAN network.
This is one of the common problem which any WLAN network normally encounters. These are caused by radio reflections of the RF by the metallic objects. The higher the number of radios in a cell, the higher the noise in a cell., hence access point Antennas should be placed such that they are far from reflective objects.
Because of Multipath reception, the signal strength may be strong but at the same time, it may also be distorted. Hence Multipath distortion should be given high priority and all steps should be taken to avoid or minimize this problem. This may include using omni-directional antennas, avoiding placements of Access Points near metallic casing, water tank etc.
Various types of WLAN site survey
Pre-deployment site survey
As we know that network design is performed to determine the location of access points, antenna types and power levels. This will save time and the cost. If the procedure of network planning is done carefully then you do not need to perform pre-deployment site survey you can directly move to deployment survey. But if there is any doubt about the designing of network then pre-deployment should be performed before deployment.
More than one access points are using when performed pre-deployment site survey. Throughout this site survey access points are placed in the planned locations. Multiple measurements are taken for the exact location of each access points so that access points should provide the planned coverage in each location. This process is further repeated after taking next access points location. With the help of computerized planning tool we can track the measurements in each location.
Deployment site survey includes access points, switches, cabling and antennas. This survey is very time consuming without using software tools.
Some of the issues related to manual works are -
- Without using any tool exact position of access points are estimated manually. This will affect the WLAN performance. Sometimes high numbers of access points are placed at a high cost.
- Manual verification process is time consuming and inappropriate. Walking in the building with laptop for taking measurements at each location of access points manually will take time.
- Analysis of co-channel interference is not possible manually during pre-deployment phase.
- If there is little knowledge of current network then planning for added capacity to the networks become very problematic.
Basic steps in conducting a WLAN site survey
In order to conduct a site survey for the installation of a WLAN, first of all the basic equipments which are required to conduct a survey need to be procured and available. These equipment includes:
- WLAN Access Point (transmitter of the RF signals)
- WLAN Adapter or Card (recipient of the RF signals)
- Antennas like Omni-direction antennas and others (based on the type of WLAN setup and companies requirement)
- Other Site Survey Utility software.
Once these equipments have been procured, the next step is to conduct a site survey. The basic steps which are required for conducting a WLAN site survey are as follows:
- Obtain a Facility Diagram: The site survey should be started with the brief study of the Facility Diagram where the WLAN is to be established. This knowledge of the premises blueprint is required as it helps in determining the possible obstacles which may cause interference to the RF signals, a possible location for the placement of the Access Point for better RF coverage etc.
- Visual Inspection of the Facility: This should be next step in performing the site survey. It helps in determining the actual building design and helps in further discovery of the obstacles such as file cabinets, electric wiring, etc.
- Identification of the User Area: The step basically intends to discover the areas which are heavily used and the areas which are less frequented by the users. This helps in fixing the areas where the WLAN usage would be heavy and the traffic load would be heavy and hence it helps in guiding the number of Access Points which may be required.
- Determine preliminary access point (AP) locations: This step helps in fixing approximate position of the wireless Access Point based on the study of the previous three steps, so that it can provide maximum coverage to the user areas. Also it shall help in
- Determining the overlapping areas where inter-access point interference may happen. This step also helps in ensuring to "be certain to consider mounting locations, which could be vertical posts or metal supports above ceiling tiles. Be sure to recognize suitable locations for installing the access point, antenna, data cable, and power line. Also think about different antenna types when deciding where to position access points. An access point mounted near an outside wall, for example, could be a good location if one uses a patch antenna with relatively high gain oriented within the facility." 
- Performing the actual survey to verify the Access Point Location : This is the step where the actual survey and verification with reference to the data rate, signal strength, and signal quality of the identified access point is performed. Various third Party software site survey tools are provided by LAN equipment vendors like Cisco, Proxim etc. Normally the survey is done by installing the Access point on the preliminary decided location determined in the previous steps and then taking on the readings of the data rate, signal quality etc. at the Access Point location and other locations which are deemed to covered by that Access Point and then analyzing the readings. Often the survey requires conducting the survey and obtaining the results in the overlapping area and the boundary area and then optimizing the Access Point location to achieve the maximum coverage and least interference. Also if the Access Point is placed so as to serve multi floor premises the survey need to be conducted both above and below the floor where the Access point is places. Similarly if the Access Point is placed in some outdoor areas then the survey need to be done inside the building premises as well.
- Documentation of the survey report: All the logs of the reports and data obtained during the previous step need to be documented so that it may be utilized during further network planning and expansion.
Reporting should include following information-
- Coverage area map
- Estimation of data rate
- Signal to noise ratio
- Interference caused by other access point in your network and outside your own network
- Installation details at particular site like location of access points, antennas mounting information, technologies used, channel number and name of the networks
- Details of network security
Signal To Noise Ratio (SNR)
It is the concept of defining the ratio of power of the signal transmitted to the power of the background noise. It helps in determining how much noise is present in the background and helps in fixing the location of the placement of the Access Point.
When to perform a site survey
Site survey done in four stages-
Pre-Installation Site survey
This is very important before installing a WLAN.It gives you opportunity to detect any volatile situation and designs around them. And this would help you to decide that weather an effective WLAN is possible in that area or not. This will save time, effort and increase the effectuality of newly installed wireless network.
Survey during Installation
Brief Site survey should be performed during installation. So there would be no problem of transmission and receiving of signals.
Survey after Installation
After installing WLAN, a complete site survey should be performed to manuscript the WLAN coverage. Even small changes in the environment can affect the performance of radio waves.
Ongoing Site survey
Performing regular site survey is very important because of dynamic nature of radio waves. If the area undergoes any new changes then a resurvey is very necessary.
Wireless LAN site survey tools
For the deploying a wireless LAN one need a site survey toolbox. That can help in site survey process. Here we explain indoor site survey and outdoor site survey. Both are very different in nature and require different tools.
Indoor Site Survey
These are the tools used for an indoor site survey
- SPECTRUM ANALYZER - This hardware is used for the measurement of amplitude and frequency. First thing we need for site survey is to determine RF coverage.
- BLUEPRINTS - For the measurement of RF signal and to map coverage we need blueprints. To edit and view electronics copy of blueprints CAD software can be used.
- SIGNAL STRENGTH MEASUREMENT SOFTWARE -
This coverage analysis is very important for the appropriate positioning of access point, right use of antennas and the access point radio card transmission power. Disappointingly some site surveys overlook spectrum analysis because of high cost of spectrum analyzer hardware.
After spectrum analyzer site survey we need to perform the RF coverage. And for RF coverage this signal strength software is used. RF measurements must be performed for the proper positioning of access point and antennas.
The most difficult part of coverage analysis is to find the accurate positioning of first access point and to find out the boundaries of first RF cell.
Below are some steps which determine how this is achieved -
- First of all we place the access point in the corner of building with some power setting.
- After place the access point, walk diagonally towards the centre of building and away from access point until we find some signal drops. And the point where we receive signal drop is the exact location for first access point.
- After positioning the first access point walk throughout the building to find cell boundaries.
- You may change the power setting depending upon the size of RF coverage and we may change the position of first access point.
After determining the first coverage boundaries you may find the position of second access point with the same above technique which we used for the positioning of first access point.
Overlapping may cause performance degradation that's why it is very important to avoid unnecessary overlapping. There are many obstacles caused by buildings etc. because of which we will require to change the distance between access points to assure proper overlap.
After finding the exact positioning of the second access point and coverage boundaries, repeat the procedure again and again until all coverage needs are found. During the site survey analysis following are the cell edge measurements are taken -
- Receive signal level-
- Noise level
- Signal to noise ratio -
- Data rates
This measurement taken during site survey is depend upon the use of WLAN
SNR is the decibel difference between the received signal and the background noise.
802.11 CLIENT CARD-
This card is used with the signal strength measurement software.
You need at least one access point.
Battery pack provides power to the access point. And battery pack make environment safer. With the use of battery pack you don't need to run electrical extension cord to power the access points and you can easily change the position of access point to the new location.
In indoor site survey binoculars can be useful with giant building.
In an environment like office you need to be silent while performing site survey. But walkie-talkie is needed because RF is three dimensional. One man has to be on one floor with access point and other man must be in another floor for the checking of received signal.
Antennas put in to three categories-
- Omni-directional - They are planned to deliver RF signal in all possible direction.
- Semi-directional -They are planned to deliver RF signal in specific direction. These types of antennas designed for short distance communication.
- Highly-directional -They are designed to use for point to point communication. They are perfect for long distance communication.
In an indoor site survey both Omni-directional and semi-directional antennas are must.
TEMPORARY MOUTING GEAR-
You need to mount the access point temporarily just below the ceiling during site survey. To mount the access point plastic tics and bungee point are used. Tripods are also used by some professional.
With the help of digital camera we can record the exact location of access point. It helps in keep the visual record of the site survey.
LASER MEASURING METER
COLOURED ELECTRIC TAPE
Colored electric tape can be applied at the location where the access point was momentary mounted during the process of site survey. This will help further in later date for the person whoever will do the installation of access point. Colored tapes are also used to trace the channel frequencies. For e.g. green color used for channel 6, red color used for channel 1 and for channel 11 blue color is used.
Ladder can be used to momentary mount the access point during site survey.
Outdoor Site Survey
Most of the tools used by outdoor site survey are same as the tools used by indoor site survey. But in outdoor site survey GPS device is also used to measure latitude and longitude coordinates. Here we discuss about Wi-Fi bridging. Wireless bridging exists at distribution layers. It can be used to provide wireless link between wired networks.
Many tools and calculation are needed for bridging link between two or more networks. Fresnel zone, earth bulge, free space path loss, link budget and fade margin are the calculation necessary for bridging links.
Following are the tools used for outdoor site survey-
Topography maps are needed for the planning of position and elevation for providing wireless link between two or more networks.
LINK ANALYSIS SOFTWARE
Link analysis software can be used with topography map to provide wireless link between networks. For this some calculations are needed like Fresnel zone and equivalent isotropically radiated power (EIRP).
As we know that necessary calculations are needed like link budget, Fresnel zone, free space path loss. And for this software calculators are used for the calculations. Some other calculators can be used to provide information of voltage standing wave ratio and Cable attenuation.
MAXIMUM TREE GROWTH AREA
Trees are potential source of obstacle for the calculation like Fresnel zone. We should plan height of antenna according to the growth of trees. We can take help from agricultural government for providing information regarding local foliage.
With the help of binoculars we can establish visual line of sight. To plan a bridge link we should have knowledge of earth bulge and topography.
Outdoor site survey required team of engineers. Team will require walkie talkie for communication.
WATT METER AND SIGNAL GENERATOR
For the testing of cabling, connectors and accessories for signal loss, watt meter and signal generator can be used together. They are also known as bird meter.
Testing gear can be used before deployment for checking cabling and connectors and used after deployment to check that environment conditions have not damaged cabling and connectors.
VARIABLE LOSS ATTENUATOR
Variable loss attenuator contains dial that allows us to arrange the amount of energy it absorbed. They can be used to simulate cable loss.
This is a special device which can be used to provide information that how high obstacles are.
GPS can be used to record the latitude and longitude coordinates.
Digital camera can be used to record the pictures of path of the cable, mounting location, grounding location, indoor mounting position and obstruction.
Spectrum analyzer can be used to test the RF levels.
Some popular software that are used in wireless site survey are -
For performing WLAN site survey netstumbler is a free commercial software tool.
To perform site survey you have to walk with the laptop running netstumbler in a building. We have to walk on a predefined path with some sample point where we want to take the position of RF signals. But before walk around the building you must start a netstumbler. You must see the access point to make sure netstumbler is working properly.
APPROACH AND SCOPE OF WORK
The approach used in this project would be that of case study and performing some practical experiments at real sites to derive the results and establish the understanding of the concepts studied in the Literature Review. We shall use Cisco Airnet and Interpret Air WLAN site survey software to do our experiments and conducting WLAN site survey.
The scope of work for the project would be to carry out the research which shall bring the importance of the site survey for installing the WLAN in a building or office. The scope of the research shall be to find the methodology involved in the site survey, guidelines to be followed while conducting the WLAN survey, and the issues which need to be taken care of while conducting a WLAN survey. Any typical WLAN survey has three major objectives:
- Finding the best possible site to place the Access Point
- Provide maximum coverage area to the recipients.
- Provide the reliable communication medium.
The research activity to be conducted shall work on the objectives defined in the previous section of Aim and Objective. After the research a small WLAN network shall be established in which the best possible location for the placement of the Access Point would be identified and then the site survey would be done using the site survey tool of CISCO 802.11 wireless Adapter and shall take the reading of the RF signals and Data rate and shall log the results of the analysis done. Also practical WLAN site survey would be done at various locations like Hospital, education institution and a corporate office to establish the concepts studied in the literature review.
RESEARCH WORK AND SIMULATION
Deploying wireless using InterpretAir WLAN survey software
InterpretAir WLAN software needs only laptop and wireless data card. It supports multi-floor surveys, means in a single project whole building can be included. It also supports 802.11a/b/g and locates even hidden access points. Through this we can also discover access points located on above or below the current floor to be operated. Figure given below illustrates a typical Wireless Lifecycles.
Above fig. shows GUI of InterpretAir. Main window display the indoor floor plan and outdoor map. Browser on the left shows the map access points and survey. To create visualization only selected access points and surveys are used. Tabs on the bottom provide information like, visualization properties, real time monitoring of signal information and properties of connected devices with device properties.
This software can also give answers like exact location of access point, channel numbers, expected coverage and performance. We can change the antenna types, move location of access point and change transmission powers with the help of mouse.
Summary of the results of the WLAN site survey conducted for the office are as follows:
- It was found the southern half of the office had fairly poor coverage which was apparent from the SNR contours. The problem was rectified by changing the positioning of the antenna as it was close to the metal ventilation unit in the northern part of the office. The antenna was so placed so as to make the antenna more suitable to the ambience of the office however towards the south of the antenna were large file cabinets which were blocking the RF signals towards the south of the hall.
- In another hall it was found that the RF coverage was very bad. Investigation revealed that the antenna was placed little lowered so as to prevent the RF signals bleeding outside the office building, which was however providing poor coverage to the inside of the building as the signals were getting blocked by lots of office cabinets. The problem was solved by positioning the antenna towards the top of the ceiling
In this section, research output of various case study of WLAN site survey done is presented. Each case study brings forth the need of WLAN site survey in these places, potential areas which might hinder the RF coverage and the placements of the Access Points.
WLAN Site survey in hospital
Site survey of hospitals is very difficult to perform. The reason for this difficulty is multistory building which contains several small rooms. Care need to be taken when placing access points so that they can avoid the interference from other access point location.
Some applications like ultrasound devices and portable XRAY require high bandwidth. They would require 802.11a to 802.11g data rates. These applications are not very friendly to RF coverage and there would be chances of wireless signal may interfere with RF devices and vice versa. Hospital management needs assurances from surveyor that there would not be any interference.
Also since Hospital complex are very large, it typically involves multiple Access points and hence the problem of interference need to be taken care of. Access point placements in the elevator zone should be typically taken care of as they are potential "dead zone" for the RF coverage.
WLAN Site survey in Hotels
As we know that demand of internet is growing day by day. Keeping this in mind WLANS are being installed more and more in the hotels to provide internet facility to the hotel guest.
Hotels construction is same as hospitals. It also contains multistory building with numerous rooms. Numerous rooms and high number of walls needs large number of access points. Hotels always want to provide their customer best quality of services which should be fast and reliable.
Network security is also concern while any one access internet. Business travelers in hotels always want secure data transfers hence security of access points is also very important. Access points should be hiding so they can avoid theft because hotels often house restaurants and convention areas which are often visited by general public.
We can avoid theft and vandalism by providing some solutions to the security issue like wireless equipment privacy encryption and building broadband service manager.
As we know that wireless has become very important in everyone's lives. Wireless is a necessity in hotels from guest services like check in, concierge to maintenance and security. Mobile devices and IP devices need their own infrastructure. VLANS can allow single usage of access points for both public and private network only if there is a permission of public access provider.
Now a day's hotel is not only a place of night spent but it is more than that. Travelers need everything in hotel perfect. Hotels have convention centre, retail areas and restaurants. All of them have their own separate providers, which may cause interference between networks.
In hotels conference centre do not have a sporadic usage and often provide fewer access points. When the conference centre is in use need a large number of access points.
Conventions centre required securities like 802.1x, WEP and many more other types of security. This area is always available for changes and further additions. This location is not connected to the network of other area of hotels because of viruses which may cause instability to the other network.
WLAN Site survey in office
Today small offices, wireless offices are the new emerging markets which are grown day by day. New technology and solutions are developed.
Most of the offices will not require a site survey if they contain fewer number of computers. Adhoc network is the best solution for them. But some customer requires site survey for the future growth. They set up single access point connected through wireless repeater.
Small offices locations are often near to the retail offices. Retail offices are also using WLAN which may cause the problem of overlapping between different businesses. Channels should be selected with a adequate signal strength which will only send signals to the required coverage area. For the security purpose transmit power is set in such a way that it only cover the required area within the office.
THE FUTURE OF WLAN SITE SURVEY
A wireless technology is maturing day by day and new applications are continuing to emerge like through GPS we can able to determine the place, you can control multimedia system, you have radios in your car, you can talk to your cordless phone, you can connect your laptop to the internet over a high speed wireless connection. Wireless is everywhere and site survey tools play a vital role for designing WLAN network to support these applications. The efficient usage of WLAN network and reliable network coverage are the key to the success of WLAN and site survey helps us in ensuring that the user is most benefitted by the WLAN network and that WLAN is not under-user or over-used.
Hence we can firmly establish the fact that the importance of WLAN site survey is only going to grow with the days to come and the research in this area would be a milestone step towards better utilization of WLAN and its successful deployment.
A WLAN site survey is an important step to ensure that the WLAN deployed is reliable, provide high performance and is secure and efficient. WLAN site survey ensures that the WLAN topography benefits the maximum user and helps to serve different users with their needs like what we discussed in our case studies.
Any WLAN site survey can be easily performed using variety of softwares like Cisco's AIRONET which simplifies the analysis of WLAN site survey and provides loads of visualization methods to analyse and interpret the site survey results. Various problems like multipath distortions, signal interference and noise can be easily delimitated by conducting WLAN site surveys.
REFFERENCES AND BIBLIOGRAPHY
- ALEXANDER, B.E., (2005).802.11 wireless network site survey and installation. Cisco
- ALEXANDER, T., (2002). Optimizing and Testing WLANS. Newnes.Oxford, U.K
- Cisco Aironet Wireless Site Survey.(2002).
- REID, N. , SEIDE, R.,(2007).802.11 (Wi-fi): networking Handbook. McGraw Hill. Osborne. (pp 224-300)
- REYNOLDS J. (2003).Going Wi-Fi. CMP Books. San Fransisco, USA. (pp 167-190)