Site Survey Report MAH

Transcription

1 Site Survey Report MAH

2 Index 1. Introduction Contact Information Scope of Survey and Spectrum Validity Report Coverage Signal Strength vs. Signal to Noise ration S/N Signal Propagation External Antennas GHz vs. 5.0 GHz Spectrum Analysis Co-Channel Interference Adjacent channel Interference Access Point/Antenna placement Omni-directional antennas Access Points using built in antennas Option to use External Antennas Access Point placement Other abgn WLAN Action plan Coverage Spectrum interference Mounting and position of AP Other WLAN Reduce Co-Channel Interference Document Information Version Sida 2 (10)

3 1 Introduction Dokumentnamn: Site Survey Report MAH AddPro AB have conducted a Site Survey and Spectrum analysis of 7 facilities held by Malmö Högskola, as a step towards identifying potential issues with coverage or disturbances in their Wi-Fi environment. This report will show the results and hold conclusion and suggestions to try and solve or improve current issues. 1.1 Contact Information This Site Survey was performed by: Martin Johansson AddPro AB Stenbärsgatan Malmö [email protected] Scope of Survey and Spectrum Site Survey is a method used to collect data from present Wi-Fi Access Point to determine coverage, signal to noise ratios, co-channel interference and Access Point placements in the existing Wi-Fi Environment. Spectrum analysis is a tool to identify none interferences caused by other equipment or environment. 1.3 Validity The validity of this report is based on todays and the days of the site surveys current situation. If there is any changes made to current environment or infrastructure it could affect the conclusions of this report and must so be taken into account. Sida 3 (10)

4 2 Report Dokumentnamn: Site Survey Report MAH Coverage plans, floor plans and other notations will be attached in Appendix A and B. Any reference point made in this report is to these separate documents. 2.1 Coverage Attached in Appendix A (2,4Ghz) and Appendix B (5.0 GHz) in floor plans showing the coverage of the floors in etch building separately. These floor plans should be reviewed and where there is insufficient coverage one should take action. To achieve better coverage of areas where there is poor S/N one of following steps can be taken: Change position of Access Point closer to area where there is low coverage Add additional Access Point Add External antennas to Access Point Signal Strength vs. Signal to Noise ration S/N Signal strength represents the value of coverage based on output and propagation of the Signal. However Signal quality is based on other factors as well. Therefore you measures Signal to Noise ratio rather than only signal strength. If the background noise is 10dBm and Signal Strength is 50dBm you have an S/N ratio of 40dBm. You should always strive to have at least 25dBm for Laptops and 30dBm for Pads, Phones and alike Signal Propagation Different materials can either reduce or entirely block a Wireless signal. So when choosing a spot for an Access Point you must be aware of the surrounding walls and materials used. If Signal is completely dampened or blocked you could be required to install additional AP or change position of AP External Antennas The Access Point used by MaH is capable of using externally mounted antennas. This has several benefits. More regarding this under section GHz vs. 5.0 GHz Due to better penetration of lower frequency trough materials 2.4 GHz coverage is far greater than that of 5.0 GHz. This can better be seen if comparing the same floor in Appendix A and B. This must be kept in mind if an area is planned to provide full coverage of 5.0 GHz. Sida 4 (10)

5 2.2 Spectrum Analysis All areas were during the Survey check for none disturbances. What this means is that there are several items that can produces signals matching the frequency used by Wi-Fi bgn uses the frequency range of 2.4 GHz where an uses 5.0 GHz. Microwave ovens, radio detectors, Bluetooth and more all interfere with 2.4 GHz band. 5.0 GHz band is much less crowded with items and is considered better quality if used. Below is a normal signature of two 2.4 GHz Access Point, one communicating on channel 1 and one on channel 6. Below is an example of an interference effecting channel 1 and all Access Points communicating on this channel in its vicinity. Overall there where very little interferers from none equipment. Please refer to section 2 of Appendix A for more details regarding areas with potential interference. Sida 5 (10)

6 2.3 Co-Channel Interference Co-Channel Interference is when neighboring Access Point transmit on the same as one another. This is generally avoided by using none overlapping channels. As seen below a channel in the 2.4 GHz spectrum uses ~20 MHz wide channel stream. So if you are using channel 6 on an Access Point the transmission in sending from Mhz. So when planning your WLAN Network its industry standard to use Channel 1, 6 and 11 and thus avoid overlapping frequency. However sometimes there will be spots where one Access Point will see more than 2 neighboring Access Points. If possible it s recommended to move the Access Point or lower power output so that interference is limited. In areas where there is a lot of APs and good coverage there is more likely interference. Here you can try and lower output 1-2dBi per AP and still have sufficient coverage but lower interference. 2.4 Adjacent channel Interference This is when neighboring Access Point is divergent in its Channel selection. For example if an Access Point is using a channel outside of the normal channel 1,6 or 11, this will have a greater effect on interference then if it was using the same Channel, i.e. Co-Channel Interference. As an example see below where Access Points using channel 4 in Orkanen Plan 1 will effect MaH APs on both Channel 1 and 6 and cause more Interference than if it was on the same Channel. Sida 6 (10)

7 2.5 Access Point/Antenna placement When using Access Points with built in antennas one must consider the propagation of the signal when placing and mounting the Access Point. If using external antennas one can turn and angel the antenna to suit the coverage pattern one wants Omni-directional antennas Using Omni-directional antennas pointing vertically signal propagation looks like below. The recommendation is to mount/point Omni-directional antennas in this ways to get the greatest coverage and also avoid leaking coverage to adjacent floors above and/or below Access Points using built in antennas. However most APs with build in antennas have a coverage patter looking like the shape of an umbrella. Taking this into account placing an AP vertically might not give the desired coverage. It will also cause increased coverage leaks between floors so that Co-Channel Interference (covered in section 2.3) will be greater Option to use External Antennas The Access Point used by MaH has to option to use externally mounted antennas designed for n. This is recommended in the following cases: There is need for increased coverage. When using vertically mounted Access Point and you wish to alter the signal propagation. Sida 7 (10)

8 2.5.4 Access Point placement When selecting a position for your Access Points you should make sure that the signal propagates to the areas where you desire coverage. You should also plan ahead if you are going to install Access Points in a building with several floors. In some building all Access Point are placed vertically on the same spot on etch floor. This will cause increased interference and lower total coverage in the building. Is common best practice to cross place Access Points so that instead of causing interference you use the benefits of the AP on the floor above and below to complement coverage. 2.6 Other abgn WLAN In today s infrastructure it is normal that neighboring company s and facilities house their own WLAN service. These cannot be avoided but normally the interference caused by these WLANs is so low that it s not considered a problem. However in-house WLAN that s not a part of the own company s infrastructure will cause unwanted interference and should be removed or integrated in the designed solution. In Appendix A for etch floor and building you will see if and where there is other WLANs that isn t part of MaHs current network. Sida 8 (10)

9 3 Action plan Dokumentnamn: Site Survey Report MAH Where 3.1 are your main priority and 3.5 is lowest. For details see comments in attached Appendix. 3.1 Coverage First step would be to ensure sufficient coverage of all floor plans and areas where there is users using WLAN. Initially on could try and see the benefits of using external antennas and see the improvement. Choose a spot with low coverage. Check you the Signal Strength on a Laptop. Mount the antennas and check again for improvement. If using external antennas isn t sufficient additional APs should be used. However consider lowering output of Access Point to avoid Co-Channel Interference. 3.2 Spectrum interference Make sure you check areas with Interference and remove the interference or plan the APs closest so that they don t transmit on the same frequency as the interference. 3.3 Mounting and position of AP Make sure you position your APs so that they provide coverage according to where you want it. If it s not possible to mount an AP in the ceiling try and use external antennas and angel them so the propagation is as you desire. Also consider the design philosophy where all APs aren t on the same spot on each floor. 3.4 Other WLAN All WLAN that will be shown I Appendix A should, if possible, be shut down or integrated in the current H3C solution to minimize interference. 3.5 Reduce Co-Channel Interference Most of the above steps will all help in this area. Remove unwanted WLANs, change position of AP and look into the possibility of lowering Output in areas with dense AP deployment. Sida 9 (10)

10 4 Document Information 4.1 Version Version Description Author Date 0.1 First version Martin Johansson Spellcheck, adjusted language Martin Johansson Finished version Martin Johansson Sida 10 (10)