RF site survey basics
This article describes RF site survey basics, RF survey types and RF survey tools used for pre-installation verification of GSM,LTE,CDMA,UMTS networks.
RF Survey is collection of data from the site or in the field required to install a new site. This is essential for various reasons such as cell site analysis, determining coverage region of proposed new cell Site, for deciding the type of link connectivity with another cell site. This task will result into physical changes in the existing network due to modification or addition of new sites/equipments.
In order to perform RF survey work customer will usually provide following details referred as
nominal point or reference point.
• Latitude value and longitude value
• X-Y co-ordinates
• Details of North/East co-ordinate
• Location Area name
RF Survey can also helps in analyzing issues in the existing GSM/CDMA/LTE or VSAT networks. Issues can be intereference or multi path distortion or construction of new building near to the existing cell tower. By doing RF Survey, we can eliminate these problems so the installed RF network will function satisfactorily. Like other project planning, RF site survey work also should be well planned so that its execution as well as final network roll-out will be executed effectively and efficiently. Before going for RF site survey of the earth region, it is essential to analyze the region first. For this all the available resources should be used such as aerial photos, Google Maps, Google Earth etc.
There are different types of tower for which RF survey need to be done:
• Ground Base Tower(GBT)-Avg. Tower height-30-60 meter
• Roof Top Tower(RTT)-Avg. Tower Height-18-27 meter
• Roof Top Pole(RTP)-Standard Height of Roof Top Pole is 3M, 6M & 9M from ARL (Above Roof Level).
The procedure or steps to perform a RF site survey are as follows:
➤Identify the potential probable RF obstacles using facility diagram.
➤Visually inspect the location to look for any barriers in the path of RF signal propagation. Also identify metallic structures if any.
➤Identify highly congested mobile user areas as well as less congested areas.
➤Determine locations including the power and wired network access at the facility. Also determine cell coverage and overlap maps. Finalize frequency channel for the site as well as mounting structures to be build with proper specifications as per size of the antenna and other equipments(if any) etc.
➤Perform the actual surveying in order to verify and finalize the Base Station/Node-B/eNB/eNodeB location. Make sure to use the same Base Station model for the survey that is used in production for future network roll-outs. While the RF survey is being performed, relocate the Base Stations as needed and re-test to obtain max. signal strength condition.
➤Finalize and document the analysis made during the survey. Record the signal readings along with data rates as well as network logs(if any) at various locations of the facility. Do the same at outer boundary regions.
Types of RF Survey
There are two types of RF Survey as mentioned below:
1. Radio Network Design (RND) survey
2. Transmission Network Design (TND) survey
RND survey is used for deciding the coverage zone of a cell Site & feasibility of cell site, for which we
have to decide the following thing.
• Cell Site Location Point
• Orientation/Azimuth of GSM Antenna
• Height of GSM Antenna
• Tilt of the GSM Antenna
RND surveys are of two types viz. Coverage Site Survey and Capacity Site Survey.
TND Survey is the path study between the new site point to the existing Site Point for deciding the height of microwave antenna that is for fresnel zone clearance.
There are various methods for connecting different cell sites such as microwave link, satellite link using VSAT and optical fiber cable.
Microwave antenna is used to construct radio frequency link with another nearby
cellular site. This RF link is referred as microwave link due to microwave frequency.
There are totally three different microwave link frequencies which are categorized on the basis
of distance between the two cell sites. These are as follows:
• 23 GHz for 0 to 3 Km
• 15 GHz for 0 to 10 Km
• 7 GHz for 10 Km and above
RF Survey Tools for GSM, LTE, CDMA network Installation
Following are the list of RF survey tools used by engineers for RF site survey to
install GSM, CDMA, UMTS, LTE networks across
• GPS: It is a space-based satellite navigation system that provides location and time information. This works irrespective of weather conditions provided there is an un-obstructed LOS with 4 or more GPS satellites placed above the earth. It help us to provide informations such as Lat-Long, Acceleration, Highway Map, Direction and Distance between to Lat-Long etc. There are two types viz. 12 channel GPS and 72 channel GPS.
• Distance Laser Meter: An electronic Tool which measures the distance by using laser beam. It is mainly used to measure the height or dimensions of Building or the site.
• Magnetic compass: It is used for checking antenna direction. It is used for taking 12 pictures each taking after exact 30 degree to complete 360 degree view.
• Binocular with high visual range
• Digital camera: Used to take photographs for various situations as required in the RF survey report. • Take photos of nearest building/buildings which are within 20 meters radius of candidate. • Any building of height G+5 or above within 20meters search ring of candidate, will be considered as Obstruction. • Obstruction photo will be require in the report.
• Ultimeter It is used for measuring AMSL(Above Mean Sea Level) value.
The items are also be essential e.g. measuring tape and Laptop.
Following software tools are also required in addition to the RF survey tools mentioned above.
• MapInfo Professional (Version 6.5,7,8,8.5,9)
• Path Loss (Version 3.0 & 4.0)
• RL Tool (Demo Version)
• Global Mapper (Version 7,8,9 & Now 10)
• Mint Tool (For MapInfo Tools)
• Cell Tool/ Make Sector/Sitesee (For MapInfo Tools)
• Google Earth
• Microsoft Office
GSM radio frequency planning
The tutorial covering GSM radio frequency bands vs ARFCN, channel number, radio frequency planning, frequency re-use to efficiently use GSM RF spectrum and frequency allocation to GSM channels,