Carrier wave tuning proof of concept solution to support the roll out of a 4G network for mobile network operator
When Ericsson wanted to develop a new generic cellular model for LTE deployment in the UK, it required expert assistance to consult, build and operate an RF propagation model tuning system, which could be used to test and measure a range of carrier waves. Ericsson turned to Affini, a systems integration and communications specialist with fifteen years of experience in connecting enterprise mobile, data, wireless and radio systems in challenging environments. The assignment was complex – the equipment had to be portable, capable of being assembled on rooftops, or in the field, and used to reliably measure signal strength.
As a provider of mobile and fixed networks, multimedia solutions and telecommunications services, Ericsson is large telecommunication system integrator, supporting more than half the global smartphone traffic on their networks. They have delivered more than 180 RAN and Evolved Packet Core networks worldwide, of which more than 110 have been commercially rolled out to end users.
Ericsson was selected by a joint venture organisation between two of the largest Mobile Network Operators, to manage the operation and maintenance of its UK network.
When mobile network operators are planning their network roll outs and optimising their choice of site location, they call on Ericsson to model the expected coverage which will be available to support voice and data services for end users. While all of the prospective 4G operators have had their licences allocated, many still require the additional model calibration quality data for bands not currently used (800 and 2700MHz), so that a predicted coverage can be accurately established for each category of data service user (voice, low/medium/high data rate).
To address this issue, Ericsson issued an RFP requesting assistance to develop a service test and measurement system which could be used from roof tops, or in the field, for the collection of real data to assist in the planning of a Mobile Network Operator’s 4G network.
Ericsson has worked with a number of application service providers, including Affini, during the roll out of 2G and 3G networks. However, when the RFP was sent out, Affini was the only company that was able to draw on fifteen years of wireless, mobile and communications experience, to challenge and point out potential pitfalls with the implementation of some of the requirements.
Ericsson’s RFP requested proposals for a system that would allow roof-top test equipment to be set up within dense urban conurbations such as Sheffield and Birmingham, transmitting at all UK cellular frequency bands. The system was also required to be portable, self-powered, weather-proof and deployable in rural locations. At the receiver end of the system, the engineers had to be able to drive around the test areas with scanners that could receive the individual test frequencies. The purpose of the measurement system was to collect a large enough set of data that would later be used to predict signal strength, service levels and the optimal distance for the spacing of sites within urban environments. The measurement system was to be deployed in different geographical environments, such as hills and flat terrain, as geographical features would affect the propagation of the signals in different ways. Ericsson’s ultimate aim was to develop a generic model that could be reused and applied across a broad range of cellular frequency bands.
Affini takes a consultative engineering approach to projects:
working with Ericsson to derive the optimal solution. A proof of concept, put together at the start of the project, was intended to initiate an iterative process that would yield innovations in model tuning and data collection for 4G network planning. Input from Ericsson and its joint venture organisation influenced changes to the test system and development of the data collection approach.
Ericsson had provided its ideal requirements within the RFP, of which an achievable dynamic range of 175dB was stated. affini advised that the desired dynamic range was extremely hard to achieve, knowing that this would demand high specification antennae which were not available on the market and that high power transmitters would need to be used. Affini engineers also knew from experience that the system needed to be robust and ruggedized for testing out in the field, because high spec equipment is more vulnerable to the elements.
affini was able to draw on its mobile, wireless and radio experience, including model tuning undertaken for critical communications specialists, such as Airwave, to develop the most successful technical solution to meet this challenge. The solution finally developed for Ericsson provided high dynamic range, by way of sensitive and finely tuned scanning receivers, very high power amplifiers and a custom-made antenna.
Of the range of frequencies specified by Ericsson that could be measured with the system, the one in the 2700 MHz band was the limiting case. As a best of breed integration specialist, Affini used a combination of different manufacturers. equipment to create the ideal solution.
Affini researched the market to find a sensitive enough scanning receiver that could measure sufficiently low signals and used 100 Watt amplifiers per frequency band to generate sufficient power to be enable it to meet the dynamic range requirement at all four bands. The four amplified signal generators fed into a single wideband antenna, which was custom-made by Ericsson, via a quad-band combiner, thus allowing the same drive test footprint to be achieved for all of the frequencies. The system also allowed an economy of scale, as a single drive was sufficient to collect data at all four frequency bands.
As part of the proof of concept, Affini designed a portable rooftop tripod that is able to host a Carrier Wave (CW) signal transmitter, capable of transmitting at four frequencies simultaneously. The test vehicle used to collect the data was equipped with a single wideband antenna mounted on the roof and carried four scanners (one for each of the test frequencies), with a fifth scanner used to measure background interference at the four frequencies: this afforded a very practical solution.
Design and deployment of the proof of concept system took around three months and resulted in an innovative system that can be used for upgrading existing 3G sites as well as testing the suitability of new sites for 4G roll out.
The proof of concept demanded an innovative, iterative and collaborative approach from the Affini and Ericsson teams.
Frequency Bands For Testing:
- 800 MHz
- 1800 MHz
- 2100 MHz
- 2700 MHz
The whole solution was tested for line-of-sight accuracy on the same airfield used by the Top Gear crew, where the surrounding area is flat and free from clutter and trees.