LTE “Ready when you are” says RFS
Date: Wed, 04/29/2009 - 17:18
RFS (Radio Frequency Systems), the wireless infrastructure specialist, is ready for the next great switchover in the wireless business - the migration to Long Term Evolution (LTE) technology
"More than any other wireless technology, LTE has the capability to change the face of communications as we know it. That's why our research and development teams have expended considerable effort in the last few years preparing for this point in LTE's development, when the first carriers are preparing for technology trials later this year," said David Kiesling, global product manager for RFS Wireless Infrastructure Solutions.
"The message we are taking to our carrier customers - both old and new - is that we can help them in what is certain to be a revolution at the cell tower top. We can do this because our products offer an evolutionary path that keeps the real-estate changes to an absolute minimum," he added.
According to Kiesling, the key question that carriers are asking leading suppliers like RFS is: `Will the technology that we install at the top of the cell tower today need to be changed in the next 12 to 18 months? And what is the lifespan of the LTE hardware and associated systems?'
And the answer, he says, is that RFS can help reduce the headache that carrier operations and planning managers are certain to face in the next few years as the industry evolves to an LTE ecosystem.
Forwards and backwards compatibility
One of the major issues facing today's carriers says Kiesling, is how to support the introduction of LTE at the cell site with a minimum of extra real estate and yet ensure that support for legacy wireless technologies - as GSM is rapidly becoming - together with 3G services, is constantly available.
"Then, of course, there is the requirement to future-proof the antenna, diplexers and other base station systems, as end-users change the role that LTE technology plays in their lives," he explained.
These changes, says RFS' global product manager, are likely to involve the displacement of fixed-line broadband with mobile broadband, the possibility of home/office LTE-delivered ADSL solutions and - just to make life interesting - the arrival of femtocells into the transmission equation.
The LTE solutions that carriers install today, says Kiesling, must ensure the highest possible forwards and backwards-wireless capabilities, at the optimum cost, and so ensure that carriers are able to secure a reasonable return on their investment in as short a timeframe as possible.
"RFS' LTE technology solutions can achieve all of these requirements, efficiently and cost-effectively," he said.
RFS can help carriers solve technical issues
One of the biggest problems facing carriers as they prepare for trials of LTE technology later this year, or in 2010, will be how to support frequencies at the antenna ranging all the way from 1700 MHz to 2600 MHz.
This is achieved using RFS' groundbreaking broad-band antenna technology by also using, as an example, an RFS LTE diplexer at the bottom supporting GSM 1800 and LTE 2600, with the signals combined onto the feeder and sent up into the broad-band antenna. On the receive side of the technology, the antenna can handle the complete wireless spectrum and then the relevant frequencies can be divided out at the base of the antenna.
From a real-estate perspective, says Kiesling, carriers can have the same antenna form factor and cable runs, but have two services operational. This is, he observes, the best solution from an equipment simplicity perspective.
This multi-band approach, he adds, also works for carriers that need support for quad-band operations at the cell tower.
"Traditionally, this would be achieved using separate antennas under a single radome (cover), however each antenna within the radome would still have its own Tx and Rx feeder connectors - meaning that either individual feeders would still be required or that diplexers and combiners would be needed at the bottom and top of the tower to share feeders.
"To support say 900, 1800, 2100 and now 2600 MHz using multiple arrays would lead to eight RF-connectors at the tower top. No carrier can realistically afford eight feeder cable runs per sector, explained Kiesling nor is there physically room for eight feeders times the number of sectors to run up most towers. "Using RFS multi-band antennas and our diplexer and triplexer technology, carriers can significantly reduce the number of feeders required, "he explained.
He went on to say that RFS is in fact developing a very exciting broadband antenna which covers the complete 1700 to 2600 MHz frequency range. "We are exhibiting a 2100/2600 MHz common connector dual band antenna at our booth at the GSMA event and will be discussing our LTE technology roadmap which includes other multiband antennas supporting LTE 2600 MHz," he added. The roadmap includes a dual band broad-band antenna (824-960 MHz/1710-2700 MHz) with internal diplexers which allows a carrier to compress the eight feeder lines into two - the most efficient use of tower real estate ever.
RFS' discussions with carriers suggest that the biggest technical hurdles to be faced with effective LTE deployments are in metropolitan (city) areas, specifically the interworking with legacy 2G (GSM) and 3G networks.
In the first phase of metropolitan deployment of LTE, Kiesling predicts that cell reselection (handoff) with a legacy 2G network will almost certainly be required, but real-time handover of a VoIP service between an LTE and a 2G network may not be supported or required at this time.
"Interworking with W-CDMA (2100/900MHz) networks, however, is going to be a high priority. This is especially true in situations where the legacy network is providing a high degree of service continuity in a metropolitan environment, or in areas at the edge of coverage," he said.