Radio for next generation cellular puts strain on equipment makers
The move to high speed cellular systems, all IP networks and the next generation architectures is putting strain on the equipment developers, especially for the radio stages of the network.
3G technologies of High Speed Data Packet Access (HSDPA) and HSPA technologies are rolling out today and potentially bringing broadband data rates of 14.4Mbit/s to mobile phones, requiring more capacity linking the radio and basestations into the network.
This is accentuated by planning for the move to Long Term Evolution (LTE) networks for the next generation of systems will see that increase to possibly 100Mbit/s, (Fig.1) and needs new antenna technologies such as Multiple In, Multiple Out (MIMO).
The move to high data rates is moving into the pico and femto cells that are being developed as mini-basestations in the home.
Andrew in the US has introduced high-speed packet access (HSPA) capabilities to its OneBase Micro Node B and Pico Node B products for wireless network coverage and capacity enhancement, enabling a more than 20-fold increase in data transfer rates.
“The expansion of the mobile workforce, as well as new interactive services and mobile video applications, threaten to strain wireless networks worldwide,” said Mickey Miller, group president of Wireless Network Solutions Segment at Andrew. “These enhanced 3G capabilities to our products helps our customers better manage this rising tide of traffic, while enabling network service levels to improve.”
“As deployments supporting HSDPA and HSUPA take hold, we expect continued growth in use of our Pico Node and Micro Node products to support data hotspots where more and more bandwidth is required,” said Miller. “These enhancements will help our customers avoid capacity issues on the macro network, while addressing the ever-increasing requirements for wireless services that support content-rich applications.”
The radio stage is a key issue for these femtocells, as interference issues threaten to slow down the roll out.
“Femtocells are still under standardisation and this looks at the effects of interference and that’s a non-understood issue,” said Alan Gatherer, CTO of TI’s communications infrastructure and voice division. “The field trials will throw a lot of light on this and there’s a lot of work that still has to be done and it would be a mistake to put a lot of effort into coming up with a solution,” he said. “This is not the time to be claiming victory.”
“Interference was a big worry a year ago but a lot of people have been working very hard on this,” said Rupert Baines, vice president of marketing at PicoChip, which supplies many of the femtocell designs, including UK companies IPaccess and Ubiquisys. “Yes, there are things that we need field trials for, to find and fix and optimise and there’s always things you learn but you have got to have 80 to 90percent confidence that you know what the issues are and how to address them. For interference, it’s higher than that.”
US startup Radioframe has developed its own chips for its femtocells, designed by Faraday Technology in Taiwan, which will ship later this year. “We are working on this (interference) with carriers,” said Matthieu Tallegas, Senior Director of product marketing. “We have to listen to the environment and then take the appropriate action on power control.”
The need for MIMO in next generation basestations is a potential problem where existing cell sites have to be upgraded, as there is often not the space available, says Alan Gatherer, chief technology officer of the cellular broadband division at Texas Instruments. “It’s the cost of the antennas that limits the use of MIMO,” he said. “If you become too dependent on MIMO just to get your functionality you are dead in the water – you can’t just keep adding antennas as each one comes with the power amplifier.”
Despite that, TI is working with ArrayComm’s smart antenna technology (Fig. 1) for wireless infrastructure applications in WiMAX and WCDMA/HSDPA networks. The combination of ArrayComm’s Network MIMO smart antenna software and TI’s digital signal processors (Fig.2) on a WiMax reference design provides base station equipment manufacturers with critical differentiation.
“Coupling TI’s DSP (Fig.3) with our smart antenna software will yield substantial improvements in the service providers’ network implementations for both 3G and WiMAX,” said Steve Sifferman, executive vice president of operations with ArrayComm.
The reference design supports a MIMO adaptive antenna system (AAS) and ArrayComm’s Network MIMO software implements all the antenna processing.
There are alternative technologies, such as the Bi-Sector Array (Fig.4) developed by US startup TenXc Wireless. This has been used in the US at different frequencies but the company is now coming to Europe with a design for 1800MHz systems. It provides additional service capacity using existing cell site infrastructure at a fraction of the cost and time required to install additional sites or source new spectrum.
It does it with a highly optimised, asymmetric antenna design with just two sectors that provides significantly more coverage. This can replace existing antenna systems in ‘hot spots’ and overlay 3G networks using the existing 2G sites, both of which are difficult to do with MIMO.
“Operators all around the world are faced with an increasing challenge providing a reliable network to meet the exploding growth in user services they are experiencing today,” said Joe Hickey, President and CEO of TenXc Wireless. “In many markets, spectrum remains both a scarce and expensive resource. To profitably support growth and enable the transition to 3GSM services, operators are seeking new solutions which optimise their existing network investments. Our expanding Bi-Sector Array portfolio provides service providers a highly cost effective way to increase network capacity to support service growth and the rollout of new data rich mobile services.”
Powerwave Technologies Inc (NASDAQ:PWAV), a global source for end-to-end wireless infrastructure solutions, today expanded its growing line-up of tower mounted amplifiers (TMAs) with the introduction of a 1900MHz TMA at CTIA Wireless 2007, the world’s largest event for the wireless industry.
The 1900MHz TMA is designed to enhance coverage and improve up-link signal quality for Remote Electrical Tilt (RET) antennas used in Universal Mobile Telecommunication System (UMTS) and Advanced Wireless Services (AWS) cellular networks.
The product is compliant with Antenna Interface Standards Group (AISG) specifications designed to control antenna products with digital remote control and monitoring facilities, including RET functionality. Powerwave’s 1900MHz TMA offers exceptional performance and power handling, low noise figure, low insertion loss and high reliability.
“Powerwave has deployed more than 1.3million tower mounted amplifiers for hundreds of cellular, PCS, GSM and 3G networks around the globe,” said Ronald J. Buschur, President and Chief Executive Office, Powerwave Technologies. “Our TMAs offer state-of-the-art functionality, a compact design and the power to optimise the coverage and capacity of today’s next-generation networks that benefits both network operator and subscriber.”
Powerwave’s 1900MHz TMA leverages active components integrated within the filter body, providing an extremely reliable, compact, lightweight and cost-effective solution. Easy to install, the 1900MHz TMA simplifies network logistics, particularly when the frequency bands are scattered, and is comprised of high-Q band-pass filters and balanced low-noise amplifiers with circuits for active bias, supervision, alarms and lightning protection. A vented enclosure design prevents condensation, ensuring long, reliable, maintenance-free service in all environments.