4 G World, the annual conference and exhibition that returns to McCormick Place in Chicago (October 18-21), claims to be the largest event in the world covering the entire ecosystem of next-generation technologies that enable the mobile Internet revolution, including mobile network infrastructure, advanced devices, applications and content. This year, the event organizers report that more than 8,000 professionals are already registered.

This conference is for all levels of the 4G eco-system to come together, exchange information and learn about the challenges of implementing next generation networks from infrastructure down to mobile devices and all the components in between. This market opportunity is what attracts numerous members of the microwave community, from test & measurement equipment providers to component (cables, RFICs, antennas, etc) manufacturers. Some of the challenges facing the deployment of next generation wireless were discussed in our September cover story on mobile device RF front-ends, namely multi-mode, multi-band support.

With the global mobile market evolving towards 4G, overlaid networks must support an increasing variety of radio technologies and frequency bands. In most markets service providers will evolve their networks to simultaneously support an average of three radio technologies (such as GSM/EDGE, UMTS/HSPA and LTE) and between four and six frequency bands. As this evolution occurs, service providers face a variety of challenges:
1. Minimizing site modification requirements and incremental site costs with network overlays. This is particularly the case in markets that have overly challenging (and often unrealistic) land use regulations for cell site deployments and modifications.
2. Implementing flexible solutions that can be easily and economically upgraded to meet market demands. This encompasses support for new radio technologies and new spectrum bands, as they become available, and advanced techniques such as MIMO for capacity and coverage improvements. In some cases also includes the miniaturization of infrastructure to minimize incremental costs as networks are expanded.
3. Carefully balancing investments in new network and legacy network architectures. For example, implementation of fiber fed remote radio heads benefit from reduced footprint and operational costs for a cell site, but might prove challenging to implement on sites for which traditional coaxial fed architectures are approved, deployed and operational.

Infrastructure vendors like Alcatel-Lucent, Ericsson, Huawei, Nokia Siemens Networks, and ZTE have responded to market demands by enabling software implementations of base band radio technologies on standard platforms (i.e. software defined radio). These same infrastructure vendors and specialist radio technology vendors like Antone, Comba, Commscope, and Powerwave provide multi-band and multi-carrier radio solutions that aim to address the need for multiple spectrum bands to be supported. As these developments come to market, service providers must pay careful attention to ensure that solutions they deploy meet current and future network demands. For example:
- Not all solutions can be implemented without requiring zoning approval and potentially lease amendments. This is particularly the case, when alternative architectures require tower configurations changes. While these solutions might be inevitable, service providers must take care in evaluating their promise.
- Certain spectrum band combinations experience interference problems. For example, intermodulation interference between AWS require state-of-the art filtering and combining technologies to ensure reliable performance. New entrant players like Antone have developed sophisticated solutions to address this challenge.
- Although low cost radio technologies adhere to the requisite standards, performance is sometimes compromised. This can have a significant impact on the overall technical and commercial performance of a mobile network, and often proves difficult to identify.

Technology advancements in SDR, multi-carrier amplifier solutions and state of the art radio techniques will play a critical role in enabling the deployment of multi-mode and multi-band systems. As these solutions take hold, careful attention must be paid to the implications of legacy network configurations, integration requirements, and the impact of discrete innovations on the overall performance of radio networks.

Analysts expect that there will be significant activity throughout 2011 and 2012 in commercializing LTE services. During this time period we anticipate that service providers will face performance and reliability hurdles that are typical on any new technology launch, most notably in optimizing the radio technology, deploying carrier grade Ethernet backhaul, and in integrating services and maintaining feature transparency across the all-IP core which is inherent to LTE.

Microwave backhaul and radio technology are two areas of considerable interest and I will be visiting with companies such as Dragonwave and Exalt, two regular exhibitors at this event. There will also be strong representation from the microwave test & measurement community with Agilent, Aeroflex, Anritsu, Rohde & Schwarz, Berkeley Varitronics Systems and National Instruments all exhibiting. I'll have more on what they had to present at 4G World next week.