Heterogeneous Network, or HetNet, technology is rapidly ascending to the top of 2012’s mobile hype mountain. Grandiose claim after claim has the industry in a tizzy over the potential of having a radio network made up of varying base station sizes, cloud-based processing, and advanced relays and antenna systems all working together like a colony of ants marching home with the spoils of unprecedented mobile capacity, coverage and performance.

Pardon me if I come off a bit contrite, for it is not my aim to belittle this technology. In fact, I desperately want to save HetNets from the infamous hype cycle. Too many technologies have been crushed under the weight of unreachable expectations and without HetNet technology, mobile networks will struggle to keep up with consumer demand.

I need you to join me in preaching pragmatism and openly discussing what can be delivered today and what challenges our industry needs to tackle so that we can lay out a roadmap for deploying cost-effective, manageable and coordinated HetNets.

There are three primary HetNet components available to operators including single-mode small cells, cloud-based base stations and security infrastructure.

Single-mode small cells are being deployed for both coverage and capacity reasons. These devices range from residential to metro, as well as a revitalization of picocells to deliver campus-type solutions. Small cells include support for key aspects of Self-Organizing Networks (SON) such as self-establishment and configuration, as well as interference mitigation. They are being used to fill in gaps in operator coverage or alleviate areas of particular capacity strain. However, it is still early for small cells; they remain predominantly single-mode and apply a distributed approach to SON focused on limiting operational costs and mitigating interference. Altogether, small cells are far from the vision of optimized meshing across radio access technologies to deliver coverage where it is not and increased capacity and performance to operators’ entire customer base.

The industry is also adopting the cloud principal and taking the remote radio head to new levels. By leveraging fiber connectivity and intelligent radio systems, cloud radio access network (RAN) platforms can consolidate modem processing into a single service shared across geographically-dispersed radio heads. This approach allows for the delivery of coverage where it is needed and the dynamic balancing of capacity, which provides macro-grade quality of service in the most difficult areas to reach (i.e., no dropped calls as you race through San Francisco). The biggest economic challenge for the cloud approach remains the reliance on high-speed and densely-deployed fiber connectivity. In an industry already strapped by backhaul limitations and costs, cloud RAN requires the most reliable and expensive variant. Additionally, the ability to deploy a multi-vendor cloud solution is very far away (leading to the age-old concerns of vendor lock in) and combining small cells with cloud RAN so that they work together seamlessly can be challenging.

The last piece of the HetNet puzzle is security. HetNets require advanced, adaptive and high-capacity security gateways to be successfully deployed. Securing the link between distributed base station technology and the core is complicated because the type of backhaul, and the provider, is drastically different than with traditional radio access networks. The number of links to be secured also increases as one deploys more nodes into the network. The good news is that the security gateway industry is well established; there are a multitude of existing solutions on the market today and many of these products have been fashioned recently to support femtocell deployments so they have high capacity and meet the demands of uncontrolled backhaul. However, there is still a need for constantly evolving security approaches as HetNets develop and grow.

As outlined here, the technology we are deploying today includes solid, innovative and useful systems, but clearly we have not reached HetNet utopia yet. The next task, if you choose to join the army of HetNet hype diffusion, is to focus on what needs to be done to shepherd HetNets forward. There are three critical challenges that must be addressed.

The first is wireless backhaul technology development. We have a number of early solutions for reliable, cost-effective wireless backhaul, but we need a fully-proven and mature market of products. The cost of backhaul—whether it be from small cell to the core or from radio head to cloud—is prohibitive to the mass deployment of HetNets and the solution is certainly not to bury more wires.

The second is continued silicon innovation. One of the single largest challenges to multi-mode small cells remains cost-effective system-on-a-chip (SoC) platforms that deliver the foundation for these devices. Additionally, the SoC market not only provides the modem, but must also support advanced radio sniffing capabilities that feed the data necessary for improved SON algorithms and performance. To this end, we do have a strong existing ecosystem of innovative semiconductor vendors working tirelessly to meet these demands and the industry stands to benefit from their efforts.

Lastly, the HetNet vision requires the evolution of SON approaches, from OPEX savings and “good-neighbor” solutions to techniques that deliver optimized, multi-standard and multi-vendor systems. There is a growing opinion that the need for SON is equivalent to vendor lock-in which sinks the business case for HetNets. The key to multi-vendor SON is a hybrid approach that blends centralized SON coordination, possibly through operations and maintenance systems, with today’s highly decentralized techniques to allow both for vendor differentiation and interoperability.

Despite the aforementioned challenges, the conceptual benefits of HetNets are difficulty to deny. HetNets allow an operator to get maximal benefit from its spectrum and existing radio network assets, while delivering a better overall customer experience. The ability to deliver service where it’s needed through a laser-shot approach is appealing, and therefore significant investment is going into solving these HetNet challenges. Like any useful technology, it takes time to reach its potential, even more so in the case of licensed spectrum-based systems. So, I plead with you, join me in the effort to save HetNets from the hype and help deliver them into reality.

Todd Mersch is director of Product Line Management, Software and Solutions, at Radisys.