The wireless industry
is currently in the middle of the 4G technology cycle. The major LTE coverage builds in first-mover markets are largely done, and we are now in the phase of adding capacity to those networks. The industry is also in the midst of the evolving to the next generation of virtualized wireless networks. The 5G vision is blurry, but there are three primary trends
for the evolution of the outdoor radio access network (RAN): densification
A recent report[i] predicts that total monthly mobile data traffic will increase at a compounded annual growth rate of 45 percent from 2015-2021. The ever-pressing need for wireless operators to add capacity to their networks to meet this demand will continue over this span. Small cell deployments were expected to be the leading network densification tool. However, operators continue to face some serious challenges when deploying small cells outdoors, namely site acquisition, power and backhaul. Getting access and permits to tenable sites, and delivering power and backhaul to them, can be roadblocks. And the cost factors can be prohibitive depending on these variables and the number of users that can be served by them.
Some operators have devised creative solutions, such as Vodafone when it collaborated with advertising giant JCDecaux to put small cells in bus shelters in Amsterdam[ii]. But I expect more macro network solutions to be deployed in 2016 than small cells. A leading way to add capacity in the macro network is via sector splitting. Taking a three sector site and turning it into six sectors basically doubles the capacity. Sector splitting tends to be more cost-effective and I expect to see more focus on such macro network solutions this year.
The long-term goal of many network operators is to evolve to Cloud RAN architecture. Cloud RAN moves the baseband processor into the core network from the cell site. A network that is completely run in the cloud would have equipment placed centrally in a big data center with digital to RF converters located at the edge. To accomplish this, you need dedicated fiber links with very low latency and very high capacity from every cell site to the central core.
Cloud RAN architecture will improve network performance with capacity that can be optimized dynamically. We are already seeing the benefits of this model in-building where centralized capacity can be adjusted dynamically to meet actual usage. For example, when all employees gather in a large auditorium in a large office building, Cloud RAN architecture enable capacity to be re-allocated automatically to these areas.
The next phase of Cloud RAN will be outdoors. This evolution will not be completed in 2016, but some operators are making significant progress. I expect to see more cell sites with baseband processing moved into centralized locations. Of course, the challenges of site acquisition, power and backhaul apply to these centralized sites, as well.
In the midst of this Cloud RAN evolution, one rule still applies. Network operators need to squeeze every bit of capacity out of their existing networks as possible. Optimization is like what you might do to make your car more energy efficient. You take the excess weight out of the trunk, use better gasoline, drive on good tires and other measures. When it comes to optimizing the RAN, it’s largely about having the best signal to noise ratio. Simplistically, you want the desired signals to be really loud and everything else to be really quiet.
In LTE networks, the most significant source of interference is passive intermodulation (PIM). PIM can result in significantly degraded voice quality, dropped calls and reduced data throughput. The effects of PIM can be drastic – just a one decibel drop in uplink sensitivity due to PIM can shrink the wireless coverage area by more than 10 percent. Network operators continue to address PIM in all phases of network deployment. They are even raising their key performance indicators to further decrease its impact on their networks.
The next year will be an interesting one for the wireless industry. On the one hand, we are in a lull between the major roll-outs of LTE and future deployment of 5G. But the seedlings of what will ultimately make 5G are appearing now. More sites, with more virtualization and a continued emphasis on optimization, will undergird the wireless networks of tomorrow. A denser, more nimble and more efficient network is the goal. 2016 will be an important significant milestone on that journey.