LTE Network and Backhaul Trends

Phil Marshall is the chief research officer of Tolaga, where he leads software architecture and development, and directs Tolaga's thought leadership for the mobile industry. Before founding Tolaga, Dr. Marshall was an executive at Yankee Group for nine years, and most recently led its service provider technology research globally, spanning wireless, wireline, and broadband technologies and telecommunication regulation. He serves on the advisory boards of several startup companies and was a non-executive board member of Antone Wireless, which was acquired by Westell in 2012.

Marshall has 20 years of experience in the wireless communications industry. He spent many years working in various engineering operations, software design, research and strategic planning roles in New Zealand, Mexico, Indonesia and Thailand for Verizon International (previously Bell Atlantic International Wireless) and Telecom New Zealand. In addition, Marshall was an electrical engineer at BHP New Zealand Steel before he attended graduate school. He has a PhD degree in Electrical and Electronic Engineering and is a senior member of the IEEE.

This is a speech by Dr. Phil Marshall, chief research officer, Tolaga Research, at the 2014 LTE & Backhaul Forum at MWC 2014.

I want to talk to you today about what’s needed within LTE networks and the way in which networks are evolving to support services beyond just being broadband access. I want to talk about embracing certain architectures as well as concepts of the way in which services can be distributed.

If we look at the global deployment of LTE, the rate at which networks have been deployed is staggering. We’re heading to about 300 LTE networks, and this trend is going to continue into the future. Even though many networks are deployed, we haven’t yet really leveraged them to the full extent in terms of subscriber adoption. So certainly that needs to happen, and indeed I’d say that the major activity with LTE network subscriber growth has been in North America and Asia Pacific. So we’re certainly anticipating these other markets to grow.

LTE Implementation Phases

If we look at the phases of evolution, you can really tell where service provider is at in terms of their mobile service ecosystem, how they are positioning their LTE deployments, and the extent to which they’re embracing the digital services like those presented earlier in this session by China Mobile and certainly talked about by other operators. We see in the first phase an emphasis on being very network centric, and then an evolution towards how to use LTE for service enhancement. When that occurs, you start to see a lot more devices advertised on the websites of service providers as well as packages that talk about much more than the speeds and feeds associated with LTE. LTE is starting to enable true service evolution when we start to look at what companies like NTT DOCOMO are doing with their data offerings, what Telefonica is talking about with its digital service strategies, and other companies like Telstra who are leveraging some of the advanced features, such as eMBMS broadcast, in LTE as well. These companies are really trying to push the envelope in terms of the service experience that you’re trying to create for subscribers and what the next generation of services looks like. Certainly that’s an important evolution the industry needs to go through. The real challenge today is the operational inertia of traditional business and the challenges of being able to evolve operational environments in order to take advantage of these new capabilities. 

Case Study: Verizon Wireless Traffic Simulation

At Tolaga Research, we do a lot of network simulation work. We simulate several hundred service providers looking at different traffic profiles and the impact of implementing different types of technologies in their networks. What I want to do is just a very basic analysis of Verizon Wireless in the US, just to demonstrate the importance of a service provider implementing advanced technologies. This particular scenario shows dramatic growth in LTE traffic. This really comes about as Verizon migrates its device base across to LTE and starts to launch more data services. As this occurs, we notice that the macro network essentially requires twice as many cell sites, and this is in conjunction with a small-cell overlay. Obviously, this isn’t really an achievable practice when you think of site acquisition issues and so forth. So it’s a complicated challenge that the service providers face in the sense that they can’t really do this within their network. They need the innovations that were presented earlier today in terms of squeezing more capacity out of the existing sites. They need more radio spectrum etc. to achieve that.   

In the same simulation, you can see what we’ve considered from a small-cell standpoint. There’s actually a lag in this particular simulation because we assume there are some operational challenges, particularly around site acquisitions and so forth, to bringing small cells to the market at a meaningful scale. This demonstrates that you’re getting to about 120,000 small cells; bearing in mind that you’ve got about 80,000 macro cells to support that traffic profile, which is quite plausible within the simulation that we are considering. So a lot more is needed than just building more cell sites to support this traffic.

So there’s no doubt that mobile operators are going to end up with networks with massive scale. The question is how they’re configured and what kinds of innovations do you use to achieve this scale. Small cells will become a reality and when that occurs, the mobile network will start to look more like a broadband network than a traditional macro cell network that we’re accustomed to. The backhaul considerations are immense, and what we see already is a variety of innovative alternatives to the conventional point-to-point architectures, such as millimeter wave and point-to-multipoint architectures. Certainly, operational automation is crucial. There’s a lot of talk around implementing SON. When we evaluate the business case for mobile broadband, the way in which network operations are automated is crucial. This will drive in a few key areas; particularly with small-cell deployments and to address other challenges that service providers find as the network becomes more complicated to manage.

Once we’ve done that, traffic optimization and management solutions are also needed. So you can’t underestimate interference management, the role of schedulers and so forth as these networks evolve and the fact that these will change between different types of cell sites that are implemented. We also must consider the way in which traffic is prioritized, considering different traffic flows that are associated with different services, and the way which these services utilize network resources. In terms of media-management technologies, we’ve already seen some efforts around CDN and pushing content closer to the edge of the network. Particularly when we start to look at network function virtualization, the device itself must become part of the network and part of the virtualized architecture. This is obvious when we start to look at the price memory and the amount of capacity and memory that you can put in mobile devices. We see the media going all the way down to the device, and service discovery functions and content distribution networks extend that far down as well.        

LTE Backhaul Strategies

When we look specifically into backhaul, certainly the fixed network is becoming increasingly important as a part of a mobile architecture, and obviously we’ve seen an aggressive migration towards Ethernet and further innovations in all types of backhaul. Dark fiber is seeing a significant resurgence since many service providers have provisioned inadequate capacity with their existing infrastructure. We also see very high capacity microwave as well as the mainstreaming of some more exotic technologies, like millimeter wave and FSO. So you’re starting to see these technologies come to the fore, and indeed there’s a lot of interest in them just because of the bandwidth capabilities they can achieve, particularly for small-cell environments and particularly because they can be architected in a way that enables you to manage them effectively. Even with satellite, with HTS satellite capabilities and MEO/LEO solutions for remote rural areas, you start to see business cases where higher bandwidth WiFi and LTE makes sense in rural and remote areas.  

When we look at the economics of backhaul solutions specific to small cells, firstly I think with small cells we have to reduce planning and implementation costs. The rule of thumb is to try to get this down to 5000 dollars for an all-in implementation. That is very challenging, and certainly from a backhaul standpoint, it requires a lot of innovation. Beyond the point-to-point, point-to-multipoint, and the types of radio and fiber technology that are implemented, I think you actually start to see SON and automated optimization techniques emerge as well. In other words, you essentially have your backhaul as part of the hierarchy of an access network. We’re already starting to see solutions in the backhaul arena and I think is particularly important.  

LTE Continues to Fuel Market Change

There’s a lot of uncertainty in this market, so I thought I’d trying to put some stakes in the ground in terms of things I think are more likely to happen and what won’t. This is almost an arbitrary list, but I just want to illustrate there are some things we  can be certain about in this industry, and we should focus on these and build strategies around them while dealing with some things that are a little bit less certain. Policy-based approaches to service delivery make a lot more sense than billing caps. We can start to see changes in the way in which service providers implement their services, recognizing that the bill is actually quite an important component of the overall purchase decision and should not be hindered by usage cap constraints.

Other trends will be the use of TDD spectrum, and certainly listening to China Mobile on that, as well as wider-spread usage of TDD and recognizing ZTE’s role in the TDD arena. If you actually look at TDD spectrum in terms of megahertz-POPs, about 30% of the available MHz POPs for mainstream mobile technologies are the TDD band. So there’s plenty of spectrum there.

The number of LTE networks continues to expand, and there we expect the challenges will remain within the backhaul arena.

It’s unlikely that mobile traffic growth will bankrupt the industry. The industry has to transition, and I think we are starting to see these changes occur.