The increasing adoption of Long Term Evolution (LTE) and small cells is driving a fundamental shift in how mobile network operators (MNOs) approach mobile backhaul. To successfully prepare for this change, MNOs must focus on a strategy of building simple, scalable, and flexible mobile backhaul networks.
The quest for capacity, coverage and QoS
Revenue from mobile services is expected to reach $1.3 trillion (in constant U.S. dollars) by 2016. For MNOs, the key to capturing this revenue growth is to deliver an outstanding customer experience at the right price. Doing so requires delivering superior capacity, coverage and quality of service (QoS) at the lowest possible cost. Increasingly, MNOs are addressing these needs by evolving to LTE and introducing small cells.
Each MNO chooses a different path to improved mobile services (Figure 1). Each step places new challenges on the mobile backhaul network.
The key for MNOs is to ensure that any renovations undertaken on the backhaul network are done with an eye to possible future evolution. After the backhaul network is prepared for small cells and the transition to LTE, additional capacity and coverage can be added more quickly and at a lower cost to meet future customer demand.
How LTE and small cells affect the backhaul
The shift to LTE has a major impact on mobile backhaul. To support LTE, MNOs will undertake a transition from traditional time division multiplexing (TDM)-based networking to IP over packet-based networking backhaul. New models for how cell sites interact with each other and with their controller sites will drive an evolution in backhaul network topologies. Increasing bandwidth demand will drive a need for more network capacity.
The introduction of small cells adds additional backhaul challenges. In embracing small cells as part of a heterogeneous mobile network of small cells and macro cells, MNOs have to manage three key changes in the way they design, build and operate the backhaul network:
- More cell sites: In high-density urban areas where small cells will be used to complement and offload traffic from macro cells, it is anticipated that anywhere from 3 to 10 or even more small cells could be deployed for every macro cell. This large increase in the number of cell sites to deploy, operate and manage will have a significant impact. The network must now be designed to support many more end nodes, and network operations must now be able to scale to manage and support more sites. Both have to be accomplished without scaling costs.
- More diverse locations: Macro cells are traditionally deployed on towers. Small cells will be deployed wherever there is a “hotspot” or a “not spot” in mobile coverage. This means they will be deployed in a much more diverse range of locations including inside stadiums, on the sides of buildings, on utility poles, and even on street furniture such as lampposts. This diversity in location will bring new challenges to connecting these sites into the backhaul network.
- More ways to connect: New cell sites located in a diversity of areas means multiple access technologies will be leveraged. MNOs need the flexibility to provide connections over fiber, copper, and a variety of microwave technologies — whichever technology is accessible, can meet the service requirements of the site, and deliver the lowest TCO.
In looking more closely at the small cell site itself, there are some additional considerations to be taken into account. Which mobile services will be supported: 3G, LTE, Wi-Fi®, or a combination? Is the cell site located indoors or outdoors? How will it be powered? What are the timing and synchronization requirements? Is there a requirement for a demarcation function? How will backhaul service to the site be monitored? The addition of small cells is a complex task from a deployment and operations perspective, especially in conjunction with the network considerations of volume, location diversity and more ways to connect. The path to managing this complexity is through simplification.
The road to simplification
MNOs require mobile backhaul that can smooth the transition to LTE and streamline the deployment of small cell sites. Mobile backhaul must provide the scalability, speed and capacity to not become a bottleneck. Ultimately, they need backhaul that can deliver operational simplicity. MNOs can take steps toward simplicity by addressing three key backhaul requirements:
- Reduce the complexity of scale and diversity: Be ready with a heterogeneous network (HetNet) backhaul architecture that can efficiently handle an increase in scale in the number of cell sites to connect and manage, as well as be able to address the requirements of both small cells and macro cells.
- Mitigate small cell site customization: Have the flexibility to accommodate the diverse needs of different small cell locations with optimized platforms that integrate the key functions required at the cell site and adapt to support any mobile service, over any media access technology, leveraging any network topology.
- Take a strategic approach to backhaul: Ensure that the backhaul network is ready to accommodate small cells, LTE and capacity expansion.
By building operational simplicity into the mobile backhaul, MNOs can transform backhaul into an enabler of modern HetNets that deliver optimized mobile service capacity and coverage in the most efficient manner possible.
End-to-end is essential
Mobile backhaul can be defined as connecting the cell site to its controller site. Providing this connection for HetNets will involve a mix of access technologies, as well as an aggregation and transport network. As the network scales and evolves to address LTE and small cells, it becomes increasingly challenging to keep track of the mobile service as it traverses multiple networks that may be built by different vendors, or that may have parts leased from a backhaul transport provider.
This limited view makes it tougher to add capacity, troubleshoot, resolve issues, and guarantee service across the backhaul network. It also makes it difficult to introduce new services quickly and deliver the seamless experience customers expect.
An IP/MPLS service layer in the backhaul network can be leveraged to provide end-to-end connectivity, visibility, and control from cell site to controller site regardless of the underlying network infrastructure. This is key to streamlining ongoing backhaul network management, maintenance and operations processes.
A look ahead
Over time, many mobile networks will evolve to support a combination of LTE and small cells. As part of this transition, the backhaul network must also evolve to support the delivery of high-value mobile experiences like video, streaming and live event coverage. These experiences are essential for capturing customer loyalty and driving market share gains.
The key is to approach mobile backhaul strategically. The backhaul needs to have the flexibility, scalability and simplicity to accelerate the delivery of mobile network capacity and coverage to deliver the highest possible mobile subscriber quality of experience (QoE) at the lowest possible TCO.
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-  Mobile Services, Worldwide, 2008-2016, 3Q12 Update, September 2012, Gartner Inc. ↩