A Q&A with CommScope on network densification for the transition from LTE to 5G

As U.S operators light up 5G services in select markets this year, small cell is a key element of the network densification needed to provide high-throughput services using millimeter wave frequencies, particularly the 28 GHz and 39 GHz bands. But small cell-based network densification is inherently difficult to scale given the site acquisition, power and backhaul needs. Here we discuss relevant issues with CommScope Vice President of Site Solutions and Services Mike Fabbri.

Q: CommScope has regularly discussed the challenges associated with small cell deployment, particularly power, backhaul and site acquisition. Given the scope of these challenges relative to LTE, how do you see the problem compounding as operators scale out 5G using millimeter wave frequencies?

A: We are already being asked to incorporate 5G into our outdoor small cell (ie. Metro Cell) designs. Although driven primarily by tactical 4G densification deployments today, our MNO customers are looking to future-proof these sites with the ability to add 5G mmWave technology in the future. Given the RF propagation characteristics of mmWave, it is likely that additional ‘5G-only’ sites will be required to provide the level of coverage and capacity, which will pose the same deployment challenges on a much larger number of sites. Consistency in design and aesthetics is a key driver to municipality and zoning approvals.

Q: As operators deploy using a combination of owned and leased fiber, how can they leverage technologies like DWDM to make the most out of the fiber that’s available?

A: Passive WDM modules increase bandwidth on existing fiber for better utilization—an immediate, easy and inexpensive alternative to deploying new fiber to increase network capacity. WDM combines and separates multiple wavelengths of light into and out of a single strand of fiber to create separate, independent data pathways that increase the data-carrying capacity of the fiber cable. The same WDM components can also be used to separate the wavelengths (de-multiplexing) at the remote location. CWDM can be utilized initially with the ability to seamlessly upgrade to DWDM as needs grow.

Passive WDM has the advantage of requiring no power to operate and these devices can be simply integrated into existing telecom equipment in both the central office and at the remote end.

Q: C-RAN offers a lot of benefits around lowering equipment and real estate costs, and also enabling centralized coordination of radio sites. What’s your perspective on how C-RAN is being used in the U.S. compared to other major markets, particularly APAC?

A: C-RAN is the architecture of choice for the vast majority of 4G/LTE Advanced small cells that are being deployed in the U.S. Small cell radios being used by U.S. MNOs generally do not include the baseband functions; thus the need to centralize the baseband at a “hub” location. BBUs are being centralized in adjacent macro sites or in central offices.

5G has a different architecture than 4G, with the BBU functions being split between a centralized unit (CU) and a distributed unit (DU). But we expect C-RAN will continue to play a significant role in 5G. Both the CU and DU functions could be centralized.

In APAC, many MNOs are also deploying C-RAN–especially in Japan, South Korea and Australia. Like in the U.S., they are deploying centralized RAN, where the BBU is based on proprietary hardware of the OEM. The main driver for C-RAN in these markets is the availability of good quality fiber for fronthaul/backhaul and the improvements in quality/performance when managing a heterogeneous network. Most C-RAN deployments start in commercial business districts where the macro cells and small cells are densely located. This enables high efficiencies in RF performance and also the optimum utilization of the fiber network.

Q: The FCC recently passed an order removing local-level regulations to small cell deployment by limiting review fees and establishing a shot clock. This will make things easier but, when it comes to working with municipal leaders and residents, how can concealment solutions help?

A: The FCC continues [to]push to simplify small cell deployment, either by limiting fees, establishing shot clocks, etc..  These efforts do help at the local level, but there is still a fair amount of autonomy at the municipality around zoning and approvals. Aesthetics play a key role in the approval process, and we have seen instances where, when we work collaboratively with our customers and the municipalities themselves on specific designs, the approval process can be significantly streamlined.


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