The move to bolster LTE services has seen wireless carriers spend billions of dollars on new spectrum assets in support of ballooning consumer demand, resources that are rapidly being put into place. Most carriers entered the LTE market with a single band of spectrum, similar to past “generational” deployments, with carriers now beginning to look at adding more spectrum bands to the efforts.
Verizon Wireless is expected to lead the move, as the carrier is actively rolling out 1.7/2.1 GHz spectrum support for its current LTE network that is running across 700 MHz spectrum. The move is a template for a number of carriers that are looking to supplant their initial LTE deployments typically running on lower spectrum bands with capacity enhancements from spectrum running in higher bands.
AT&T Mobility is following a similar path to Verizon Wireless, with its initial LTE deployment relying on 700 MHz, with plans to begin adding upper frequency support. Sprint, for its part, is working from a different angle with its initial LTE rollout relying on 1.9 GHZ spectrum, with plans to add support from its 800 MHz spectrum being freed up from the turn down of its iDEN network as well as 2.5 GHz spectrum from its recent full acquisition of Clearwire.
T-Mobile US is currently relying exclusively on its 1.7/2.1 GHz spectrum holdings for its LTE deployment, but with its recent acquisition of MetroPCS has said it will be able to throw a full 40 megahertz of spectrum in that band at its LTE efforts.
Looking at the carrier’s plans, Mike Haberman, VP of network support at Verizon Wireless, noted that integrating the new spectrum band into its LTE network is a move to keep ahead of consumer demand for mobile broadband services.
“We are adding AWS just to stay ahead of expected consumer demand,” Haberman explained. “Our 700 MHz capacity is still able to handle current demand, so we just want to make sure that as usage continues to ramp up that consumers continue to have a great experience.”
At the ground level, Haberman said that integrating the AWS spectrum into the fold is typically handled on a case-by-case basis depending on what is already in place at the cell site.
“From a physical standpoint, there is obviously going to be more gear needed a the tower, or pole or on the building, but the equipment we already have in place is for the most part able to support the new spectrum with just some new motherboards and amplifiers geared toward the AWS spectrum,” Haberman explained.
There are some needed upgrades to antennas, with the carrier in many cases looking to combine support for the 700 MHz and 1.7/2.1 GHz band into the same antenna when possible. This becomes more important at sites where space constraints make it difficult to put in multiple antennas.
“There are various antenna products out there and we have a number of different configurations, so to say that there is one configuration would be wrong,” Haberman said. “We tailor our deployments to the location. There are some trade-offs in that we are looking at the customer; we are looking at where we are trying to improve coverage; and we are looking at the use case situation and making those engineering trade-offs.”
The carrier is also in some cases looking at enhancing backhaul at sites where it expects usage will continue to grow. Haberman said the carrier relies nearly exclusively on Ethernet solutions for its backhaul needs, with fiber as the main component of that support.
Like a number of operators, Verizon Wireless also uses remote radio heads at sites that have the room for such deployments or that might see a needed efficiency benefit from such deployments.
“We go with remote radio heads on a case-by-case basis,” Haberman said. “It depends on whether it will benefit you are not. There are trade-offs in that if you go with remote radio heads you put the radio at the top of the tower, which makes it tougher to get to if there is an issues The implementation dictates a lot of the choices. You also have to make sure you take in account performance because there are some advantages to having it up there.”
Earlier this year, Sprint SVP of networks Bob Azzi, noted that the carrier’s use of remote radio heads as part of its Network Vision program was returning far better than expected coverage results, with little downside. He did admit that there might be a higher case of failure for the radio equipment being now outside on top of the antenna instead of being tucked away in an enclosure at the bottom of the site, but that the efficiencies gained from the new location made the investment worthwhile.
“It’s too early to tell the exact sort of failures we may see, but we have seen a few,” Azzi said. “But, it has been worth it considering the performance we are seeing.”
Another challenge Verizon Wireless said it’s tackling is the ability to hand off LTE sessions between the 700 MHz and 1.7/2.1 GHz band. These sort of hand offs have in the past required a data session be re-established on the new spectrum, something that is not acceptable as carriers looking to deploy voice over LTE services, which Verizon Wireless has said it plans to do beginning next year.
“We don’t anticipate any issues with that,” Haberman noted. “We have done a lot of testing.”
Overall, Haberman said Verizon Wireless would continue to rely on its traditional macro cell network to support a majority of its LTE services and that it was not expecting to add new sites as part of its 1.7/2.1 GHz spectrum enhancement as it already has sites supporting its various spectrum bands in enough places to ensure coverage and capacity improvements.
For more insight into the topic of advanced technologies being deployed at the cell site, check out our latest feature report: Extending intelligence to the tower as well as our hosted webinar on the topic.
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