What Your DAS Needs for LTE

Luigi Tarlazzi-high-res-8-31-16--thumb Luigi Tarlazzi June 17, 2015

DAS-chapter-compressedAn LTE network has three key requirements that must be accounted for in network design and equipment selection, including for distributed antenna systems (DAS).

  • The network needs to be high capacity, supporting a large number of frequency bands to support the devices and mobile apps that subscribers use.
  • An LTE network must have a high signal quality to deliver high speeds and throughput.
  • And for the operators, rapid deployment and cost-efficiency are critical to meeting business objectives.

LTE has been specified to operate on as many as 44 bands including FDD and TDD modes. LTE-Advanced also supports aggregation of different portions of spectrum, even largely separated ones, by introducing Carrier Aggregation.

In the U.S. a number of new spectrum initiatives have been or may be undertaken such as the AWS-3, 600 MHz and 3.5 GHz small-cell band auctions. The result is that wireless solutions including DAS have to support a variety of frequency bands using a single infrastructure. Today even a single operator DAS deployment with five bands looks more like what was a neutral host scenario with multiple operators a few years ago.

LTE is all about high data speed. To achieve that, the Signal to Interference plus Noise Ratio (SINR), a key performance indicator, must be high. Many factors can degrade SINR levels throughout the network, however. Interference due to excessive footprint overlap between sectors, poor coverage levels due to bad power calibration and inherent interference in the transmitted signal all can contribute.

Most notably, passive intermodulation (PIM) can have a detrimental effect, especially when a large number of bands are combined on the same infrastructure. Poor quality of passive components and bad installation practices play a crucial role in increasing PIM in a DAS. All of these interference sources can substantially limit the performance of an LTE DAS network in terms of download/upload data speed.

Like all businesses, wireless operators want to get their return on investment as soon as possible. For that reason a fast time-to-market is crucial. Ideally in their network deployments, operators would like to go from months, to days, to minutes if possible. Ease of deployment, operation, optimization, maintenance and a seamless upgrade path are important factors here. The entire life cycle of a DAS needs to be considered—including the initial equipment costs and operating expenditures in a total cost of ownership calculation.

CommScope addresses these three LTE requirements in our latest generation DAS, and I write about them in the new LTE Best Practices ebook. See the chapter about DAS implementation for real-world advice about equipment selection, environmental practices and network installation. The LTE Best Practices ebook is free of charge after a brief registration and can be downloaded as an app on tablets and smartphones.

Any questions? Leave me a comment, and I’ll reply.

About the Author

Luigi Tarlazzi-high-res-8-31-16--thumb

Luigi Tarlazzi

Luigi Tarlazzi is director of product line management, Small Cells, for the Distributed Coverage and Capacity Solutions (DCCS) group of CommScope. In this role, Luigi manages the ONECELL product line, especially in regards to integration with CommScope’s distributed antenna system (DAS) solutions.

Prior to this role, Luigi served as product line manager, ION-U DAS, Americas, and 4G networks engineer in the DCCS R&D department, where he oversaw all scientific aspects of next generation mobile communication networks. He previously worked on the DCCS Future Technologies team, providing LTE technical training to business operations teams globally, designing MIMO-based LTE DAS and supervising LTE MIMO DAS trials across the world.

Prior to CommScope, Luigi worked for Siemens COM S.p.A. in Milan, Italy as a UTRAN entity integration testing engineer. He received a master of science degree in telecommunications engineering from the University of Bologna.