Implementing TVWS networks: suggested approaches

Implementing TVWS networks: suggested approaches

Planning a TVWS network? Here are suggestions to help save time and improve installation quality, based on findings from UNH BCoE’s Phase 1 implementation of a TVWS network in Durham, N.H. in late 2013, early 2014:

  • Bench testing: Verify the electronics on the bench before you begin the installation – that’s especially important considering radios may be mounted on a tower.
  • Antenna configuration: Omnidirectional antennas seem best suited for general-purpose access with minimal line-of-site obstructions and lightly populated client locations within 1-3 miles of the base station. Sectorization using directional antennas can improve RF access to more difficult-to-reach areas (because of topology, vegetation or distance), but also will reduce the coverage scope and may require additional base stations to achieve required coverage.
  • Theoretical analysis: Perform a line-of-sight analysis between the base and client because obstructions such as hills and rock outcroppings do impact the performance of a system. For example, the UNH BCoE installation was unable to produce sufficient upstream signal performance over one of its links because of a line-of-sight obstacle that turned out to be a steep hill. On the other hand, the effect of trees within the line of sight does not seem to pose a significant concern: The UNH BCoE team was able to provide high-quality broadband connectivity to a client site through a thick tree canopy eight miles from the base station. It’s also important to engineer the deployment before beginning field installation, paying attention to factors including line-of-site; field propagation; antenna selection (type, gain, directionality); base station orientation and location versus desired client location; and traffic analysis and segmentation.
  • Installation expertise: The technology used by BCoE in the Phase 1 trial was not quite ready for commercial-scale, plug-and-play deployment by installers with average skill levels, requiring a fairly high level of expertise in the area of antenna technology and wireless deployment.
  • Diagnostics: Have ready analysis tools to aid in installation of client devices that help optimize connectivity and diagnose absent or poor signal conditions. Tools can be a combination of those integrated into the client radios (preferable) as well as external test equipment such as spectrum analyzers.
  • Future advancements: Recognize that longer-term open access over large geographic areas will require standardized coexistence methodologies to be built into all equipment using the shared TVWS spectrum. In contrast, Wi-Fi works well because of limited range and easier to control environment.

UNH BCoE’s early conclusion was that TVWS could be best-suited for providing broadband connectivity in rural areas where broadband is currently unavailable. However the equipment available during our Phase 1 trial would be unlikely to support carrier class broadband connectivity over an extended area or as an overlay technology.  As the technology evolves and improves this perception could change.

For more information about TVWS findings and to initiate a dialogue, contact UNH BCoE using this webform.