Ongoing NTIA Spectrum Efficiency Efforts

Article Index

First up, in the US the 5G Landscape is unfolding rapidly, though more than a few companies have been caught on the hop over ZTE and the seven year, on-off, component hiatus. They shall quickly get over it and find new markets elsewhere if the worst comes to the worst. Alas is a Huawei component still to unfold, caveat emptor?

Two recent Spectrum Sharing publications from the NTIA are relevant to this 5G landscape.

First, the NTIA Report 18-530 A 53-Year History of Spectrum Efficiency Studies and Recommended Future Directions by Frank H. Sanders Kristen E. Davis Keith D. Gremban.

This report critiques the history of the NTIA involvement in Spectrum Efficiency from 1964, when the general form of the FFT appeared. Clearly the NTIA have at their fingertips the institutional memory to detail this important milestone document. Also very clearly the NTIA is positioning itself even further to play a global role in the Spectrum Sharing Era.

In this report the authors state:

“We recommend that future spectrum efficiency (SE) studies, including those in which SE metrics will be developed, should be informed by the results of this detailed literature review. Chief among our recommendations are:

1) Only similar systems delivering like service to users should be compared to each other for SE metrical purposes.

2) SE metrics and comparisons should be relative, not absolute.

3) Band-dependent SE should compare similar radio systems operating in those bands.

4) Recent technical innovations should be significantly included in future SE studies and metrical development. These include software defined control (SDC) of transmitters and receivers that can take advantage of intelligence about local environments; smart or intelligent antenna designs including electronic beam steering and gain control; and dynamically controlled frequency agility. Such technical features have barely been considered in many past studies, because they have only recently become widely available.

5) Receiver selectivity characteristics are just as important for spectrum blocking as transmitter out of band (OoB) and spurious characteristics. Future SE studies and SE metrical development need to focus equally receivers and transmitters. Recent technological developments make possible widespread implementation of smart transmitters and receivers. This will produce more opportunities for spectrum sharing than ever before. Spectrum sharing can be based on dynamically controlled systems that respond to their local environments. Spectrum sharing is barely addressed in many earlier SE studies because of technology limitations, but can now be implemented in field-deployed radio systems. The time is right to re-consider SE of many systems and to carefully examine new SE software tools and metrics that can take advantage of new technologies."

Readers will understand that, whereas I completely see the logic behind recommendations 1 and 2, I nevertheless would advocate a more ambitious approach based on the insights gleaned from all the studies cited and a more fuller appreciation of the limitations of the FFT. Otherwise, how are we to overcome diverse system interference issues which arise with both legacy systems and new radio technologies? Thus we still are at the foothills in this landscape.

One key review they bring to our attention is from a very well-known US independent consultancy:

“In 2014, an independent researcher, Rysavy, published his own analysis of recent CSMAC, FCC, and ITU-R documents. Rysavy provides a broad survey of the current state-of-the-art in SE metrics calculations and assessments for various types of radio systems. The concept of peak versus average SE is discussed. Spectrum sharing is addressed in the context of SE studies: “Once disparate systems share the same spectrum, calculating the resulting efficiency will likely require a combination of the types of metrics discussed above, or new sharing metrics not yet defined.” This discussion of spectrum sharing as it relates to SE is novel, and may lay the groundwork for substantial work yet to be performed at the nexus of radio system sharing and earlier SE metric development.”