Millimeter Wave Bugs Can be Features

Oddly enough, some might argue, there are times when a “bug becomes a feature.” Some argue millimeter wave signal propagation is a “bug” that actually provides a valuable feature.

Millimeter waves (3 GHz to 300 GHz radio waves) have propagation issues that limit the distance such signals can travel, for example. That is why, in the analog era, before low-cost signal processing, such frequencies were not so extensively used to support communications networks, and when used, were restricted to point-to-point backhaul applications, where high-cost equipment could support trunking functions (per-instance, per-user, per-customer or per-passing economics always are much better wherever such functions are shared in the network).

But Siklu argues that propagation limitations actually are a feature, not a bug. Such propagation limits also mean that millimeter wave signals are less prone to interference than signals that propagate much farther.

Less interference means base stations and radios can be deployed close together, according to Yigal Leiba, Siklu CTO.

In terms of implications for bandwidth, huge new amounts of millimeter wave spectrum are expected, as part of the 5G evolution. The U.S. Federal Communications Commission, for example, has decided to release about 11 GHz for flexible, mobile and fixed use wireless broadband, including 3.85 GHz of licensed spectrum and 7 GHz of unlicensed spectrum.

The rules create a new Upper Microwave Flexible Use service in the 28 GHz (27.5-28.35 GHz), 37 GHz (37-38.6 GHz), and 39 GHz (38.6-40 GHz) bands, and a new unlicensed band at 64- 71 GHz.

The U.S. Federal Communications Commission, for example, already is on a path to open up 14 GHz of additional spectrum (an order of magnitude more access spectrum than currently is available for all mobile and Wi-Fi use.

The Commission also adopted a Further Notice of Proposed Rulemaking to apply the flexible use service and technical rules to another 18 GHz of spectrum encompassing eight additional high-frequency bands.

Just in the range from 57 GHz to 71 GHz, that millimeter spectrum represents 100 times more spectrum than typically is available to support mobile access networks, says Leiba.

That new spectrum, with other shared and unlicensed new spectrum, will allow internet access providers to provide the 1000-fold increase in internet access capacity envisioned for 5G. Small cells, better radios and modulation methods also will help.