The Urgency and Importance of National Z-Axis Testing

In order to improve 911 caller accuracy in 2019, the Federal Communications Commission (FCC) established a Z-axis vertical location requirement to be plus or minus three meters from a handset for 80% of all indoor wireless E911 calls. This Z-axis vertical location was in addition to the horizontal (X and Y axes) coordinates already required. In June 2020, the FCC issued their Sixth Report and Order (R&O) which established deadlines for carrier compliance to improve Z-axis location accuracy for all wireless 911 calls. Non-compliance would result in substantial financial penalties.

The implementation process has already begun. In a phased approach, major wireless providers worked to meet the first deadline which required compliance in the top 25 cellular market areas (CMAs) in the U.S by April 2021. The major carriers complied, including AT&T, T-Mobile, and Verizon, providing vendor-neutral testing data to validate that their Z-axis solutions were delivering as planned and met regulatory requirements.

The next FCC deadline targets the top 50 CMAs in the U.S, where the nationwide carriers must comply by April 3, 2023. But now, it’s not just the top wireless service providers that must comply. A host of Tier 2 providers and hyperscalers are part of this group. Some are more prepared than others to certify their compliance while the deadline is fast approaching. The carriers engaged in the first phase of FCC compliance are well prepared for the next deadline. Others will need to implement their Z-axis validation strategy in the very near future.

The carriers engaged in the first phase of FCC compliance are well prepared for the next deadline. Others will need to implement their Z-axis validation strategy in the very near future.

How do carriers validate FCC compliance with qualified authority?

To start with, all carriers need to be ready to answer these essential questions:

• Does my Z-axis technology deliver accuracy within regulatory guidelines?

• Which Z-axis technology should I use?

• Does my network comply with regulatory guidelines in all markets/cities required?

• Which devices do not deliver acceptable accuracy and yield?

Challenges for carriers include:

• Device compliance

• Sensor performance

• Cost of solution

• Uptime / Reliability

• Security

• Lab-to-Live inconsistencies

• Handset and backend platform interaction

These are no small challenges, and some carriers don’t have the expert specialists in-house to answer all these questions with satisfactory results. In essence, carriers need multiple elements of a testing capability that will address a number of logistical issues. They include:

• Multi-market, multi-building, multi-morphology Z-axis test bed

  • Mix of morphologies (Dense Urban, Urban, Suburban, Rural)

  • Diversity of floors

• Managed test bed management including site selection/management, surveys, access

• Field engineering, project management, quality control, analysis, and reporting

Z-Axis Testing Methodology

The path to successful FCC compliance involves four components of testing methodology:

• Building selection

• Calibration

• Measurement

• Analysis and Reporting

Recognizing when a test partner is needed for comprehensive Z-Axis testing

The range of requirements for testing Z-axis comprehensively is significant and necessitates an independent partner with industry-recognized experience and expertise. These requirements include an established track record of driving industry testing standards and methodologies that draw from crowd sourcing techniques, and account for hybrid methods of location determination. Areas of established industry expertise for a test partner should include the capabilities of location solutions and services for GNSS, Sensor, LTE/5G network emulation, and Wi-Fi, with decades of facilitating nationwide FCC compliance and Tier 1 partnerships.

The certification of hundreds of devices should also be a part of the proven delivery experience. These are all areas where Spirent has established industry leadership in solution delivery. With all these exacting testing requirements accounted for, a carrier can be confident their Z-axis testing strategy is in a good state.

To learn more, download our solution brief and visit our 5G Network Benchmarking page.