NextNav Inc.
11/11/2025 | Press release | Distributed by Public on 11/11/2025 15:33
Setting the Record Straight: The Truth About 5G-Powered 3D PNT, Security Devices, and the Lower 900 MHz Band
Setting the Record Straight: The Truth About 5G-Powered 3D PNT, Security Devices, and the Lower 900 MHz Band
Dr. John Kim
Published Nov 11, 2025
Paper sponsored by Security Industry Association contains deeply flawed assumptions and analyses including claims of interference even when 5G is not transmitting
When it comes to safeguarding our national security and enabling a complement and backup to GPS, the process at the Federal Communications Commission (FCC) must be guided by facts, sound engineering, and rigorous technical analysis.
But a recent Security Industry Association (SIA) sponsored paper produced by Pericle Communications Company lacks rigorous analysis, transparent assumptions and a sound understanding of 5G RF principles. The SIA-sponsored paper makes unrealistic claims of interference that do not hold up under scrutiny. It's important to set the record straight.
Hidden and Unrealistic Assumptions Lead to Deeply Flawed Results
Pericle makes 5G network assumptions that are hidden, cannot be reproduced, and appear to be specifically invented to create the appearance of interference. The paper's purported findings reveal unreasonably high levels of 5G emissions because Pericle assumed the impossible. According to Pericle's notional 5G network analysis, 5G propagation losses will be less than the theoretical minimum of free space path loss (FSPL). NextNav's FSPL analysis shows that Pericle exaggerated the maximum 5G channel power by at least 16 times, leading to unrealistic and greatly exaggerated levels of interference to Part 15 devices. The unrealistic results that follow Pericle's unrealistic assumptions should have prompted Pericle to reexamine its assumptions and implementation, rather than presenting the results as facts.
Pericle also fundamentally misunderstands how 5G Positioning Reference Signals (PRS) function. Engineers have spent years in 3GPP standards bodies developing standards that can use current base station locations for trilateration. Yet, Pericle invented its own notional network design with no technical justification or reasoning.
In reality, the PRS functionality in 5G is very sophisticated and is specifically designed to overcome the shortcomings that Pericle claims exist. The design of PRS in the 3GPP 5G standard ensures that 5G PRS coverage is greater than 5G data coverage, through features including comb patterns and muting, allowing devices to receive PRS from multiple sites even if they can only receive 5G data from one.
NextNav examined the FSPL model, which is the most conservative model for quantifying potential interference, but even that does not produce the maximum 5G signal level reported by Pericle. Accurate 5G RF prediction analysis must consider, among other things, 3-dimensional building data, clutter and clutter height data, vertical diffraction and horizontal guided RF propagation models, outdoor-to-indoor building penetration loss, and indoor-to-indoor propagation considerations, which will realistically further attenuate resulting 5G emissions. Pericle does not appear to have applied any of those in its paper.
Pericle's Monte Carlo Analysis is not Replicable or Reliable
The SIA-sponsored paper relies heavily on a Monte Carlo analysis that is based on numerous incorrect and inconsistent assumptions. NextNav built a simulator using all the inputs and methodologies provided in the Pericle paper and obtained results showing a far lower likelihood of interference. Even making dramatically unrealistic assumptions, such as assuming that all 5G transmitters always had a line-of-sight view to Part 15 receivers, or forcing the Part 15 devices to use only the frequency range of the proposed 5G downlink channel, led to lower interference probabilities than those reported by Pericle. In addition, it appears that Pericle does not apply basic building penetration loss to the 5G transmissions for analysis of Part 15 devices located indoors. As NextNav has previously explained, 20 dB plus 0.5 dB per meter penetration loss into the building is appropriate. Such losses will greatly reduce the likelihood of interference. These are common RF engineering principles used in any credible study or realistic design.
Pericle's Monte Carlo analysis uses incorrect, unrealistic, and inconsistent assumptions. For example, Pericle uses an "envelope" antenna pattern to model 5G base station transmissions, instead of a realistic antenna pattern. An "envelope" pattern is one that real antenna patterns must fit within, so it does not contain any nulls, as all actual patterns do. A more realistic antenna pattern would have shown a much lower probability of interference. Similarly, Pericle assumes that out-of-band emissions will be flat at exactly the regulatory limit across the entire band, which is both physically and practically impossible. Just like ripples caused by a rock dropping in water decrease in size as they get farther from the impact, out-of-band emissions typically decrease as frequency separation increases. However, equally important is the practical aspect that out-of-band emissions are not constant across all manufactured base stations; therefore, manufacturers must build in production tolerances to ensure that regulatory limits are met. This results in base stations meeting the regulatory limit by a sizable margin at the channel edge, with that margin increasing as frequency separation increases.
Pericle's choice of interference thresholds is arbitrary and questionable. For example, for wideband 802.11ah devices, Pericle uses a minimum carrier-to-interferer ratio (C/I) threshold of 18 dB, yet the specifications provided in Appendix A of the paper implies a lower C/I of 13 dB, assuming a conservative receiver noise figure (NF) value of 5 dB. This means that Pericle portrayed 802.11ah Part 15 devices as three times more vulnerable to interference than they are because the interfering power should have been 5 dB greater, or three times stronger, before the threshold is exceeded. Moreover, Pericle does not explain what happens when the threshold is exceeded. Pericle instead calls every exceedance "interference" and implies that every Part 15 device that experiences this condition is rendered unusable. In reality, exceedances are common in unlicensed bands. When a Part 15 device experiences one, it may shift to a more robust modulation and coding scheme with a lower C/I requirement, retransmit, or change channels rather than losing service. In addition, Pericle also assumes Part-15 receiver blocking thresholds such as narrowband devices and 802.11ah devices block and selectivity thresholds of 40 dB at 200 kHz and 12 dB at 2 MHz, respectively, which are low and greatly exacerbate the probability of interference. Specifications governing Z-Wave and 802.11ah call for much more stringent block requirements and typical devices perform far better than the specifications as these are "minimum" requirements. For example, Digi Part-15 modem receiver sensitivity and interference blocking specifications state, "With the MaxStream 9XStream radio modem, an interfering signal 1MHz away from the carrier frequency must be 60 dB stronger than the desired signal to cause the receiver sensitivity to degrade by 3dB1".
Pericle appears to claim that NextNav would interfere with unlicensed systems even when a 5G base station is not transmitting. Pericle states that a 50% loading factor is used for the 5G base station, meaning that the base stations transmit only 50% of the time, but its simulation results show interference occurring more than 50%, which cannot be possible. This fact alone should undermine any other claims of interference by Pericle. Also, the typical 5G base station loading factor is 20%, not 50%, which will further reduce the probability of interference. NTIA has said 20% loading factor should be used for evaluating interference to critical DoW systems2.
Pericle appears to have assumed line-of-sight (LOS) propagation from the 5G base station to the Part 15 device in all cases. In reality, LOS propagation will occur rarely and becomes much less likely as distances increase. The 500 meter 5G site radius that Pericle assumes is also unrealistically low for a 900 MHz 5G network and therefore represents a 5G network that is much denser than required to provide either 5G coverage or PNT. At the very least, Pericle's probabilistic analysis should have taken into account the low probability of the smallest coverage radius of 500 meters. Even if the coverage radius of 500 meters were realistic, any 900 MHz 5G network with a 500 meter coverage radius would reduce power and employ a down-tilt greater than 4 degrees to reduce self-interference. Pericle assumes neither and unrealistically keeps power and down-tilt constant regardless of the coverage radius, which has the effect of greatly exaggerating interference to Part 15 devices for smaller radii. Combined, these factors greatly exaggerate the probability of interference.
Pericle Does Not Analyze Actual Home Security Devices Using the Z-Wave Standard
The Pericle paper does not directly analyze the very devices that the security industry states are predominant in home and business security systems today. For example, it fails to specifically analyze Z-Wave, the technology that, according to the Z-Wave Alliance, is utilized by more than 90% of professionally monitored security systems in North America3. Importantly, Z-Wave operates on frequencies that are primarily outside NextNav's proposed 5G spectrum allocation [see Chart 1].
Pericle's claim that the modeled narrowband transceiver in the study be considered Z-Wave, is not valid since the modeled transceiver is inconsistent with Z-Wave including the number of channels, frequencies and transmit power level. Z-Wave uses fixed channels which do not overlap with NN's proposed 5G band except for one backup channel supported in a much smaller "long range" device base. In fact, Z-Wave has stated that only 100 out of 4500 of its certified devices are long range.4
The Pericle paper further claims that under NextNav's proposal, Part 15 devices will be forced to operate only within an 11 MHz span (907 - 918 MHz). NextNav's multiple technical studies have shown that this is not the case. Yet, even if it were, those frequencies are where the vast majority of Z-Wave already operate today.
Further undermining Pericle's credibility, the paper claims that there are 500 million residential security, alarm, and monitoring devices. However, this claim directly contradicts previous statements by the security industry and greatly inflates the affected device number.
The Alarm Industry Communications Committee (AICC) told the FCC that its members have deployed "tens of millions of wireless sensors, detectors and other devices to equip homes and businesses with fire and other life safety capabilities.5"
The Chamber of Commerce reported to the FCC, "the 900 MHz band is vital for millions of security cameras, including popular models used in homes and small businesses.6"
The AICC reported that the SIA estimated "millions of security cameras, as well as millions of electronic access control (EAC) devices are deployed in the Lower 900 MHz band7."
Pericle Ignores Built-in Device Protections
Pericle's discussion of notional 5G network design focuses only on a scenario in which 5G downlink and Part 15 are operating in the same frequency (i.e. co-channel), claiming that the predicted 5G levels would be devastating to Part 15 devices. That claim is simply not supported by the facts. Modern unlicensed devices - including those used in security systems - already employ coexistence technologies, such as frequency hopping, frequency agility, forward error correction and retransmissions to avoid interference. These features are essential to the operation of Part 15 devices. In fact, the three Part 15 devices Pericle characterized in its paper all support multiple channels and are frequency agile.
Pericle's paper acknowledges the powerful coexistence features in the context of sharing with unlicensed devices in the band. However, Pericle conveniently ignores these critical features that ensure Part 15 devices are robust and resilient to interference when it discusses the effects of 5G transmissions.
In addition, Pericle grossly overstates the power multiplier when it states that a Part 15 device's power, "would need to be a minimum of 538 times greater, and a maximum of 741 million times greater" to overcome the interference from 5G. First, as stated previously, the 5G power values are extremely exaggerated; but more subtly, Pericle bases the multipliers on the Part 15 device's receiver sensitivity (the minimum signal strength at which the Part 15 device can reliably decode a signal), which inherently implies that every Part 15 device is operating at the edge of its coverage. For example, Pericle claims that the lowest predicted 5G power is -77.7 dBm/200 KHz (or -61 dBm/10 MHz) over a ten-square-mile study area. In other words, Pericle is saying that the 5G signal strength will never be lower than -61 dBm at any location within the ten-by-ten-mile study area. This doesn't pass the straight-face test even in the best-case scenario. Next, Pericle assumes that all Part 15 devices always operate at the outermost edge of the Part 15 system's coverage, when in fact the vast majority typically operate well above the outer limits of performance. More realistic assumptions of 5G signal strength and Part 15 operating power will significantly reduce or eliminate the Part 15 power increase required to overcome any interference from 5G. If interference were to occur when the Part 15 device is operating on a channel within the 5G downlink spectrum (918-928 MHz), as explained earlier, the device may shift to a more robust Modulation and Coding Scheme with a lower C/I requirement, retry transmissions, or change channels rather than losing service.
Finally, Pericle's notional 5G design focused on outdoor 5G signal level is inconsistent with the "Notional Home Security Layout" shown in Figure 3 of the report. Their diagram shows most sensors that are typically located indoors, such as smoke detectors, entry sensors, and motion sensors. The key device in any home security system is the hub - the primary aggregate receiver of data from the various sensors. The hub is most at risk from interference but is always located indoors. Pericle's decision to completely ignore building entry penetration losses for the 5G signal leads to further flawed results.
NextNav's Engineering Studies Are Sound
NextNav has submitted two comprehensive technical engineering studies that have already demonstrated that introducing 5G operations will not cause unacceptable interference to unlicensed devices. Those studies specifically examined five different unlicensed technologies, including the Z-Wave technology.
As we have repeatedly stated - we stand by our engineering studies, and the appropriate venue to resolve any remaining technical questions is a NPRM, so that the FCC can optimize the lower 900 MHz band and deliver 5G-based 3D PNT: a win for national security, public safety, and the American economy.
Citations:
1. Receiver sensitivity and interference blocking specifications | Digi International
2. Letter from Charles Cooper, Associate Administrator, Office of Spectrum Management, NTIA, to Ronald T. Repasi, Chief, Office of Engineering and Technology, FCC and Joel Taubenblatt, Chief, Wireless Telecommunications Bureau, FCC, GN Docket Nos. 15-319 & 17-258, at 2-3 (June 11, 2024), https://www.fcc.gov/ecfs/document/1061155768162/1
3. https://www.fcc.gov/ecfs/document/109052635520230/1
4. Z-Wave Continues to Dominate the Residential Smart Home and Security System Market while Z-Wave Long Range Breaks Barriers for Edge-of-Property Applications - Z-Wave Alliance
5. Alarm Industry Communications Committee, FCC Submission ID: 10905147419079 ECFS - Filing Details
6. US Chamber of Commerce, FCC Submission ID: 109051542218002 ECFS - Filing Details
7. Alarm Industry Communications Committee, FCC Submission ID: 1042899975534, ECFS - Filing Details
NextNav Inc. published this content on November 11, 2025, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on November 11, 2025 at 21:33 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]