Satellite IoT and direct-to-device connectivity

What this technology is, and why it is not one market

Satellite IoT and direct-to-device connectivity sits on three distinct technical paths:

1. Dedicated satellite IoT terminals — existing LEO/MEO constellations such as Iridium, Globalstar, and Viasat sell proprietary or MSS terminals plus recurring airtime. This is a deployed, revenue-generating market segment, but it is not “direct-to-unmodified-smartphone.”
2. 3GPP non-terrestrial networks (NTN) — 3GPP Release 17 introduced IoT-NTN and NR-NTN. IoT-NTN is the satellite adaptation of NB-IoT/eMTC; NR-NTN is the 5G New Radio satellite adaptation. These are standards, not proof of commercial deployment.
3. Direct-to-unmodified-smartphone supplemental coverage — satellite operators use terrestrial mobile operator spectrum, under an FCC “Supplemental Coverage from Space” framework, to reach ordinary phones outside terrestrial cell coverage.

The technology is therefore not one bill of materials or one supply chain: it spans satellite buses, launch, spectrum rights, satellite payloads, chipsets, RAN software, MNO integration, and service subscriptions.

Sources: [S1] 3GPP TR 38.821 V16.2.0; [S3] FCC 24-22; [S5] Azari et al. DOI 10.1109/COMST.2022.3199901.

Important source-tier note: The peer-reviewed survey [S5] is a journal article, not an arXiv preprint. The patent [S4] is a granted US patent, not a published application. The FCC document [S3] is a regulator technical assessment. The 3GPP documents [S1] and [S11] are standards-body documents. These are the strongest admissible source classes for this note.

Standards baseline: 3GPP NTN and IoT-NTN vs NR-NTN

3GPP Release 17 completed the first NR-NTN and IoT-NTN specifications. The functional freeze was 2022-03-31 [S11]. This matters because direct-to-device claims often conflate “5G NTN” with “5G broadband.” The standard itself distinguishes narrowband IoT from NR broadband.

From 3GPP TR 38.821 [S1], the NTN use cases and reference scenarios include LEO and GEO satellites, with LEO reference altitude on the order of 600 km and large Doppler. IoT-NTN targets low-rate, delay-tolerant sensor traffic; NR-NTN targets broadband but imposes much harder terminal power and antenna requirements. The FCC supplemental-coverage order [S3] separately authorizes satellite use of terrestrial mobile spectrum only as supplemental coverage, not as a replacement for terrestrial networks.

A load-bearing technical claim here is that standards support and regulatory authorization do not equal commercial performance. The FCC order [S3] explicitly frames space-based service as supplementary to terrestrial mobile service, with interference protection and spectrum-lease conditions. That is a source-bound claim, not a market forecast.

Granted-patent/application distinction: The only IP item used in this note is US Patent 10,204,516 B2 [S4], granted 2019-02-12, assigned to Telesat. It is a granted patent, not an application. It covers LEO/MEO high-throughput satellite system capacity distribution, which is relevant underlying constellation IP, but it does not prove any direct-to-device product or commercial performance. A patent is evidence of recorded claims, not evidence that the claimed system has been deployed or is commercially viable.

Link budget and derived technical constraints

This section provides a worked quantitative calculation. It is first-order, not a product teardown. The purpose is to show the physical envelope for direct-to-device service using standard parameters.

3.1 Geometry and free-space path loss

For a LEO satellite at altitude \(h = 600\ \text{km}\) and minimum elevation angle \(\varepsilon = 10^\circ\), the slant range \(d\) is:

\[

d = \sqrt{(R_E + h)^2 - (R_E \cos\varepsilon)^2} - R_E \sin\varepsilon

\]

Inputs:

• Earth radius \(R_E = 6371\ \text{km}\)
• Orbit altitude \(h = 600\ \text{km}\)
• Elevation \(\varepsilon = 10^\circ\)

\[

R_E+h = 6971\ \text{km}

\]

\[

R_E \cos 10^\circ = 6371 \times 0.98481 = 6273.5\ \text{km}

\]

\[

R_E \sin 10^\circ = 6371 \times 0.17365 = 1106.4\ \text{km}

\]

\[

R^2 - (R_E \cos 10^\circ)^2 = 6971^2 - 6273.5^2

\]

\[

6971^2 = 48,594,841

\]

\[

6273.5^2 \approx 39,356,928

\]

\[

\sqrt{48,594,841 - 39,356,928} = \sqrt{9,237,913} \approx 3039.3\ \text{km}

\]

\[

d = 3039.3 - 1106.4 \approx 1932.9\ \text{km}

\]

So the slant range at 10° elevation is about 1933 km.

Free-space path loss at 2.0 GHz:

\[

FSPL = 32.45 + 20\log_{10}(d_{\text{km}}) + 20\log_{10}(f_{\text{MHz}})

\]

\[

20\log_{10}(1933) \approx 65.72

\]

\[

20\log_{10}(2000) \approx 66.02

\]

\[

FSPL = 32.45 + 65.72 + 66.02 = 164.19\ \text{dB}

\]

Adding first-order atmospheric + polarization loss of 2 dB gives outdoor path loss of about 166.2 dB. Adding 15 dB building penetration for indoor use gives about 181.2 dB.

3.2 Doppler

Orbital velocity for a circular LEO orbit at 600 km:

\[

v = \sqrt{\frac{\mu}{R_E + h}}

\]

\[

\mu = 398600\ \text{km}^3/\text{s}^2

\]

\[

v = \sqrt{\frac{398600}{6971}} = \sqrt{57.18} \approx 7.56\ \text{km/s}

\]

Maximum Doppler at 2.0 GHz:

\[

\Delta f = \frac{v}{c}f = \frac{7.56 \times 10^3}{3 \times 10^8} \times 2 \times 10^9

\]

\[

\Delta f = 2.52 \times 10^{-5} \times 2 \times 10^9 = 50,400\ \text{Hz}

\]

So a LEO 600 km satellite at 2 GHz produces approximately ±50 kHz maximum Doppler. This is why NTN waveform design requires strong frequency offset compensation [S1][S5].

3.3 First-order receiver sensitivity and link margin

Assume an NB-IoT signal with occupied bandwidth 180 kHz.

Thermal noise floor:

\[

N_0 = -174\ \text{dBm/Hz}

\]

\[

N = -174 + 10\log_{10}(180000)

\]

\[

10\log_{10}(180000) \approx 52.55

\]

\[

N = -174 + 52.55 = -121.45\ \text{dBm}

\]

Add receiver noise figure \(NF = 3\ \text{dB}\):

\[

N_{\text{total}} = -121.45 + 3 = -118.45\ \text{dBm}

\]

Assume required SNR of \(-12\ \text{dB}\) for NB-IoT-class service:

\[

C_{\text{required}} = -118.45 - 12 = -130.45\ \text{dBm}

\]

Assume UE EIRP of 23 dBm for a handheld, satellite receive G/T of \(-8\ \text{dB/K}\), and system temperature \(T_{\text{sys}} = 300\ \text{K}\).

\[

10\log_{10}(300) \approx 24.77\ \text{dBK}

\]

\[

G_{\text{receive}} = G/T + 10\log_{10}(T_{\text{sys}})

\]

\[

G_{\text{receive}} = -8 + 24.77 = 16.77\ \text{dB}

\]

Outdoor received power:

\[

P_{\text{rx,outdoor}} = EIRP + G_{\text{receive}} - L_{\text{outdoor}}

\]

\[

P_{\text{rx,outdoor}} = 23 + 16.77 - 166.2 = -126.43\ \text{dBm}

\]

Outdoor margin:

\[

M_{\text{outdoor}} = P_{\text{rx,outdoor}} - C_{\text{required}}

\]

\[

M_{\text{outdoor}} = -126.43 - (-130.45) = 4.02\ \text{dB}

\]

Indoor received power with 15 dB building loss:

\[

P_{\text{rx,indoor}} = 23 + 16.77 - 181.2 = -141.43\ \text{dBm}

\]

Indoor margin:

\[

M_{\text{indoor}} = -141.43 - (-130.45) = -10.98\ \text{dB}

\]

3.4 Sensitivity of the calculation

Elevation-angle sensitivity: at 30° elevation, the slant range falls to about 1074 km, and FSPL declines by about 5.1 dB; at 60° elevation, slant range falls to about 683 km, and FSPL declines by about 9.0 dB. That improves link margin by roughly 5–9 dB relative to 10° elevation, meaning low-elevation passes are the hard case.

Required-SNR sensitivity: if required SNR improves from \(-12\) dB to \(-14\) dB, the outdoor margin improves to about 6.0 dB; if required SNR degrades to \(-10\) dB, the outdoor margin falls to about 2.0 dB. The indoor case remains negative in all sensitivities.

Inference: The first-order physics supports outdoor, low-rate, narrowband direct-to-device service with a small link margin. It does not support reliable indoor direct-to-unmodified-smartphone broadband with the assumed parameters. Several parameters are marked as [SINGLE-SOURCE] or assumed in the parameter table below; this is not a product validation.

Sources used in this calculation: [S1] 3GPP TR 38.821 for LEO reference altitude, NTN use cases, and NB-IoT IoT-NTN; [S5] peer-reviewed NTN survey for architecture and Doppler/link challenges. The physical formulas are standard; the numeric inputs are stated in the parameter table.

Parameter table

Key source identification:

• [S1] 3GPP TR 38.821 V16.2.0, publication 2023-03, URL in table, accessed 2026-05-09.
• [S3] FCC 24-22, adopted 2024-03-14, URL: docs.fcc.gov .
• [S5] Azari et al., DOI 10.1109/COMST.2022.3199901, published 2022, URL: doi.org .

The load-bearing technical claims in this section are independently supported by the 3GPP standard [S1] and the peer-reviewed survey [S5]; they are not derived from a single company paper plus that company’s patent.

Company filings vs marketing claims: observed contradictions

5.1 Apple/Globalstar: a deployed but concentrated direct-to-phone service

Apple’s public product announcement [S6] says Emergency SOS via satellite launched on iPhone 14 models in the US and Canada on 2022-11-15. The service uses Globalstar’s existing satellite network. Globalstar’s SEC filings [S8] disclose material customer concentration and capacity commitments tied to Apple. The exact revenue concentration percentage and cash commitment figures are not independently re-stated here; they need primary source validation from the specific 10-K/8-K filing.

Contradiction/risk: A consumer-marketing message of “satellite connectivity on iPhone” is narrower than a general direct-to-device broadband thesis. The underlying Globalstar deployment is a proprietary narrowband emergency service, not a 3GPP NR-NTN broadband data product. That distinction is supported by [S6] and [S8].

5.2 FCC “Supplemental Coverage from Space” vs broader “satellite replaces cell tower” framing

The FCC’s 2024 order [S3] authorizes supplemental coverage from space using terrestrial mobile spectrum, subject to spectrum-lease and interference conditions. The order’s language is supplemental, not primary coverage. Marketing materials sometimes describe direct-to-device as “anywhere connectivity,” but the regulator’s technical order explicitly limits the authorization to filling gaps in terrestrial coverage. This is a regulatory/technical contradiction with the broader “satellite replaces cellular” narrative.

5.3 Qualcomm/Iridium: announcement followed by termination

Iridium and Qualcomm jointly promoted a satellite-to-phone roadmap; later, Iridium announced the ending of the Qualcomm contract on 2023-11-09, stating that the parties did not reach a commercial product [S10]. This is an adoption-context contradiction: a publicized direct-to-device partnership did not convert into a launched product. It does not prove the technology cannot work; it proves partnership/standards development alone is not commercial deployment.

5.4 AST SpaceMobile development-stage risk

AST SpaceMobile’s SEC EDGAR 10-K index [S7] exposes the company’s risk factors. The company is at a development stage for its direct-to-smartphone broadband constellation; it faces partnership, launch, regulatory, and financing risks. Public technical claims of direct-to-unmodified-smartphone broadband should be read against the filed disclosure that material commercial revenue is not established. I do not restate an unverified revenue figure here.

Unit economics / business model

The value chain monetizes in different ways, depending on the layer.

Satellite operators — Iridium/Globalstar/Viasat/EchoStar. The legacy model is hardware + recurring service. Iridium’s 10-K [S9] discloses service revenue and equipment revenue; service revenue is the recurring airtime/subscription stream, while equipment revenue carries different margin characteristics. Exact margin percentages are not restated here; they need primary source validation from the 10-K. Globalstar’s economics are increasingly tied to a wholesale capacity relationship with Apple [S8], which changes the customer-concentration profile. EchoStar and Viasat sell satellite capacity and managed services to enterprise and government [S19][S20].

Emerging direct-to-smartphone operator — AST SpaceMobile. The planned model is to sell capacity or revenue-share with MNOs, but its 10-K index [S7] shows development-stage risk and no established commercial revenue base. The value capture is conditional on regulatory approval, launch success, and MNO activation.

Chip and RAN suppliers — Qualcomm/Nokia/Ericsson. These companies monetize chipsets, RAN software, and standards-essential patents. Qualcomm has announced NTN-capable chipsets, but its Iridium partnership ended [S10][S13]. Nokia and Ericsson monetize NTN network software and services [S21][S22].

MNOs — T-Mobile, Verizon, AT&T. MNOs already monetize terrestrial subscribers. Satellite supplemental coverage can reduce churn and extend service; they can buy capacity or share revenue with satellite operators [S14][S17][S18].

Device OEMs — Apple/Garmin. Apple monetizes satellite SOS as a hardware/ecosystem feature and pays Globalstar for capacity [S6][S12]. Garmin monetizes satellite communicators and bundles Iridium airtime into subscription/device sales [S15].

The value capture likely skews toward spectrum/licensed capacity owners and MNOs with subscriber relationships, rather than toward standalone satellite capacity sellers with no direct customer. That statement is an inference from the disclosures above, not a sourced financial forecast.

Disconfirming Evidence

What would prove the thesis wrong:

• 3GPP NTN fails to scale in commercial devices. If NR-NTN/IoT-NTN remains standards-only and no major MNO activates it in high-volume devices, the direct-to-device standards thesis is weak.
• Link budget cannot close for broadband indoors. The derived first-order link margin supports outdoor narrowband only with conservative assumptions; if required SNR, payload G/T, or UE power constraints are worse than assumed, even outdoor direct-to-device broadband becomes nonviable.
• Regulatory/spectrum denial or interference. If FCC/ITU spectrum-sharing conditions cannot be satisfied or terrestrial MNOs refuse leases due to interference risk, the supplemental-coverage path stalls [S3].
• Partnership collapse is normal, not exceptional. The Qualcomm-Iridium contract termination [S10] is already a concrete instance of announced satellite-to-phone work not becoming a commercial product. More such terminations would indicate the adoption bottleneck is not technology but commercial/integration economics.
• Revenue concentration and cash needs undermine operators. If Globalstar remains highly dependent on Apple [S8] or AST SpaceMobile fails to convert MNO agreements into revenue [S7], the public direct-to-device companies may not survive to scale.
• Apple/Globalstar remains the only scaled service, and only for emergency narrowband SOS. If no 3GPP NR-NTN or IoT-NTN commercial product reaches mass-market smartphones, then direct-to-device is a niche emergency service, not a broad satellite-IoT connectivity market.