D.1 Starlink: a LEO mega-constellation
Each Starlink Gen2 satellite is ~800 kg with a phased-array antenna covering ~40 spot beams. 540-570 km altitude in inclined shells (53°, 70°, 97° polar). Inter-satellite laser links (100 Gbps) allow traffic to be routed in space. User terminals are flat phased-array dishes ($500), tracking satellites electronically. Throughput: 100-300 Mbps down, 20-50 Mbps up. Latency: 25-40 ms.
Starlink has changed remote-area connectivity globally. In Ukraine, Starlink provided uplink for civilian and military communications when terrestrial was destroyed. In the South Pacific, islands previously served only by GEO (250 ms latency, 100/month broadband.
Hardware-security note. Starlink terminals run general-purpose Linux. The 2022 Black Hat presentation ("Glitched on Earth by Humans") demonstrated firmware extraction via voltage glitching the boot ROM. This is a reminder that consumer satellite gear is just embedded Linux with a special antenna, not magical.
D.2 Smart agriculture: vineyard monitoring
A typical vineyard has 100-500 wireless sensors (soil moisture, leaf wetness, temperature, humidity) feeding data to a LoRaWAN gateway and cloud analytics platform. Decisions: when to irrigate, when to expect frost (and turn on protective fans/heaters), when to spray for fungus. John Deere precision tractors with RTK GPS plant rows within 2.5 cm of the prior year's path, enabling no-till agriculture and herbicide reduction.
D.3 Industrial: oil pipeline monitoring
Pressure, flow, and temperature sensors at intervals along pipelines. Low-power radios (LoRaWAN, NB-IoT, satellite IoT for remote stretches). Detect leaks within seconds of onset, vs. hours for human inspection. Notable deployments: Trans-Alaska, North Sea offshore, Saudi Aramco fields.
D.4 5G in city deployment
Sub-6 GHz macrocells provide coverage. mm-wave small cells provide capacity in dense areas (stadiums, transit hubs). Massive MIMO at base stations exploits spatial multiplexing. Network slicing carves out QoS classes for different verticals (autonomous vehicles, public safety, IoT). Korea, China, and US have led 5G deployment; expected to reach 6 billion subscribers by 2027.
D.5 GPS dependence
GPS underpins:
- Cell-tower timing synchronization (every cell needs sub-microsecond time for OFDMA frame alignment).
- Financial trading: timestamp accuracy is regulated; firms colocate GPS-disciplined oscillators in datacenters.
- Power grid: PMU (phasor measurement unit) phase angles measured against GPS time.
- Aviation, maritime, rail.
Loss of GPS for even an hour would be a serious crisis. The US, EU, and Russia are studying terrestrial backups (eLoran). The vulnerability is well-known and intentional defense is patchy.