All-Indoor
Understanding All-Indoor Microwave Systems
If a cell phone company builds a massive 300-foot tower in the freezing mountains of Alaska, they cannot put fragile computer chips at the top of the tower. The -40°C wind and ice would destroy the electronics instantly. Instead, they use an All-Indoor architecture, hiding the entire multi-million dollar radio system safely inside a heated bunker at the bottom of the tower.
The Architecture of Safety
In an All-Indoor system, the tower itself is completely 'dumb'.
- The massive, high-power radio amplifier, the digital modem, and all the fragile power supplies are bolted into a massive server rack inside a secure, air-conditioned concrete building.
- A massive, thick copper pipe (an Elliptical Waveguide) runs out of the building and all the way up the 300-foot tower.
- The radio wave is generated inside the building and physically pumped up the massive pipe to the empty dish antenna at the top.
The Heavy Cost of Maintenance
This architecture is incredibly expensive because copper waveguide pipe is massively expensive and causes severe signal loss. However, it is entirely worth the cost for mission-critical networks (like 911 dispatch radios). If the radio amplifier suddenly blows up during a massive blizzard at 3 AM, an engineer can simply walk into the warm, heated building, pull the broken radio out of the rack, and plug a new one in. If the radio was at the top of the tower, the entire city's 911 network would be offline for days until the blizzard stopped and a human climber could safely scale the ice-covered steel.
Key Equations
An All-Indoor microwave radio architecture is a legacy, high-capacity telecommunications deployment model where 100% of the active electronic components—both the baseband modem and the RF...
Key specifications:
100 % | -40 °C | 3 A | 32.44 dB | 60 km | 99.999 %
Path loss: FSPL = 20log(d)+20log(f)+32.44
Comparison
| Aspect | All-Indoor Spec | Typical Range | Impact | Design Note |
|---|---|---|---|---|
| Primary function | The only component located outside on th... | Application-dep. | Critical | Verify in sim |
| Operating range | This architecture requires a massive, co... | Application-dep. | Critical | Verify in sim |
| Performance | Understanding All-Indoor Microwave Syste... | Application-dep. | Critical | Verify in sim |
| Integration | The -40°C wind and ice would destroy the... | Application-dep. | Critical | Verify in sim |
| Trade-off | Instead, they use an All-Indoor architec... | Application-dep. | Critical | Verify in sim |
Frequently Asked Questions
Why are telecom companies moving away from All-Indoor?
Because of 5G frequencies. All-Indoor systems only work at low microwave frequencies (e.g., 6 GHz). At modern 5G millimeter-wave frequencies (like 40 GHz), the radio wave is so fragile that if you try to pump it up a 300-foot copper pipe, 99.9% of the signal will be absorbed by the copper and die before it ever reaches the dish. High frequencies legally require the radio to be placed at the very top of the tower (All-Outdoor).
What happens if the waveguide pipe leaks?
Catastrophic water damage. Because the pipe is hollow, any crack will allow rain to pour inside. The water will run straight down the pipe and empty directly into the multi-million dollar radio inside the building, instantly destroying it. Engineers attach industrial air compressors (Dehydrators) to the pipe, constantly pumping pressurized dry air into it so that if a crack forms, the high-pressure air blows outward, stopping the water from coming in.
Is All-Indoor still used in broadcasting?
Almost exclusively. If you look at a massive 1,000-foot FM Radio or TV broadcast tower, it is always an All-Indoor system. A TV station blasts 50,000 Watts of raw power. An amplifier that massive is the size of three refrigerators and requires massive industrial liquid cooling pipes. It is physically impossible to bolt an amplifier of that extreme size to the top of a skinny steel tower.