Eli5:Why is it that cell phones , with their tiny antenaes are able to download files at LTE speeds inside concrete buildings from cell towers kilometers away yet getting wifi to work behind a corner is an exercise in frustration?
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Power and contention.
1. A cellular tower transmits with a power level several thousands of times higher than your wireless access point. A typical cellular tower will transmit an ERP (effective radiated power — the actual transmission power, with antenna gain factored in) of 100-500W while maximum power for a 2.4GHz wifi access point is 100mW; the transmission power of the cellular tower is 1000-5000 times higher. At a range of 1km the signal from a 500W cellular tower will fall to 0.5mW thanks to the inverse square law. Your wifi access point falls to the same level at a distance of just 30m. This is all in open air with no obstructions.
2. It’s likely there are dozens if not hundreds of wifi hotspots and a few times that many client devices around you fighting for space in the radio spectrum, unless you’re well out into the countryside. There will be a half of that number or less of cellular clients though, and less than a dozen cellular towers, and everyone on the cellular network is cooperating to share the space through the protocol. Meanwhile wifi clients on the same channel but talking to different access points are fighting with one another, causing collisions and retransmits that slow down throughput.
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