Electronics notes/Cell phone notes: Difference between revisions
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Note that many of these were never really made for indoor use. You can generally expect | Note that many of these were never really made for indoor use. You can generally expect |
Latest revision as of 19:05, 22 April 2024
⌛ This hasn't been updated for a while, so could be outdated (particularly if it's about something that evolves constantly, such as software or research). |
Note that many of these were never really made for indoor use. You can generally expect -10dB difference between outdoor and indoor near a window, and more for some types of buildings/isolation/reinforcement (and may make it impossible to phone in such a building).
Given speeds are download speeds (upload speeds may be lower),
and ideally real-world (which may be ~70% of the lab-test speeds, and much less than the theoretical variant)
See also:
2G (second generation) - GSM family
Speed: 0.3Mbps in theory, 0.1Mbps in practice
Latency: ~500ms
GSM
GSM is digital communicated of voice calls.
Uses one of 850MHz, 900MHz, 1800MHz, or 1900MHz, depending on location.
CSD:
- alternative to modem, using data rather than sound.
- Uses a single time slot, for 9.6kbit/s
HSCSD:
- improved variant of CSD: more efficient data coding (14.4kbit/s per time slot) and can use more than one time slot
- Speed up to 57.6 kbit/s (four slots), theoretically 115.2kbit/s with eight.
- Voice calls take precedence over data transfer, so speed is typically between one and four slot worth(verify)
Between second and third generation
GPRS
- '2.5G'
- Extension of GSM networks, that can work on existing GSM base stations(verify)
- Not unlike HSCSD in speed/timeslot details.
- seen as the predecessor of EDGE. Also has some relation to UMTS.
- http://en.wikipedia.org/wiki/GPRS
EDGE
(GSM) EDGE, Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC)
- '2.75G' (marketing may call it 3G, which is arguable)
- backwards-compatible extension on top of standard GSM(verify)
- Real-world speed: ~100kbit/s (sometimes more, typically under 200kbps)
- can work on existing GSM base stations(verify)
- http://en.wikipedia.org/wiki/Enhanced_Data_Rates_for_GSM_Evolution
EDGE Evolution, a.k.a. Evolved EDGE
- improves on EDGE in terms of latency, somewhat higher speed
- perhaps 500kbit/s in good conditions?(verify) (more in theory)
- http://en.wikipedia.org/wiki/Evolved_EDGE
CDMA2000
- sort of 3G, backwards compatible with 2G CMDA standards(verify)
- Not very widely used(verify)
- Real-world speed: ~100kbit/s (In theory some up to ~2mbps in some variants?)(verify)
- Regularly abbreviated to CDMA (does indeed use CDMA, Code Division Multiple Access)
- http://en.wikipedia.org/wiki/CDMA2000
3G
Note: 3GPP[1] (3rd Generation Partnership Project) is a collaboration to which most real-world third generation standards belong to.
UMTS (a.k.a. FOMA)
The common 3G network in Europe.
Speed: 7Mbps in theory, 1Mbps in practice Latency: ~200ms
See also:
- http://en.wikipedia.org/wiki/UMTS
- http://en.wikipedia.org/wiki/UMTS_frequency_bands (used/shared by UMTS, HSDPA, HSUPA, HSPA+, LTE)
HSPA: HSDPA, HSUPA, HSPA+ (Evolved HSPA)
'3.5G', and if you like that sort of thing, 3.75G, 3.9G and whatnot.
UMTS extension to support higher data speeds.
Speed: 50Mbps in theory, 2-10MBps in practice
See also:
- http://en.wikipedia.org/wiki/High-Speed_Downlink_Packet_Access
- http://en.wikipedia.org/wiki/High-Speed_Uplink_Packet_Access
- http://en.wikipedia.org/wiki/Evolved_HSPA
UMTS-TDD: TD-CDMA, TD-SCDMA
Variation of UMTS (that is not compatible) that makes it more of a mobile internet, WiFi-style network.
See also:
(3GPP) LTE, (not yet 4G)
3G LTE, sometimes marketed as 4G.
≥100 Mbit/s? (peak)
E-UTRA
http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution
4G
Data speed: 100 to 1000Mbit/s in theory, 10-50MBit/s in a lot of practice (verify)
Data latency: 50-150ms (varies with 4G variants)
The term has been so over-used in marketing, basically for anything that came after most basic 3G, that the term is almost meaningless.
It was not given a formal definition until years after it was used in marketing, at which point almost nothing qualified with what said marketing projected.
And of course marketing added 4.5G and 4.9G with fuzzy meanings. As usual.
http://en.wikipedia.org/wiki/4G
5G
Data speed: A few gBit in theory, maybe 50Mbit in a lot of practice
Data latency: Aims for 1-10ms, seems more like 20-50ms in a lot of practice.
https://en.wikipedia.org/wiki/5G
Android indicators
From what I can tell, the letters over the network icon:
(nothing) Just GSM G GPRS (2G) E EDGE (2.5G) 3G UMTS (3G) H HSDPA (3.5G), possibly also used for HSPA+? R Roaming?