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Lecture 24

PHYS-P 150 Lecture Notes - Lecture 24: 2G, Time-Sharing, 5GPremium

3 pages69 viewsFall 2018

Department
Physics
Course Code
PHYS-P 150
Professor
John Carini
Lecture
24

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PHYS-P150 Lecture 24 Digital Cell Networks
Many factors have led to cell phone companies being able to include more users
Increasing Users
- Smaller cells allow you to share a channel more densely in an area with many people
Digital Transmission allows:
- Compression
- More efficient use of bandwidth
- Sharing of channels
- Digital systems are incompatible which allows users from different networks to share
the same band
Increasing Data
- Now because everyone has cell phones, the defining technology now is faster data
rate
- Each generation involves rebuilding the network, which would in the past often
involve getting a new phone
- Data Rate per User
o 2G: 10 kb/s
1990s
o 2.5G: 100 kb/s
o 3 G: 1 Megabit/second (Mb/s) or 1 GB/s
2000s
o 4G: 100 Mb/s-1000 Mb/s
2010s
o 5G: will be over 1 GB/s
Will probably be here after 2020 or so
Global System for Mobile
- GSM changed the band from analog systems of the past (1850-1990 MHz)
o 8-way time sharing now in 200 kHz wide channels-people can take turns
using them
o This is because sound data can be compressed without noticing a difference
in sound quality-and the compressed sound can be transmitted more quickly
- Wider bands and greater compression mean more users can use the system at a
time
- Users transport short bursts of data in about 0.577 milliseconds
- Since there is more bandwidth and channels, people can now send data other than
voices
- Minimum-Shift Keying: results in the data capacity of a GSM channel being
increased to 270 kb/s.
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