Sunday, February 17, 2013
Technology beyond 3G
From 2G, 2.5G, 3G (IMS, IP Multimedia Subsystem), 3.5G/HSDPA, to 4G
Computer Communications (IT), IP-based, WiFi (Data Comm.), VoIP
Computer Communications (IT), IP-based, WiFi (Data Comm.), VoIP
Data Services
- GSM, Circuit Switching, 9.6 (*2), 12.4(*2, HSCSD)
- GPRS, General Packet Radio Services, Packet Switching, 9.05 kbps/13.4 kbps (*1,2,3,4), speed denoted as *u*d
- EDGE, 3 times of speed of GPRS by using 8-PSK instead of binary GMSK
- 3G, 384kbps, up to 2 Mbps, uplink is 128 kbps
- 3.5G HSDPA (High Speed Downlink Packet Access) 8-10 Mbps (R5), and 20 Mbps (R6) by MIMO, uplink is 384 kbps
- 4G communication at 100 Mbit/s while moving, and 1 Gbit/s while stationary.
In general, a generation is defined by the result of technology changes over a 10-15 year time frame. Thus, 4G would refer to whatever is deployed in the 2010-2015 period, assuming 3G deployment spans the 2000-2009 period.
cellular technology
2. the bottleneck of capacity
3. Examine capacity of FDMA, TDMA, and CDMA (Is TDMA of the same efficiency as FDMA?))
- TDMA:FDMA 7(theoretically), 3(practically)
- CDMA:FDMA 40(theoretically), 10 (practically)
4. Why cellular is better than broadcast?
5. Digital wireless with TDMA, CDMA
- advanced of digital ICs
- price drop
6. Major issues with CDMA
7. and their solutions
- Power control
- soft handoff
8. Make use of dead time in telephone conversations, about 65% of the time
- variable-rate coder
reference: Chap. 1~Chap. 6, Dave Mock, the Qualcomm Equation, AMACOM, 2005
Monday, August 6, 2012
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