显示标签为“4g modem”的博文。显示所有博文
显示标签为“4g modem”的博文。显示所有博文

2012年7月17日星期二

What is Wireless 3G Modem and 4G Modem?

Definitions of 3G modem and 4G modem.

3G Modem:
A 3g modem is a terminal device for dialup. Also known as a Cellular Modem, Mobile Modem, Mobile IP Modem, Wireless Modem) A wireless adapter that connects a laptop computer or other device to a cellular telephone system for data transfer. Cellular modems, often contain their own antennas and plug into a PC Card slot, a serial port or into the USB port of the computer or other device. Cellular modems can operate on a variety of wireless data services such as GPRS, EDGE, UMTS, HSPDA, HSPUA, 1x and EV-DO.
4G Modem:
A 4g modem is from tourth generation mobile communications technology. A somewhat vague term used to describe wireless mobile radio technologies that offer faster data rates than current 3G (third generation) technologies. 4G networks are also more data-centric and based on standard Internet technologies such as IP. Voice service is typically provided using a special form of VoIP. WiMAX and LTE are examples of 4G technologies. 4G LTE is most popular with 4G TDD LTE and FDD LTE.

2011年10月9日星期日

Cellular 3G Technology Vs 4G Technology


4G technology is with us already in some cities. What can 4G bring us?
The following table shows comparisons between some key parameters of 3GVs possible 4Gsystems.

 
 Item
         3G
                   4G

Frequency Band 
1.8 – 2.5 GHz 2 – 8 GHz
Bandwidth 
5-20 MHz 5-20 MHz
Data rate
Up to 2Mbps ( 384 kbps WAN) Up to 20 Mbps or more
Access 
Wideband CDMA Multi-carrier-CDMA or OFDM(TDMA)
FEC 
Turbo-codes Concatenated codes
Switching 
Circuit/Packet Packet
Mobile top speeds
200 kmph 200 kmph
 In the next topics, we mainly discuss the 4g terminal and 3g terminal comparasion, especially the 4g lte router and 4g lte modem.