22-06-2012, 04:21 PM
4G –IP BASED MOBILE COMMUNICATION
4G-IP.ppt (Size: 293 KB / Downloads: 37)
GSM
GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity.
GSM networks operate at various different radio frequencies.
Most GSM networks operate at 900 MHz or 1800 MHz.
CDMA
CDMA (code division multiple access) is a mobile digital radio technology that transmits streams of bits and whose channels are divided using codes (PN sequences)
CDMA permits many radios to share the same frequency channel. Unlike TDMA (time division multiple access), a competing system used in GSM , all radios can be active all the time, because network capacity does not directly limit the number of active radios.
How 4g works
In the 4G wireless networks, each node will be assigned a 4G-IP address (based on IPv6), which will be formed by a permanent “home” IP address and a dynamic “care-of” address that represents its actual location [1].
When a device (computer) in the Internet wants to communicate with another device (cell phone) in the wireless network, the computer will send a packet to the 4G-IP address of the cell phone targeting on its home address.
What's New in 4G
Entirely packet-switched networks.
All network elements are digital.
Higher bandwidths to provide multimedia services at lower cost (up to 100Mbps).
Tight network security.
HSDPA
High-Speed Downlink Packet Access
HSDPA defines a new W-CDMA channel, the high-speed downlink shared channel (HS-DSCH) that operates in a different way from existing W-CDMA channels, but is only used for downlink communication to the mobile.
When a corrupted packet is received, the user device saves it, and combines it with subsequent retransmissions, to formulate an error-free packet as quickly and efficiently as possible
EV-DO
EVDO or Evolution Data Only,Evolution Data Optimized, is a fast wireless broadband access without needing a WiFi hotspot. You can have fast internet access, anywhere. No need to find a hotspot.
For example, get high speed internet access in a car, train, clients, anywhere you can open your laptop.
Currently, available is Verizon EVDO and Sprint EVDO
Relatively low cost with high capacity - allows rich web browsing and application usage