28-01-2011, 04:49 PM
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3G: Some Unfinished Business
Technical
Improved coverage (e.g., residences)
Inter technology roaming
Inter carrier compensation (esp. data services)
Financial
Balance sheet cleanup (debt reduction)
Capacity Utilization
Business Models for New Services
EDGE Technology Enhanced Data-rates for Global Evolution
Evolutionary path to 3G services for GSM and TDMA operators
Builds on General Packet Radio Service (GPRS) air interface and networks
Phase 1 (Release’99 & 2002 deployment) supports best effort packet data at speeds up to about 384 kbps
Phase 2 (Release’2000 & 2003 deployment) will add Voice over IP capability
GPRS Air-link
General Packet Radio Service (GPRS)
Same GMSK modulation as GSM
4 channel coding modes
Packet-mode supporting up to about 144 kbps
Flexible time slot allocation (1-8)
Radio resources shared dynamically between speech and data services
Independent uplink and downlink resource allocation
GPRS Networks
consists of packet wireless access network and IP-based backbone
shares mobility databases with circuit voice services and adds new packet switching nodes (SGSN & GGSN)
will support GPRS, EDGE & WCDMA airlinks
provides an access to packet data networks
Internet
X.25
provides services to different mobile classes ranging from 1-slot to 8-slot capable
radio resources shared dynamically between speech and data services
OFDM Characteristics
High peak-to-average power levels
Preservation of orthogonality in severe multi-path
Efficient FFT based receiver structures
Enables efficient TX and RX diversity
Adaptive antenna arrays without joint equalization
Support for adaptive modulation by subcarrier
Frequency diversity
Robust against narrow-band interference
Efficient for simulcasting
Variable/dynamic bandwidth
Used for highest speed applications
Supports dynamic packet access
Key Features of 4G W-OFDM
IP packet data centric
Support for streaming, simulcasting & generic data
Peak downlink rates of 5 to 10 Mbps
Full macro-cellular/metropolitan coverage
Asymmetric with 3G uplinks (EDGE)
Variable bandwidth - 1 to 5 MHz
Adaptive modulation/coding
Smart/adaptive antennas supported
MIMO/BLAST/space-time coding modes
Frame synchronized base stations using GPS
Network assisted dynamic packet assignment
