23-12-2010, 11:57 AM
Prepared by:RENJITH M.I
[attachment=7556]
WHAT IS 4G ?
A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an "Anytime, Anywhere" basis, and at higher data rates than previous generations.
WHY 4G ?
3G performance may not be sufficient to meet needs of future high-performance applications like multi-media, full-motion video, wireless teleconferencing.
There are multiple standards for 3G making it difficult to roam and interoperate acros networks.
we need global mobility and service portability.
We need all digital packet networks that utilize IP in its fullest form with converged.
4G FEATURES
100 Mbit/s for high mobility such as mobile access and up to approximately 1 Gbit/s for low mobility.
A data rate of at least 100 Mbit/s between any two points in the world
Flexible channel bandwidth, between 5 and 20 MHz, optionally up to 40 MHz
4G FEATURES
An all IP, packet switched network(IPV6).
VOIP.
Seamless connectivity and global roaming across multiple networks
Interoperability with existing wireless standards.
WiMAX
Providing portable mobile broadband connectivity across cities and countries through a variety of devices.
Providing a wireless alternative to cable and DSL for "last mile" broadband access.
Providing data, telecommunications (VoIP) and IPTV services (triple play).
Providing a source of Internet connectivity as part of a business continuity plan.
KEY 4G TECHNOLOGIES
OFDM.
SOFTWARE DEFINED RADIO.
MULTIPLE INPUT MULTIPLE OUTPUT .
HANDOVER AND MOBILITY.
OFDM
Orthogonal Frequency Division Multiplexing (OFDM) not only provides clear advantages for physical layer performance, but also a framework for improving layer 2 performance by proposing an additional degree of free- dom. Using OFDM, it is possible to exploit the time domain, the space domain, the frequency domain and even the code domain to optimize radio channel usage. It ensures very robust transmission in multi-path environments with reduced receiver complexity.
Next Generation Wireless – 4G
3 Major Components to 4G
Modulation/Demodulation
Multiple-Input Multiple-Out (MIMO)
Channel Decoder/Encoders
MIMO
MIMO uses signal multiplexing between multiple transmitting antennas (space multiplex)
and time or frequency. It is well suited to OFDM, as it is possible to process independent
time symbols as soon as the OFDM waveform is correctly designed for the channel. This
aspect of OFDM greatly simplifies processing. The signal transmitted by m antennas is
received by n antennas. Processing of the received signals may deliver several performance
improvements:range, quality of received signal and
spectrum efficiency
SDR
Software Defined Radio (SDR) benefits from today’s high processing power to develop
multi-band, multi-standard base stations and terminals. Although in future the terminals will
adapt the air interface to the
available radio access technology, at present this is done by the infrastructure.
HANDOVER AND MOBILITY
Handover technologies based on mobileIP technology have been considered for data and voice.
These methods are applicable to data and probably also voice. In single-frequency networks,
it is necessary to reconsider the handover methods. Several techniques can be used when the
carrier to interference ratio is negative (e.g. VSFOFDM,bit repetition), but the drawback of
these techniques is capacity. In OFDM, the same alternative exists as in CDMA, which is to
use macro-diversity. In the case of OFDM, MIMO allows macro-diversity processing with
performance gains
BENEFITS
1 Benefits for Operators:Higher bandwidths
Lower cost of networks and equipment.
The use of licence-exempt spectrum.
Higher capacity and QoS enhancement.
Higher revenue.
2 Benefits for Users:
Access to broadband multimedia services with lower
cost and where mostly needed.
Inter-network roaming.
CONCLUSION
Projected 4G systems offer this promise
of a standard that can be embraced worldwide through its key concept of integration. Future
wireless networks will need to support diverse IP multimedia applications to allow sharing of
resources among multiple users. There must be a low complexity of implementation and an
efficient means of negotiation between the end users and the wireless infrastructure. The
fourth generation promises to fulfill the goal of PCC (personal computing and
communication)—a vision that affordably provides high data rates everywhere over a
wireless network.
4G is expected to be launched by 2010 and the world is looking forward
for the most intelligent technology that would connect the entire globe.
