International Mobile Telecommunications-Advanced (IMT Advanced), better known as 4G, 4th Generation or Beyond 3G, is the next technological strategy in the field of wireless communications. A 4G system will upgrade existing communication networks and is expected to provide a comprehensive and secure IP based solution where facilities such as voice, data and streamed multimedia will be provided to users on an "Anytime, Anywhere" basis and at much higher data rates compared to previous generations (see QoS).
Objective and approach
Objectives
4G is being developed to accommodate the QoS and rate requirements set by forthcoming applications like wireless broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB), minimal services like voice and data, and other services that utilize bandwidth.
The 4G working group has defined the following as objectives of the 4G wireless communication standard:
- A spectrally efficient system (in bits/s/Hz and bits/s/Hz/site),
- High network capacity: more simultaneous users per cell,
- A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R,
- A data rate of at least 100 Mbit/s between any two points in the world,
- Smooth handoff across heterogeneous networks,
- Seamless connectivity and global roaming across multiple networks,
- High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)
- Interoperability with existing wireless standards, and
- An all IP, packet switched network.
In summary, the 4G system should dynamically share and utilize network resources to meet the minimal requirements of all the 4G enabled users.
Approaches
As described in 4G consortia including WINNER, WINNER - Towards Ubiquitous Wireless Access, and WWRF, a key technology based approach is summarized as follows, where Wireless-World-Initiative-New-Radio (WINNER) is a consortium to enhance mobile communication systems.
Consideration points
- Coverage, radio environment, spectrum, services, business models and deployment types, users
Principal technologies
- Baseband techniques
- OFDM: To exploit the frequency selective channel property
- MIMO: To attain ultra high spectral efficiency
- Turbo principle: To minimize the required SNR at the reception side
- Adaptive radio interface
- Modulation, spatial processing including multi-antenna and multi-user MIMO
- Relaying, including fixed relay networks (FRNs), and the cooperative relaying concept, known as multi-mode protocol
4G features
According to the members of the 4G working group, the infrastructure and the terminals of 4G will have almost all the standards from 2G to 4G implemented. Although legacy systems are in place to adopt existing users, the infrastructure for 4G will be only packet-based (all-IP). Some proposals suggest having an open Internet platform. Technologies considered to be early 4G include: Flash-OFDM, the 802.16e mobile version of WiMax (also known as WiBro in
An even higher speed version of WiMax is the IEEE 802.16m specification. LTE Advanced will be the later evolution of the 3GPP LTE standard.
Applications
At the present rates of 15-30 Mbit/s, 4G is capable of providing users with streaming high-definition television. At rates of 100 Mbit/s, the content of a DVD-5 (for example a movie), can be downloaded within about 5 minutes for offline access.
4G wireless standards
3GPP is currently standardizing LTE Advanced as future 4G standard. A first set of 3GPP requirements on LTE Advanced has been approved in June 2008. The working groups are currently evaluating various proposals for standardization. LTE Advanced will be standardized as part of the Release 10 of the 3GPP specification.
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