4G or Fourth Generation is technology for mobile and wireless comunications. It will be the successor for the 3Rd Generation (3G) network technology. Currently 3G networks are under deployement. Approximatly 4G deployments are expected to be seen around 2010 to 2015.
The basic voice was the driver for second-generation mobile and has been a considerable success. Currently , video and TV services are driving forward third generation (3G) deployment. And in the future, low cost, high speed data will drive forward the fourth generation (4G) as short-range communication emerges. Service and application ubiquity, with a high degree of personalization and synchronization between various user appliances, will be another driver. At the same time, it is probable that the radio access network will evolve from a centralized architecture to a distributed one.
The evolution from 3G to 4G will be driven by services that offer better quality (e.g. multimedia, video and sound) thanks to greater bandwidth, more sophistication in the association of a large quantity of information, and improved personalization. Convergence with other network (enterprise, fixed) services will come about through the high session data rate. It will require an always-on connection and a revenue model based on a fixed monthly fee. The impact on network capacity is expected to be significant. Machine-to-machine transmission will involve two basic equipment types: sensors (which measure parameters) and tags (which are generally read/write equipment).
It is expected that users will require high data rates, similar to those on fixed networks, for data and streaming applications. Mobile terminal usage (laptops, Personal digital assistants, handhelds) is expected to grow rapidly as they become more user friendly. Fluid high quality video and network reactivity are important user requirements. Key infrastructure design requirements include: fast response, high session rate, high capacity, low user charges, rapid return on investment for operators, investment that is in line with the growth in demand, and simple autonomous terminals. The infrastructure will be much more distributed than in current deployments, facilitating the introduction of a new source of local traffic: machine-to-machine.
Technologies used in 4G:
1-Orthogonal Frequency Division Multiplexing (OFDM)
2-Software Defined Radio (SDR)
3-Multiple-input multiple-output ( MIMO )
Initially DoCoMo planned to introduce 4G services around 2010. Recently DoCoMo announced plans to introduce 4G services from 2006, i.e. four years earlier than previously planned. NTT DoCoMo, Inc. announced that high-speed packet transmission with 1 Gbps data rate in the downlink was achieved successfully in a laboratory experiment using fourth-generation (4G) mobile communication radio access equipments.
The key enablers for the 4G are:
1-Sufficient spectrum, with associated sharing mechanisms.
2-Coverage with two technologies: parent (2G, 3G, WiMAX) for real-time delivery, and discontinuous pico cell for high data rate delivery.
3-Caching technology in the network and terminals.
4-OFDM and MIMO.
6-Multi-technology distributed architecture.
7-Fixed-mobile convergence (for indoor service).
8-Network selection mechanisms.