A. First generation
The process began with the designs in the 1970s that have become known as 1G. Almost all of the systems from this generation were analog systems where voice was considered to be the main traffic. The first generation wireless standards used plain TDMA and FDMA. These systems could often be listened to by third parties. Some of the standards are NMT, AMPS, Hicap, CDPD, Mobitex, DataTac, TACS and ETACS.
2G (Second generation)
The 2G (second generation) systems designed in the 1980s were still used mainly for voice applications but were based on digital technology, including digital signal processing techniques. These 2G systems provided circuit switched data communication services at a low speed . All the standards belonging to this generation were commercial centric and they were digital in form. The second generation of wireless mobile communication systems was a huge success story because of its revolutionary technology and the services that it brought to its users. Besides high-quality speech service, global mobility was a strong and convincing reason for users to buy 2G terminals. The second generation standards are GSM, iDEN, D-AMPS, IS-95, PDC, CSD, PHS, GPRS, HSCSD, and WiDEN.
3G (Third generation)
To meet the growing demands in network capacity, rates required for high speed data transfer and multimedia applications, 3G standards started evolving. The systems in this standard are essentially a linear enhancement of 2G systems. They are based on two parallel backbone infrastructures, one consisting of circuit switched nodes, and one of packet oriented nodes. The third generation (3G) has been launched in several parts of the world, but the success story of 2G is hard to repeat.
Features of fourth generation technology
There are several reasons which are sufficient to answer a simple question- why do we need to adopt 4G technology?
Below are some of the features of 4G which make it an “above all” technology.
- High performance
Industry experts say that users will not be able to take advantages of rich multimedia content across wireless networks with 3G. In contrast to this 4G will feature extremely high quality video of quality comparable to HD (high definition) TV. Wireless downloads at speeds
reaching 100 Mbps, i.e. 50 times of 3G, are possible with 4G.
- Interoperability and easy roaming
Multiple standards of 3G make it difficult to roam and interoperate across various networks, whereas 4G provides a global standard that provides global mobility. Various heterogeneous wireless access networks typically differ in terms of coverage, data rate, latency, and loss rate.
Therefore, each of them is practically designed to support a different set of specific services and devices, 4G will encompass various types of terminals, which may have to provide common services independently of their capabilities.
- Fully converged services.
If a user want to be able to access the network from lots of different platforms: cell phones, laptops, PDAs he is free to do so in 4G which delivers connectivity intelligent and flexible enough to support streaming video, VoIP telephony, still or moving images, e-mail, Web browsing, e-commerce, and location-based services through a wide variety of devices. That means Freedom for consumers.
- Low cost
4G systems will prove far cheaper than 3G, since they can be built atop existing networks and won’t require operators to completely retool and won’t require carriers to purchase costly extra spectrum. In addition to being a lot more cost efficient, 4G is spectrally efficient, so carriers can do more with less.
- Devices: more user friendly interface
4G devices are expected to be more visual and intuitive rather than today’s text and menu based systems. They will be able to interact with the environment around it and act accordingly.
- Enhanced GPS Services
In addition to locating individuals, a 4G version of GPS tech might be able to let people be virtually present in a variety of places.
It is most challenging aspect of the mobile networks. It refers to ability to handle ever increasing number of users and services. Since an all IP core layer of 4G is easily scalable, it is ideally suited to meet this challenge.
- Crisis-Management applications
Natural disasters can affect the entire communications infrastructure is in disarray. Restoring communications quickly is essential.With wideband wireless mobile communications Internetand video services, could be set up in hours instead ofdays or even weeks required for restoration of wireline communications.
challenges in migration to 4G
- Multimode user terminals With 4G there will be a need to design a single user
terminal that can operate in different wireless networks and overcome the design problems such as limitations in size of the device, its cost and power consumption. This problem can be solved by using software radio approach i.e. user terminal adapts itself to the wireless interfaces of the network.
- Selection among various wireless systems.
Every wireless system has its unique characteristics and roles. The proliferation of wireless technologies complicates the selection of most suitable technology for a particular service at a particular place and time. This can be handled by making the selection according to the best possible fit of user QoS requirements and available network resources.
Heterogeneity of wireless networks complicates the security issue. Dynamic reconfigurable, adaptive and lightweight security mechanisms should be developed .
- Network infrastructure and QoS support
Integrating the existing non-IP and IP-based systems and providing QoS guarantee for end-to-end services that involve different systems is also a big challenge.
- Charging/ billing
It is troublesome to collect, manage and store the customers’ accounts information from multiple service providers. Similarly, billing customers with simple but information is not an easy task.
- Attacks on application level
4G cellular wireless devices will be known for software applications which will provide innovative feature to the user but will introduce new holes, leading to more attacks at the application level.
- Jamming and spoofing
Spoofing refers to fake GPS signals being sent out, in which case the GPS receiver thinks that the signals comes from a satellite and calculates the wrong co-ordinates. Criminals can use such techniques to interfere with police work. Jamming happens when a transmitter sending out signals at the same frequency displaces a GPS signal.
- Data encription
If a GPS receiver has to communicate with the central transmitter then the communication link between these two components is not hard to break and there is a need of using encrypted data.