UMTS AND 3G

UMTS is well known as the technology of 3G; many people say it is the 3GSM. Basically, the UMTS technology is one of the advanced mobile communication technologies for wideband or broadband operations on the GSM infrastructure and its evolved versions. In its modern 3G version UMTS uses WCDMA as the air interface multiple access method.

UMTS system was mainly using the GSM framework for two reasons: first, to retain the existing customers in the same network, and second, to provide new dimensions which are able to give broadband services in personal communication systems.

At present all the major 3G Networks are using the FDD (frequency division duplex) mode of operation. As far as time division duplex is concerned, there are no commercial TDD networks at the moment, although some of the network service providers like T-Mobile have announced that they would install TDD Network in Europe and North America. The reason why TDD has not been used yet is the difficulty in its implementation; when both of them (TDD and FDD) stay together, the situation becomes even more complex.

4G became necessary when it was found that the 3G was lagging behind the competing technologies like the WiMAX. The 4G project and its road map was not very much related to the WiMAX development, but it was later found to be a basic need for the 3GPP members to come out with a better technology. Though there is not much difference between them, it is quite obvious that the 3GPP members do not want to lag behind.

The migration of the 2G to 3G was so smooth in the European countries that many people did not even realize that a transition had taken place. Just using the 3G handsets they were able to get the advanced services from their same service provider. Of course, UMTS subscribers differentiated from GSM subscribers based on a SIM card. For UMTS and GSM subscriber the SIM is different; UMTS subscribers use USIM while GSM subscribers use SIM. However, if the service provider wants, it can provide the 3G services on the same existing GSM SIM. Similarly, in case of the 4G it is expected that the UMTS's advanced version may make it quite flexible for the change from 3G to 4G

DIFFERENCES BETWEEN 3G AND 4G

Though the 4G is the evolved version of 3G there are many fundamental differences between the two systems, the greatest of these being speed enhancement of 3G network services.

The main differences between the 3G and 4G have been listed below.

1 The Speed or Data Rate

The maximum speed or the data rate of 3G system is 2MBPS. With that speed we can definitely get a better service than the 2G system or its advanced versions like the GPRS (where the maximum possible speed is 204 KBPS). Although 3G substantially enhanced the data rate, the data contents of the present wireless broadband services make it impossible to carry on far with the 3G system. 4G was the solution to overcome that bottleneck of the 3G technologies. In 4G the aim is to get a data rate of 100MBPS or even more in the indoor environment. In theory, 4G will be at least 50 times faster then the 3G system; this is the main difference between the 3G and 4G technologies. In other words, the bandwidth of 4G system would be much higher than the 3G system.

2 Packet Switched Infrastructure

In 4G, the whole network will be packet switched. The IP based infrastructure will be used for the 4G system exclusively. IPv6 is the version on which the whole protocol system will govern the different kinds of switching for the data transfer. 4G switching aspects will therefore be more sophisticated and complex than the 3G system.

3 Quality of Service or QoS

The quality of services in 4G networks is going to be much better than the 3G and its contemporary technologies. The improvement in main service factors will be due to the high broadband of the 4G systems, the improved quality of service of the IPv6 systems compared to previous IP versions, and better reception and transmission services from the smart antenna based MIMO system.

4 Network Security

Network security is another important aspect, one for which people are ready to pay. Network security in 4G is different from that of the 3G or 2G versions, in part because the security provided through the 4G networks is made up of two tiers. That means not only the MSC authentication is required but along with that there are some adder securities. We have seen the added security arrangement of the 4G systems in the OSI model. The Information Privacy Layer is there to take care of the security related aspects of the information that is exchanged in the 4G networks.

5 Management of Resources

The resource management in 4G is much better than 3G. Optimization is present in the 3G system, but most of the optimizations are not that adaptive and dynamic. In contrast to that, 4G would have very smart adaptations in the resource management sector. Adaptive algorithms are used to provide optimization everywhere, from the modulation and coding, to the individual scalable channel bandwidth allocation.

6 Differences between the WiMAX and the 4G

Some people mistakenly believe that 4G and WiMAX are the same technology and only the application domains of the two are different. Here we would like to clarify that 4G and WiMAX are different types of technologies and the standards for the technologies are also different in many respects. Of course, there are some similarities between the two. The truth is that the WiMAX business group and the people who are working with the WiMAX technology want to popularize WiMAX as the 4G wireless technology, leading people to think that WiMAX and 4G are the same thing. In reality it is not accepted by the research community and the technology development group of either technology.

Like 4G, WiMAX can deliver high data rate (up to 70 Mbps over a 50Km radius). However, as mentioned in the earlier sections, with 4G wireless technology people would like to achieve up to 1Gbps (indoors). Additionally, WiMAX technology (802.16d) does not support mobility very well. To overcome this mobility problem 802.16e, or Mobile WiMAX, is being standardized in the same way as 4G. Ultimately though, when it comes to performance and speed 4G remains the winner.

The important thing to remember here is that all the research for 4G technology is based around the orthogonal technology OFDM. WiMAX is also based on OFDM, and this fact gives more credibility to those in the WiMAX lobby who would like to term WiMAX as a 4G technology. It is worth mentioning that 4G is going to be an ultramodern, high performance mobile system. Most of the advanced features of 4G are due to OFDM, MIMO and other advanced technologies. It is seen as a hybrid system which is based on both 3G and other advanced systems, including WiMAX.