4G

Growth of Internet, of quality and quantity of interactive services presumes simultaneous widening of communication channels which bind user with World Wide Web. Now, when data transmission bitrates are measured in Mb/s and Gb/s, the preceding technologies have gone into history and there are new appearing which let to integrate all the devices and accomplish centralized control. Such services as online-broadcasting of popular TV and radiochannels, VoIP-telephony are becoming more and more traditional and available for the user. Despite the fact that the amount of users of broadband access to Internet is still a small part of the whole, this amount is growing up all the time. There were official research results presented on a IDF conference in 2006 in Moscow, which show quick dynamics of Internet growth, which testify of its high being in demand.

The developed data transmission technologies for 3G networks in some cases are not able to manage tasks. Providing in case of an ordinary user the data transmission delays might not matter, but in case of business applications a 1-second delay might cost thousands and even million of dollars. In such situations UMTS, CDMA2000 and WCDMA are not enough for the high-growing need. The using of 802.11 a/b/g standard, which could’ve improved the situation a bit, is restricted by several values, the main of which is the distance to the access point.

One of the main aims which were counted when developing 4G standards family is the integration of all the kinds of communications in one structure, the scheme of which is presented on the picture below.

Networks integration scheme

WiFi networks, 3G, satellite video and audio broadcasting, WiMAX networks and 4G networks will communicate through a set of devices called Internet Gateway Router, the task of which is to produce the environment for a transparent usage of the technologies mentioned above and connection of the Internet networks with terrestrial telephone lines. It will let to use not the expensive technologies for transmitting huge volumes of data, but the existing IP-networks. This will influence the cost of service of cellular networks.

There were several obstacles on the way of developing 4G. These were because of the search of new effective means of using the air, algorithms of compression and data transmission. Initially cellular networks were designed for voice transmission, that is why simply increasing equipment powers was not enough. Main innovations in 4G cellular communications are: Variable-Spreading-factor Spread Orthogonal Frequency Division Multiplexing, VSF-Spread OFDM, and Multiple Input Multiple Output, MIMO. VSF-Spread OFDM lets to use simultaneously several frequency bands, which gives opportunity to increase bandwidth capacity of the channel several times. MIMO lets to transmit information through several routs for or from base stations.

Experts promise public distribution of 4G technology in 2006-2007, but there’s no talking about public commercial maintenance. It is assumed that not before 2010 the cost decrease to $100 is not expected, so the main users of 4G networks will be large enterprises and corporations. At this stage the main rival of 4G networks is wireless data transmission standard WiMAX, or IEEE 802.16. Before the appearance of the devices working with a mobile realization of WiMAX 802.16e, the cost of which would be compared with 3G networks equipment, wide availability of the standard among average users is not expected. Not everyone could give $600-1000 for a set of client equipment, getting vague profits in bitrate and quality of service. In the first place it is connected with the realization of WiMAX technology which has some disadvantages. They should be taken into account in a big city with a high population density.

Now we will present some numbers in order to verify the above said. Coverage radius of one WiMAX base station in a city is 4 km in average. Such territory might be inhabited by approximately 180000-240000 people. If one of users is given a 1 Mb/s channel, then maximum number of simultaneously serviced clients would be approximately 1900 people from 240000.

In some regions before the realization of WiMAX there existed networks, namely pre-WiMAX, which hasn’t become popular because of high cost of a slightly known subscriber’s equipment.

In that situation 3G and 4G networks are far more attractive for an ordinary user. Despite the fact that the provided services - UMTS, WCDMA and CDMA2000 let to achieve a bitrate only up to 2 Mb/s in comparison with a rival - WiMAX, it is in most cases not enough for a comfortable Internet surfing and access to provided nowadays services. The realization and implementation of 4G networks will let to transmit data several times faster than it is possible to do now. For example, when testing the first 4G network by NTT DoCoMo company, the bandwidth capacity of communication channel was 1Gb/s in subscriber’s static state. Such bitrate is explained in a way that in 4G networks only effective packet data transmission is used, in contradiction with the existing packet transmission comprised with the voice traffic transmission. This let to abandon “braking” technologies and to replace them with a more productive, having saved and improved their functionality

According to the latest researches, while testing 4G network there was achieved 1Gb/s bitrate to a subscriber moving with a speed under 20 km/h, which is quite high for the existing technologies.

Gigabit wireless networks are already near. Along with a global roaming they will bring huge data transmission bitrates, perfect quality of the transmitted voice and video, will let to integrate the existing networks in one complicated structure. Any person, who has got a mobile phone, will be able to put in to global processes brought by 4G cellular communications.

Summary

What will 4G cellular networks introduce to us? Nothing revolutionary, except for the improving of services, presented by 3G cellular communications. The enhanced quality of videocalls and voice, higher Internet access bitrates, global roaming, corporate networks communications. In any case it is hard to imagine how to use 100 Mb/s, which are selected for a telephone. In conditions of quite high costs of Internet access in our country an ordinary user will not be able to pay for such a bandwidth of the channel, while for the connection of the existing corporate networks 5-10 Mb/s is enough, which are possible to provide by pre-WiMAX and WiFi. That is why it is possible to assume that 4G was being developed for a long perspective and all its resources wouldn’t be depleted for a long time.

During the last 20 years cellular communications was being transferred from an ordinary primitive means of communications into a high-speed technology able to make people’s life easier and better. The coming of 4G networks might be counted as a new milestone in the evolution not only in cellular communications but in the life of many people who will get a new level of mobility and availability. Business will become truly controlled due to high data transmission bitrates with minimal delays, which will let to avoid faults and to prevent critical situations. Life without wires – that is the motto for the next millennium.