General requirements of the new systems

Several are the factors contributed to the success of mobile telephony in general and GSM in particular. However, one that can not be disregarded is the existence of compatible standards and an objective spectrum definition. In particular, the availability of a spectrum organized for GSM allowed to the user to do and receive calls and / or messages, independent of the country place. That was a key ingredient for the success. Other technologies that also used compatible standards and similar sprectrum also had similar dividends.

Today, mobile communications industry is in a similar crossroad, and is the possibility of make a true mobile internet the problem that must be solved. Towards that objective plain collaboration is required, in addition to the use of the planification and experiences of industry and administrations at a global scale.

These taks can be developed taking into account:

- Integration: Differences between urban and rural services, like those specific to developed or emergent markets, must be solved in an economic affordable manner.

- Performance: System capacity must be guaranteed to asure efficient broadband services.

- Flexibility and reconfigurability: Scale economy and terminal adecuation must be guaranteed using similar RF components globally.

To solve the differences between services, next generation of mobile networks requires access to a spectrum below the actually allocated to mobile services (i.e, below 850 / 900 MHz bands). This type of access will allow benefits in cities with high density of population, improving indoor coverage and descreasing coverage costs. In addition, economic and social benefits only will be realized if the availability of spectrum happens in a harmonized and shared form. Such availability will allow global roaming, and also scale economy suitable for production of low cost infrastructure and device technology.

Even when an apropiated spectrum is available at low frequencies, it is not enough to asure the success of the new services. Success will require satisfying the predicted traffic demand that will also require sufficient bandwidth. That spectrum is only available at higher ranges (above 1 GHz) and its availability is required to maintain the service quality.

As previously commented, availability of a global harmonized spectrum and a consistent regulatory framework were the basis for the worldwide success of GSM. Similar conditions were proposed for the standard associated to broadband mobile communication, IMT-2000 by ITU in the World Radio Conference (WRC), and until today that leads to the installation of more than 100 UMTS/IMT-2000 networks. Such conditions will be required also for the next generation of mobile networks, and recently additional bandwidth requirements were discussed (IMT-advanced). The following figure illustrates the evolution of some standards of mobile communications and the performance expected.

Mobile communications market is experiencing big changes. Some of these changes are related to: requirements of new services (similar in performance to wired services), new business models introduced by market competitivity and the improvements in radio and infrastructure technologies. However, service evolution is not relevant if the final user is not satisfyied. It is not easy to predict user behaviour in terms of evolution of service demand. That evolution depends on multiple factors such as: life style, fashion or other necessities of short term. As a consequence, flexilibility and fast installation are essential to satisfy the demand. In the future, services must be installed faster and in a more personalized form than today. While voice will continue as a universal service, there exists certain number of tendencies that will have influence on mobile communications, for example:

- Internet access. Used before to obtain text and imagen, nowadays is used to obtain movies.

- Mobile TV. This implies the distribution of individual video for on-demand services with interactive capacities.

- Mobile interactive games and real time games are are taking gradually more space in the entairtainment field.

- Several types of services of data, voice and video available by DSL providers are now in the mobile market replacing wired lines by services not only to home but also to companies.

As a consequence, new services will be concentrated in data and multimedia communications in parallel with, or in the same context that, voice services. Some of the services, and the typical bandwidth and network latency requirements, are illustrated comparatively in the following figure.

It is expected that these services will experience a big grow, what will bring benefits to users and industry. To be accepted and appealing to the user, many of these services (for example, video based services, or machine to machine communications) will require high transmission rates, or an answer with low delay (or both). It is expected that the new services will absorb half of the web resources by 2010. To that point, attention must put in the following aspects:

- Efective and maximum rates required by the user, which must be supported by the network.

- Latency (or response time) of the data channels and control channels.

- Radio coverage at the cell borders for optimum quality of service.

- Efficient metohodologies to maintain quality of service of the individual conection and the whole system.

Specifically, next generation services that will take these parameters into account must reach 100 Mbs for mobile communications and 1 Gbs for fixed wireless communications. These transmission rates will demand considerable increase in bandwidth as discussed in the recent literature.