Introduction

The word bandwidth is used in telecommunication to indicate the maximum rate at which data can be transferred over a network. Its amplitude becomes an important factor when implementing a new service or application by using innovative infrastructure and technologies, since it is possible to increase the communication speed and allow users to take advantage of multimedia services with a higher interactivity by using an always on connection. Today a bandwidth of about hundreds of Kb/s is considered enough for the private users but soon this capacity could not be sufficient to allow the ever growing multimedia applications demand.

On the other side, organizations or public administrations do need more bandwidth (at least some Mb/s) to use or provide their services. There are two important means used to transfer data on a network: cable and radio technology. Whereas cable technology is known and used in many network applications, wireless communication is becoming an important alternative due to its good performance and relatively low costs. Wireless networks are based on three different technologies: Wi-Fi, Wi-Max and satellite.

Wi-Max (acronym for Worldwide Interoperability for Microwave Access) can be considered as a complementary technology of Wi-Fi since it uses the same protocols of LAN and WAN the Logical Link Control (LLC) and this allows seamless interconnections with any Wi-Fi devices. WiMAX can be used for a number of applications, including ULL (Unbundling Local Loop), hotspots, mobile internet and high-speed connectivity for business. It uses the IEEE 802.16e protocol for the wireless communication, approved in December 2005, that bears an important feature: it defines a media access control (MAC) layer and a physical layer that allow to use different kinds of services such as VoIP, video-conferences, video on demand, online gaming and so on. This is important to allow equipment producers to differentiate their offerings and is one of the main reasons why Wi-MAX can be described as a "framework for the evolution of wireless broadband" rather than a static implementation of wireless technologies.

In 2002, a consortium for the promotion of Wi-Max technology was born in collaboration with Intel, Siemens, Alcatel, Fujitsu, Sumitomo Electric, Redline Communications, Wavesat and many producers of devices and semi-conductors such as Alvarion and Flarion, and, later, some big telecommunications companies like British Telecom, France Telecom and Qwest.

The objective of the Wi-Max consortium is to promote the creation of wireless networks with high bandwidth and throughput using a global standard and to certifying the adaptability of products and technologies by releasing unique protocols, products certification and qualification for test laboratories.

In this sense, what the consortium aims to do is the identification of a set of tools for the testing of devices and a set of specific features to allow producers to release products that are conformed to the standards and that can be marked as Wi-Max certified.Wi-Max technology can be considered as the natural evolution of the cable networks and, in the last years, many producers and suppliers are testing the use of WLL (Wireless Local Loop) for everyday applications. In this sense, the use of wireless technology can produce benefits in terms of costs reduction, for implementing the network infrastructure, and service deployment time.

This kind of point-multi point network is able to distribute data and information within a wide range of covering (about 50 km) with a throughput of 70 Mbps that allows supporting the simultaneous connections of about 60 companies with 1 Mbps bandwidth, and hundreds of private users by offerings DSL services.

The ability of Wi-Max networks to offer a high performance within elevated distance with high spectral efficiency and signal tolerance is based on a strong adaptative modulation scheme.

If the base station is not able to establish a connection with a remote user using the higher modulation protocols, the modulation level will in fact be decreased with a loss in throughput rate but with an increase in efficiency. Moreover, to facilitate the cells planning, the standard allows operators to segment their bandwidth in little fragments in order to serve a higher number of users with different needs and typology of services.

The Wi-Max standard will use different levels of Quality of Service (QoS) control, depending on the application running. For example, voice and video needs little delay in the packets transmission but, at the same time, are less sensible to data errors; on the other hand, critical applications (such as e-mails, database queries and so on) can tolerate little delays but are very sensible to the minimal transmission error. The QoS is thus applied at physical level in order to increase efficiency and reduce control to higher levels.

A future addition to the Wi-MAX standard will add full mesh networking capability.

Mesh networking is a way to route data, voice and instructions between nodes specifically for wireless and wired networks. An important feature is that this kind of network can still operate even when a node breaks down or a connection goes bad and this can lead to great reliability. A mesh network effectively extends a network by sharing access to higher cost network infrastructure. This will lead to a widespread adoption of Wi-MAX technologies in many fields and applications. Aside from the above mentioned benefits, there are also some problems related to its use like the possibility to easily interact with the network and intercept data during a transmission or to undergo denial of service attacks with loss of signal quality and bandwidth.

Wi-max technology uses a wide range of features to ensure the safe exchange of data: data authentication by the Subscriber Station by use of certificate; user authentication by the Extensible Authentication Protocols; data encryption by using Data Encryption Standard or Advanced Encryption Standard that seem to be more safe than the previous WEP (Wired Equivalent Privacy) used in WLAN.

A possible application: the virtual Healthcare District

Many fields, ranging from telecommunications, to gaming and e-health, can benefit of the Wi-Max technology in the near future. In the following, we present a practical application of the Wi-Max technology to the e-health system developed by the researchers of Polytechnic of Bari (Digregorio, 2005). The aim of this application is to describe the boundaries of an organizational network model for the healthcare facilities, based on a WMAN (Wireless Metropolitan Area Network), that allows the creation of an Integrated Information System supporting the communication and promotion of the local healthcare services. The e-Health revolution is centred around the Local Health Authority and its relationships with patients, through an offer of services that will have to be more and more customized and rich, using both traditional and innovative channels. A valid direction into which to develop this integration is the use of networking.

The ubiquity and the huge possibilities offered by internet-based architectures have given a strong impulse to the use of the ICTs, setting flexibility and mobility as new technological paradigms. In this sense, internet has given a strong impulse to the use of information technologies in the inter-business processes management (Hope et al, 2001). Dewett and Jones (2001) gather the functions developed by the ICT in five great categories: to connect the personnel of a firm that operates inside the same function e/o in functions and different divisions (through database shared, teleconference, cyber meeting, information centers); to codify the organizational knowledge (through the so-called Executive Information Systems); to widen the boundary of the organization, involving external subjects (through forum of professionals, chat line, exploration of network, virtual groups); to improve the organizational efficiency, through the diffusion of bests practices and the reduction of the costs of coordination of resources to promote the innovation, through the use of encoded knowledge, the dynamic positioning of the information resources, the parallel information processing. The quality and accessibility of information are key to the efficiency of a Health Care System, since they affect both the amount of the expense and the quality of the assistance, considering the information as the main decision support tool of the managers, the operators and the users.

Two different levels of analysis can be identified. The first is the identification of a model of organization useful to reach, through the use of ICTs, the objectives foreseen. The second is strictly related to the first one and deals with the identification of those services to deliver inside and outside the network (e-health) in order to analyse their potential effects and advantages. The Italian National Health Plan 2003-2005 foresaw the elaboration of an integrated network of firms, endowed with all the necessary characteristics, to offer citizens an elevated quality in Health Services in conditions of efficiency and effectiveness:

“[..] the Services and the Institutions owe becoming nodes of a net of assistance in which it is guaranteed to the patient the integration of the social and sanitary services, as well as the relief continuity in the gateway from a node to the other, having care that the permanence in the single nodes is optimized on the effectiveness state of health", (Ugolino et al., 2002).

In this context, the implementation of the proposed model aims at redesigning the organization of the services, by joining the operations of higher complexity in centres of excellence (Hub) and by distributing the terminals of access in subordinated centres (Spoke). In practice, it deals with transferring the centre of the assistance from peripheral productive unities to central unities of reference, when a determined threshold of complexity is overcome. In line with this vision, the reorganization of the network aims at getting the smallest possible congestion in the coordination and communication systems, a strong specialization of competences or focused factory (Skinner, 1974), and the maximum level of cooperation inside the network, based on the different levels of complexity of the assigned intervention.

E-health

By now the process of integration of ICTs in Health, also known as e-Health (Oh et al., 2005), has played a key role in improving health and healthcare system. Although, as underlined by Landoni (2003), there are important aspects related to the success and failure of telemedicine projects, flexibility being maybe the most important, that is necessary to cope with in a highly changing environment.

The relevant technological progress of telecommunications, computer science, biomedical and diagnostic technologies in Healthcare, allowed e-health to become reality by providing a wider integration and cooperation of all the functions and components of the Health Care system.

This implies an effective interoperability between heterogeneous applications and the semantic integration of the structured clinical data (Buccoliero, 2005). This integration must be performed in a networked environment. If we consider the e-health system as the centre of a complex and articulated network, made up of firms, digital communities, web portals with services to citizens, we can immediately understand the importance of integration between corporate body and different departments and, therefore, among heterogeneous information systems that share and exchange information.

The integrated network can be considered as a virtual organization of services, whose professional competences and technological resources are directed either towards the resident population in a proper reference area or towards specific categories of users. The organization of services, according with the integrated network model, is based on the fact that the technical and professional competences and the necessary technological resources have to be available in every point of the network. So, the integration of all the competences and the diagnostic technologies must be guaranteed.

The development of an integrated network organization needs the identification of two main components: the services and their functional relationships; essential services, that can be displaced in every point of the network, and complementary services and activities, that can be displaced in a certain spoke of the network; the logistic and professional development of the communication systems, both for the transmission of the necessary clinical information required by the patient’s assistant at any distance and for the production of guide lines and relief routes to be available and shared.

In this way, the networked system allows to use the available resources more effectively, in order to access services of homogeneous quality, and to develop solutions that exceed the boundary of each network node. Wi-MAX technology seems to be a valid answer to the high costs of investment, compared to a traditional wired technology. It could also represent a valid tool to reduce the problem of lack of information, due to its characteristic of ubiquity. Moreover, the same technology could contribute to create a network of services and a set of applications immediately available to the e-health system.

The ubiquity of the technology allows in fact an immediate connection to the broadband network in every place covered by the signal. The ability of allocating a symmetric and modular bandwidth, according to the service needs, allows to send and quickly receive information, data and medical images to and from a sanitary structure, a patient's domicile or a unity of mobile aid. Finally, the low latency time and the presence of mechanisms to differentiate the QoS, according to the different requirements, allow to run and use real-time sanitary applications that strongly require the reliability of the connection (video-consultation, tele-cardiology, distance monitoring, etc.).

Moreover, the high efficiency, both in uplink and downlink, decreases data losing during the transmission and this ensures the integrity of medical information (data and images) during the transfer. A ubiquitous communication network could then empower physicians, ambulances, patients, sanitary structures, etc., and allow them to exchange and share valuable information from each point inside a wide metropolitan area, creating the so-called Virtual Healthcare District.

Future directions

Nowadays, if we look at the retail market we cannot say that there are a wide range of Wi-Max certified devices or products available. The Wi-Max Forum announced that products actually exist but many of them probably will never arrive on the market. Indeed, many of these products are chipsets and base or subscriber stations. According to the ICT analysts, the first products certified for Wi-Max will be Base Stations destined to expand the connectivity in remote areas and decrease traffic in congested one.

Wi-Max networks will be developed in three different steps: first, the creation of peer-to-peer network in order to decrease time and costs for future installations and to connect users to providers. In a second stage, the installation of antennas inside the buildings to create a peer-to-peer connection with the base station. Only in the final stage of the implementation then, there will be made available the technologies to allow the roaming and to fully use all of the services and applications. The first generation of certified CPE (Customer Premises Equipment) will be made of Subscriber Station that will be installed outside the buildings and that look like little parabolic antennas. The second generation of CPE will be made of plug and play wireless modems and will be available by the beginning of 2006. The third generation will be embedded in notebooks and laptops and will be available by the end of 2006.

There is also an interesting potential for interoperability of Wi-Max with cellular networks. A cellular network has a hierarchical structure and it is formed by three components: mobile phones, base station and mobile switching centre (MSC). Cellular networks use the base station to connect the mobile phones to the public telephone network. MSC is the connection between BS and mobile phones since it stores information about the subscribers located within the cluster and it is responsible for directing calls to them.

In this sense, Wi-Max antennas can share a cell tower without compromising the function of cellular already in place. Some mobile producers are evaluating this emerging technology as a means for increasing bandwidth for a variety of mobile applications. Other possible areas of applications are: dedicated radio link to solve specific technical problems, decreasing of digital-divide in those countries or areas that are difficult to be reached by standard communication technologies, emergency, security and surveillance.

Another application under consideration is gaming. Microsoft is closely considering the addition of Wi-Max as a standard feature in the Xbox 360. This would allow gamers access to ad hoc local networks of other players with the same gear.

References

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