WIMAX AND ITS APPLICATIONS

Transcription

1 WIMAX AND ITS APPLICATIONS

2 The extraordinary spread of broadband technology in telecommunication networks is opening a new way in the transfer of contents and digital applications. Broadband is now a stable technology and it is requested by a high percentage of the population; broadband connections in the world are expected to reach 200 millions within The Italian situation, for example, reflects such a trend, with 5,6 millions of broadband connections in June 2005, reaching 19% of the families, 37% of the enterprises and 61% of Public Administration sites. From the beginning, operators offering wired broadband connections usually locate their network infrastructures in the areas with the highest density of population, where the economical engagement for network implementation is more easily compensated by users number. But now it is becoming more urgent to ensure services also in suburban and rural areas, to satisfy the requirements of users of those zones and for the governments engagement in the "digital divide" bridging. In such scenario, wireless broadband access represents today a strategic opportunity in the communication market. The perspective of a valid and convenient wireless alternative to traditional wired broadband connections grows the interest in this new radio technology, in areas where it is already available, as well as where traditional solutions cannot arrive, for both private users and public administrations. A strong engagement of the various national communications administrations is now in progress, to make available frequency bands suitable for the new technologies. WiMAX (Worldwide Interoperability for Microwave Access) is considered today the most interesting opportunity, able to provide radio coverage distances of almost 50 kilometers and data troughput up to 70 Mbps, and to complete wired network architectures, ensuring a flexible and cheap solution for the last-mile. WiMAX is expected to have an explosive growth, as well as the WiFi, but compared with the Wi-Fi WiMAX provides broadband connections in greater areas, measured in square kilometers, even with links not in line of sight. For these reasons WiMAX is a MAN, highlighting that metropolitan is referred to the extension of the areas and not to the density of population. But WiFi and WiMAX are not competing technologies. While WiMAX can provide high capacity 2

3 Internet access to residences and business seats, WiFi allows the extension of such connections inside the corporate sites buildings. Therefore WiMAX and Wi-Fi are complementary technologies, defined to work together and able to ensure the best connection according to user needs. The main operators have concentrated their interests and efforts on the future applications of this new technology. Created in April 2002, the WiMAX Forum is a no-profit organization that groups companies promoting the broadband access based on the wireless communication standard, point to multipoint IEEE for Metropolitan Area Network (MAN). WiMAX Forum activities aim to: support the standardization process of IEEE for MAN select and promote some of the WiMAX profiles defined in the certificate the interoperability between WiMAX equipment of different suppliers make WiMAX a universally accepted technology The interoperability is a very strategic issue, on which equipment cost and volume of sales will be based. Operators will not be bound to a unique equipment supplier, as the radio base stations will be able to interact with terminals produced by different suppliers. Operators can benefit of suppliers competition in terms of costs and innovation. It is important to underline that WiMAX is not based on new revolutionary technologies, but on technologies tested and already applied in existing radio systems. The WiMAX main value is therefore the boost to the standardization. The work in progress for a fast reinforcement of the WiMAX industry standard is essential to make this wireless technology a stable, reliable and cost-effective solution to be applied by millions of users in the last-mile connections. For such a necessity, the Companies joining the WiMAX Forum cover more than 75% of the whole broadband wireless access sector, and the importance of this organisation is shown also by the participation of international suppliers of chip sets, components and services. 3

4 From the normative point of view, at present WiMAX is related to the d release of the standard IEEE , approved during August 2004, and it supports broadband wireless fixed connections, while the evolution of e is in development, focused on the broadband wireless access in mobility. A typical Metropolitan Area Network architecture is similar to the access part of a mobile network, with radio base stations located to optimise PMP connections and able to provide services in a coverage area depending on frequency, transmitted power and receiver sensitivity. Typically radio base stations are connected to the backbone network through optical fiber or microwave PTP link. The bandwidth for WiMAX equipment can vary from 1,5 to 20 MHz, being able to support different throughput, from a few hundred kbps for typical residential users or small offices, or an E1 trunk (2 Mbps), up to 70 Mbps. The frequency spectrum is from 2 to the 11 GHz, but the WiMAX Forum is focusing at first on the 3,5 GHz band. This flexibility allows to adapt the connectivity to the regulatory situation of different countries and to the frequency availability of different service providers, maintaining high performances also for voice and video transmission thanks to the expected requirements of quality of service. WiMAX supports three types of physical layers. The mandatory one is the Orthogonal Frequency Division Multiplexing (OFDM) with 256 points FFT, the same specified by the of HiperMAN European ETSI standard. For comparison, WiFi ensures very reliable wireless connections using the 64 OFDM physical layer (the number preceding the acronym represents the carriers that is possible to use in the whole modulation diagram) In the specification activity, security aspects have been considered of the maximum interest and developed in depth; the mandatory security algorithm is at present the Data Encryption Standard (DES), but US National Institute of Standards is evaluating the possibility of applying more complex algorithms. The effort for the definition of customized levels of quality of service (QoS) is also considerable, based on technologies able to optimise radio resources availability 4

5 and data throughput, according to the expected user profile, the actual traffic and the power signal level. Besides the general attention to the quality of service, WiMAX provides special technologies to improve it, specifically for voice and video communications; for example, the identification process of each speech burst allows the radio base station to transmit them with latency time univocally determinated. WiMAX standard allows the equipment manufacturers to propose a large set of products, with different configurations of radio base stations and user equipment (Customer Premises Equipment CPE), supporting different types of broadband wireless connections: metropolitan networks as well as residential urban connections and small-business, in alternative or substitution of wired connections, backhaul for radio base stations able to bypass the PSTN or to Internet WiFi hotspot, extension to rural areas of broadband services already available in the urban areas. 5

6 SOHO Metropolitan Area MOBILE/ NOMADIC Office Home Last Mile - Multimedia Access instead of DSL and optical fiber TETRA BROADBAND OVERLAY Portable Office Hotel Car Continuos Service - On the move and On the Pause Mobile Network Home Train BACKHAUL Airport UMTS GSM Wi-Fi hotspot Backhaul - instead of wired connection to the backbone Increase in multimedia features - WiMax networks overlay and interoperate with existing networks Thanks to the standard flexibility, a WiMAX radio base station can be able to control a small number of user terminals or it can work as a sophisticated equipment able to manage thousands of customer equipment ensuring all grades of service. From the hardware point of view, this flexibility entails, for radio base stations, the use of microprocessor architectures and discrete RF components. In user equipment this way would be very expensive, but the standardization, the main strength of WiMAX, is already allowing the implementation of integrated chipsets, produced on a large scale and able to provide several features, bridging in this way the main obstacle to the diffusion of proprietary wireless first generation systems. 6

7 The future market of WiMAX equipment will be characterized by the diffusion of low cost user equipment, based on chipsets integrating all the requested services. But the issue of radio base stations and CPEs for special applications will be in charge of companies able to design and offer complex solutions based on discrete components hardware. Companies already involved in WiMAX application areas will take advantage of various experiences, leading to the introduction of innovative services. The consolidated skills in areas needing WiMAX technology in a extremely specialized way, such as civil applications, public administration, public security and defence, allow Selex Communications to be among the first companies involved in the large WiMAX experimentation in course in Italy, with the perspective to employ the new technology for new advanced services: backhaul and last-mile applications for emergency scenarios, interface towards public safety institutional networks, mobile applications in transportations (videosurveillance, command and control systems, passenger information systems), mobile applications in military and homeland security areas (integration with military and police networks, evolution to Meshed and Ad hoc networks). The implementation of these applications will be modulated in time according to the standard evolution, to ensure reliable solutions based on a standard destined to become the most popular mean for broadband wireless communication. 7