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Evolution of Wireless Access systems

Evolution of Wireless Access systems. Maria Missiroli. (source: Nokia). WiMAX: basic aspects. WiMAX is the implementation of standard IEEE802.16 (physical and MAC layers) The standard ensures the interoperability among products of different manufacturers

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Evolution of Wireless Access systems

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  1. Evolution of Wireless Access systems Maria Missiroli

  2. (source: Nokia)

  3. WiMAX: basic aspects • WiMAX is the implementation of standard IEEE802.16 (physical and MAC layers) • The standard ensures the interoperability among products of different manufacturers • It is more efficient and flexible in spectrum use than basic WiFi (employs OFDM modulation) • Can be used for point-to-point or point-to-multipoint communications allowing high capacity channels over large distances (many km in rural areas, about 1 km in urban areas) • Licensed or unlicensed frequency bands • In Europe the frequency band initially identified for WiMAX is the 3.5 GHz band • Fixed and mobile standards (16d, 16e)

  4. WiMAX applications • Countermeasure to Digital Divide • many rural or mountain communities have no access to cable wideband - the answer to digital divide is an increasingly compelling issue • Broadband Wireless Access in metropolitan areas • possible alternative or complement to ADSL in densely inhabitated areas by new operators • avoiding the unbundling (particularly crucial in Italy) • user nomadicity (and/or mobility) while maintaining the link to the same operator, if large coverage areas are provided

  5. Architectures Backhaul Directive Point-To-Point links to connect base stations Last mile Point-To-MultiPoint links to connect business or home subscribers to the base stations Large areas coverage WiMAX base station to repeater station link for WiFi subscriber access

  6. Adaptive modulation A robust scheme of adaptive modulation enables WiMAX to offer high data-rate at great distance, with high spectral efficiency and tolerance to Non-Line-Of-Sight propagation

  7. WiMax vs WiFi • Coverage and performance • WiMax can operate over large distances by using licensed frequency bands (the required Tx power is allowed) • WiFi uses unlicenced frequency bands, with strict limits to tx power (hot-spot coverage) • Costs • User equipment will have similar costs • WiMAX networks requires costly infrastructure, while WiFi operates through low cost access-points • Time to market • WiFi has been present for some years (mature technology) • WiMAX is currently unfergoing licence assignment or infrastructure deployment • Quality-Of-Service • WiFi uses CSMA/CA for radio access with no QoS guarantee • WiMax allows QoS management at the MAC level

  8. Mobile WiMax vs HSPA • Costs • Equipment cost is lower for WIMAX • WiMAX requires new infrastructures while HSPA works on UMTS infrastructure • Coverage and performance • Grossly equivalent • Time to market • HSDPA launched in 2006, HSUPA expectedly launched in 2008 • WiMAX mobile standardised in 2005, first equipment ready in 2007 • Acceptance • HSPA is favoured by current mobile operators

  9. Digital Divide in Italy (source: Infratel)

  10. The BWA regulatory situation in Italy • In the band 3.4-3.6 GHz: 150 MHz to be liberated by the Defense Ministry and allocated to BWA services • On 30 May 2005 the Italian Authority for Communication has published the Regulations for Assignment of Right of Use for BWA systems • The Ministry of Communications will then issue the notice for the auction of the frequency bands

  11. Rules for BWA frequency assignment in Italy • 3 rights of use, for each geographic area, of at least 2x21 MHz (one reserved for newcomers) • geographic areas to be defined as regions or groups of regions • some minimum coverage requirements, to be fulfilled within 30 months from the release of the rights of use, defined in terms of covered municipalities, as well as some obligations of actual frequency use, in order to avoid an action of foreclosure • the Ministry of Communication could enforce such requirements in order to ensure an effective measure against the digital divide • fulfilling the technology neutrality principle, no limitations on final services are defined

  12. Flexible use of radio spectrum • New wireless systems offer converging service classes (triple play) • To optimise BWA access to the public, the EC (Radio spectrum Policy Group) is considering a process of “liberalisation” of some spectrum bands to be assigned following the approach of technology neutrality and/or service neutrality • A common approach among European countries is desirable • Envisaged actions • Open IMT-2000 bands to complementary data-optimized technologies like WiMAX • Permit mobile broadband services in other bands that have common global allocations • Let operators decide which services to offer within their spectrum holdings • Allow spectrum licensees to choose the duplexing scheme whether TDD or FDD • Introduce trading in rights of use in the secondary market

  13. Some frequency bands initially candidate to flexible use • 470-862 MHz: presently TV broadcasting; digital dividend after digitalisation • 880-915 MHz / 925-960 MHz e 1710-1785 MHz / 1805-1880 MHz: currently GSM mobile telephony • 1900-1980 MHz / 2010-2025 MHz / 2110-2170 MHz: currently IMT-2000/UMTS • 2500-2690 MHz (2.6 GHz band): still undergoing concession, intended for 3G mobile service (IMT-2000) • 3400-3800 MHz: 3.4-3.6 GHz undergoing licensing for BWA applications. Used for satellite communications in Russia and many African countries.

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