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Fondazione Ugo Bordoni

Evolution of Wireless Access systems

Maria Missiroli

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(source: Nokia)

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WiMAX: basic aspects

WiMAX is the implementation of standard IEEE802.16 (physical and MAC layers)

The standard ensures the interoperability among products of differentmanufacturers

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 highcapacity channels over large distances (many km in rural areas, about 1 km inurban 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)

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WiMAX applications

Countermeasure to Digital Divide

many rural or mountain communities have no access to cablewideband - the answer to digital divide is an increasinglycompelling 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 tothe same operator, if large coverage areas are provided

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Architectures

BackhaulDirective Point-To-Point links toconnect base stations

Last milePoint-To-MultiPoint links toconnect business or homesubscribers to the base stations

Large areas coverageWiMAX base station torepeater station link for WiFisubscriber access

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Adaptive modulation

A robust scheme of adaptive modulation enables WiMAX to offerhigh data-rate at great distance, with high spectral efficiency andtolerance to Non-Line-Of-Sight propagation

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WiMax vs WiFi

Coverage and performance

WiMax can operate over large distances by using licensed frequency bands (therequired 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

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Mobile WiMax vs HSPA

Costs Equipment cost is lower for WIMAX

WiMAX requires new infrastructures while HSPA works on UMTSinfrastructure

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

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Digital Divide in Italy (source: Infratel)

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The BWA regulatory situation in Italy

In the band 3.4-3.6 GHz: 150 MHz to be liberated by theDefense Ministry and allocated to BWA services

On 30 May 2005 the Italian Authority for Communicationhas published the Regulations for Assignment of Right of Usefor BWA systems

The Ministry of Communications will then issue the notice

for the auction of the frequency bands

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Rules for BWA frequency assignment in Italy

3 rights of use, for each geographic area, of at least 2x21 MHz (onereserved for newcomers)

geographic areas to be defined as regions or groups of regions

some minimum coverage requirements, to be fulfilled within 30months from the release of the rights of use, defined in terms ofcovered municipalities, as well as some obligations of actualfrequency 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

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Flexible use of radio spectrum

New wireless systems offer converging service classes (triple play)

To optimise BWA access to the public, the EC (Radio spectrumPolicy Group) is considering a process of liberalisation of somespectrum bands to be assigned following the approach oftechnologyneutralityand/or service neutrality

A common approach among European countries is desirable

Envisaged actions

Open IMT-2000 bands to complementary data-optimized technologieslike WiMAX

Permit mobile broadband services in other bands that have commonglobal allocations

Let operators decide which services to offer within their spectrumholdings

Allow spectrum licensees to choose the duplexing scheme whetherTDD or FDD

Introduce trading in rights of use in the secondary market

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Some frequency bands initially candidate to flexible use

470-862 MHz: presently TV broadcasting; digital dividend afterdigitalisation

880-915 MHz / 925-960 MHz e 1710-1785 MHz / 1805-1880MHz: currently GSM mobile telephony

1900-1980 MHz / 2010-2025 MHz / 2110-2170 MHz: currentlyIMT-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 BWAapplications. Used for satellite communications in Russia and manyAfrican countries.