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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.