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Broadband Broadband at sea


For Italy’s coastguard service, the PMR concept has been successfully applied to mobile Internet access to create an efficient, privately-run broadband network which operates wholly under the user organization’s control, subscription-free


A


novel broadband private mobile radio system based on WiMAX technology went into operation earlier this year


with Italy’s coastguard service. Developed for the coastguard by the consult-


ants Accenture, the system initially provides ra- dio coverage of coastal waters off 15 main Italian ports, including Genoa, Livorno, Rome, Naples, Reggio di Calabria, Palermo, Bari, Pescara, San Benedetto del Tronto, Jesolo, Ravenna, Trieste, Catania (Sicily) and two ports in Sardinia. Accenture’s brief was to provide broadband


network access aboard the coastguard’s fleet of 325 vessels, offering them mobile intranet ac- cess at sea with the same functionality, service quality and performance that users would ex- pect in a land-based office. Te system would provide access to internal


databases and to the government’s public ad- ministration network; it would have to assure access from mobile devices and it would be re- quired to work in all weathers.


Commercial technology In essence, the WiMAX network is a broad- band private mobile radio system based on commercial wireless technology. Te coast- guards manage and operate it themselves, though Accenture remains on hand to provide third-line support if needed. A satellite service could have provided similar broadband facili- ties, but for the WiMAX system there are no subscription or usage fees to pay. For the new network, the government


ministry allocated FDD channels in military spectrum at 3·4GHz and 3·5GHz – but Ac- centure’s engineers chose to use the two 5MHz spectrum slots independently in TDD mode, via separate antenna sectors. Using commercial WiMAX infrastructure


supplied by Alvarion, with base station anten- nas mounted on the rooftops of coastguard buildings rather than on high sites, the system achieves ranges of up to 20km at full band- width. Aboard the ships, specially designed electrically-steerable antennas keep the beams pointing towards the base station as the vessel rolls and turns. Network access on board is distributed to PCs and smartphones via fixed cabling and Wi-Fi.


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Stretching coverage Special dual slant antennas were chosen to provide polarization diversity and to mitigate depolarization and multi-path scattering by the sea surface. With the completed system, uplink and


The Italian Coastguard’s WiMAX network initially serves waters off 15 major Italian ports. Its backbone is a government network which interconnects the regional maritime directorates and links all the radio sites to a service hub in Rome (diagram from Accenture)


Weather conditions From early planning to the roll-out of the last site, the project took 10 months. Te main problem was in the testing, Accenture says, since this appeared to be the first project in the world where commercial 3·5GHz technology had been employed for ship-to-shore commu- nications. Te only literature about seagoing use of these frequencies which Accenture’s en- gineers were able to uncover related to radar propagation, not communications. Tus there was some uncertainty about the performance to be expected. Simulations and trials were therefore needed


to verify that the WiMAX signal would operate satisfactorily across a sea path under all possible conditions. “It’s working really good”, confirms Emanuele Procaccioli, who has managed the project from Accenture’s Rome office. “Tey are quite satisfied and it’s very stable.” He adds that propagation actually seems bet-


ter when the sea is not calm; he believes that diffraction effects on the sea surface may help rather than hinder.


downlink speeds from 12 to 20Mbit/s are achieved, depending on the weather. Te cell edge is calculated as 12 nautical miles from the coast, the limit of Italian territorial waters and of the area which coastguard vessels are re- quired to patrol. Tis was a little beyond the normal WiMAX limit, but by adjusting para- meters the Accenture team was able to stretch the coverage. In the Alvarion implementation of WiMAX, by sacrificing about 7 per cent of the maximum bandwidth it was possible to achieve the required 12-mile range. Mr Procaccioli explains that the 12-mile


limit is a ‘soft’ cell edge beyond which the achievable bandwidth begins to diminish. Te real cell edge is at about 19 or 20 miles, where contact is lost. At the core of the system, an existing govern-


mental high-speed data network interconnects the sites and links them to a service hub at the coastguard’s general command office in Rome. Tis centre supports a wide variety of remote of- fice functions, including audio and video con- ferencing and recording, voicemail, PABX func- tions, instant messaging, a centralized address book, file transfer, database access, interconnec- tion with the Internet and integration with the coastguard service’s email and fax servers.


Expansion potential Te initial network has been in operation since April, but the coastguard hopes to expand cov- erage to the whole coastline of Italy as soon as money permits. One area which is a priority is the south,


where Italy has a continuing problem with un- authorized migrants reaching its shores from Africa. Te coastguard service would like to have connectivity for checking the documents of people its vessels pick up. Accenture is confident that the security of


the WiMAX transmission is sufficient to elimi- nate the possibility of eavesdropping or inter- ception.


LAND mobile October 2011


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