Telecom­mu­ni­ca­tions spec­trum

Finweek English Edition - - Communication & technology -

THE NEWS that South Africa’s sec­ond fixed-line provider Neo­tel has been al­lo­cated a part of the 800MHz fre­quency on which to run part of its net­work raises the ques­tion: Why is ev­ery­one get­ting into a state about spec­trum al­lo­ca­tion?

Sim­ply put, the amount of ra­dio spec­trum is lim­ited and it’s the re­spon­si­bil­ity of SA telecom­mu­ni­ca­tions reg­u­la­tor Icasa to en­sure that each part of the spec­trum is al­lo­cated to those com­pa­nies that need it.

The spec­trum cov­ers the am­bit of elec­tro­mag­netic waves – from long wave through to X-rays and gamma rays. But only a small part of that, just above the broad­cast spec­trum, is suit­able for send­ing data wire­lessly.

The prob­lem is that if you have two com­pa­nies us­ing the same tech­nol­ogy, then there’s the po­ten­tial that the two sig­nals will in­ter­fere with each other, like two peo­ple talk­ing loudly at the same time. To coun­ter­act that, Icasa al­lo­cates a sub­set of the fre­quency to each player. It’s the po­ten­tial for in­ter­fer­ence that ne­ces­si­tates the strict con­trol of wire­less providers and the sys­tems they use.

Parts of the ra­dio spec­trum aren’t reg­u­lated and those are used for the wire­less net­work­ing you’d find on a lap­top or the Blue­tooth tech­nol­ogy on cell­phones. With those the peo­ple de­sign­ing the tech­nol­ogy work out ways to en­sure that mul­ti­ple de­vices and net­works don’t in­ter­fere with each other too much.

Dif­fer­ent wire­less tech­nolo­gies broad­cast in dif­fer­ent parts of the wire­less spec­trum. Those are set at an in­ter­na­tional level but usu­ally there are dif­fer­ent parts of the spec­trum al­lo­cated in dif­fer­ent coun­tries, mostly for his­toric rea­sons. For ex­am­ple, the cell­phones we use ev­ery day can send and re­ceive at 900MHz and 1800MHz – the two main fre­quen­cies we use in SA – as well as at 1900MHz, the fre­quency they use in the US.

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