LightSquared -with its proposition to use satellite (L-) band spectrum to build a terrestrial LTE network in the US has picked up another 265MUSD in financing. To me its clear that the company has picked a fight with the wrong guys – the airline and GPS industry. The company recently obtained a license for 1525-1559 MHz spectrum to operate a satellite based (but “terrestrial supported”) 4G system and has even launched a satellite last November, although it is quite obvious that the trust of the operation must be a terrestrial network. In fact the company plans for a network of 40000 (!) terrestrial towers – since this is the only way you can provide mobile users with any competitive data rates.
Since then it has become clear that the system will create interference to nearby GPS receivers both in airlines and in GMs vehicle tracking system. The FCC has asked the company for a remedy plan. Now the company is in the middle of a shouting match about the extent of the problem and who’s to blame and what can be done.
Unfortunately its not about who’s right and who’s wrong. Electromagnetic compatibility is a difficult issue and technical specs about out of band emission are not going to solve the problem, contrary to what many engineers may think. Even if LightSquared technically is doing the right thing, and the problems is caused by inexpensive GPS receivers picking up out of band interference they should not, regulators cannot stand by and watch a situation were GPS systems are rendered useless in many densely populated areas – in particular if critical transport infrastructure is affected.
This illustrates, (similarto the TV Whitespace problem) that existing systems where large investments already have been made, have “squatters rights” beyond their formal technical specs. Adjacent band or channel users will not only have to abide by out of band emission rules (e.g. WAPECS) but also satisfy interference requirements set by poorly designed receivers in the incumbent system. I have the distinct feeling that LightSquare will (and should, in fact) loose this fight, no matter the technical issue. The value provided by GPS usage by far overshadows the value provided by (yet another) mobile data provider. The traditional solution, i.e. replacing or modifying existing GPS receivers is simpy not possible due to their sheer numbers.