Innovative satphone provider LightSquared officially submitted it’s plan to use satphone frequencies on terrestrial towers to U.S. regulators today.
LightSquared claims their proposed solution resolves interference for approximately 99.5 percent of all commercial GPS devices- including 100 percent of the 300 million GPS-enabled cell phones.
Its plan to reduce interference would not use half the frequencies that it initially planned to use which nearest the adjacent GPS band, and Lightsquared said it would reduce power by 50% to the remaining terrestrial frequencies, effectively eliminating 99.5% of any interference. The company said it would work with the remaining .5% to resolve any remaining interference problems.
The GPS community is largely opposed to Lightsquared’s proposal, especially those who use very high accuracy devices such as John Deere.
Deere says the company’s engineers have determined that there is currently no practicable technical solution, or solutions in combination, available to avoid or substantially mitigate interference from LightSquared’s base stations to Deere’s existing precision GPS system and to similar systems operated by others, particularly in the agriculture and construction industries.
Differential GPS obtains precise positions using a separate radio transmitter on known points such as survey markers. Augmentation signals are the most at risk by the Lightsquared system, say opponents. StarFire and Omnistar, which broadcast additional “correction information” for high precision receivers, are swamped by nearby LightSquared base stations.
The Differential GPS system developed by John Deere called StarFire can resolve to 10cm (4 inches). It does that by comparing a GPS broadcast on two frequencies, L1 and L2, then compares the effects of the ionosphere on propagation time. GPS satellites broadcast at, 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal).
Assisted GPS improves the startup performance of GPS on cellular phones while GPS augmentation refers to techniques used to improve the accuracy of positioning information.
The Coalition to Save Our GPS, a group of GPS makers said they found “consistent and overwhelming evidence that LightSquared’s proposed operations would cause massive interference to every type of GPS device.” Members of the Coalition to Save Our GPS includes FedEx and United Parcel Service, GPS-unit makers Trimble and Garmin and the Air Transport Association with members Delta Air Lines and American Airlines.
“The direct economic costs of full GPS disruption to commercial GPS users and GPS manufacturers are estimated to be $96 billion per year in the United States, the equivalent of 0.7 percent of the U.S. economy”, said one study sponsored by the Coalition to Save Our GPS.
Lightsquared hoped to launch a nationwide LTE network and avoid the cost of acquiring new frequencies by using terrestrial repeaters. Interference from the geosynchronous satellite were never a problem. The terrestrial towers, however, would swamp nearby GPS receivers, opponents argue.
In the FCC’s National Broadband Plan, some 90 megahertz of spectrum was allocated to the Mobile Satellite Service (MSS) – in both the 2 GHz band, and the 1.6 GHz L-band.
The S-band, in the 2 GHz range, is largely interference-free and used by satphone providers TerreStar and ICO. The L-band, centered around 1.6 GHz, is adjacent to GPS frequencies and used by Inmarsat (1525-1544 MHz/1545-1559 MHz) and Lightsquared (1626.5-1645.5 MHz/1646.5-1660.5 MHz).
LightSquared planned to devote 40 MHz of L-Band spectrum to terrestrial use (pdf), worth approximately $12 billion according to the Brattle Group. LightSquared acquired rights to 46 MHz of LBand frequencies between 1626.5 MHz – 1660.5 MHz (uplink) and 1525 MHz – 1559 MHz (downlink) in a deal with Inmarsat. Inmarsat provides services mostly to the maritime industry. The remaining 6 MHz of its L-Band will be devoted to MSS (Mobile Satellite Services).
Harbinger initially planned to have 23 MHz available from Lightsquared – 8 MHz of 1.4 GHz terrestrial spectrum, 5 MHz of 1.6 GHz terrestrial spectrum and 10 MHz of MSS L-Band spectrum (ATC waiver). By 2013, they hoped to add an additional 30MHz available through cooperation with Inmarsat and additional ATC waivers in the L-Band. Now the plan is to use the Inmarsat spectrum first. But that may be easier said than done.
Under the FCC authorization, LightSquared committed to build-out 4G terrestrial LTE based service to at least 36% of the population (100 million people) by the end of 2012 and at least 92% of the U.S. population (260 million people) by 2015.
Related DailyWireless Space and Satellite News includes; Lightsquared: Plan “B”, Lightsquared: Lawmakers Skeptical, Lightsquared + Sprint Deal Done?, Lightsquared Gets 2-week Extension, Charlie Ergen’s Spectacular Triple Play, Lightsquared Interference: No Immediate Fix?, LightSquared: GPS Interference Found, Lightsquared: Plan B from Outer Space?, Harbinger: 59MHz or What?. Time Warner Cable + Lightstream?, Lightsquared Signs Cricket Wireless, Another Rumor: Lightsquared + Sprint?, Lightsquared + Sprint?, Charlie’s Big Play, LTE Spectrum: It’s War, Lightsquared: What GPS Interference?, Harbinger Sells Inmarsat Shares, FCC Green Lights Lightsquared, LightSquared: In Trouble?, Lightsquared Unfurled
