Feeds

LightSquared shuffles away from GPS bands

Slides into Inmarsat for the sake of sat nav

Designing a Defense for Mobile Applications

LightSquared's national rollout has shifted frequencies to avoid interfering with GPS kit, taking early advantage of a deal with Inmarsat for 10MHz of bandwidth further down the dial.

The wannabe operator, which aspires to cover the USA in an LTE network for wholesale leasing, has also offered to cut its permitted transmission power in half, back to what was permitted before the FCC started mucking about with the licences. That should avoid interfering with GPS, but it will also make building the network a good deal more complicated.

LightSquared doesn't even have access to the frequency in which it now plans to deploy a national network - that spectrum is owned by Immersat who had agreed that LightSquared could use it in a few years for increasing capacity.

LightSquared admits it will now have to "accelerate the schedule... to begin using the frequencies", while the band in which it originally intended to launch will sit fallow until needed, and even then it will be at much-reduced power.

That should avoid interfering with all but the most sensitive of GPS receivers, though we'll have to wait until 1 July to see how sensitive as that's when the FCC-mandated investigation into the problem publishes its results. LightSquared asked for, and got, a two-week delay on those results, presumably in order to get this plan announced.

The problem is that LightSquared's original frequency is right next to that used by GPS. That was OK when it was only used for satellite-to-earth communications which are, by necessity, very low power, but when the FCC changed the licence to allow LightSquared to build a national mobile network in the band alarm bells began to ring.

One generally talks about radio transmissions being square - starting at full power and remaining at that point for the width of the signal before dropping to nothing - but in reality they are bell-shaped with full power only be achieved at the centre point and the tails of the bell extending into the neighbouring bands. A great deal of work is put into making signals square, and they are much squarer than they used to be, but neighbouring spectrum users still have to watch each other's toes.

LightSquared thought it could create a signal that was square enough to avoid leaking significantly into the neighbouring band, despite the comparative weakness of the GPS broadcast. That has obviously proved impossible, so LightSquared has little alternative but to shift bands and is lucky to have another place to call home.

That shift will increase the complexity of the network, and the LTE handsets needed to support it, and will increase pressure on the company to confirm its deal with Sprint if it's going to restore some credibility.

Adding another frequency to LTE's roster might seem problematic, but LTE is already expected to be deployed in more than 40 different frequencies, and it's very questionable how many bands will be supported by different handsets - the tri-band handsets of the GSM days aren't going to cut it this time around. ®

HP ProLiant Gen8: Integrated lifecycle automation

More from The Register

next story
Scotland's BIG question: Will independence cost me my broadband?
They can take our lives, but they'll never take our SPECTRUM
Auntie remains MYSTIFIED by that weekend BBC iPlayer and website outage
Still doing 'forensics' on the caching layer – Beeb digi wonk
Bring back error correction, say Danish 'net boffins
We don't need no steenkin' TCP/IP retransmission and the congestion it causes
NBN Co adds apartments to FTTP rollout
Commercial trial locations to go live in September
Samsung Z Tizen OS mobe is post-phoned – this time for good?
Russian launch for Sammy's non-droid knocked back
Telstra to KILL 2G network by end of 2016
GSM now stands for Grave-Seeking-Mobile network
Seeking LTE expert to insert small cells into BT customers' places
Is this the first step to a FON-a-like 4G network?
What FTC lawsuit? T-Mobile US touts 10GB, $100 family-of-4 plan
Folks 'could use that money for more important things' says CEO Legere
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Securing Web Applications Made Simple and Scalable
Learn how automated security testing can provide a simple and scalable way to protect your web applications.