OnQ Blog

Seamless LTE FDD-TDD Mobility without Compromises!

12 sept. 2013

Qualcomm products mentioned within this post are offered by Qualcomm Technologies, Inc. and/or its subsidiaries.

On a recent road trip, I was able to relax and listen to streaming music for hours on my smartphone while I was driving. While it is amazing to see how connectivity on the move is changing our lives, we almost take it for granted these days. Putting my technical hat on, I realize that my smartphone must have handed over my streaming data connection from one cellular tower to the other hundreds of times, while I blissfully enjoyed the music. So what made this smooth handover experience possible? Well, it was a cellular modem from Qualcomm Technologies, Inc. inside my smartphone that did it for me, and today I’m here to tell you that Qualcomm Technologies is at it yet again, powering seamless LTE mobility this time around.

This is not plain LTE mobility or LTE handover to 3G, which Qualcomm Technologies chipsets have supported ever since the first LTE networks launched, but the first truly connected LTE TDD (Time Division Duplex) and FDD (Frequency Division Duplex) handover mobility, now commercial with the Samsung Galaxy S4 and Galaxy S4 Mini on the Optus 4G LTE TDD Network in Australia.

Mobile users can now enjoy uninterrupted streaming videos, web browsing, music, and voice calls as they roam freely across LTE TDD and LTE FDD network coverage. More broadly, this launch heralds the maturing of LTE as the global 4G standard, and stimulates broader ecosystem support for both LTE TDD and LTE FDD. By enabling services that are seamless across TDD and FDD, operators can now pursue acquisition and deployment of additional radio spectrum, purely on the merits of coverage footprint, economics, and available bandwidth —regardless of whether the spectrum is suited for TDD or FDD.

But what is special about LTE TDD and FDD handover? To begin with, TDD and FDD are two slightly different duplexing modes of the same LTE standard. The difference is that a device uses two frequencies, one for communications to, and the other for communications from the network, in FDD mode, versus using only one frequency in TDD mode. While you can initiate a connection to either a TDD or FDD type of network depending upon your coverage, the problem is that you would likely experience a drop in service if you moved from TDD coverage to FDD coverage, or vice versa. This is because your device needs to drop out of one type network, go to idle, and then reconnect to the other type of network, thereby causing a glitch in connectivity.

Your phone going to idle during an TDD/FDD handover is similar to how you might take a quick break before getting back to work again. While taking a break might be good for you, when your device takes a break to switch between TDD and FDD, that just means compromised connectivity for you. Qualcomm Technologies' chipsets are designed to solve this problem by helping your device stay connected all the time as you move freely from one type of LTE network to the other. Coordination between the device and the network ensures that the network is already prepared to accept a new connection, without the device having to take a break in order to reconnect. And that means you can now enjoy all your content on the move, without any interruptions. You’re free to do more, in more places.

As operators start to deploy a mix of TDD and FDD in their networks to meet growing data demand, providing seamless mobility between FDD and TDD networks has become essential. So whether you will be taking a road trip or going globe trotting, you can look forward to a world of seamless LTE connectivity, as Qualcomm Technologies continues to execute on its vision of enabling global LTE mobility without compromises.

Kanu Chadha

Senior Manager, Technical Marketing

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