What LTE means for Apple's new iPad

By Glenn Fleishman, Macworld |  Mobile & Wireless

LTE is also much more flexible than the two dominant 3G standards that are part of CDMA and GSM networks. Those standards work with fixed channel widths, measured in megahertz. If a carrier can only obtain licenses in a given geographical area or even an entire country for ranges of frequencies that don't precisely match up with those fixed widths, it can't make use of 3G or use it efficiently. But with LTE, carriers can use slices of 1.4, 3, 5, 10, 15, and 20 MHz, so far. The wider the channel, the more data that can be carried across it at one time in ideal circumstances. LTE also can be used in many different spectrum bands—another advantage, but one that makes it harder for device makers like Apple to produce single models of hardware that work across many LTE networks.

LTE has yet another trick up its sleeve: the use of multiple antennas with multiple-in, multiple-out (MIMO) technology. This lets LTE use different amounts of signal power to transmit each data stream. The multiple antennas on the receiver let it interpret the transmission distinctly from others passing in the same space. The result is that MIMO lets carriers double up (and, in the future, even octuple up) the throughput of the network.

Fast, fast, fast

At Wednesday's iPad announcement event, Apple made it clear that LTE is fast, fast, fast! And in every way, that's true. LTE networks will nearly always be faster than comparable 3G networks in the same place.

But that's not the best part of LTE. It won't be just faster; it will remain faster in a consistent and reliable fashion a greater portion of the time than 3G. (It's worth noting that the new iPad also supports the faster versions of 3G, so you get a speed and coverage advantage on the most up-to-date HSPA+ and DC-HSPA networks, too—just not as much.)

Where you might have coverage gaps, high congestion with other users in the same mobile cell in a city (or even a small town with few base stations), or a huge variation in speed, it's likely that LTE will smooth all that out. Carriers will have a much larger pool of bandwidth that the technology lets them more precisely divide up among users trying to gain access. The use of MIMO helps by reducing the number of coverage holes and poor reception areas. MIMO's ability to bounce data around lets areas with marginal signal strength get better results than they'd get with single-antenna systems.


Originally published on Macworld |  Click here to read the original story.
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