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Why is LTE faster than EVDO or WiMax?

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Sprint Product Ambassador

A few weeks ago you asked in a blog comment, why is LTE faster?  I posted a quick reply, then went and did some research.  After checking with our network wizards - this is what I found out:

In simplest terms, LTE and WiMAX are capable of sending more bits of data in the same radio wave as EVDO, and both WiMAX and LTE allow for much larger pieces of spectrum, or bands, to be used.  Those two things, more data over larger bands, allow for the fourth generation of cellular networks to send very high rate data streams.

EVDO uses a 1.25 MHz band of frequency to communicate one way with a modulation scheme which allows 4 bits of data in an allocated piece of spectrum at a given time, commonly referred to as a symbol.  Today, LTE and WiMAX can use anywhere from 5 MHz to 20 MHz of frequency to communicate using a higher modulation scheme which allows 6 bits of data symbol.

Since LTE and WiMAX can send more bits and use larger amounts of radio frequency, they can send significantly more data to a device.

Spectral Efficiency Calculation

EVDO rA and QAM-16 modulation can push a theoretical 2.5 bits/sec/hz down the pipe for all users of that frequency slice.

1.25*10^6 * 2.5 = 3.125Megabits/ second.

LTE and WiMAX with QAM-64 modulation can push a theoretical 15 bits/sec/hz down the 20mhz pipe with 10x10 MIMO antenna arrays:

15*20*10^6 = 300Megabits / second.

Today, LTE and WiMAX networks use 2x2 and 4x4 MIMO antennas, and the modulation efficiency is effected by numerous environmental factors.  These impact the real-world experience so that it will always be less than the theoretical capabilities of the technology.  Citi recently did a study showing approximately 0.8 b/s/hz for EVDO rev A and 2.6 b/s/hz for LTE; a 300% improvement in spectral efficiency using real world experiences.

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