WiMax vs LTE: Part 2 LTE

by [Published on 12 Jan. 2010 / Last Updated on 12 Jan. 2010]

In part two of the series, the author discusses Long Term Evolution as a competitor to WiMax.

If you would like to read the other parts in this article series please go to:

Introduction

In my previous article in this series, I discussed the popular and well known 3G wireless technology called WiMax. In this article I will discuss its competitor, LTE. LTE stands for Long Term Evolution and is also known as 3GPP LTE, with 3GPP short for 3rd Generation Partnership Project, a standards partnership responsible for the evolution and maintenance of the GSM standards. LTE is also commonly, though incorrectly, thought to be a 4G, or 4th Generation, technology; it is not.

3G or 4G?

The confusion people have over whether LTE is 3G or 4G is understandable and stems from how the technology was introduced. In my previous article I discussed the history of WiMax which started in the mid 1990s and quickly gained widespread recognition. In fact many people have considered WiMax synonymous with the term 3G for many years now. So why do people incorrectly think that LTE is a 4th Generation technology? Well, LTE was introduced considerably later than WiMax (about 2004) and there are some distinct advantages LTE has over WiMax (more on this later and in my next article which will more directly compare the two standards and their technologies), these factors cause most people to assume that since LTE is newer, with some additional advantages so it must be the next generation of technology. In fact, LTE is not 4G because it does not meet the 4G specifications set out by the International Telecommunication Union (ITU). It does however meet the ITU's 3G specifications, which is why I am referring to it as a 3G technology.

History

The 3GPP was formed in the late 1990s with the goal of evolving the specifications for technologies around GSM. Since that time all of the standards associated with GSM technology are developed and maintained by the 3GPP. The 3GPP, as its name implies, is made up of a number of partners. These partners are themselves standards organizations located around the world which are responsible for; approval and maintenance of the 3GPP scope, allocation of resources, and acting as a body of appeal on procedural matters.

Originally, GSM was developed as a circuit-switched network which was excellent for voice transmissions but very bad for data transmissions. This all changed with the introduction of the General Packet Radio Service (GPRS) standard, now maintained by the 3GPP like all GSM standards. The GPRS standard provided a method of routing packets over a GSM network and is often described as a 2.5G standard. 

The data transmission capabilities of GSM networks further evolved with the introduction of Enhanced Data Rates for GSM Evolution, also known as EDGE. Introduced in 2003, EDGE provides three times the performance of GPRS and is itself a 3G technology, based on the ITU's 3G specification.

Data transmission capabilities improved further still with the introduction of another 3G standard from the 3GPP called High Speed Packet Access (HSPA). While EDGE networks can provide a theoretical down link data rate of up to 1 MB/s, HSPA networks can provide a theoretical down link data rate of up to 14 MB/s. So there should be a significant throughput advantage of HSPA networks; however, in practise this has not been the case. For instance, in early 2009 Vodafone completed a test of an HSPA+ network which promised a down link data rate of up to 16 MB/s but admitted that most users would only experience a download data rate of up to about 4 MB/s.

HSPA+, also known as Evolved HSPA, is an extension of the base HSPA standard and provides for a theoretical down link data rate of 56 MB/s. An additional aspect of HSPA+ is the introduction of an optional all-IP architecture. An all-IP architecture is a major innovation in the wireless telecommunications industry and is something that is necessary for LTE. HSPA+ also utilizes an antennae technology called Multiple Input Multiple Output (MIMO). Like the all-IP architecture, MIMO is a technology used in LTE.

So if you look at where GSM started as a circuit switched network designed for efficient, high mobility voice applications, and where it is today with EDGE, HSPA, and HSPA+ you can see that the 3GPP has progressively evolved the GSM standard to be efficient for high mobility data applications (which does include voice data). Along with consistent and significant increases in data rates, the 3GPP has also slowly introduced significant architectural changes which are required to meet their objectives of maximizing GSM's capabilities in the third generation as well as moving towards the fourth generation.

Technology

As I mentioned early there are two major evolutions in LTE. The first of these evolutions is the move to an all-IP architecture. That means that the technology has left behind for good the circuit switched network of GSM's roots. This is a significant move the telecommunications companies which will adopt LTE as their 3G technology of choice. To date the advantages that the 3GPP's standards had was that they were simply upgrades to the existing GSM networks which provided more throughput and allowed for more data intensive applications to communicate over the network. Now that the standards have moved away from the circuit switched architecture it's hard to make that argument that this is merely an upgrade. No, this is a significant change. In fact I feel that it's analogous to the software Operating System (OS) industry. Where the EDGE and HSPA were like service pack upgrades to Windows XP, while LTE is similar to a full OS version release like Windows 7. I guess that would make HSPA+ kind of like Vista; technically there, but nobody really cares :).

The second major evolution in LTE is with the use of MIMO. This is a technology which is also used in WiMax and I suspect that every wireless technology will soon use it both for its promise of speed improvements as well as the promise of reduced interference (or at least the reduced effects of the interference). Basically what MIMO is, is a system of transmitting data wirelessly where the sending side uses multiple antennae to transfer either the same data or different parts of the same data, while the receiving end used multiple antennae to receive the different signals. This setup can either be used to increase the throughput data rates or it can be used to reduce the effects of interference; this can be done when the sending side transmits the same data over each antennae, and when the receiving side receives multiple copies of the same data it can compare them and is more easily able to determine what the original signal was meant to be (that is without the effects of the interference).

So that, in a nutshell, is LTE. I hope I have done an adequate job explaining the roots of the LTE as well as the basis for it's capabilities. This article, along with my previous article on WiMax form the basis for my next article which will compare and contrast the two competing technologies. Also in my next article I will discuss the successes of each technology as well as give my opinion on which one will come out on top. Until then, and as always, feel free to send me an email if you have any questions.

If you would like to read the other parts in this article series please go to:

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