Everything you need to know about LTE
Broadband-like speeds for mobile data is slowly becoming a reality, with the current 4G craze that is gripping the world, spearheaded by new network technology called LTE (Long Term Evolution). While the current official definition of 4G grudgingly includes LTE as a fourth generation technology (with LTE-Advanced considered “True” 4G), LTE does feature a significant improvement from current 3G technologies, with benefits for not only consumers, but for network providers as well.
LTE is being adopted around the world as the primary mobile network service, with 2G and 3G cellular radio tech slowly being phased out as network carriers continue to build and expand their LTE networks. Granted, it’ll be a while before this expansion is complete, and even longer when 4G, as it should be, is available, and until then, older technologies like CDMA and GSM will continue to co-exist with LTE.
In this article, we’ll be taking a look at what some of the technical aspects of how LTE works and the technology associated with it, some of the benefits of LTE, and current global subscriptions and expected growth rate of LTE.
How LTE works
The first thing to note when it comes to LTE is the change in frequency and bandwidth usage. While GSM 3G use 5 Mhz channels, LTE can use a channel size from 1.4 Mhz to 20 Mhz (The standard is set up to allow bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz). This wide range is particularly useful in markets where spectrum is sparse, or on the flip side, where a lot of unused frequencies are available. Of course, the wider the channel, the higher the throughput, that is, higher data rates and access to a lot more users (if all other factors are considered equal). The carrier selects the bandwidth depending on country of operation and the state of their spectrum holdings.
Most of the bands are set up for Frequency Division Duplexing (FDD), which uses two separate bands for uplink and downlink, and will be the LTE variation that will be seen in North American, European, and some Asian markets. Time Division Duplexing, which uses the same frequency for both downlink and uplink, is what is being implemented in China and India, as TD-LTE conserves spectrum, and allows for more user per Mhz.
LTE uses two different radio links for downlink and uplink, that is, from tower to device, and vice versa.For the downlink, LTE uses an OFDMA (orthogonal frequency division multiple access), which requires MIMO. MIMO, which stands for Multiple Input, Multiple Output, uses two or more antennas to reduce latency significantly and boost speeds within a given channel. Standard LTE can accommodate up to a 4×4 arrangement (the first digit is the number of transmit antennas, and the second, the number of receive antennas).
For the uplink (from device to tower), LTE uses a SC-FDMA (single carrier frequency division multiple access) signal. Most LTE devices, don’t have a strong uplink signal (benefits of OFDMA would be lost with a weak signal), and as opposed to OFDMA, SC-FDMA is better for uplink because it has a better peak-to-average power ratio.
Benefits of LTE
The biggest benefit of LTE from the perspective of the consumer is of course the faster data rates possible with LTE. LTE offers a theoretical downlink of greater than 100 Mbps and uplink greater than 50 Mbps. Granted, the data rates actually achieved depend on a lot of factors such as channel bandwidth, modulation type, MIMO configuration and the quality of wireless path. Currently, most LTE networks feature a download range of 5 Mbps to 25 Mbps, but with further expansion, network enhancement, and shift towards LTE-Advanced, these data rate numbers are going to increase to rates that are faster than a lot of fixed Internet services that use DSL or cable or DSL.
Along with faster data rates, consumer electronic devices such as notebooks, smartphones, tablets, and even gaming devices and cameras will use LTE modules since LTE supports handover (selection of the best available network between mobile data or WiFi hotspot without dropping the network), allowing for full mobile broadband coverage from the start.
From the perspective of a network carrier, the network architecture for LTE is greatly simplified from its predecessors because LTE is an Internet Protocol (IP) based packet-switched network only. Granted, it doesn’t have the capability to handle voice calls and text messages natively (which should change with the introduction of VoIP with LTE-A), but the overall cost of building and maintaining these next generation networks will reduce, with features such as plug and play, self configuration, and self optimization.
Global Network and Subscription Growth
Regardless of the chatter surrounding LTE-Advanced and even 5G, LTE itself is still in its very early stages, from a global adoption perspective. As expected, the largest LTE connections can be found in the US and Canada with a whopping 64.8 million LTE connections, as of Q2 2013.
Global LTE subscriptions have also been increasing at an impressive rate, increasing from 75 million in December 2012, to 126 million by June 2013.
As far as network growth is concerned, LTE is currently available as many as 200 markets as of August 2013, with that number set to grow to 425 by 2016. Granted, this is not an indication of coverage in the particular markets, but a sign of the commitment of various mobile network operators around the world.
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