Page 326 - From GMS to LTE

312 From GSM to LTE-Advanced Pro and 5G

devices. However, LTE was never designed to be extremely power efficient, to handle
potentially tens of thousands of IoT devices per cell or to support low‐complexity, cheap
devices that only transmit very small amounts of data. Over the past few years, 3GPP
has thus specified a number of enhancements for LTE from simple procedural modifi-
cations to a new air interface to enable connectivity for IoT devices with the following
goals in mind:
Low‐cost radios in devices that cost $5 or less;
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Thousands of devices per cell that transmit only a few bytes per day;
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Ultra‐low power consumption, battery life of up to 10 years for devices that transmit
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only a few bytes per day;
Efficient support for devices with low datarates, i.e. a few hundred kilobits per second
●
maximum throughput in exchange for simplicity, low cost and significantly increased
radio sensitivity (deep indoor coverage).
In practice, one technology does not fit all potential use cases. Some IoT applica-
tions might want to transmit data quite frequently and at a bitrate of a few hundred
kilobits per second while a compromise can be made on power efficiency and indoor
coverage in return. Other IoT devices might want to exchange only a few bytes a day
but must do so from a considerable distance from a base station or may be installed in
a basement where the 10 or 20 MHz channels used by LTE today simply do not reach.
To address the different requirements, several independent enhancements have been
specified and a number of new device categories have been specified to address the
different use cases:
LTE Category 1: Offers speeds up to 10 Mbit/s
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LTE Category 0: Offers speeds up to 1 Mbit/s
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LTE Category M1: Offers speeds up to 1 Mbit/s with power efficiency enhancements
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LTE Category NB1: For Narrow‐Band IoT (NB‐IoT) applications, devices with top
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speeds of a few hundred kbit/s but typically using much less, significant power‐
efficiency enhancements and deep indoor‐coverage extensions.
All enhancements that were specified over time have in common that no new network
infrastructure is required, i.e. the already existing LTE infrastructure of a network opera-
tor can be reused with a software update of the eNode‐Bs and core network components.
No extra base station sites need to be deployed as an existing eNode‐B can simultane-
ously communicate with traditional LTE mobile broadband devices and devices that
implement the new device categories. In 3GPP these enhancements are referred to as
enhancements for Machine Type Communication (MTC) and Cellular Internet of
Things (CIoT) applications.

4.19.1 LTE Cat‐1 Devices
Perhaps it is somewhat surprising that even the very first version of the 3GPP LTE
specification (Release 8) contains a device category (Cat‐1) for simpler and more power‐
efficient devices that are only required to support a throughput of 10 Mbit/s. To drive
down complexity, Cat‐1 devices can be built with a single antenna, i.e. without MIMO
(Multiple Input Multiple Output) capabilities. In practice, however, not many devices of
this category have appeared on the market.