IoT Applications and Networks

INTERNET OF
THINGS
PREPARED BY ABDELRAHMAN FADY
PHOTO BY WILGENGEBROED ON FLICKR / CC BY 2.0

CONTENTS
 Background
 Use Cases
 Standardization
 Requirements
 Network
 Physical Layer
 Operation Modes
 Downlink
 Uplink
 Protocol Stack
 Cell Access
 System information
 RACH
 Cell Selection and reselection
 Connection Handling
 Connection Control –RRC
 Connection Control –UE Capability
 Connection Control- Paging
 Power control
 Data Transfer
 Control Plane
 User Plane
 Performance

BACKGROUND
 The LPWA market has existed for about 10 years; it’s not a
new thing. The current technologies (solutions) supporting
this market are fragmented and non-standardized, therefore
there are shortcomings like poor reliability, poor security, high
operational and maintenance costs. Furthermore, the new
overlay network deployment is complex.
 NB-IOT overcomes the above defects, with all the advantages
like wide area ubiquitous coverage, fast upgrade of existing
network, low-power consumption guaranteeing 10 year
battery life, high coupling, low cost terminal, plug and play,
high reliability and high carrier-class network security, unified
business platform management. Initial network investment
may be quite substantial and superimposed costs are very
little. NB-IOT perfectly matches LPWA market requirements,
enabling operators to enter this new field.

BACKGROUND
 Business opportunities
 NB-IOT enables operators to operate
traditional businesses such as Smart
Metering, Tracking, by virtue of ultra-low-
cost ($ 5 ) modules and super connectivity
(50K / Cell), also opens up more industry
opportunities, for example, Smart City,
eHealth.
 NB-IOT makes it possible for more things to
be connected, but also managing the
commercial value of the resulting Big Data is
a big task, operators can carry out
cooperation with related industries, in
addition to selling connections, they can
also sell data.

BACKGROUND
 below shows as one output example of five-year revenue forecast (connectivity only) by Huawei
for Germany divided by nine industries

BACKGROUND
The business is scalable and can be grown by demands by orienting the service introduction and go to market strategy
on use cases which are profitable at a given point of time and contributing to the operator’s bottom line allowing
further business expansion. As the operator can reuse his existing sites, no specific investment in towers or acquisition
of sites are needed.

IOT USES
CASES
the various services and applications supported by LPWA has
been classified under four categories; IOT Appliance, Personal,
Public and Industry.

IOT USES
CASES
Smart metering helps saves manpower by remotely collecting electricity, water
and gas meter data over the cellular network. This is gaining quite an amount of
momentum with most of the top European MNOs taking an interest in this topic
mainly due to the market opportunity it presents. Smart metering will
consequently help cut down cost generated from manual meter reading and
changing of meter batteries, which seems to be the two major cost drivers for
conventional metering. Smart metering includes smart meters for water, gas and
electricity.

IOT USES
CASES
Security has always been a very important aspect of human living , people
at all times want to be guaranteed of home safety. Alarms and event
detection will help to rapidly inform that user about a detected home
intrusion. This system will not only offer inteligent protection from
intrusion but will also offer intelligence for detected events that can lead to
a fire outbreak like a sudden increase in home temperature or smoke.
Alarms and events detectors will make use of sensors placed devices in
ideal locations in the home that constantly communicates with the LPWA
network, this use case will make use of a very low data throughput and
battery life of the devices will be ultra critical.

IOT USES
CASES
Garbage bins in city are not built by demand, and most of time the collecting
trucks routes and schedule are fixed which is not optimal for a smooth
collection. Smart garbage cans can signal to the waste management agent
when the garbage can is full and in need of service, the best collection route
will be calculated and delivered to the drivers. Historical collection data can
provide optimized routes and guide on the right-size garbage can for each
location. Charging for this service can be done on sensor amount or on
monthly fee basis.

IOT USES
CASES
Large volumes of sensor data sent from tracking devices on shipping
containers are aggregated and taken into an analysis to ensure that real time
tracking of the location of shipments can be made possible. Alerts and
optimized service recommendations are sent to technicians on their iPads, so
that they can take preemptive actions in -real time. Charging model for this
application can be done on a monthly payment or postpaid basis.

IOT USES
CASES
Asset tracking mainly deals with monitoring methods of physical assets
made possible by a module on the asset broadcasting its location.
Assets are usually tracked using GPS technology. This service is best
leveraged in the logistics and transportation management industry,
where through the use of sensors in modules sending information over
the cellular network it is possible to gather and manage data relating
to the current geographical location of assets. Asset tracking helps the
owners of the assets to detect and preemtively react to unexpected
events.

IOT USES
CASES
Farming industry is a sector with slim margins, and the way to survive
in this industry is to optimize the general agriculture production
including crops and livestock. Developing a sensor function to ensure
the feeding of cattle has an optimized mix of nutritions to improve the
yields from farming, and to reduce the waste of cattle feed. Installing
sensors in the farming equipment that mix the cattle’s feed, through
sensors measurements the variation in the cattle diet can quickly be
identified, assessed and corrected. Charging model for this application
can be done on a monthly payment or postpaid basis.

IOT USES
CASES
Conventionally, smart home application are deployed on short range
technologies like Z-Wave, Zigbee but a home gateway is needed. In
the case, where the appliance is embedded with an NB-IOT chipset the
benefits are surprising. For example, management becomes more
efficient through improvements in big data analysis. IOT appliance
mainly comprises of LPWA applications that aims to provide
intelligence for the user through sensors and devices that are found in
the local area.

IOT USES
CASES
Connected wearables in the past few
years have taken center stage and
increasingly becoming a lucrative
industry as it is an application that
mainly revolves around health, fitness
and wellness. According to Cisco, there
will be 177M connected wearables by
2018. Its market value is estimated at
$250M in 2015 and is set to rise to
$1.6B in 2022. A report released by
Research&Markets and Berg Insight
also estimated that global shipments of
connected wearables in 2014 was 19
million and this figure is set to hit
168.2million by 2019 growing at a
CAGR of 74.8%. Some of the few
products that are making inroads in
this industry are JawBone, GoPro &
Nike just to name a few. While
smartphone giants like Apple, Sony and
Samsung are more linked to
For bike rental companies it is vital to keep
track of where the bike is at the moment,
especially if it gets stolen. A bike rental
company in Holland has embedded an M2M
SIM card into the bike’s frame, and in this
way the bike rental company can always find
the bike. The M2M SIM is embedded into
the bike in a non visible placeIf the bike is
not returned to the rental company then the
bike is positioned via the SIM. The rental
cost for bikes can be reduced since the
number of stolen bikes dramatically
decrease. Stolen bikes can easily and quickly
be located by the police via the SIM.
Charging model can be done on a
monthly payment or postpaid
basis.

IOT USES
CASESThe world’s population is aging, and senior people living alone at home
need care in an easy and affordable way. Also parents have a great
interest in being assured about their wellbeing and
activities. This use case provides realtime tracking of kids and the
elderly. The information about their activities to the cloud. Real-time
insights about the their status can be received on the users smartphone or
other device.

IOT USES
CASES –
OPERATOR
REFRENCE
CASES
Parking can be a challenging issue, especially in urban areas where 30 % of all traffic
congestion is caused by drivers circling around to find a parking space. Smart parking
provides parking information to citizens in real time to enable better parking management.
Huawei and a top operator are working on a smart parking project. Operator expects tens of
millions of devices to be connected with this smart parking service. Another collaborator in
this project is Neul, who provides the platform. In this service, sensors that are placed under
cars will communicate with the parking server through the cellular network to gain parking
information. The operator and Huawei completed field trials for the smart parking project in
July 2015 with Proof of Concepts already done. The commercialization of this project is
expected in the second quarter of 2016.

IOT USES
CASES –
OPERATOR
REFRENCE
CASES
Smart metering as mentioned earlier enable the automated collection of utility
meter data (Electricity, Water & Gas). Huawei and another operator are
collaborating on an end to end smart metering solution. During Mobile World
Congress 2015, Huawei and the operator unveiled this partnership on end to
end smart metering project. Other players like Neul, Veolia, Kamstrup and
Ublox are all collaborating efforts on this project that is planned to be
launched in the first half of 2016.
Proof of Concept for the smart metering project have already been completed,
Huawei and the operator are looking forward to conducting field trials in
November 2015.Commercialization of the smart metering project is expected
in the third quarter of 2016.

REQUIREMENTS
From the general MTC requirements mentioned in the previous chapter, the following standard specific
requirements for NB-IoT were derived:
 Minimize the signaling overhead, especially over the radio interface
 Appropriate security to the complete system, including the core network
 Improve battery life
 Support delivery of IP and non-IP data [
 Support of SMS as a deployment option

REQUIREMENTS
In order to fulfill these requirements, many advanced and even basic features of LTE Release 8/9 are not
supported. The most striking example is the lack of handover for UEs in the connected state. Only cell
reselection in the idle state is supported, which is even restricted to be within the NB-IoT technology. As
there is no interaction with other radio technologies, also the associated features are not supported.
Examples are the lack of LTE-WLAN interworking, interference avoidance for in-device coexistence, and
measurements to monitor the channel quality. Most LTE-Advanced features are also not supported. This
concerns e.g. Carrier Aggregation, Dual Connectivity, or device-to-device services. In addition, there is no
QoS concept, because NB-IoT is not used for delay sensitive data packets. Consequently, all services
requiring a guaranteed bit rate, like real time IMS, are not offered in NB-IoT as well.

NETWORK  Core Network
 Access network
 Frequency Bands

CORE NETWORK
In order to send data to an
application, two optimizations
for the cellular internet of
things (CIoT) in the evolved
packet system (EPS) were
defined, the User Plane CIoT
EPS optimisation and the
Control Plane CIoT EPS
optimisation. Both
optimisations may be used but
are not limited to NB-IoT
devices.

CORE NETWORK
On the Control Plane CIoT EPS optimisation,
UL data are transferred from the eNB
(CIoT RAN) to the MME. From there, they
may either be transferred via the Serving
Gateway (SGW) to the Packet Data Network
Gateway (PGW), or to the Service Capability
Exposure Function (SCEF) which however is
only possible for non-IP data packets.
From these nodes they are finally forwarded
to the application server (CIoT Services).
DL data is transmitted over the same paths
in the reverse direction. In this solution,
there is no data radio bearer set up, data
packets are sent on the signaling radio
bearer instead. Consequently, this solution
is most appropriate for the transmission of
infrequent and small data packets.

CORE NETWORK
The SCEF is a new node designed
especially for machine type data. It is
used for
delivery of non-IP data over control
plane and provides an abstract interface
for the
network services (authentication and
authorization, discovery and access
nework
capabilities).
With the User Plane CIoT EPS
optimisation, data is transferred in the
same way as the
conventional data traffic, i.e. over radio
bearers via the SGW and the PGW to the
application
server. Thus it creates some overhead on
building up the connection, however it
facilitates a sequence of data packets to
be sent. This path supports both, IP and
non-
IP data delivery.

ACCESS
NETWORK
The eNBs are connected to the
MME and S-GW using the S1
interface, with the difference
of carrying the NB-IoT messages
and data packets. Even though
there is no
handover defined, there is still an
X2 interface between two eNBs,
which enables a fast resume after
the UE goes to the idle state, "RRC
Connection Establishment",

FREQUENCY BANDS
For the frequency bands, the
same frequency numbers as in
LTE are used, with a subset
defined for NB-IoT. In Release
13, these are the following
bands
It is worth mentioning that
most frequencies are in the
lower range of existing LTE
bands. This reflects that for
machine type communications
there are a lot of devices
expected in difficult radio
conditions.

PHYSICAL LAYER  Operation Modes
 Downlink structure
 Uplink Structure
 Power Control

OPERATION MODES
NB-IoT technology occupies a
frequency band of 180 kHz bandwidth
[8], which corresponds to one
resource block in LTE transmission.
With this selection, the following
operation modes are possible:
 Stand alone operation. A possible
scenario is the utilization of
currently used GSM frequencies.
With their bandwidth of 200 kHz
there is still a guard interval of 10
kHz remaining on both sides of
the spectrum
 Guard band operation, utilizing
the unused resource blocks within
an LTE carrier’s guard-band
 In-band operation utilizing
resource blocks within an LTE
carrier
In the in-band operation, the assignment of resources between LTE and
NB-IoT is not fixed. However, not all frequencies, i.e. resource blocks within
the LTE carrier, are allowed to be used for cell connection. They are
restricted to the following values:

OPERATION MODES
In order to cope with different radio conditions, there may be up to 3 coverage enhancement (CE) levels, CE
level 0 to CE level 2. CE level 0 corresponds to normal coverage, and CE level 2 to the worst case, where the
coverage may be assumed to be very poor. It is up to the network, how many CE levels are defined. A list of
power thresholds for the received reference signals is broadcasted in the cell for each CE level. The main
impact of the different CE levels is that the messages have to be repeated several times.
For Release 13, FDD half duplex type-B is chosen as the duplex mode. This means that UL and DL are
separated in frequency and the UE either receives or transmits, however not simultaneously. In addition,
between every switch from UL to DL or vice versa there is at least one guard subframe (SF) in between,
where the UE has time to switch its transmitter and receiver chain.

DOWNLINK
For the DL, three physical channels
● NPBCH, the narrowband physical broadcast
channel
● NPDCCH, the narrowband physical downlink
control channel
● NPDSCH, the narrowband physical downlink
shared channel
and two physical signals
● NRS, Narrowband Reference Signal
● NPSS and NSSS, Primary and Secondary
Synchronization Signals
Channels and Signals

DOWNLINK
In the DL, OFDM is applied using a 15 kHz subcarrier
spacing with normal cyclic prefix (CP). Each of the
OFDM symbols consists of 12 subcarrier occupying
this way the bandwitdh of 180 kHz. Seven OFDMA
symbols are bundled into one slot, so that the slot
has the following resource grid.
There are 1024 cyclically repeated radio frames, each
of 10ms duration. A radio frame is partitioned into 10
SFs, each one composed of two slots. In addition to
the system frames, also the concept of hyper frames
is defined, which counts the number of system frame
periods, i.e. it is incremented each time the system
frame number wraps. It is a 10 bit counter, so that
the hyper frame period spans 1024 system frame
periods, corresponding to a time interval of almost 3
hours.
Frame structure

DOWNLINK
The narrowband reference signal (NRS) is
transmitted in all SFs which may be used for
broadcast or dedicated DL transmission, no matter
if data is actually transmitted or not.
Depending on the transmission scheme, NRS is
either transmitted on one antenna port or on two.
Its values are created like the CRS in LTE, with the
NCellID taken for the PCI.
NRS is additionally cyclically shifted by NCellID
mod 6 in the frequency range. When NRSs are
transmitted on two APs, then on every resource
element used for NRS on AP0, the same resource
element on AP1 is set to zero and vice versa.
Narrowband Reference Signal

DOWNLINK
For a first synchronization in frame and subframe and
in order to determine the NCellID, the LTE concept of
Primary Synchronization Signal (PSS) and Secondary
Synchronization Signal (SSS) is reused. With these
signals, also timing and frequency estimation may be
refined in the UE receiver. In order to distinguish
these signals from their LTE counterparts, they are
denoted as NPSS and NSSS, respectively.
The first 3 OFDM symbols are left out, because they
may carry the PDCCH in LTE when NB-IoT is operated
in the in-band mode. Note that during the time when
the UE synchronizes to the NPSS and NSSS, it may
not know the operation mode, consequently this
guard time applies to all modes. In addition, both
synchronization signals are punctured by the LTE's
CRS. It is not specified, which of the antenna ports is
used for the synchronization signals, this may even
change between any two SFs.
Narrowband Sync Signals

DOWNLINK
A length 11 Zadoff-Chu sequence in frequency domain is taken
for the sequence generation of the NPSS. This sequence is fixed
and therefore carries no information about the cell. It is
transmitted in SF5 of each radio frame, so that its reception
allows the UE to determine the frame boundary.
The NSSS sequence is generated from a length-131 frequency
domain Zadoff-Chu sequence, binary scrambled and cyclically
shifted depending on the radio frame number. NCellID is an
additional input parameter so that it can be derived from the
sequence. Like in LTE, 504 PCI values are defined. NSSS are
transmitted in the last SF of each even numbered radio frame.
For the in-band operation, transmission of the NPSS and NSSS,
as well as the NPBCH described in the next section, may only be
done on PRBs ,The carrier selected for receiving this information
is called anchor carrier.
Using this construction, the UE can not confuse the NB
synhronization signals with those transmitted by the LTE system.
Consequently, there is no danger of a false detection and UEs
with either technology are automatically routed to the correct
frequency range.
Narrowband Sync Signals

DOWNLINK
 NPBCH carries the Narrowband Master
Information Block (MIB-NB). The MIB-NB contains
34 bits and is transmitted over a time period of
640ms, i.e. 64 radio frames. The following
information is provided therein:
 4 bits indicating the most significant bits (MSBs) of
the System Frame Number (SFN), the remaining least
significant bits (LSBs) are implicitely derived from the
MIB-NB start
 2 bits indicating the two LSBs of the hyper frame number
 4 bits for the SIB1-NB scheduling and size
 5 bits indicating the system information value tag
 1 bit indicating whether access class barring is applied
 7 bits indicating the operation mode with the mode
specific values
 11 spare bits for future extensions
Narrowband broadcasting channel

DOWNLINK
After physical layer baseband processing, the resulting MIB-NB
is split into 8 blocks. The first block is transmitted on the first
subframe (SF0) and repeated in SF0 of the next 7 consecutive
radio frames, respectively. In SF0 of the following radio frame,
the same procedure is done for BL2. This process is continued
until the whole MIB-NB is transmitted. By using SF0 for all
transmissions, it is avoided that NPBCH collides with a potential
MBSFN transmission on LTE, if NB-IoT is deployed as in-band
operation.
Symbols are mapped around the NRS and the LTE CRS, where it
is always assumed that two antenna ports are defined for NRS
and 4 antenna ports for CRS. This assumption is necessary,
because the UE gets the actual antenna port information only
from reading the MIB-NB. The reference signal location in the
frequency range is given by the NCellID, provided by the NSSS.
Although the NCellID may be different to the PCI in the in-band
operation, its range is restricted so that it points to the same
frequency locations, hence the CRS's cyclic shift in the frequency
range is known to the UE. Again, the first 3 OFDM symbols are
left out in order to avoid a possible conflict with the LTE's
control channel.
Narrowband broadcasting channel

The principle of control and shared channel
also applies for NB-IoT, defining the
Narrowband Physical Downlink Control
Channel (NPDCCH) and the Narrowband
Phsyical Downlink Shared Channel
(NPDSCH). Not all SFs may be used for
transmission of the dedicated DL channels.
In RRC signaling, a bitmap of either 10 or 40
bit indicating the valid SFs may be signaled,
which is applied in a periodic way. For the
case that a SF is not indicated as valid,
dedicated DL channel transmission is
postponed until the next valid SF.
The NPDCCH indicates for which UE there is data in the
NPDSCH, where to find them and how often they are repeated.
Also, the UL grants are provided therein, showing the resources
the UE shall use for data transmission in the UL. Finally,
additional information like paging or system information update
is contained in the NPDCCH as well.
Resource elements used for NPDCCH are indicated in green
color. They have to be mapped around the NRS shown in blue,
and for the in-band operation also around the CRS (violet).
NPDCCH

NPDCCH
A parameter lN start, the control region size signaled by
NB-SIB1, indicates the OFDM start symbol. This way
conflict with the LTE control channel can be avoided for
the in-band operation. For the guard-band and
standalone operation modes, the control region size is
by default 0, which provides more resource elements for
the NPDCCH. On each SF, two narrowband control
channel elements (NCCEs) are defined, NCCE0 and
NCCE1. They are indicated in Figure with dark green
color (NCCE0), and light green (NCCE1). Two NPDCCH
formats are defined to use them:
 NPDCCH format 0 taking one NCCE. Consequently, two
of them can be transmitted within a SF.
 NPDCCH format 1 taking both NCCEs.

NPDCCH
In order for the UE to find the control information with a reasonable
amount of decoding complexity, NPDCCH is grouped into the
following search spaces
 Type-1 common search space, used for paging
 Type-2 common search space, used for random access
 UE specific search space.
Each NPDCCH may be repeated several times with an upper limit
configured by the RRC. In addition, Type-2 common search space
and UE specific search space are provided by RRC, whereas the
Type-1 common search space is given by the paging opportunity
SFs, Different radio network temporary identifier (RNTI) are
assigned to each UE, one for random access (RA-RNTI), one for
paging (P-RNTI), and a UE specific identifier (CRNTI) provided in the
random access procedure. These identifiers are implicitely indicated
in the NPDCCH's CRC. So, the UE has to look in its search space for
that RNTI, and, if found, decodes the NPDCCH.

NPDCCH
Three DCI formats are defined in Release 13, DCI format
N0, N1 and N2
When the UE receives the NPDCCH, it can distinguish the different
formats in the following way: DCI format N2 is implicitly indicated in the
way that the CRC is scrambled with the P-RNTI. If the CRC is
scrambled with the C-RNTI, then the first bit in the message indicates
whether DCI format N0 or N1 is contained. For the case that the CRC
is scrambled with the RA-RNTI, the content is a restricted DCI format
N1 including only those fields required for the RACH response.
Included in the DCI formats N0 and N1 is the scheduling delay, i.e. the
time between the NPDCCH end and the NPDSCH start or the
NPUSCH start. This delay is at least 5 SFs for the NPDSCH and 8 for
the NPUSCH. For DL transmission via DCI format N2, the scheduling
delay is fixed to 10 SFs.

NPDSCH
An NPDSCH SF has the same structure as for the NPDCCH shown in
Figure. It starts at a configurable OFDM symbol lN start and is mapped
around the NRS and, for inband operation, the LTE CRS. lN start is
provided by RRC signaling for the in-band operation, and is 0
otherwise.
A maximum transport block size (TBS) of 680 bit is supported. The
mapping of a transport block spans NSF SFs. The transport block is
repeated providing NRep identical copies, using an SF interleaving for
an optimized reception at the UE. Both values, NSF and NRep are
indicated in the DCI. The resulting SF sequence is mapped to
NSF·NRep
consecutive SFs defined for NPDSCH.
For the DL there is no automatic acknowledgement to a transmission,
the eNB indicates this in the DCI. If this is done, the UE transmits the
acknowledgement using Downlink Physical Layer The associated
timing and subcarrier is indicated in this DCI as well. There is multi-
carrier support for all operation modes, see Chapter 5.2.2, "Multi
Carrier Configuration", on page 35, which means that another carrier
may be used when the UE is in the connected state. In the idle state,
the UE camps on the NB-IoT carrier from which it received the
synchronization signals and broadcast information, i.e. the anchor
carrier. It waits there for paging or starts access for mobile originated

SIB-NB
SIB1-NB is transmitted over the NPDSCH. Its has a period of 256 radio
frames and is repeated 4, 8 or 16 times. The transport block size and
the number of repetitions is indicated in the MIB-NB. 4, 8 or 16
repetitions are possible, and 4 transport block sizes of 208, 328, 440
and 680 bits are defined, respectively. The radio frame on which the
SIB1-NB starts is determined by the number of repetitions and the
NCellID. SF4 is used for SIB1-NB in all radio frames transmitting SIB1-
NB. As the other transmission parameters are also fixed, there is no
associated indication in the control channel. SIB1-NB content may only
be changed on each modification period, which has a length of 4096
radio frames, i.e. 40.96 seconds. This corresponds to 4 SFN periods,
which is why the 2 LSBs of the hyper frame number are indicated in
MIB-NB. If such a modification occurs, it is indicated in the NPDCCH
using DCI format N2. Although sent over the NPDSCH, SIB1-NB
resources are mapped like the MIB-NBshown in NPBCH Figure i.e.
leaving out the first 3 OFDM symbols. This is necessary,
because the UE knows the start of the resource mapping from SIB1-NB,
so it needs to decode this SIB first.

UPLINK
For the uplink (UL), the two physical channels
● NPUSCH, the narrowband physical uplink shared
channel
● NPRACH, the narrowband physical random access
channel
● DMRS, Demodulation Reference Signal
Except for RACH transmission, all data are sent
over the NPUSCH. This includes also
the UL control information (UCI), which is
transmitted using a different format. Consequently
there is no equivalent to the PUCCH in LTE.

IN THE UL, SINGLE
CARRIER
FREQUENCY
DIVISION MULTIPLE
ACCESS (SC-FDMA)
IS APPLIED,
EITHER WITH A 3.75
KHZ OR 15 KHZ
SUBCARRIER
SPACING. ENB
DECIDES WHICH
ONE TO USE.
The resource grid for the UL is the same as for the DL,
when the 15kHz subcarrier
spacing is applied,
For the 3.75kHz subcarrier spacing, the resource
grid for a slot has a modified structure:
Again there are 7 OFDM symbols within a slot. According to the
OFDM principles, the symbol duration for 3.75 kHz subcarrier
spacing has four times the duration compared to 15 kHz, which
results in a slot length of 2 ms.

PHYSICAL
UPLINK SHARED
CHANNEL
On the physical UL shared channel NPUSCH, two formats are
defined. NPUSCH format 1 is for UL transport channel data over the
UL-SCH, with transport blocks not bigger than 1000 bits. NPUSCH
format 2 carries UL control information (UCI), which in Release 13 is
restricted to an acknowledgement of a DL transmission. The smallest
unit to map a transport block is the resource unit (RU). Its definition
depends on the PUSCH format and subcarrier spacing. For
NPUSCH format 1 and 3.75 kHz subcarrier spacing, an RU consists
of 1 subcarrier in the frequency range, and 16 slots in the time range,
i.e. an RU has a length of 32 ms. On the 15 kHz subcarrier spacing
there are 4 options:
Number of
subcarriers
Number of
slots
RU Duration
1 16 8 ms
3 8 4 ms
6 4 2 ms
12 2 1 ms

PHYSICAL
UPLINK SHARED
CHANNEL
For NPUSCH format 2, the RU is always composed of one subcarrier
with a length of 4 slots. Consequently, for the 3.75 kHz subcarrier
spacing the RU has an 8 ms duration and for the 15 kHz subcarrier
spacing 2 ms. For NPUSCH format 2, the modulation scheme is
always BPSK. The allowed modulations for NPUSCH format 1 depend
on the selected RU:
● For RUs with one subcarrier, BPSK and QPSK may be used
● For all other RUs, QPSK is applied
A grant for UL-SCH transmission is indicated in the NPDCCH via DCI
format N0. The start time of the NPUSCH, the number of repetitions,
the number of RUs used for one transport block, and the number of
subcarriers including their position in the frequency range are indicated
in this DCI. Also the MCS index is contained, providing the modulation
scheme for the one subcarrier RUs and in addition, together with the
number of RUs, the transport block size.
Finally, For the 15kHz subcarrier spacing, this CP is the same
as for LTE using normal CP, while for 3.75kHz it is 256 samples,
corresponding to 8.3 μs. For the latter case, a period of 2304 samples
(75μs) at the end of each slot remains empty, which is used as a guard
interval. For the in-band operation, this guard interval may be used to
transmit Sounding Reference Signals in the LTE system
PHYSICAL
UPLINK SHARED
CHANNEL

PHYSICAL
UPLINK SHARED
CHANNEL
REFERENCE SIGNALS
DMRS SYMBOLS ARE
CONSTRUCTED FROM
A BASE SEQUENCE
MULTIPLIED BY A
PHASE FACTOR.
THEY HAVE THE SAME
MODULATION AS THE
ASSOCIATED DATA.
FOR NPUSCH
FORMAT 2 DMRS
SYMBOLS ARE
SPREAD WITH THE
SAME ORTHOGONAL
SEQUENCE AS
DEFINED FOR THE LTE
PUCCH FORMATS 1, 1A
AND 1B.
In UL, demodulation reference signal (DMRS) is defined. It is
multiplexed with the data so that it is only transmitted in RUs containing
data transmission. There is no MIMO transmission defined for the UL,
consequently all transmissions use a single antenna port.
Depending on the NPUSCH format, DMRS is transmitted in either one
or three SCFDMA symbols per slot. For NPUSCH format 1 these are
the symbols indicated in red
As one can see from this figure, the SC-FDM symbols for DMRS
transmission depend on the subcarrier spacing. This is also true for
NPUSCH format 2 shown

PHYSICAL
UPLINK SHARED
CHANNEL
RANDOM
ACCESS
CHANNEL
In the Random Access Channel, NPRACH, a preamble is transmitted.
The associated random access procedure may be used to signal to
the cell that the UE is camping on it and wants to get access.
The preamble is based on symbol groups on a single subcarrier. Each
symbol group has a cyclic prefix (CP) followed by 5 symbols. The
following structure shows this sequence:
Two preamble formats are defined, format 0 and format 1, which
differ in their CP length. The five symbols have a duration of TSEQ =
1.333 ms, prepended with a CP of TCP = 67 μs for format 0 and 267
μs for format 1, giving a total length of 1.4 ms and 1.6 ms,
respectively. The preamble format to be used is broadcasted in the
system information.

PHYSICAL
UPLINK SHARED
CHANNEL
RANDOM
ACCESS
CHANNEL
The preamble is composed of 4 symbol groups transmitted without gaps.
Frequency hopping is applied on symbol group granularity, i.e. each
symbol group is transmitted on a different subcarrier. By construction, this
hopping is restricted to a contiguous set of 12 subcarrier. Depending on the
coverage level, the cell may indicate that the UE shall repeat the preamble
1, 2, 4, 8, 16, 32, 64, or 128 times, using the same transmission power on
each repetition. NPRACH resources are provided for each CE group
separately. They consist in the assignment of time and frequency resources
and occur periodically, where NPRACH periodicities between 40 ms and
2.56 s may be configured. Their start time within a period is provided in
system information. The number of repetitions and the preamble format
determine their end. In the frequency range, subcarrier spacing of 3.75 kHz
is applied. NPRACH resources occupy a contiguous set of either 12, 24, 36
or 48 subcarriers and are located on a discrete set of subcarrier ranges.
Depending on the cell configuration, the resources may be further
partitioned into resources used by UEs supporting multi-tone transmission
for msg3 and UEs that do not support it.

PHYSICAL
UPLINK SHARED
CHANNEL
RANDOM
ACCESS
CHANNEL
Among the 12 possibilities, the UE selects the subcarrier for the transmission of the
first preamble symbol group, if not provided by the eNB for the case of an ordered
preamble transmission. The next 3 symbol groups are determined by an algorithm
which depends only on the location of the first one. For the subcarrier selection of
the first symbol group of the next repetition, a pseudo-random hopping is applied,
where NCellID and the repetition number are used as input. The subcarrier selection
of the following symbol groups again depend only on this result. This frequency
hopping algorithm is designed in a way that different selections of the first subcarrier
lead to hopping schemes which never overlap. Hence there are as many different
congestion free preambles as there are subcarrier allocated to the NPRACH. No
further partitioning is done for NB-IoT, i.e. there is no concept like the preamble
indices applied in LTE. The preamble sequence is built upon a Zadoff-Chu
sequence, which depends on the subcarrier location. Modulation and upconversion
to the carrier frequency is done in
the same way as for LTE.

PROTOCOL STACK
The general principle for the protocol layers is to
start with the LTE protocols, reduce them to a
minimum and enhance them as needed for NB-
IoT. This way, the proven structures and
procedures are re-used while overhead from
unused LTE features is prevented. Consequently,
the NB-IoT technology can be regarded as a new
air interface also from the protocol stack point of
view, while being built on a well established
fundament.

PROTOCOL STACK
One example thereof is the bearer structure.
Signaling radio bearer are partly re-used from LTE.
There is the SRB0 for RRC messages transmitted
over the CCCH logical channel, and the SRB1 for
RRC messages and NAS messages using the
DCCH logical channel. However, there is no SRB2
defined.
In addition, a new signaling radio bearer, the
SRB1bis is defined. It is implicitely configured with
SRB1 using the same configuration, however
without the PDCP. This channel takes the role of
the SRB1 until security is activated, then SRB1bis is
not used anymore. This also implies that for the
Control Plane CIoT EPS optimisation, only SRB1bis
is used at all, because there is no security
activation in this mode.

CELL ACCESS
SIBs are indicated with the suffix NB. Each of these SIBs is defined with a
reduced and modified set of information elements, however, the type of
content is the same as in LTE, e.g. SIB16-NB describes the time information.
UEs exclusively use these SIBs and ignore those from LTE, even in the case
of in-band operation.
It is always mandatory for a UE to have a valid version of MIB-NB, SIB1-NB
and SIB2-NB through SIB5-NB. The other ones have to be valid if their
functionality is required for operation. For instance, if access barring (AB) is
indicated in MIB-NB, the UE needs to have a valid SIB14-NB. System
information acquisition and change procedure is only applied in the
RRC_IDLE state. The UE is not expected to read SIB information while being
in the RRC_CONNECTED state. If a change occurs, the UE is informed either
by paging or direct indication.
The eNB may also release the UE to the RRC_IDLE state for the purpose of
acquiring modified system information.
SYSTEM
INFORMATION

CELL ACCESS
Scheduling of the SIB information is done in an analogous way to LTE: SIB-NB
messages are grouped into SI messages, which are then transmitted in separate SI-
windows. The SI windows of different SI messages do not overlap. Their length is
indicated in SIB1-NB and is the same for all SI messages. The maximum size
of each SIB and SI message is 680 bit. Within an SI window, the SI messages are sent
over 2 or 8 consecutive valid DL SFs, depending on their transport block size, and
may be repeated several times. Scheduling information is indicated in SIB1-NB,
consequently there is no indication in the NPDCCH necessary and there is no SI-RNTI
needed.
SYSTEM
INFORMATION system information may only change at the time boundaries of a modification
period and is indicated with a paging message. An exception is the change in the
access barring (AB) indicated via SIB14-NB, this information may be changed at
any given point in time. The reason behind this exception is that AB parameters
may be required to change in a much shorter time scale. Of course, SIB16-NB is
not indicated by a paging notification, as it changes its content regularly. An
additional way to indicate changes in SIB1-NB or in SI messages is the concept of
the value tag. The associated field systemInfoValueTag is contained in MIB-NB.
This concept is used for UEs returning from an out-of-coverage location back to
coverage and for returning from a longer DRX cycle. In these cases the UE could
not receive the paging message, so it checks the value tag. If there were SIB
changes, the value tag is modified. However, the UE must read the system
information anyway if it was out-of coverage for more than 24 hours.

CELL ACCESS
RACH
For NB-IoT the RACH procedure is
always contention based and starts
with the transmission
of a preamble
After the associated response from
the eNB, a scheduled message,
msg3, is transmitted in order to start
the contention resolution process. The
associated contention resolution
message is finally transmitted to the
UE in order to indicate the successful
completion of the RACH procedure.
Upon transmission of the preamble, the UE first calculates its RA-RNTI
from the transmission time. It looks then in the PDCCH for the DCI format
N1 scrambled with the RA-RNTI, in which the Random Access Response
message is indicated. The UE expects this message within the Response
Window, which starts 3 SFs after the last preamble SF and has a CE
dependent length given in SIB2-NB
C-RNTI, TA and UL Grant

CELL ACCESS
CELL SELECTION
NB-IoT is designed for infrequent and short messages between the UE
and the network. It is assumed that the UE can exchange these
messages while being served from one cell, therefore, a handover
procedure during RRC_CONNECTED is not needed. If such a cell
change would be required, the UE has first go to the RRC_IDLE state
and re-select another cell therein. For the RRC_IDLE state, cell re-
selection is defined for both, intra frequency and inter frequency cells
Inter frequency refers here to the 180 kHz carrier, which means that
even if two carriers are used in the in-band operation embedded into
the same LTE carrier, this is still referred to as an inter frequency re-
selection.
In order to find a cell, the UE first measures the received power and
quality of the NRS. These values are then compared to cell specific
thresholds provided by the SIB-NB. The S-criteria states that if both
values are above these thresholds, the UE considers itself to be in
coverage of that cell. If the UE is in coverage of one cell, it camps on it.
Depending on the received NRS power, the UE may have to start a cell
re-selection. The UE compares this power to a re-selection threshold,
which may be different for the intra-frequency and the inter-
frequency case. All required parameters are received from the actual
serving cell, there is no need to read SIB-NBs from other cells.

CELL ACCESS
CELL SELECTION
Among all cells fulfilling the S-criteria, the UE ranks the cells with
respect to the power excess over another threshold. A hysteresis is
added in this process in order to prevent too frequent cell
reselection, and also a cell specific offset may be applied for the
intra frequency case. Contrary to LTE, there are no priorities for the
different frequencies. The UE finally selects the highest ranked cell
which is suitable, i.e. from which it may receive normal service.
When the UE leaves RRC_CONNECTED, it does not necessarily
select the same carrier to find a cell to camp on. The
RRCConnectionRelease messsage may indicate the frequency on
which the UE first tries to find a suitable cell. Only if the UE does
not find a suitable cell on this frequency, it may also try to find
one on different frequencies
The cell selection criterion S is fulfilled when: Srxlev > 0 AND Squal
> 0 where: Srxlev = Qrxlevmeas – Qrxlevmin – Pcompensation -
Qoffsettemp Squal = Qqualmeas – Qqualmin - Qoffsettemp

CELL ACCESS
CELL RE-SELECTION
When evaluating Srxlev and Squal of non-serving cells for
reselection purposes, the UE shall use parameters provided by the
serving cell. Following rules are used by the UE to limit needed
measurements: - If the serving cell fulfils Srxlev > SIntraSearchP,
the UE may choose not to perform intra-frequency measurements.
Otherwise, the UE shall perform intra-frequency measurementsThe
UE shall apply the following rules for NB-IoT inter-frequencies
which are indicated in system information: - If the serving cell
fulfils Srxlev > SnonIntraSearchP, the UE may choose not to
perform inter-frequency measurements. - Otherwise, the UE shall
perform inter-frequency measurements.
The cell-ranking criterion Rs for serving cell and Rn for
neighbouring cells is defined by:
Rs = Qmeas,s + QHyst – Qoffsettemp
Rn = Qmeas,n - Qoffset - Qoffsettemp

CONNECTION
CONTROL
RRC CONTROL
With a system not supporting handover to a different technology ,
the state model of the RRC becomes quite simple
As in LTE, there are only two states, RRC_IDLE and
RRC_CONNECTED. However, there are no transitions to the
associated UTRA and GSM states, because handovers to
these technologies are not supported. There is also no
handover to LTE, because LTE is regarded as a different RAT.

CONNECTION
CONTROL
RRC CONTROL

CONNECTION
CONTROL
UE CAPABILITY
When the UE connects to the network, the eNB does neither
know on which release the UE is built upon, nor which of the
optional features defined therein it supports. In order to get
this information the UE Capability Transfer procedure is
defined as shown.
UE capability transfer is always initiated by the eNB, because
the UE cannot know whether the eNB has this information
already from the network or from a previous session.
The capabilities include the release the UE is built upon, the
UE category, the list of supported bands and the capability to
set up multiple bearer. In addition, the UE may indicate
whether it supports multi carrier operation, and multi tone
transmission in UL. Also the maximal number of RoHC context
sessions and the supported profiles may be contained.

CONNECTION
CONTROL
PAGING
Paging is used to trigger an RRC connection and to indicate a change in system
information for UE in RRC_IDLE mode. A paging message is sent over the NPDSCH
and may contain a list of UEs to be paged and the information, whether paging is for
connection setup or whether system information has changed. Each UE which finds its
ID in this list forwards to its upper layer that it is paged, and may receive in turn the
command to initialize an RRC connection. If system information has changed, the UE
starts to read SIB1-NB and may obtain from there the information, which SIBs have to
be read again. The UE in the RRC_IDLE state only monitors some of the SFs with
respect to paging, the paging occasions (PO) within a subset of radio frames, the paging
frames (PF). If coverage enhancement repetitions are applied, the PO refers to the first
transmission within the repetitions. The PFs and POs are determined from the DRX
cycle provided in SIB2-NB, and the IMSI provided by the USIM card. DRX is the
discontinuous reception of DL control channel used to save battery lifetime. Cycles of
128, 256, 512 and 1024 radio frames are supported, corresponding to a time interval
between 1.28s and 10.24s. Due to the fact that the algorithm to determine the PFs and
POs also depends on the IMSI, different UEs have different paging occasions, which are
uniformly distributed in time. It is sufficient for the UE to monitor one paging occasion
within a DRX cycle, if there are several paging occasions therein, the paging is repeated
in every one of them. The concept of extended DRX (eDRX) may be applied for NB-IoT
as well. This is done using the hyper frames If eDRX is supported, then the time interval
in which the UE does not monitor the paging messages may be considerably extended,
up to almost 3 hours. Correspondingly, the UE must know on which HFN and on which
time interval within this HFN, the paging time window (PTW), it has to monitor the
paging. The PTW is defined by a start and stop SFN. Within a PTW, the determination of
the PFs and POs is done in the same way as for the non-extended DRX.

POWER CONTROL - UPLINK
In the UL, the transmitted power depends on a combination of cell specific parameters,
the selected RU and UE measured parameters . For the case that there are maximally
2 repetitions, the power on slot i is given by
If there are more than two repetitions, the transmission power is generally given by
PCMAX,c(i).
PCMAX,c(i) is the cell specific maximum transmit power on slot i. With the above construction, the transmitted
power may never exceed this threshold. MNPUSCH,c depends on the bandwidth of the selected RU and the
subcarrier spacing, PO_NPUSCH,c a combination of different parameters signaled by the RRC, which depends on
whether the transport block is for UL-SCH data (j=1) or for the RACH message (j=2). PLc is the
path loss estimated by the UE. This factor is weighted by αc (j), which for NPUSCH format 1 is provided by
RRC, otherwise the fixed value of 1 is applied. In other words, this factor indicates how strong the path loss
shall be compensated.

DATA TRANSFER
There are two ways for the data transfer, the Control Plane CIoT EPS optimisation and the User Plane CIoT
EPS
optimisation. The MME indicates support for each of those optimizations. For mobile originated data, the
UE may select among the supported options. For mobile terminated data the MME choses the
optimization and may take the UE preference into account, which is signaled to the network in the attach
procedure.Control Plane CIoT EPS Optimisation
For the Control Plane CIoT EPS optimisation, data exchange
between the UE and the eNB is done on RRC level. In the DL, data
packets may be piggybacked in the RRCConnectionSetup message
or in the UL in the RRCConnectionSetupComplete message. If this is
not sufficient, data transfer may be continued using the two
messages DLInformationTransfer and ULInformationTransfer:
For this data transfer method, security on AS level is not applied. As
there is also no RRC connection reconfiguration, it may immediately
start after or during the RRC connection setup or resume procedure,
respectively. Of course, the RRC connection has to be terminated
afterwards with the RRC connection release.

DATA TRANSFER
User Plane CIoT EPS optimisation
In the User Plane CIoT EPS optimisation data is transferred
over the conventional user plane through the network
Two cases have to be distinguished: When the previous
RRC connection was released with a possible resume
operation indicated, the connection may be requested as a
resume procedure If this resume procedure is successful,
security is established withcupdated keys and the radio
bearer are set up like in the previous connection. If there
was no previous release with a resume indication, or if the
resume request was not accepted by the eNB, security and
radio bearer have to be established.
After having set up the RRC connection, the first
step is to establish AS level security. This is done via the
Initial security activation procedure:

DATA TRANSFER
User Plane CIoT EPS optimisation
In the SecurityModeCommand message, the eNB provides the UE
with the ciphering algorithm to be applied on the SRB1 and the
DRB(s), and the integrity protection algorithm to protect the
SRB1. All algorithms defined for LTE are also included in NB-IoT.
With this message, the SRB1bis automatically changes to the
SRB1, which is used for the following control messages. After the
security is activated, DRBs are set up using the RRC connection
reconfiguration procedure In the reconfiguration message, the
eNB provides the UE with the radio bearer, including the
configuration of the RLC and the logical channels. The latter
includes a priority used to balance the data transmission
according to the actual requirements. PDCP is only configured for
DRBs, because the SRB only uses the default values.
In the included MAC configuration, the configuration for buffer
status report (BSR), scheduling request (SR), time alignment and
DRX are provided. Finally, the physical configuration provides the
necessary parameters for mapping the data to the slots and
frequencies.

DATA TRANSFER
The RRCConnectionReconfiguration may contain the settings for an additional carrier
in UL and DL, the non-anchor carrier. When a non-anchor carrier is provided in DL, the UE shall receive all
data on this frequency. This excludes the synchronization, broadcast information and paging, which
are only received on the anchor carrier. A bitmap may be provided indicating the allowed DL SFs. The non-
anchor carrier may contain considerable more SFs for data, since it does not require synchronization and
broadcast information. Once the non-anchor carrier is configured, the UE solely listens to this one while it is
in the RRC_CONNECTED state. Consequently the UE requires only one receiver chain. In UL the same
principle applies. If an additional UL carrier is configured, the UE only takes this one for data transmission,
there is no simultaneous transmission in this carrier and the anchor carrier. For both, DL and UL, the UE
returns to its anchor carrier when it is released to the RRC_IDLE state.

DATA TRANSFER
UE1 is configured with the anchor carrier, UE2 with other carrier
in DL and UL, and UE3 with a different carrier only on DL. For
simplicity, this diagram neither considers the NPDCCH period
explained in the next section nor the SFs which are not allowed
for DL data. It shall only be interpreted in a schematic way. Even
in the in-band operation, the assigned DL carrier is not restricted
to the previously mentioned values. This restriction is only for
those carrier transmitting the NPSS, NSSS and NPBCH, i.e.
which may be used as anchor carrier. For a provided DL
frequency, all carriers are allowed. This structure allows to roll out
an NB-IoT broadband network, although each UE only has one
transmitter / receiver chain with a narrow bandwidth available.
The overhead of synchronization, broadcast in DL, and the
NPRACH resources in the UL may be restricted to one or a view
pairs of carrier, while the other ones may be completely used for
data transmission. As the reception and transmission is never
done simultaneously and always restricted to one band,
respectively, it is sufficient that the UE only has one transmitter /
receiver chain with a bandwidth of 180 kHz.

DATA TRANSFER – RECEIVING CONTROL CHANNEL
In the RRC connected state, the UE only monitors the UE
specific search space (USS) to obtain its UL grants and DL
assignments. The reconfiguration message contains the
maximum number of repetitions, which ranges from 1 up
to 2048 in powers of 2. However, the actual number of
repetitions may be smaller, as indicated in the following
table:
For the case that the actual number of repetitions is
smaller than its maximum number, the remaining
SFs may be used to send a different NPDCCH to
another UE. For example, if the maximum number
of repetitions is 4, then all SFs may contain the DCI
for one UE, or two SFs may be used for each of
two UEs, or each SF for a different UE,
respectively. Of course, the UE has to monitor all
these candidates. The reconfiguration message
also contains a parameter to describe the
NPDCCH period. With respect to the start of this
period, the USS starts either at the beginning or
at an offset of 1/8, 1/4 or 3/8 of the period length.

DATA TRANSFER – TRANSMITTING UL DATA
The DCI format N0 indicates an UL grant for transmission on the
NPUSCH, including all relevant parameters. One transport block can be
repeated several times. The arrangement of the repetitions depends on
the number of subcarriers for one RU, the subcarrier spacing and the
number of repetitions. This shall be first illuminated with an example
shown in Figure
For the case of a 15 kHz subcarrier
spacing, a transport block, named
test word (TW), is transmitted on two
RUs (a), where each RU has the
format of 3 subcarrier over 8
slots (b). A total number of 8
repetitions is applied. In figure Tn
denotes the n-th slot of the first RU,
Wm the m-th slot of the second RU.

DATA TRANSFER – RECEIVING DL DATA
The DCI format N1 indicates a DL assignment describing where and how the data symbols are transmitted on the
NPDSCH. The principle is essentially the same as for the UL, see the example shown in previous figure , however the
data packets are not grouped first into RUs. If there are no repetitions, the data packets are consecutively mapped
into slots and sent in NPDSCH SFs. For the case that there are repetitions, the mapping is similar like in multi-tone UL.
Data for two slots are first mapped into one SF, which is now repeated with the total number of repetitions, again with
an upper limit of four. Then the mapping is continued the same way until all SFs are transmitted. Finally this whole
structure is repeated until the desired number of repetitions is reached. There is an exception, when the DL data
contains SIB-NB information. In this case, the slots are transmitted consecutively like in the example in(b), and then this
whole block is repeated the appropriate number of times. Transmission gaps may be configured by the RRC for
NPDSCH transmissions with a large number of repetitions. The RRCConnectionReconfiguration message may provide
the information how big the number of repetitions shall be in order to trigger such gaps, the periodicity and the length of
their occurences. When the gap occurs, the NPDSCH transmission is postponed to the next available SF after the gap.
These gaps do not apply for NPDSCHs carrying MIB-NB or SIB-NB information.

PERFORMACNE
Capacity
•NB-IoT supports massive IoT
capacity by using only one
PRB in both uplink and
downlink. Sub-PRB UE
scheduled bandwidth is
introduced in the uplink,
including single subcarrier
NPUSCH. Note that for
coverage limited UE,
allocating higher bandwidth is
not spectrally efficient as the
UE cannot benefit from it to
be able to transmit at a higher
data rate. Based on the traffic
model , NB-IoT with one PRB
supports more than 52500
UEs per cell . Furthermore,
NB-IoT supports multiple
carrier operation. Thus, more
IoT capacity can be added by
adding more NB-IoT carriers
Peak Data rate
•NDSCH peak data rate can be
achieved by using the largest
TBS of 680 bits and
transmitting it over 3 ms. This
gives 226.7 kbps peak layer-1
data rate. NPUSCH peak data
rate can be achieved by using
the largest TBS of 1000 bits
and transmitting it over 4 ms.
This gives 250 kbps peak
layer-1 data rate. However,
the peak throughputs of both
downlink and uplink are lower
than the above figures, when
the time offsets between DCI,
NPDSCH/NPUSCH, and HARQ
acknowledgement are taken
into account.
Coverage
•NB-IoT achieves a maximum
coupling loss 20 dB higher
than LTE Rel-12 . Coverage
extension is achieved by
trading off data rate through
increasing the number of
repetitions. Coverage
enhancement is ensured also
by introducing single
subcarrier NPUSCH
transmission and bi/2- BPSK
modulation to maintain close
to 0 dB PAPR, thereby
reducing the unrealized
coverage potential due to
power amplifier (PA) backoff.
NPUSCH with 15 kHz single-
tone gives a layer-1 data rate
of approximately 20 bps when
configured with the highest
repetition factor, i.e., 128, and
the lowest modulation and
coding scheme. NPDSCH
gives a layer-1 data rate of 35
bps when configured with
repetition factor 512 and the
lowest modulation and coding
scheme. These configurations
support close to 170 dB
Latency
•NB-IoT targets latency
insensitive applications.
However, for applications like
sending alarm signals, NB-IoT
is designed to allow less than
10 s latency [3]. NB-IoT aims
to support long battery life.
For a device with 164 dB
coupling loss, a 10-year
battery life can be reached if
the UE transmits 200-byte
data a day on average
Complexity
•Small TBS
•No MIMO
•One Redundancy version
•Single Antenna
•Single HARQ oricess
•No need for Turbo Coder
•Low sampling rate
•HD_FDD only
•No HO
•No Parallel processing

NB-IOT VS CAT-M Parameter CAT-M1 (CAT-M) NB-IoT
Bandwidth 1.4MHz 200KHz
Modes of Operation In-band In-band, Guard-band,
standalone (GSM
bands)
Duplex Mode HD-FDD / FDD / TDD HD-FDD (TDD under
discussion)
Peak Data Rate 375Kbps (HD-FDD),
1Mbps (FDD)
~50kbps for HD-FDD
(not decided yet in
3GPP)
UL Transmit Power 23dBm 20dBm 23dBm, lower power
under discussion
VoLTE support Will be supported Not supported
Mobility support Full mobility support No connected mobility
(only idle mode
reselection)
TTM 6-9 month advantage
(estimated)
Standard is not
yet

NB-IOT VS CAT-M
CAT-M1 NB-IoT
References 3GPP 36.888, RP-150492 3GPP 45.820 7A
Downlink Uplink Downlink Uplink
Tx Power 46dBm/9MHz23dBm 43dBm/180k
z
23dBm
Noise Figure 9dB 5dB 5dB 3dB
Cost comparison goes in sake of NB-
IOT

IoT Applications and Networks

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