LTE-M Evolution Towards 5G Massive MTC

Rapeepat Ratasuk, Nitin Mangalvedhe, David Bhatoolaul, Amitava Ghosh

Nokia Bell Labs, Arlington Heights, IL, USA
Email: {rapeepat.ratasuk, nitin.mangalvedhe, david.bhatoolaul, amitava.ghosh}@nokia.com

Abstract—Massive machine type communication (mMTC) TABLE I. KEY LTE-M FEATURES

has been identified as an important use case for 5G New Radio
3GPP
wireless technology. In 4G Long-Term Evolution (LTE), 3GPP Release
Features
has previously introduced LTE-M for low-power, wide-area
networks supporting the Internet of Things. Rel-13 specifications Bandwidth limited operations (1.4 MHz), coverage
enhancement (CE Mode A/B), half-duplex support, in-
for LTE-M were completed in 2016. Rel-14 enhancements were Rel-13
band operation mode, RRC connection
completed in 2017 while Rel-15 enhancements are ongoing and (2016)
suspend/resume, data transmission via control plane,
expected to be completed in 2018. In this paper, we provide an extended DRX, mobility support
overview of LTE-M and describe its evolution in subsequent
Positioning enhancements (E-CID requirements and
releases. The features of the technology that have specifically OTDOA support), multicast support using SC-PTM,
been designed for mMTC are discussed. In addition, we present Rel-14 larger channel PDSCH/PUSCH bandwidth (up to 5 &
evaluations of LTE-M against 5G performance targets and show (2017) 20 MHz), higher data rates, VoLTE enhancements,
that mMTC requirements can be satisfied by LTE-M. To meet HARQ-ACK bundling, support inter-frequency
the 5G mMTC requirements, 3-dB power spectral density measurements
boosting is used in the downlink. In addition, for some Reduce latency and power consumption, improve
requirements, 4 receive antennas at the eNB are required instead Rel-15 spectral efficiency, support higher UE velocity, lower
of the more typical 2 receive antennas. Thus, LTE-M will (2018) UE power class, improve load control of idle UEs,
comprise an important component of 5G New Radio technology. eDRX enhancements

Keywords— LTE-M; low power wide area cellular IoT; 5G • Battery life in extreme coverage beyond 10 years (15
massive MTC. years is desirable). Battery life is evaluated at 164 dB
I. INTRODUCTION MCL with mobile originated data transfer consisting of
200 and 50 bytes of uplink and downlink data per day,
The communications industry is in the middle of respectively, and a battery capacity of 5 Wh.
transitioning to the fifth generation (5G) of wireless • Latency of 10 seconds or less on the uplink to deliver a
technology. In 3GPP, 5G has been given the name New Radio 20-byte application layer packet measured at 164 dB
(NR). Three important use cases have been identified for NR MCL.
[1] – enhanced mobile broadband, massive machine type
communications (mMTC), and ultra-reliable low latency In this paper, we provide an overview of 4G LTE-M and
communications. Massive MTC support is important for the describe its evolution in subsequent 3GPP feature releases as
Internet of Things (IoT) which is projected to grow massively, enhancements are introduced. In addition, we present
with tens of billions of devices expected to be connected in the evaluations of LTE-M against 5G mMTC performance targets
next few years. Many of these devices will rely on low-power, and show that LTE-M can also meet 5G requirements. Note
wide-area (LPWA) networks for connectivity. that related enhancements have also been undertaken for NB-
In 4G LTE, 3GPP has specified two LPWA technologies IoT and are summarized in [4].
for IoT – LTE-M and Narrowband IoT (NB-IoT) [2][3]. LTE- The remainder of the paper is organized as follows. In
M is intended for mid-range IoT applications and can support Section II, a brief overview of LTE-M is provided. This is
voice and video services, while NB-IoT can provide very deep followed, in Section III, by a description of Rel-14
coverage and support ultra-low-cost devices. Core enhancements that have been standardized. Section IV presents
specifications for LTE-M were completed in June 2016. an overview of ongoing Rel-15 enhancements. Performance
Further work to enhance the technology has been ongoing in evaluations of LTE-M against mMTC requirements are given
3GPP. Rel-14 enhancements were completed in June 2017, in Section V. Finally, conclusions are drawn in Section VI.
while Rel-15 enhancements are ongoing and expected to be II. LTE-M OVERVIEW
completed by June 2018. Table I summarizes key LTE-M
features from different LTE releases. In 3GPP Rel-13, LTE-M was introduced with the following
With respect to 5G NR, the following mMTC performance design objectives – support low-cost devices, improve
objectives have been identified [1] – coverage by 15 dB, support massive number of devices,
• Ultra-low complexity and low-cost IoT devices and support 10-year battery life, and support latency of 10 seconds
networks. or less. To keep device cost low, a new User Equipment (UE)
category (Cat-M1 UE) was introduced. Cat-M1 UE has an RF
• Maximum Coupling Loss (MCL) of 164 dB for a data
bandwidth of 1.4 MHz (compared to 20 MHz for normal LTE
rate of 160 bps at the application layer.
devices), one receive antenna chain (compared to two for
• Connection density of 1 million devices per square km in
normal LTE devices), maximum transport block size of only
an urban environment.

978-1-5386-3920-7/17/$31.00 ©2017 IEEE

1000 bits, and typically operates in half-duplex mode. Despite To extend cell coverage for LTE-M, repetition of
being bandwidth-limited, Cat-M1 UE can operate within any transmissions has been specified. Two coverage enhancement
LTE system bandwidth. This is accomplished by defining (CE) modes were introduced – CE Mode A and B. CE Mode
special procedures and channels in the cells for bandwidth- A is intended to provide small to medium coverage
limited operations. Additional features that are supported enhancement, while CE Mode B is intended to provide large
include mobility (i.e., handover), extended discontinuous coverage enhancement. Since the Cat-M1 UE has only 1
reception (eDRX), radio resource control (RRC) connection receive antenna and operates within a narrowband, downlink
suspend/resume, and data transmission via control plane. performance can be up to 5 dB worse than for legacy LTE
Fig. 1 illustrates bandwidth-limited operations for cells UEs. Therefore, CE Mode A is a mandatory feature for Cat-
supporting LTE-M. First, legacy synchronization signals and M1 UE. Table III summarizes the key differences between the
Physical Broadcast Control Channel (PBCH) are used since two modes [5].
they are completely contained within the center 1.4 MHz TABLE III. COVERAGE ENHANCEMENT MODE A AND B
regardless of the system bandwidth. Furthermore, the wideband
LTE system is divided into narrowbands. Each narrowband Channel CE Mode A CE Mode B
comprises 6 physical resource blocks (PRBs) and spans
Aggregation levels 2,4,8,16,24 8,16,24
1.08 MHz, which is within the radio frequency (RF) bandwidth MPDCCH Maximum number
of narrowband LTE-M UEs. UEs can retune from one 256 256
of repetitions
narrowband to another as configured or scheduled by the eNB. Supported QPSK,
QPSK
The Master Information (MIB), which is transmitted on the PDSCH
modulation levels 16-QAM
PBCH, contains additional scheduling information for the Maximum number
32 2048
of repetitions
LTE-M system information block. From decoding the MIB, Supported QPSK,
IoT devices can determine whether the system supports QPSK
modulation levels 16-QAM
LTE-M operations or not. PUSCH
Maximum number
32 2048
of repetitions
Power control Max power is
Power control
on always used
ACK/NACK, ACK/NACK,
Supported formats
CQI, SR SR
PUCCH
Maximum number
8 32
of repetitions

Note that there is no additional repetition for the PSS/SSS

since coverage can be extended by allowing longer
synchronization acquisition time at the UE. The PBCH can be
repeated in one additional subframe.
III. REL-14 ENHANCEMENTS
In 3GPP Rel-14, completed in June 2017, these major
Fig. 1. Bandwidth-limited operations for Cat-M1 UE. enhancements were introduced for LTE-M:
• New UE category (Cat-M2) supporting 5-MHz
If the cell supports LTE-M operations, UE can obtain cell- bandwidth. Higher peak data rates for both Cat-M1 and
specific LTE-M system information blocks. UE then accesses Cat-M2 UE categories.
the system using random access procedure. Upon completion • Multicast downlink transmission based on single-cell
of random access procedure, the UE is in connected mode and point-to-multipoint (SC-PTM).
can receive or transmit data using dedicated channels. Table II • Location services using enhanced PRS resource
lists LTE-M physical channels and signals. configuration for Observed Time Difference of Arrival
TABLE II. LTE-M PHYSICAL CHANNELS AND SIGNALS (OTDOA) positioning.
Abbreviation Physical channel or signal • Increased Voice over LTE (VoLTE) coverage for half-
duplex Cat-M1 UE.
PSS/SSS Primary/Secondary Synchronization Signal
In this section, we summarize key enhancements that have
PBCH Physical Broadcast Channel
been introduced.
MPDCCH Physical Downlink Control Channel
PDSCH Physical Downlink Shared Channel A. New UE Category and Higher Data Rates
PRACH Physical Random Access Channel The Cat-M2 UE category can support RF bandwidth of 5
CRS Common Reference Signal MHz and higher data rates. It can support a maximum transport
PRS Positioning Reference Signal block size (TBS) of 4008 bits in the downlink and 6968 bits in
PUSCH Physical Uplink Shared Channel the uplink. This UE category has higher complexity than Cat-
PUCCH Physical Uplink Control Channel M1 UE but is still considered low-cost. It can be used to
support multimedia IoT applications such as voice and video. location server for positioning estimation. In Rel-14, PRS
Note that this wider bandwidth operation is supported only in transmissions are defined. An eNB can transmit PRS with up to
RRC_CONNECTED mode and enabled by the eNB. 3 PRS time-frequency configurations. The number of PRS
RRC_IDLE mode operations reuse Rel-13 design (i.e., limited subframes per PRS occasion can vary from 1 to 160. In
to 1.4 MHz). In addition, only the PDSCH and PUSCH can use addition, the UE can indicate its maximal PRS bandwidth for
5 MHz bandwidth. Other channels remain limited to operating measurement purpose which can be up to 20 MHz (i.e., larger
within the narrowband. This was done to minimize changes to than PDSCH/PUSCH bandwidth). Frequency hopping and
the specifications. In addition to introducing a new UE repetitions are also supported on the PRS to help improve
category, Rel-14 Cat-M1 UE capabilities are also enhanced. measurement accuracy for UEs in poor coverage.
Besides being capable of higher data rates, the maximum TBS Measurement reporting is enhanced through additional
has been increased to 2984 bits in both downlink and uplink. measurement results and RSTD reporting with higher
These larger TBSs can be supported by using higher coding resolution. Interference suppression during PRS measurements
rate. is enabled through PRS muting in neighbor cells.
In Rel-13, legacy LTE UE can operate in coverage
D. VoLTE
enhancement mode by behaving like LTE-M UE and limiting
its bandwidth to 1.4 MHz. In Rel-14, the legacy UE can use up An important trend for IoT is the integration of voice
to 20 MHz for the downlink and 5 MHz for the uplink. This is communication capability into the devices. Use cases include
because, in the downlink, the peak rate can be increased by using voice as the user interface (e.g., voice command over the
using more bandwidth (since power is divided among all network), supporting two-way communication (e.g., for
PRBs). However, this is not true in the uplink since the UE can wearable devices, alarms and eHealth), and for customer
choose to transmit using all available power in only PRB. In service. Voice capability can be supported in an LTE network
this case, the peak data rates are 27 Mbps in the downlink and via VoLTE.
7 Mbps in the uplink. In Rel-14, VoLTE coverage using half-duplex Cat-M1
Several other enhancements have also been introduced to devices has been enhanced. An example of VoLTE
support higher peak rates. They include supporting up to 10 transmission diagram is shown in Fig. 2. A speech frame
downlink Hybrid Automatic Repeat reQuest (HARQ) arrives every 20 ms in both downlink and uplink directions.
processes (instead of 8 in Rel-13) in CE mode A for half- The total time of 20 ms must then be divided between uplink
duplex operation, supporting HARQ-ACK bundling, and and downlink transmissions.
reducing guard period for retuning.
B. Multicast
Multicast support is beneficial for IoT use cases such as
firmware updates and group message delivery. Multicast
support for LTE-M will use SC-PTM feature. SC-PTM uses
two logical channels, the control channel (SC-MCCH) and the
transport channel (SC-MTCH). Fig. 2. VoLTE transmission diagram for Cat-M1 UE.
The SC-MCCH contains SC-PTM configuration message
and is transmitted periodically. The SC-MCCH can be repeated To improve coverage, several techniques have been
to reach UEs that are in poor coverage. The SC-MTCH logical specified. They include introducing an additional repetition
channel is used to carry Multimedia Broadcast Multicast factor to help fill any gap, adjusting the scheduling delays, and
Service (MBMS) sessions. Each MBMS session is transmitted enabling modulation step down to allow larger packet size to
on a separate SC-MTCH, where a unique group identification be transmitted. Please refer to [5] for detailed analysis of
is assigned to each MBMS session. At the physical layer, SC- VoLTE for LTE-M.
MTCH is transmitted by the PDSCH that is scheduled by the IV. REL-15 ENHANCEMENTS
PDCCH. Like SC-MCCH, these channels can be repeated to
reach UEs that are in poor coverage. Note that SC-PTM applies Rel-15 work on LTE-M is ongoing and is expected to be
only to LTE-M UEs in RRC_IDLE mode. completed by June 2018. Per the work item description in [6],
the following features are expected to be introduced –
C. Positioning
• Support coverage enhancement for higher UE velocity
For LTE-M, two positioning techniques can be used – (e.g. 200 km/h).
Enhanced Cell-ID (E-CID) positioning and OTDOA. E-CID • Specify new UE power class (e.g., 14 dBm) for small
positioning uses geographical coordinates of its serving cell form factor devices such as wearables.
and measurements from UE to estimate its location. In LTE • Reduced system acquisition time by improving cell
Rel-14, E-CID performance requirements for LTE-M UEs search and system information acquisition performance.
were defined. • Latency and power consumption reduction techniques
In OTDOA, UE measures the time of arrival of the such as wake-up signal or channel, relaxed monitoring for
reference signals received from multiple transmission points cell reselection, data transmission during random access
and reports the reference signal time difference (RSTD) to the procedure, etc.
 • Techniques to improve spectral efficiency such as 64- is in the process of defining a new physical signal or channel
QAM support, sub-PRB resource allocation, etc. for both idle mode paging. Its use would be such that the
• Improved load control via access barring based on decoding of PDCCH would be contingent upon first
coverage enhancement level. detecting/decoding this new signal or channel. The objective is
In this section, we summarize some key enhancements that to specify such a signal or channel if studies show substantial
may be standardized. savings in power consumption from it.

A. Reduced System Acquisition Time C. Spectral Efficiency Improvement

An objective for Rel-15 is to improve cell search and/or In Rel-15, spectral efficiency improvements techniques are
system information (SI) acquisition performance to reduce being considered. For the downlink, 64-QAM will be
latency. It has been observed in Rel-14 that the requirement for introduced, which will allow UEs with good condition to be
a UE to acquire the MIB of the target cell during handover scheduled using less resources. For the uplink, sub-PRB
procedures significantly increases the handover delay for Cat- resource allocation will be specified, which increases system
M1 UEs in CE Mode B. Furthermore, the total time required to capacity by allowing multiple users to be multiplexed within
acquire both the MIB and the System Information Block 1 the same PRB.
(SIB1-BR) may exceed the SIB1-BR modification period, V. 5G mMTC EVALUATION RESULTS
causing the UE to reacquire the MIB. The main enhancements
for improving system acquisition times being studied include: In this section, performance of LTE-M is evaluated against
• Additional repetitions of PSS/SSS/PBCH enhanced in 5G mMTC requirements listed in Section I through link-level
such a way to minimize false detection and/or improve and system-level simulations. Simulation parameters are listed
correlation properties. in Table I [1].
• Improving PBCH acquisition times using joint decoding TABLE I. SIMULATION ASSUMPTIONS
techniques.
Parameter Assumption
• Reducing the number of required repetitions for SI
messages through CRS and PDSCH power spectral LTE system bandwidth 10 MHz
density boosting. LTE system bandwidth 6 PRBs (1.08 MHz)
• Additional repetitions of SIB1-BR on other subframes or Carrier frequency 900 MHz
carriers. Hexagonal grid, 19 cell sites,
• New mechanisms (e.g., new wake-up signal) to allow UE Cellular Layout
3 sectors per site
to skip reading of MIB, SIB1-BR and/or SI-messages. Path loss determination Refer to [7]
B. Latency and Power Consumption Reduction Fraction power control with Ks=0
Power control setting
α = 0.8, Po=-84
Latency improvement through support of data transmission
during random access procedure is being standardized in Rel- Total eNB transmit power 46 dBm
15. When a UE resumes its RRC connection, it transitions from LTE-M transmit power 39.8 dBm (3 dB PSD boosting)
idle mode after waking up to transmit a data packet on the UE transmit power 23 dBm
uplink. In the RRC resume procedure, the UE goes through
several steps including synchronization, random access, RRC Propagation channel TU
connection resume, data packet transmission, and HARQ Doppler spread 1 Hz
acknowledgment processing. This accounts for a relatively DL: eNB: 2Tx/4Tx, UE: 1Rx
large latency, considering the typically short data packets, Antenna configuration
which can be reduced if the uplink and downlink data can be UL: eNB: 2Rx/4Rx, UE: 1Tx
transmitted during random access procedure. Frequency error Random from [-50, +50] Hz
Further power consumption reduction for LTE-M devices Thermal noise density -174 dBm/Hz
continues to be emphasized in Rel-15. To this end, Rel-15
eNB receiver noise figure 5 dB
enhancements are targeted towards improving the efficiency of
receiver operation. LTE-M technology is targeted towards a UE receiver noise figure 9 dB
broad variety of use cases for some of which (e.g., public
safety, advertising billboard, voice supported services) the Note that 3-dB power spectral density (PSD) boosting is used
network should be able to reach the UE within a reasonable in the downlink. This PSD boosting reduces the power for the
time. Therefore, the UE cannot go to sleep for long periods LTE PRB from 29 to 28.4 dBm per PRB, which is a small
even when the devices are required to send or receive data reduction.
infrequently. To meet the requirement, devices are configured A. Coverage
to monitor the PDCCH relatively often, whether in connected
mode or idle mode. This receiver operation consumes a lot of For coverage, the requirement for mMTC is to reach MCL
power. When the device is only rarely scheduled, the operation of 164 dB while supporting a data rate of 160 bps at the
causes very poor receiver efficiency. Recognizing this, Rel-15 application layer. Table IV illustrates LTE-M link budget to
meet this extreme MCL and the associated number of
repetitions required for each channel. From the table, it is seen data per day, respectively, uplink system simulations have been
that meeting 164 dB MCL is very challenging and extensive performed according to assumptions in [1]. Note that only the
amount of repetitions is required for some channels. uplink has been considered here since it is the limiting link for
Fig. 3 shows the performance for PUSCH using sub-PRB capacity in this case.
allocation (6 subcarriers in this case) which is a Rel-15 feature. Fig. 4 shows the uplink capacity per PRB. From the figure,
Using 2 receive antennas at the eNB, 2048 repetitions are it is seen that approximately 1e5 devices can be supported per
required for the PUSCH to reach this extreme MCL for a PRB. In LTE-M, each carrier contains 6 PRBs. However,
packet size of 392 bits (corresponding to physical layer data overhead channels such as PUCCH and PRACH must also be
rate of 191 bps). In this case, the required application layer data accounted for. As a result, approximately 3.5×105 devices can
rate of 160 bps is unlikely to be satisfied (taking higher layers be supported using one narrowband. Therefore, approximately
overhead into account). To increase the uplink data rate, 4 three narrowbands (or around 3 MHz) would be needed to
receive antennas can be used, which would increase the uplink support connection density of 106 devices per square km. This
data rate to approximately 350 bps as shown in Fig. 3. would require LTE-M to be deployed with a minimum 3 MHz
TABLE IV. LTE-M LINK BUDGET or 5 MHz system bandwidth.
3000
Channel MPDCCH PDSCH PUSCH PUCCH PRACH

Number of successfully transmitted UEs

LTE-M (1 PRB allocation)
No of repetitions 256 512 2048 128 256 2500
Total Number of UEs
Tx power (dBm) 39.8 39.8 23 23 23
2000
Thermal noise
-174 -174 -174 -174 -174
density (dBm/Hz)
Receiver noise 1500
9 9 5 5 5
figure (dB)
Occupied channel 1000
1,080 1,080 90 180 1,080
bandwidth (kHz)
Effective noise
-104.7 -104.7 -119.5 -116.4 -108.7 500
power (dBm)
Required SINR (dB) -19.8 -19.9 -21.6 -24.8 -32.4
0
Receiver sensitivity 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
-126.5 -127.6 -141.0 -141.2 -141.1 5
(dBm) Number of devices per cell x 10

Maximum coupling Fig. 4. Uplink capacity results.

164.3 164.4 164.1 164.2 164.1
loss (dB)
C. Battery Life

PUSCH, ETU 1Hz, 6-subcarrier The UE battery life target for mMTC is at least 10 years.
0
10 For this analysis, we assume a battery capacity of 5 Wh and
power consumption as shown in Table V [7].
TABLE V. POWER CONSUMPTION ASSUMPTIONS

Power consumption power during Tx 500 mW

Power consumption power during Rx 80 mW

BLER

-1
10
Power consumption when idle but not in power
3 mW
save state

Power consumption during power save state 0.015 mW

1Tx-2Rx, TBS=392, 6-subcarrier, 2048ms

We assume that the UE is either in power save or idle state
1Tx-4Rx, TBS=680, 6-subcarrier, 2048ms and periodically connects to the network to transmit an uplink
-2
10 data report or monitor for downlink scheduling at 164 dB
-28 -27 -26 -25 -24 -23 -22 -21 -20 -19 -18
SNR (dB)
MCL. The size of the uplink report is 200 bytes and the
corresponding downlink TCP/IP ACK is 65 bytes. The UE
Fig. 3. PUSCH link-level performance results.
performs synchronization and reacquires broadcast information
when it wakes up. It then performs random access procedure
B. Connection Density
and subsequent data transmission. The following traffic model
For connection density, the requirement for mMTC is to is considered: the UE wakes up from power save state to
support 1 million devices per square km in an urban transmit uplink report once per day and returns to power save
environment. Using a traffic profile of mobile originated data state. Based on this model, it is estimated that the battery life is
transfer consisting of 200 and 50 bytes of uplink and downlink about 7.6 years, which is less than the target.
 To increase battery life, Rel-15 techniques such as wake-up DCI + Msg5 (Connection Resume Complete) 768
channel or MIB/SIB1-BR acquisition time reduction can be
DCI (UL grant) 2*256
used. This reduces the time required for the receiver to be on
and hence power consumption. For instance, PBCH acquisition UL (90% confidence) 2*2048
through joint decoding can reduce acquisition time
significantly. However, reducing the receive time does not VI. CONCLUSION
significantly increase battery life. Massive machine type communication has emerged as an
To significantly increase battery life, it is most beneficial to important use case for 5G New Radio technology. This has
reduce the transmission time. In this case, 4Rx antennas at the spurred an interest in ensuring that LTE-M, first introduced by
eNB may be considered. If 4Rx is used, the uplink data rate 3GPP under LTE Rel-13 to support the Internet of Things,
can increase significantly. In this case, it is estimated at the follows a proper evolution path towards meeting 5G mMTC
battery life can be increase from 7.6 years using 2Rx to 10.4 requirements. This paper provides an overview of LTE-M and
years using 4Rx antennas, thus meeting the 5G requirements. describes its evolution in subsequent releases. The features of
the technology that have specifically been designed for mMTC
D. Latency
are discussed. Evaluations of LTE-M against mMTC
The latency requirement for mMTC is that the time taken performance targets is an important exercise in ensuring that
by the UE to move from a battery efficient state to deliver a 20- the technology meets 5G requirements. To meet the 5G mMTC
byte application layer packet measured at 164 dB MCL should requirements, 3-dB PSD power boosting is used in the
be less than 10 seconds. Table VI shows estimates of the time downlink. In addition, for some requirements, 4 receive
required for different activities in the connection procedure antennas at the eNB are required instead of the more typical 2
using 90th percentile time or 10% BLER for 2 receive antennas receive antennas. To this end, the analysis presented herein
at the eNB. As shown by the table, approximately 9 seconds demonstrates that 5G mMTC requirements can be satisfied by
are required to deliver a packet of 85 bytes (20 bytes of LTE-M. Thus, LTE-M will comprise an important component
payload plus 65 bytes overhead), when wait times (i.e., time of 5G New Radio technology.
between reception/transmission of different messages) are also
REFERENCES
included. As discussed in Section IV.B, latency reduction is
being targeted for Rel-15. It is estimated that early data [1] 3GPP TR 38.913, “Study on Scenarios and Requirements for Next
transmission can reduce the latency by a few seconds at an Generation Access Technologies,” V14.2.0, March 2017.
MCL of 164 dB for a UE resuming connection from an idle [2] W. Yang et al., "Narrowband Wireless Access for Low-Power Massive
state. Latency reduction is also realized through reduction in Internet of Things: A Bandwidth Perspective," in IEEE Wireless
Communications, vol. 24, no. 3, pp. 138-145, 2017.
system acquisition time. Therefore, considering all the
[3] A. Díaz-Zayas, C. A. García-Pérez, Á. M. Recio-Pérez and P. Merino,
potential enhancements for Rel-15, the latency target for 5G "3GPP Standards to Deliver LTE Connectivity for IoT," 2016 IEEE
NR can be achieved. First International Conference on Internet-of-Things Design and
Implementation (IoTDI), Berlin, 2016, pp. 283-288.
TABLE VI. LATENCY ESTIMATES (164 dB MCL)
[4] R. Ratasuk, N. Mangalvedhe, Z. Xiong, M. Robert, and D. Bhatoolaul,
Activity Time (ms) “'Enhancements of Narrowband IoT in 3GPP Rel-14 and Rel-15,” to be
published in CSCN, Sept. 2017.
Synchronization 1000 [5] R. Ratasuk, D. Bhatoolaul, N. Mangalvedhe, and A. Ghosh,
“Performance Analysis of Voice over LTE using Low-Complexity
MIB acquisition 300 eMTC Devices,” VTC, June 2017.
SIB1-BR acquisition 400 [6] RP-170732, “New WID on Even further enhanced MTC for LTE,”
RAN#75, Dubrovnik, Croatia, March 2017.
PRACH 256 [7] 3GPP TR 45.820, “Cellular System Support for Ultra Low Complexity
and Low Throughput Internet of Things,” V2.1.0, August, 2015.
DCI + Msg2 (RAR) 512
[8] M. Lauridsen, I. Z. Kovacs, P. Mogensen, M. Sorensen and S. Holst,
Msg3 (Connection Resume Request) 256 "Coverage and Capacity Analysis of LTE-M and NB-IoT in a Rural
Area," 2016 IEEE 84th Vehicular Technology Conference (VTC-Fall),
DCI + Msg4 (Connection Resume) 512 Montreal, QC, 2016, pp. 1-5.
[9] R. Ratasuk, N. Mangalvedhe and A. Ghosh, "M2M communications in
HARQ ACK 128 cellular network deployments using LTE," 2014 21st International
Conference on Telecommunications (ICT), Lisbon, 2014, pp. 477-481.