–etsi m2m workshop 2013 – 6 –7 november 2013...lte evolution for m2m applications •...

Developing LTE into a ubiquitous wireless WAN for M2M

– ETSI M2M Workshop 2013 –

6 – 7 November 2013

Matthew Webb and Yuichi Morioka

Sony Europe Limited

M2M/MTC and LTE Development

• Scope of M2M-specific enhancements in 3GPP LTE has

expanded in recent years

• Reflects the unique characteristics of M2M devices, traffic and

behavior, and the need for efficient M2M/H2H coexistence

• Most recent new work is focused at physical layer (‘RAN1’)

– Complexity/cost reduction of LTE modem toward EGPRS modem cost

2

– Complexity/cost reduction of LTE modem toward EGPRS modem cost

– Coverage extension to facilitate some challenging M2M use cases

• Outline what RAN1 studied and is now working to standardize

ETSI M2M Workshop 2013

LTE Evolution for M2M applications

• LTE/LTE-A is designed to deliver high data rates, high mobility,

and short latency, but this comes at higher modem cost

• M2M communications may not have all those requirements,

so how can we exploit its differences vs. H2H to fine-tune

LTE’s capabilities?LTE’s capabilities?

• Four main efforts within 3GPP

– Enable low complexity/cost modem design at the physical layer

– Extend cell coverage to reach difficult locations for (nearly)

stationary UEs

– Reduce device power consumption, mainly at MAC and signalling

– Protect the network from being overloaded in crisis situations

3ETSI M2M Workshop 2013

3GPP low-complexity M2M LTE: Schedule

• Productization of light-weight LTE expected as soon as 2017

3GPP Standardization/Productization3GPP Standardization/Productization

20112011 20122012 20132013 20142014 20172017

Study Phase Specification Chip Development

10/2011:

Study of Low Cost LTE started

6/2013:

3GPP Rel-12 MTC Specification Starts

2017:

Product for Light Weight LTE

• Productization of light-weight LTE expected as soon as 2017

• Creating low cost LTE together with current full spec LTE could allow

ubiquitous WAN communication architecture suitable for a wide range of

consumer electronics and other devices

– Low cost LTE devices and full spec LTE devices can coexist within the same

network

• This would give confidence to manufacturers to implement M2M LTE, and

confidence to customers when buying devices


Low Cost LTE together with full spec LTE will serve a wide range of M2M applicationsLow Cost LTE together with full spec LTE will serve a wide range of M2M applications

Goals and Requirements

• Specify an LTE UE for MTC with bill-of-materials cost comparable to an

EGPRS modem – targeting a 50% cost reduction

• Ensure that coverage for a low-cost MTC LTE UE is not worse than a GSM

MTC device in a GSM network, or a normal LTE UE in an LTE network

• Extend coverage by up to 20 dB for low cost and normal cost MTC UEs

• Ensure good radio frequency co-existence with Rel 8-10 LTE, with MTC UEs • Ensure good radio frequency co-existence with Rel 8-10 LTE, with MTC UEs

on same carrier as normal UEs

• Re-use existing LTE/SAE network architecture

• Low-cost MTC device support limited mobility and are low power modules


How to achieve low-complexity LTE?

• 3GPP has studied the cost of each component in an LTE modem

• Identified cost/complexity -reduction approaches

– Reduction of maximum bandwidth – Reduction of transmit power

– Single receive RF chain – Half duplex operation

– Reduction of peak rate – Fewer downlink transmission modes

• These can eliminate up to up to 59% of the modem cost


RF

transceiver

45%

PA

25%

Duplexer

20%

Filters

10%

RX processing

20%

ADC/DAC

15%

Buffering

10%HARQ buffer

10%

Sync

10%

Turbo decoding

10%

UL

processing

10%

DL control

processing

5%

FFT/IFFT

5%

MIMO

5%

RF costs example (40% of total) Baseband costs example (60% of total)

How to achieve low-complexity LTE?

• 3GPP has studied the cost of each component in an LTE modem

• Identified cost/complexity -reduction approaches

– Reduction of maximum bandwidth – Reduction of transmit power

– Single receive RF chain – [Half duplex operation]

– Reduction of peak rate – Fewer downlink transmission modes

• These can eliminate up to up to 59% of the modem cost


RF

transceiver

45%

PA

25%

Duplexer

20%

Filters

10%

RX processing

20%

ADC/DAC

15%

Buffering

10%HARQ buffer

10%

Sync

10%

Turbo decoding

10%

UL

processing

10%

DL control

processing

5%

FFT/IFFT

5%

MIMO

5%

RF costs example (40% of total) Baseband costs example (60% of total)

Reduced maximum bandwidth

• DL bandwidth reduction options

– RF and baseband reduction

– Only baseband reduction for data + control

– Only baseband reduction for only data

• UL bandwidth reduction savings are small

• Main cost savings are in DL baseband:• Main cost savings are in DL baseband:

– Lower complexity IFFT/FFT

– Receiver baseband processing

– Turbo decoding

– HARQ buffer size

– DL control processing

• Could reduce modem cost by nearly 40%

• Impacts are mainly from loss of capacity and

loss of frequency diversity


DL

con

tro

l ch

an

ne

l

User 1 data channel

User 2 data channel

User 4 data channel

User 3 data channelfr

eq

time

Hardware simplification

• Focus on lower-performance devices

• A single receive-RF chain could save

– ~50% of RX filtering cost

– ~50% of RF chain cost

– But <<50% of overall transceiver cost due to

common components, e.g. frequency synthesiscommon components, e.g. frequency synthesis

– Baseband savings in FFT, channel estimation, ADC,

and buffering costs of approx 50%

– Overall modem saving 15% – 40%

• Half duplex FDD

– Replaces duplexer with much cheaper switch

– Could use cost-optimized HD-FDD RF components

• Impacts are mainly on coverage, capacity,

and UL/DL timing and scheduling


Reduction of peak rate requirements

• A Cat-1 LTE device must support up to 10 (dl) / 5 (ul) Mbps– But this can be relaxed for low-cost devices

• Reduce UL/DL block size– Device only has to process ~1000 bit/ms instead of 10,000

– Less UL processing, turbo (de-)coding, HARQ buffering

• Restrict size of uplink grant (if UL bandwidth reduced)

01101101001001001011

11100111111000101101

00111001010001101101

10101100011001100110

01101101001001001011

11100111111000101101

00111001010001101101

10101100011001100110

01101101001001001011

11100111111000101101

00111001010001101101

10101100011001100110

100 R

Bs

• Restrict size of uplink grant (if UL bandwidth reduced)– Allow device to support max. 6 RBs instead of 100

– Less UL processing, turbo coding, HARQ buffering

• Modem cost saving up to ~15% (all from baseband)

• Impacts are mainly on latency, on-time of TX and

relative overhead of control messages

• Restricting modulation to QPSK not recommended

due to significant cell spectral efficiency losses


10101100011001100110

1 ms

0 1 1 0 1 1 0 1 0 0 1 0 0

1 0 0 1 0 1 1 1 1 1 0 0 1

1 1 1 1 1 0 0 0 1 0 1 1 0

1 0 0 1 1 1 0 0 1 0 1 0 0

0 1 1 0 1 1 0 1 1 0 1 0 1

1 0 0 0 1 1 0 0 1 1 0 0 1

6 R

Bs

LTE coverage extension for M2M

• Coverage requirement may be more stringent for

M2M than conventional H2H communication

– Some M2M devices can not be moved

– e.g. TV or smart meter in a basement

– Could need >15 dB more link budget

• 3GPP studied ways to enhance low cost LTE so

that it can provide required coverage for M2Mthat it can provide required coverage for M2M

• M2M traffic types can be more relaxed than H2H


Challenging Coverage Requirement for M2M

WAN

Command

Response

Exception

Report Periodic

Report

WAN

module

10 sec latency20 / 100 bytes

5 sec latency100 bytes, uplink only

1 hour latency100 bytes, uplink only

Coverage extension: Repetition

• Repetition is a simple way to increase the received signal energy

• HARQ can already be used, but does not give 15 dB gain

• Simulation results:

– Broadcast data: 40 – 100 repetitions

– Downlink data: x100s of repetitions

– Downlink control data: 100-200 repetitions

• Main challenges are from:• Main challenges are from:

– Channel estimation over long transmission durations

– Coupling between repetition of control and repetition of data

– Possible cell spectral efficiency loss


Coverage extension: Power-density boosting

• Not all radio resources are in use at all times, so can concentrate

basestation transmit power into resources identified as for M2M comms

• Can give up to 12 dB gain in current LTE carriers

• Main challenges are from:

– Inter-cell interference coordination

– Availability of unused radio resource and power– Availability of unused radio resource and power

– EVM and IMD interference into adjacent frequencies


Coverage extension: Uplink relay / Small cells

• Transmit power imbalance uplink/downlink

– Macrocell can transmit with high power

– Terminal device is limited to e.g. 23 dBm

• Coverage may be improved if uplink and

downlink are provided by different nodes

– Downlink from macro– Downlink from macro

– Uplink via relay

• Main challenges are from:

– Latency of relay->basestation backhaul

– Need to deploy many small cells

– Interference management


Potential Coverage Enhancement

Summary

Ubiquitous M2M Communication through LTEUbiquitous M2M Communication through LTE

• M2M communications enables new applications with varying requirements

• M2M characteristics can be very different from H2H, but it is desirable to

have a single, reliable, cheap, wireless technology enabling the domain

• LTE is being enhanced to specifically suit M2M communications

• Low-cost modem design

• Low power operation

• Coverage extension for reach and reliability

• Network protection from M2M overload


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–etsi m2m workshop 2013 – 6 –7 november 2013...lte evolution for m2m applications •...

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