Zero-Energy MTC

Zero-Energy MTC

© 2020 InterDigital, Inc. All Rights Reserved.1

Ravi Pragada

Sr. Director & Sr. Principal Engineer

Research & Innovation, InterDigital

Nov 11th, 2020

2 © 2020 InterDigital, Inc. All Rights Reserved.

Beyond 5G / 6G – Device proliferation challenge!

2G

100,000x vs.

GSM Phase 1

WCDMAHSPA

HSPA+LTE

LTE-A

2012+

GSM-EDGE

1990+

9.6 kbpsGSM Phase 1

Downlink Peak Data Rate

Spectral Efficiency

Carrier Bandwidth

Round Trip Latency

NR

240 kbps 384 Kbps 14 Mbps 42 Mbps 150 Mbps 1 Gbps 20 Gbps

0.17-0.33 bps/Hz 0.51 bps/Hz 2.9 bps/Hz 12.5 bps/Hz 16.3 bps/Hz 30 bps/Hz 40 bps/Hz

200 kHz 5 MHz 5 MHz 5 MHz Up to 20 MHz Up to 100 MHz 400 MHz

300 ms 250 ms ~70 ms ~40 ms ~30 ms ~20 ms ~1 ms

3G 4G 5GMillions of

voice users

Billions of mobile

broadband users100’s of Billions

of devices

Broadband Era … for the few

For B5G and 6G - a key challenge is to support up to 1 Trillion connected and mobile things

2,000,000x vs.

GSM Phase 1

3 © 2020 InterDigital, Inc. All Rights Reserved.

Challenges in Scaling to 1T Devices – Battery Capacity

❖ Less than a 10x improvement in battery

energy density from 1990 to 2015

compared to 105 &106 increase in storage

density and peak wireless data rate

❖ Assuming 1T devices with 10-year battery

life results in 274 million battery changes

per day

❖ For some future deployments battery

swapping will be difficult if not impossible

❖ Significant need to enable IoT device

operations that are less reliant on its

battery 1

10

100

1000

10000

100000

1990 1995 2000 2005 2010 2015

Gro

wth

Mu

ltip

les

Battery Energy Density

CPU Speed

DRAM Density

HDD Capacity

4© 2020 InterDigital, Inc. All Rights Reserved.

Challenges in Scaling to 1T Devices – Latency vs Battery Life

❖ DRX & PSM based approaches in 3GPP MTC & NB-IoT suffer from an inherent

tradeoff between device reachability & battery life

❖ Longer DRX cycles result in extended battery life at the cost of latency

❖ Devices are not reachable during periods of deep sleep in PSM

❖ Furthermore, mobile devices must make periodic measurements thereby

limiting the maximum achievable battery life

How do we scale to 1T devices?


Power-Save Enhancements in 3GPP to date

❖ There is a need to develop novel techniques in order to

❖ Break power-save latency vs battery life tradeoff and

❖ Eliminate the need to change battery throughout the useful life of the device

Zero-Energy Air-Interface - Overview


What is Zero-Energy Air-interface?

• An air interface that does not draw power from the IoT

device’s battery

• Addresses the Beyond 5G & 6G energy efficiency

challenges and today’s drawbacks in power

consumption versus DRX and PSM latency tradeoffs

How do we get there?

• Ultra-low power RF receivers capable of operating under

1uW budget

• Enable zero-energy radio operation with simultaneous

power and information delivery thereby facilitating battery-

less operation of devices

• A scalable system framework that can support a diverse set

of deployment scenarios with on-demand features

Zero-Energy (ZE) Receiver Arch


ZE Receiver

• An ultra-low power receiver (ULP-RX) path used to decode information and

• An energy harvester path used to harvest energy

ULP-RX: Employs a rectification-first architecture consisting of

• A piezo-electric passive gain stage

• A multi-stage e.g. Dickson charge-pump rectifier

• An ultra-low power comparator and a set of ultra-low power correlators

Exemplary ZE Receiver Arch

Energy Harvester:

• Employs an impedance transformer followed by a rectifier and a large

capacitor for charge storage

• The output of the energy harvester is used to drive a boost type DC-to-

DC converter

• The output of the DC-to-DC converter is used to power the comparator

and the bank of correlators in the ULP-RX

Zero-Energy Air-Interface - Operation


How does it work?

• Network transmits a power-optimized preamble (POP)

followed by higher layer data

• Devices use passive receiver to harvest energy from

the received in-band waveform and use it to run the

necessary circuitry to process received signals

• POP may be constructed using a single un-modulated

RF carrier or a multi-tone power optimized waveform

• The information sequence may be transmitted using

simple modulation techniques (e.g., Manchester-

encoded on-off keying)

• To ensure zero-energy operation the energy harvested

from the POP must be greater than that required to

decode the information in the body

Zero-Energy Air-Interface – On demand features


On-demand Features

• Use the zero-energy (ZE) interface to introduce

on-demand features to the 3GPP system

framework

• Transmit on-demand wakeup signals that

deliver power and information on the ZE

interface

• Move mobility management related e.g. RSSI

measurements to the ZE interface

• Dynamically control the device’s UL

transmission repetition behavior using the ZE

interface

• Transfer wireless power to devices using the ZE

interface to compensate for the leakage

power of the device in deep sleep mode

Urban macro deployment with supplemental Zero-Energy Downlink (ZE-DL) for IoT devices

Proposed IoT device architecture with ZE Rx

Zero-Energy Air-Interface – Battery Life Impact


Battery Life Comparison (PSM/DRX vs. ZE-WUS)

• In transaction cycle limited regime - Battery life of Type 2 UEs can still last for much longer

than Type 1 UEs

• For transaction cycles beyond 2 days - Battery life of Type 1 UE is limited by DRX cycle

whereas Type 2 UE’s battery life can reach a 35-40 year target!!

Estimated battery life of a mobile IoT device leveraging the

proposed WUS transmissions for wireless power delivery, on-

demand paging and RSSI measurements on the ZE-DL interface

Applications enabled by Zero-Energy Technology


IoT, Wearables & other novel form-factors:

❖ Enable up to three-decade increase in battery life of IoT devices with sub-second network access latency as opposed to today’s long DRX cycle/paging latencies

❖ Huge value-add to Industrial IoT and other verticals such as asset monitoring, infrastructure monitoring, smart-cities, smart-transportation, smart oil & gas, etc. as well as connected home.

❖ Enables a host of new use-cases for Connected Home, enterprise IoT, smart-buildings, with “true wireless sensors” that go can go behind walls, embedded during construction, etc.

❖ Game changer for wearables and implants enabling new classes of devices allowing massive leaps in fluid interfaces such as smart-ring, wearables, etc.

High growth area with transformational impact and market opportunities

Infrastructure Monitoring

Asset MonitoringIndustrial IoT

Enterprise IoT

Connected Home Wearables / Battery-less Implants

12© 2020 InterDigital, Inc. All Rights Reserved.

Concluding Remarks

❖ Scaling to 1T devices will require us to re-imagine the radio transceiver, the air-interface and the overall system

❖ Not all IoT verticals are created equal – we will need to break through the power-save latency vs battery life tradeoffs in existing 3GPP duty-cycling approaches

❖ Need to develop Ultra-low power receivers that consume few 10s of nanowatt power and capable of macro-like link budgets

❖ On-demand features will have to be introduced to the cellular system framework using a new class of “zero-energy” air-interfaces that concurrently deliver power and information

❖ Using these PHY & MAC concepts a scalable system framework will have to be developed and integrated into future cellular networks!!

Zero-Energy MTC

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