lora and nb-iot
TRANSCRIPT
OUTLINE
● Background
● Motivation
● LoRa
● NB-IoT
● Conclusion
Background
IoT- Billion of Connected Devices
Radio Access ??
Different Applications have different set of Requirements
● Cost● Data Rate● Latency● Energy Consumption
● Voice, Multimedia (high data rate) → Legacy cellular licensed solutions, unlicensed WLAN solutions
● Industrial, commercial, sensors and IoT (low data rate) → IEEE 802.15.4, LPWA, BT, ZigBee
Motivation● IOT devices have requirements of wide area
connectivity for low power and low data rate devices at economical cost
● Legacy cellular solutions- high throughput, long range, but high power and costly
● WLAN 802.11 a-n- high throughput, short range, moderate-high power and cost
● LPWA- Tradeoff between above (Some technologies like LoRa and NB-IoT)
● LPWA- For applications that require multi-year batteries and send small amount of data less frequently
● Also, involving long range communications with low power
● Applications like Smart meter, seismic sensors, environmental monitoring, smart grid etc.
LPWA standards
● LoRa / LoRaWAN-○ Set up by industrial
consortia○ Unlicensed
● NB-IoT- Narrow band IoT○ Set up by 3gpp○ licensed
Reference: Course textbook
LoRa ( Long Range)● LoRa is the proprietary physical layer or
the wireless modulation technique utilized to create long Range Communication Link
● Based on chirp spread spectrum modulation
● A single gateway or base station can cover entire cities or hundreds of square kilometers
Chirp Signal
LoRaWAN (Long Range Wide Area Network)
● Star of Stars Topology● Nodes connect to multiple
gateways.● No handover needed from
gateway to gateway● Nodes are asynchronous and
communicate when they have data to send
● Device Classes-All nodes are not equal
● Division based on tradeoff between communication latency versus battery life time.
● Class A -Battery powered sensors● Class B- Battery powered actuators● Class C- Main Powered actuators
LoRaWAN (Long Range Wide Area Network)
NB-IoT (Narrow band IoT)
● Technology standardized by the 3GPP standards body
● Narrow band Technology designed for IoT which can be deployed in GSM and LTE Spectrum
● Also termed as cellular based IoT
● Standardization of NB-IoT completed with Release 13 of 3GPP published on 22 June 2016
● To be launched in early 2017
NB-IoT (Narrow band IoT)
❖ Highest modulation scheme used- QPSK❖ Minimal noise level inside a single narrowband❖ Receiver does not require to add processing gain to decode❖ Simple and inexpensive transceiver design
● Transmission schemes:
○ minimum system bandwidth for both downlink and uplink - 180 kHz
○ GSM carrier of 200 kHz,
○ 1 PRB (Physical Resource Block) inside an LTE carrier/ guardband could be replaced by NB-IoT carrier.
○ 12 subcarriers of 15 kHz in downlink using OFDM and 3.75/ 15 kHz in uplink using SC-FDMA
○ Various deployment options
REDUCEDPOWER &LOW COST
NB-IoT (Narrow band IoT)
● To enable low-complexity UE implementation, NB-IoT allows only one HARQ process in both downlink and uplink, and allows longer UE decoding time
● Asynchronous, adaptive HARQ procedure is adopted to support scheduling flexibility.
● Physical Channel/ Resource mapping
○ Extensive reuse of current LTE (Long Term Evolution) specifications
○ Few changes to physical channels used in LTE (detailed review)
● Random Access :
○ *Contention based algorithm similar to LTE [*Source- A Primer on 3GPP Narrowband Internet of Things (NB-IoT)]
UE
N/W
12
34
1. Preamble2. Response containing advance
command and scheduling of the uplink resources for the UE to use
3. Identity to the network4. Contention resolution message
NB-IoT (Narrow band IoT)
● Time acquisition and synchronization○ Critical- (Low cost Oscillators, deployment style introduces additional frequency
offsets)
○ Changes to the design of synchronization sequences in LTE
● Various pedagogical estimations and signal processing schemes are considered to estimate time delay and synchronization in LTE (detailed review and reference for figure)
NB-IoT (Narrow band IoT)
Source: NB-IoT, Accelerating Cellular IoT, Huawei
LoRa and NB-IoT overviewFeature LoRa NB-IoT
Licensed/Unlicensed Spectrum
Unlicensed Band Licensed Band
Reuse of Cellular Network No Yes
Development Status Existing Yet to develop
Modulation SS chirp QPSK
Bandwidth 500 Hz - 125 KHz 180 KHz
Data Rate 290 bps- 50 kbps 250 kbps max
Device cost/ complexity 1-5 $ (Ref- LPWA survey) < 5$ per module (Ref-IETF)
Latency and Battery Lifetime > 10 years <10 seconds, >10 years battery (Ref-IETF)
Type of Standard Proprietary open
Conclusion
● We have studied -
○ Why?
■ IoT is need of the time.
○ How it can be achieved?
■ LPWA standards like NB-IoT and LoRa were discussed and compared.
○ What?
■ Is LoRa: Entirely new technology adapted to the need of IoT platform
■ Is NB-IoT: Use of existing cellular infrastructure
References
NB-IOT:Maximum-Likelihood Detection for Energy-Efficient Timing Acquisition in NB-IoT https://arxiv.org/pdf/1608.02427.pdf
A Primer on 3GPP Narrowband Internet of Things (NB-IoT)https://arxiv.org/pdf/1606.04171.pdf
NB-IoT by IETFhttps://www.ietf.org/proceedings/96/slides/slides-96-lpwan-7.pdf
Thank You !!