NR Lite: An Initiation to Massive IoT

NR light in Release 17 is designed for mid-tier NR functionality and also meant for "reduced capability NR devices". The real time examples are, higher end MTC devices like security cameras, industrial IoTs and for wearable etc.

In this branch of design, following factors are given with higher priority

1. Very low device cost
2. Very low device energy consumption 

"Wait., Wait., I can hear you inner voice here!. The above two points are already take care in LTE-CATM and NB-IoT. Then, what is the need to introduce new category? . . Please continue reading the article. You will be answered with actual or slightly increase in requirements over already available technologies"

What is need for NR-Light over LTE based CAT-M and NB-IoT?

• There are use cases that require lower device complexity and reduced energy consumption compared what can be provided by NR Release 15/16 and which, at the same time, has higher requirements in terms of data rates and latency compared to what can be provided with LTE-MTC and NB-IoT
• To address such use cases, 3GPP has initiated Release-17 activities on reduced-capability NR devices (sometimes referred to as NR Light). [3GPP RP-193238, ” New SID on support of reduced-capability devices”] . The work will initially be carried out as a study item to be concluded at RAN #88 (June 2020), with an expected work items to follow.  

NR-Light: Actual requirements for work items

• The aim is to achieve the reduced device complexity and energy consumption without compromising the achievable coverage. This Release-17 technology capability is not intended to replace mMTC low-power wide-area devices (i.e. eMTC/NB-IoT devices), but to enhance NR to address the following use cases in Industrial IoT and other verticals
• These use cases have higher requirements than mMTC but lower than eMBB and URLLC.

1. Medium to high data rate (2-25 Mbps) video transmission
2. High data-rate wearables (5-50 Mbps) with long battery life (1-2 weeks) or  much longer than for MBB, (a week or even months)
3. Industrial wireless sensors with low latency (5-10ms) and medium data rate (<2 Mbps) 
4. Expanded coverage (MCL~143dB)
5. Enhanced Reliablity (1e-3/1e-4/1e-5)
6. The device complexity should be comparable to LTE Cat-1 or lower

NR-Light: Work areas for reduced complexity and coverage enhancements

• Support for reduced number of TX/RX antennas at the device side to reduce complexity for both RF and baseband. In addition, single antenna can be easier to integrated into wearable device
• Based on existing NR SSB and CORESET 0 designs, study and identify suitable UE bandwidth(s) for meeting the data rate, latency, and reliability requirements of IWSN and wearables Study if any physical layer changes are required to support UE bandwidth reduction compared to eMBB devices
•  Bandwidth reduction can reduce UE complexity and in order to avoid significant specification change, Rel-15 NR SS/PBCH blocks can be reused.
• Support for devices only capable of half-duplex operation (no simultaneous TX/RX) in paired spectrum 
• Contention based Uplink by Early data transmission for NR for latency reduction and energy efficient improvement
• UP data transmission in RRC-IDLE and/or RRC_INACTIVE state for both 2-step RACH and 4-step RACH
•  Relaying & sidelink for wearables
• Ensure efficient co-existence with URLLC 
• Service coverage should be same as NR Rel-15/16 or even better.

 NR-Light: Work areas for reduced power consumption and Coverage enhancement

• Reduced complexity in PDCCH monitoring by reducing the number of required blind decoding 
• Extended DRX functionality by enhancements to RRC_INACTIVE mode, i.e. longer sleep cycles and efficient RAN handling
• Optimization considering IoT traffic can provide significant power saving, e.g., small data transmission in IDLE/INACTIVE state
• Enable DMRS interpolation across repetitions PDCCH repetitions to increase coverage enhancements
• PRACH repetitions with reduced bandwidth to increase coverage enhancements

NR-Light: Visualizing a mid-low tier scope in terms of requirements

We can able to see the requirements of NR-Light lies between Premium and low end devices like LTE based CAT-M&NB-IoT.

Therefore, Release 17 NR-Light is not for LPWA use vases.

NR-Light: use case study for Industrial purposes

Wide range of use cases and connectivity requirements for industrial verticals 

• cMTC type: remote driving, motion control for industrial automation, power distribution grid fault management 
•  eMBB type: AR/VR for industrial automation 
• IWSN: Industrial wireless sensor networks 
• Sensors with connectivity requirements that cannot be addressed by NR Rel-16 in terms of battery lifetime,form factor and complexity along with  LTE-M/NB-IoT in terms of data rate , reliability and latency 

Examples: microphones, CO2 sensors, pressure sensors, humidity sensors, thermometers, cameras, video cameras, motion sensors, accelerometers, laser scanners, fluid-level sensors, inventory sensors, electric voltage meter, electric current meter, actuators

Finally, the find the requirements table for industry based uses cases.

NR-Light: use case study for wearables

 NR-Lite can be designed to address these wide-area use cases such as wearables.

Requirements for wearable section are as follows

1. Small form factor
2. Data rate not as high as eMBB, but higher than LTE-M/NBIoT
3. Latency not as tight as URLLC, but tighter than LTE-M/NBIoT
4. Battery lifetime does not need to be 10-15 years, but need to be much longer than typical recharging cycles of smartphones 

NR-Light: Collection of RAN technical design proposals

NR-Lite: Low tier half duplex changes in FDD

• Duplexer can be removed which reduces insertion loss
• Improved reference sensitivity with 0.8dB and max output power (MPR) upon removal of duplexer
• Due to the flexible frame format in NR, hardware can be re-used between FDD and TDD.

NR-Lite: Control Channel design for low Tier devices (PDCCH optimization)

• R15 CORESET #0 max BW 17 MHz (i.e., 96RBs for SCS=15kHz, 48RBs for SCS=30kHz), can be larger than the max BW (i.e., 5MHz, 10MHz) targeted for the Low Tier UE. Therefore, introduction of single CORESET that contains one CSS set and one UESS set per BWP for Low Tier UE will meet BW requirement.
• Introduction of reduced number of blind decoding and CCE's per slot shall reduce PDCCH overheads.

NR-Lite: Design should co-exist with premium and Low tier devices

•  Rel-15/16 support for reduced BW UEs tend to congregate users around the SSB/RMSI frequency
• Techniques to support distributing low tier UEs across frequency by Multiple SSB/RMSI distributed across frequency
• Efficient multiplexing of resources between low tier and high tier UEs by introducing new configuration scheme for PDCCH resources to minimize CORESET fragmentation and/or blocking for PDCCH resources

NR-Lite: Peak power and battery life optimization

• Battery saving design is critical for wearables and therefore, Peak power requirement becomes dominant factor for battery design. Hence, Lower peak power yields smaller and less expensive battery and reduce the size of the form factor
• Enhancements for battery life optimization by introducing Extended DRX with Wake-Up-Signal feature, additional RS for RRM and EDT feature for small data transmissions.
•  PHY design to support UL small data transfer for low-power UE in RRC_INACTIVE and RRC_IDLE states to reduce Shortened queuing delay and signal overhead.

NR-Lite: Relaying for Wearable and Mesh for Relaxed IoT

• As a coverage enhancements, introduction of fewer antennas and lower power along with longer battery life to uplink power save
• Relaying shall be sidelink based approach or Uu based

Conclusion:

"NR serves huge data with ultra low latency which can be used for eMBB/URLLC features. A new requirements raised based on eMTC along with Industrial IoT & wearables will leads or made us, to introduce new reduced version or reduced capability NR devices and which also to act as enhanced versions of LTE CATM & NB-IoT"

References:

• RP-190844-NRLite-R17-QCOM.pdf
• RP-191047 Motivation for new SID on NR-Lite for Industrial Sensors and Wearables.pdf
• https://www.5gamericas.org/wp-content/uploads/2020/01/5G-Evolution-3GPP-R16-R17-FINAL.pdf
• RP-191175 Motivation for NR-lite IoT over NR.pdf