NB-IoT Wake-Up Receiver for Low-Power Reachable DRX Operation
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Solution Overview
Problem
Narrowband IoT (NB-IoT) radios face high power consumption due to complex RF hardware demands, making them unsuitable for many IoT applications, especially those requiring infrequent but low-latency communication, as existing solutions like duty-cycling are not sufficient for power reduction.
Innovation Solution
A narrowband wake-up receiver is designed to efficiently receive wireless wake-up signals, optimizing power usage by using a low noise amplifier, mixer circuit, local oscillator, and fractional n phased-locked loop circuit, which can be powered down during inactive periods, reducing average power consumption without increasing communication latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If duty-cycling is used to reduce RX power, then power consumption is reduced, but the receiver becomes unreachable for the majority of the time
Solution Approach 1:
The receiver is segmented into two separate functional blocks: a wake-up receiver that remains continuously active to detect incoming signals, and a main receiver that operates only when needed. This segmentation allows the system to maintain reliability by ensuring the wake-up receiver is always reachable while reducing overall power consumption by keeping the power-hungry main receiver dormant most of the time.
Solution Approach 2:
The wake-up receiver acts as an intermediary between the external environment and the main receiver. It continuously monitors for wake-up signals and only activates the main receiver when a valid wake-up signal is detected, thereby mediating between the need for continuous reachability and the need for power savings.
2Adaptability or versatility
If NB-IoT uses 12-subcarrier OFDM with QSPK subcarrier modulation and 180 kHz bandwidth, then forward compatibility with 5G NR is achieved, but power consumption increases
Solution Approach 1:
The system applies local quality by making different parts of the receiver have different operational characteristics. The wake-up receiver uses simplified reception logic optimized for detecting wake-up signals, while the main receiver handles the complex NB-IoT protocols. This allows the system to maintain forward compatibility through the main receiver while reducing overall power consumption through the simplified wake-up receiver.
Solution Approach 2:
The system dynamically switches between different operational modes: the wake-up receiver operates continuously in a low-power state, and the main receiver is activated only when needed. This dynamic operation allows the system to maintain adaptability for complex protocols when required while minimizing power consumption during idle periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The wake-up receiver significantly reduces the average power consumption of NB-IoT devices while maintaining sensitivity and deployment range, enabling efficient operation in low-power states without compromising communication latency or range.
Implementation Method 1
an antenna configured to receive an RF signal
Implementation Method 2
a low noise amplifier interfaced with the antenna
Implementation Method 3
The mixer circuit downconverts the frequency of the RF signal to an intermediate frequency
Implementation Method 4
a local oscillator, and a mixer circuit configured to receive the RF signal from the low noise amplifier as well as a mixing signal from the local oscillator
Implementation Method 5
The wake-up receiver further includes a fractional n phased-locked loop circuit interfaced with the local oscillator
Data Source
AI summary
A low-power standard-compliant NB-IoT wake-up receiver (WRX) is presented. The WRX is designed as a companion radio to a full NB-IoT receiver, only operating during discontinuous RX modes (DRX and eDRX), which allows the full high-power radio to turn off while the wake-up receiver efficiently receives NB-IoTWake-Up Signals (WUS). The fabricated receiver achieves 2.1 mW power at −109 dBm sensitivity with 180 kHz bandwidth over the 750-960 MHz bands. The WRX is fabricated in 28 nm CMOS and consumes 5× less power than the best previously published traditional NB-IoT receivers. This disclosure is the first designed dedicated wake-up receiver for the NB-IoT protocol and demonstrates the benefits of utilizing a WRX to reduce power consumption of NB-IoT radios.