Frequency Hopping for Unlicensed IoT via LBT Channel Reservation

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Solution Overview

Problem

Current IoT technologies operating in licensed spectra face challenges with data rate limitations and compatibility issues when deployed in unlicensed frequency bands, particularly in low-frequency bands, necessitating efficient methods for frequency hopping to ensure coexistence with incumbent systems and enhance coverage.

Innovation Solution

Implementing a listen-before-talk (LBT) procedure for IoT devices to reserve unlicensed channels for frequency hopping operations, using techniques like tail-biting convolutional code (TBCC) and QPSK modulation, and employing physical downlink control channels (PDCCH) or preambles to indicate transmission durations and channel availability, allowing IoT devices to perform frequency hopping without additional backoff procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If frequency hopping is implemented in unlicensed spectra for IoT devices, then data rate and coverage are enhanced, but channel coexistence and interference management become more complex

Engineering Contradiction:

Improvedata rateVSAvoidchannel coexistence management

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by implementing Listen-Before-Talk (LBT) procedures before frequency hopping transmissions. The system performs channel sensing and reservation in advance to detect available channels and avoid collisions with incumbent systems, thereby enhancing data rate while managing channel coexistence complexity through proactive channel assessment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs feedback mechanisms through channel sensing results and transmission acknowledgments. The system continuously monitors channel conditions during frequency hopping, adjusts transmission parameters based on channel quality feedback, and manages coexistence by responding to detected interference patterns from other systems

Inventive Principle:

Principle #23Feedback

2Reliability

If LBT procedure is implemented to reserve channels for frequency hopping, then coexistence with incumbent systems is ensured, but transmission delay increases

Engineering Contradiction:

ImprovecoexistenceVSAvoidtransmission delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by implementing LBT procedures selectively rather than continuously. The system performs channel sensing only when needed for frequency hopping operations and uses truncated LBT variants where applicable, ensuring coexistence with incumbent systems while minimizing unnecessary transmission delays through targeted rather than exhaustive channel reservation

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent employs periodic LBT procedures at defined intervals during frequency hopping sequences. Rather than continuous sensing, the system performs channel assessments at periodic checkpoints, maintaining reliable coexistence management while reducing overall transmission delay by allowing uninterrupted data transmission during sensed-clear periods

Inventive Principle:

Principle #19Periodic action

3Object-affected harmful factors

If channel reservation is performed for IoT devices in unlicensed spectra, then interference is reduced, but channel availability decreases

Engineering Contradiction:

ImproveinterferenceVSAvoidchannel availability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by implementing adaptive channel reservation mechanisms. The system dynamically adjusts reservation duration and scope based on real-time channel conditions, traffic requirements, and incumbent system activity. Channel reservations are extended only when interference patterns persist and released when channels become available, thereby reducing interference while maintaining channel availability for legitimate uses

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs parameter changes by modifying LBT thresholds, reservation durations, and frequency hopping patterns based on channel conditions. The system adjusts transmission parameters such as power levels, timing advances, and channel selection probabilities to balance interference reduction with channel availability, allowing flexible adaptation to varying spectral environments

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11350449B2Frequency hopping for unlicensed internet of things

Publication Date: 2022.05.31 APPLE INC

AI summary

Downlink transmissions can be generated to schedule one or more Internet of Things (IoT) devices for communication on unlicensed channels via frequency hopping operations/procedures. An evolved NodeB (eNB) or a next generation NodeB (gNB) can perform a listen before talk (LBT) on the unlicensed channels that are scheduled for transmission by at least one of: one or more IoT devices or one or more user equipments (UEs). A preamble or a common physical downlink control channel (CPDCCH) can be transmitted to reserve the unlicensed channels for the IoT devices/UEs. The preamble or the PDCCH can include a duration of the duration to provide notice to other eNBs/gNBs or trigger the IoT devices of a successful LBT corresponding to the unlicensed channels.