NB-IoT Control Channel Allocation in Unlicensed Spectrum
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Solution Overview
Problem
Existing IoT devices face challenges in achieving low cost, low power consumption, and enhanced coverage, particularly in unlicensed frequency spectrum, with divergent UE requirements for data rate and latency, and existing technologies like eMTC and NB-IoT face limitations in licensed frequency spectrum scarcity and regulatory constraints.
Innovation Solution
The design of enhanced narrowband physical downlink control channels (eNCCEs) for UEs with wide and narrow bandwidth capabilities, including increased aggregation levels, renumbering, and flexible resource allocation, along with downlink control information (DCI) and search space design for unlicensed NB-IoT systems, optimizing channel access and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NB-IoT operates in licensed frequency spectrum, then coverage enhancement and low power consumption are achieved, but data rate boost is limited due to spectrum scarcity
Solution Approach 1:
The patent transitions NB-IoT operation from licensed spectrum to unlicensed spectrum dimension, enabling access to additional frequency resources (865-868 MHz band) to boost data rate while maintaining NB-IoT's coverage enhancement capabilities through adaptive power control and repetition mechanisms
2Ease of operation
If digital modulation is used in unlicensed band, then system bandwidth requirement is met, but transmission power is limited by PSD limitation
Solution Approach 1:
The patent implements adaptive power control that dynamically adjusts transmission power based on channel conditions, duty cycle requirements, and PSD limitations in unlicensed band, allowing the system to optimize between power efficiency and coverage while complying with regulatory constraints
Solution Approach 2:
The patent employs periodic transmissions with duty cycle control, where NB-IoT transmissions are scheduled in periodic intervals rather than continuous operation, allowing the system to meet PSD limitations while achieving effective coverage through repeated transmissions over time
3Reliability
If frequency hopping is used, then frequency diversity is exploited, but initial access timing is longer
Solution Approach 1:
The patent applies partial frequency hopping where only a subset of resource blocks undergo frequency hopping while others remain static, providing frequency diversity benefits for data transmission while maintaining faster access timing for control channels that require immediate establishment
4Productivity
If standalone LTE operates in unlicensed spectrum, then data rate is boosted, but device complexity increases
Solution Approach 1:
The patent designs NB-IoT to operate universally in both licensed and unlicensed spectra with a single device architecture, allowing low-cost NB-IoT devices to access unlicensed band resources for enhanced data rate without requiring separate hardware or complex multi-mode operation
Data Source
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AI summary
In embodiments, a base station may be able to identify whether a user equipment (UE) is to operate within the cellular network in accordance with a wideband (WB) protocol or a narrowband (NB) protocol. Based on this identification, the base station may further be able to identify a number of resource blocks (RBs) that include subcarriers occupied by enhanced narrowband control channel elements (eNCCEs). Finally, the base station may be able to transmit the eNCCEs on the subcarriers. Other embodiments may be described and/or claimed.