MulteFire eMTC Measurement in Unlicensed Spectrum
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Solution Overview
Problem
The increasing demand for data bandwidth and diverse communication requirements in 3GPP LTE systems, particularly with the rise of IoT devices like eMTC and NB-IoT, has led to challenges in managing spectrum resources, especially in unlicensed bands, where interference and channel availability become significant issues.
Innovation Solution
The implementation of MulteFire systems that allow LTE operation solely in unlicensed spectrum, using frequency hopping and Listen-Before-Talk protocols to manage channel access and reduce interference, while maintaining compliance with regulatory power spectrum density limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LTE systems use unlicensed spectrum to accommodate increasing IoT devices and data bandwidth requirements, then network capacity and throughput are improved, but interference and channel availability issues worsen
Solution Approach 1:
The system performs Listen-Before-Talk (LBT) procedures before transmitting on unlicensed carriers, and implements frequency hopping patterns that are predetermined and configured in advance. This preliminary action allows the system to assess channel availability and avoid interference before transmission occurs, resolving the contradiction between utilizing unlicensed spectrum for capacity expansion and managing interference effectively
Solution Approach 2:
The system dynamically adjusts frequency hopping patterns and transmission parameters based on channel conditions and interference levels. By making the frequency allocation dynamic rather than static, the system can adapt to changing interference conditions in unlicensed spectrum while maintaining network capacity for IoT devices
2Object-affected harmful factors
If frequency hopping is implemented to reduce interference in unlicensed spectrum, then interference reduction is achieved, but device complexity increases
Solution Approach 1:
The system changes frequency parameters according to predetermined hopping patterns and configurations. By using standardized parameter sets and patterns defined in the patent, the complexity of implementing frequency hopping is reduced while still achieving interference reduction through systematic frequency variation
Solution Approach 2:
The system uses predetermined frequency hopping patterns that can be replicated and configured through standardization. Rather than requiring complex real-time frequency selection algorithms, the system copies and applies predefined hopping sequences, reducing device complexity while maintaining interference mitigation effectiveness
3Reliability
If Listen-Before-Talk protocols are used to manage channel access in unlicensed bands, then channel availability is improved, but transmission delay increases
Solution Approach 1:
The system performs LBT procedures with configurable contention window sizes and backoff parameters. By adjusting these parameters to be partial (not always maximum) or excessive (sometimes more aggressive), the system balances channel availability reliability with transmission delay, allowing faster access when conditions permit while maintaining reliability when interference is high
Data Source
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AI summary
Systems and methods of measuring reference signals in a multefire scenario are described. A UE receives control information anchor channel dependent on whether the UE is in an adaptive frequency hopping system (FHS) and whether the FHS is a LBT FHS. The reference signals are received on an unlicensed band via the anchor and/or a non-anchor channel and measured for RRM and/or in-sync or out-of-sync measurements. RRM measurements are transmitted to the eNB for mobility management and otherwise the validity of an in- or out-of-sync indication is determined and a counter started when valid. The control information has a subframe configuration and resource allocation, which is used for SRS transmission on the non-anchor channel. Uplink scheduling information is received on the anchor channel for data transmission on the non-anchor channel based on the SRS.