Random Access Link Adaptation for Coverage-Enhanced Uplink
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Solution Overview
Problem
Existing wireless communication systems face challenges in providing reliable coverage for delay-tolerant and low-complexity devices in coverage-limited areas, such as low-cost machine type communication (LC-MTC) devices, due to high penetration loss, necessitating improved coverage enhancement techniques.
Innovation Solution
Implementing coverage enhancement techniques including channel repetition, power boosting, and reference signal improvement, along with link adaptation based on coverage enhancement levels and channel repetition levels for uplink and downlink channels, and minimizing (E)PDCCH monitoring in CE mode to optimize battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coverage enhancement techniques (channel repetition, power boosting) are applied, then coverage reliability is improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts coverage enhancement parameters (repetition number, power boosting level) based on real-time channel conditions and device requirements. The eNodeB determines the appropriate CE level and transmits physical downlink shared channel and physical downlink control channel with varying repetition numbers to optimize the balance between coverage reliability and energy consumption.
Solution Approach 2:
The patent changes key transmission parameters including the number of repetitions for physical downlink shared channel and physical downlink control channel, power boosting levels, and resource allocation based on coverage enhancement levels. This allows the system to adapt coverage enhancement intensity to match actual communication needs.
2Reliability
If channel repetition levels are increased for coverage enhancement, then communication reliability is improved, but transmission time increases
Solution Approach 1:
The system dynamically determines the number of repetitions based on actual channel conditions and device requirements. The eNodeB configures different repetition numbers for physical downlink shared channel and physical downlink control channel depending on the coverage enhancement level needed, avoiding unnecessary repetitions that would waste time.
Solution Approach 2:
The system applies partial coverage enhancement by using variable repetition numbers rather than always using maximum repetition. The eNodeB determines the appropriate CE level and applies only the necessary degree of repetition to achieve reliable communication without excessive time consumption.
3Duration of action of moving object
If (E)PDCCH monitoring is minimized in CE mode, then battery life is extended, but control information reception reliability may worsen
Solution Approach 1:
The system dynamically adjusts (E)PDCCH monitoring frequency based on coverage enhancement level and channel conditions. The eNodeB configures the WTRU to monitor (E)PDCCH at reduced frequency in CE mode, balancing battery saving with reliable control information reception through adaptive monitoring strategies.
Solution Approach 2:
The system uses feedback mechanisms where the WTRU reports channel conditions and reception status, allowing the eNodeB to adjust (E)PDCCH monitoring requirements accordingly. This feedback loop ensures that battery life extension does not compromise control information reception reliability.
Data Source
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AI summary
A method implemented in a wireless transmit and receive unit, WTRU, the method comprising: transmitting a physical random access channel preamble on first uplink resources; receiving a random access response which comprises a scheduling grant, the scheduling grant comprising first and second bit fields, wherein the first bit filed indicates second uplink resources, and wherein the second bit filed indicates a modulation and coding scheme index or at least a portion of the second bit filed indicates a number of repetitions based on at least one of the physical random access channel preamble and the first uplink resources; and transmitting a physical uplink shared channel transmission, wherein: the physical uplink shared channel transmission is transmitted on the second uplink resources for a number of times corresponding to the number of repetitions based on the at least a portion of the second bit field indicating the number of repetitions; and the physical uplink shared channel transmission is transmitted on the second uplink resources without repetition based on the second bit field indicating the modulation and coding scheme index.