HARQ Timing Alignment for eMTC via CE-Level Parameters
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing hybrid automatic repeat request (HARQ) timing and control channel timing for enhanced machine type communication (eMTC), particularly for low-cost devices with limited communication resources, which can lead to misalignment in HARQ timing and reduced uplink and downlink throughput.
Innovation Solution
The proposed solution involves a user equipment (UE) determining HARQ process identification (ID) based on coverage enhancement (CE) levels, determining subframes for transmitting physical uplink control channels (PUCCH) and machine type communication physical downlink control channels (MPDCCH), and adjusting HARQ timing to align with available uplink and downlink subframes, thereby improving HARQ efficiency and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HARQ timing is managed using conventional methods in eMTC systems, then basic communication functionality is maintained, but HARQ timing misalignment occurs and throughput is reduced
Solution Approach 1:
The patent changes the timing parameters for HARQ processes based on coverage enhancement (CE) levels. Different CE levels (CE0, CE1, CE2) have different K1 values that determine the timing between downlink data reception and uplink ACK/NACK transmission. This parameter adjustment resolves the timing misalignment issue while maintaining reliable communication for devices with varying coverage requirements
Solution Approach 2:
The system dynamically adjusts HARQ timing parameters according to the CE level of the device. The K1 value is not fixed but varies based on the coverage enhancement level, allowing the system to adapt timing to channel conditions and device capabilities, thereby achieving both timing alignment and high throughput
2Adaptability or versatility
If coverage enhancement levels are increased to support low-cost devices with limited resources, then device accessibility is improved, but HARQ timing alignment becomes more difficult to maintain
Solution Approach 1:
The patent introduces CE-level-dependent timing parameters where each coverage enhancement level (CE0, CE1, CE2) has specific K1 values assigned. This allows the system to support devices with different coverage requirements while maintaining proper timing alignment through parameter differentiation rather than a one-size-fits-all approach
Solution Approach 2:
Different timing parameters are applied to different CE levels based on their specific requirements. Each CE level receives locally optimized timing parameters rather than uniform system-wide parameters, ensuring that devices with limited resources can maintain timing synchronization appropriate to their coverage capabilities
3Productivity
If uplink and downlink subframes are optimized for eMTC operations, then communication efficiency is improved, but control channel timing alignment becomes challenging
Solution Approach 1:
The patent determines the set of possible starting subframes for monitoring MPDCCH in advance, based on the current subframe number, available subframe patterns, and repetition levels. This preliminary determination of monitoring occasions ensures that control channel timing is pre-coordinated, preventing timing losses while optimizing uplink and downlink subframe utilization
Data Source
AI summary
Aspects of the present disclosure provide hybrid automatic repeat request (HARQ) techniques for enhanced machine type communication (eMTC). In one aspect, a method is provided which may be performed by a wireless device such as a user equipment (UE) for determining a HARQ ID. The method generally includes determining a HARQ ID based, at least in part, on a coverage enhancement (CE) level, and performing a HARQ process timeline based, at least in part, on the determined HARQ ID. Another method is provided for determining a subframe to transmit feedback. The method generally includes determining at least one subframe to transmit a physical uplink control channel (PUCCH) to acknowledge one or more downlink transmissions based, at least in part, on availability of uplink subframes following one or more downlink subframes carrying the downlink transmissions to be acknowledged and transmitting the PUCCH in the determined at least one subframe.