MTC Terminal Feedback Timing Adjustment for Narrow Band Reception
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Solution Overview
Problem
Low-cost Machine-Type Communication (MTC) user terminals face challenges in receiving transmission acknowledgment information due to limited uplink and downlink bands, leading to inadequate communication with radio base stations when using partial frequency blocks in a system band.
Innovation Solution
Adjusting the feedback timing of transmission acknowledgment information for MTC terminals to ensure receipt in predetermined subframes, allowing for adequate reception even when bands are limited to partial frequency blocks, and implementing frequency hopping to spread traffic and achieve frequency diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MTC terminals use partial frequency blocks (narrow bands) to reduce cost and improve coverage, then device cost is reduced and coverage area is improved, but the ability to receive transmission acknowledgment information deteriorates due to limited downlink control signal subframes
Solution Approach 1:
The patent applies dynamics by making the downlink control signal subframes configurable and adaptable. Specifically, the system dynamically selects which subframes can carry downlink control signals (MPDCCH) based on the terminal's capability and network configuration. This allows the system to optimize the balance between coverage enhancement and reliable acknowledgment reception by adjusting the timing and frequency of control signals according to actual channel conditions and terminal requirements.
Solution Approach 2:
The patent changes key parameters including the subframe offset (k) for HARQ-ACK feedback, the periodicity of MPDCCH transmission, and the frequency location of narrow bands. By adjusting these parameters, the system ensures that acknowledgment information is transmitted in subframes where MTC terminals can reliably receive them, while maintaining the cost and coverage benefits of narrow band operation. The parameter k can be configured to ensure proper alignment between uplink data transmission and downlink acknowledgment reception.
2Device complexity
If MTC terminals are limited to partial frequency blocks for cost reduction, then device complexity is reduced, but communication adequacy with radio base stations deteriorates due to insufficient downlink control signal transmission opportunities
Solution Approach 1:
The patent segments the downlink control signal transmission across multiple subframes and frequency locations. Instead of relying on a single control channel, the system divides control information transmission into multiple opportunities (MPDCCH in configured subframes), allowing terminals to receive control signals even with limited bandwidth. This segmentation ensures that critical control information is transmitted reliably despite the terminal's restricted frequency block access.
Solution Approach 2:
The patent makes the downlink control channel (MPDCCH) multi-functional by enabling it to carry various types of control information including uplink grants, downlink assignments, and HARQ acknowledgments within the same narrow band structure. This universal control channel design allows MTC terminals to receive all necessary control signals through a single configured downlink control channel, maintaining communication adequacy while preserving the simplified hardware structure benefits of narrow band operation.
3Adaptability or versatility
If existing LTE feedback techniques are applied to MTC terminals with limited bands, then conventional communication protocols are maintained, but transmission acknowledgment information cannot be received adequately due to mismatched subframe timing
Solution Approach 1:
The patent applies local quality by customizing the feedback timing and control signal transmission specifically for MTC terminals operating in narrow bands, while maintaining compatibility with overall LTE framework. The subframe offset k and MPDCCH periodicity are locally optimized for MTC requirements, allowing adequate acknowledgment reception in the specific context of narrow band operation without disrupting the broader LTE protocol structure. This localized adaptation ensures both protocol compatibility and reliable communication.
Data Source
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AI summary
The present invention is designed so that transmission acknowledgment information in response to uplink data signals can be received adequately when the bands for use are limited to partial frequency blocks in a system band. According to one aspect of the present invention, a user terminal, in which the band to use is limited to a narrow band in a system band, has a receiving section that receives transmission acknowledgment information in response to an uplink data channel via a downlink control channel that is transmitted in a starting subframe of a predetermined cycle, and a control section that controls retransmission of the uplink data channel based on the transmission acknowledgment information. The feedback timing for the transmission acknowledgment information is adjusted base on the starting subframe.