Single Subcarrier Retransmission Control for NB-IoT
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Solution Overview
Problem
In Machine-Type Communication (MTC) systems, particularly in Narrow Band Internet of Things (NB-IoT), there is a challenge with properly performing retransmission control of downlink signals due to the restricted bandwidth, which affects the transmission method used in existing LTE systems.
Innovation Solution
A user terminal equipped with a reception section for downlink control information and a control section that determines the appropriate single subcarrier for retransmission control information of the downlink shared channel, enabling effective retransmission control in future radio communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-tone transmission is supported in NB-IoT uplink with restricted bandwidth, then device complexity is reduced and coverage area is improved, but proper retransmission control of downlink signals becomes difficult to implement
Solution Approach 1:
The patent changes the parameter of subcarrier quantity from multiple to single, and adjusts the transmission power parameter to be concentrated on the single subcarrier. This allows single-tone transmission to achieve proper retransmission control by modifying these key parameters while maintaining the restricted bandwidth constraint.
Solution Approach 2:
The patent introduces dynamic adjustment of transmission power and resource allocation for the single subcarrier based on channel conditions and retransmission requirements. The base station dynamically controls the single subcarrier transmission parameters to ensure reliable retransmission control despite the simplified single-tone structure.
2Ease of manufacture
If transmission is restricted to a single subcarrier in NB-IoT, then device cost is reduced, but the ability to properly conduct retransmission control of downlink signals deteriorates
Solution Approach 1:
The patent modifies transmission parameters including concentrating power on a single subcarrier, adjusting modulation schemes, and optimizing resource allocation for single-tone transmission. These parameter changes enable cost-effective single-subcarrier devices to achieve proper retransmission control functionality.
Solution Approach 2:
The patent implements feedback mechanisms where the user terminal sends acknowledgment signals based on downlink signal reception quality, and the base station adjusts subsequent transmissions accordingly. This feedback loop ensures reliable retransmission control even with the simplified single-subcarrier hardware structure.
Data Source
AI summary
Disclosed is to properly perform retransmission control of a downlink signal (e.g., a downlink shared channel) in a future radio communication system. The present invention provides a user terminal comprising a reception section that receives downlink control information and a control section that determines, based on the downlink control information, a single subcarrier that is used for transmission of retransmission control information of a downlink shared channel.