LTE Downlink Reception on Unlicensed Bands
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Solution Overview
Problem
LTE systems face challenges in properly receiving downlink channels and reference signals on unlicensed bands due to incomplete subframes and limited maximum transmission durations, leading to resource wastage and potential interference with other wireless systems.
Innovation Solution
The method involves configuring LTE user equipment to receive downlink channels and reference signals by adjusting the number of OFDM symbols in incomplete subframes, either by completing the last subframe, stopping reception early, or modifying the subframe structure to utilize remaining symbols efficiently, while ensuring compliance with unlicensed band usage rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station transmits downlink channel and reference signal for the complete subframe duration, then the transmission completeness is improved, but the interference with other wireless systems increases due to exceeding limited maximum transmission duration on unlicensed bands
Solution Approach 1:
The patent segments the downlink transmission into two parts: (1) downlink control channel transmitted for the complete subframe duration, and (2) downlink data channel and reference signals transmitted only for the remaining time before the limited maximum transmission duration expires. This segmentation allows the control information to be fully transmitted while limiting the data transmission to avoid exceeding the regulatory time limit, thus resolving the contradiction between transmission completeness and interference reduction.
2Object-affected harmful factors
If the base station stops transmission early to comply with limited maximum transmission duration, then the interference with other wireless systems is reduced, but the resource utilization deteriorates due to incomplete subframes
Solution Approach 1:
The patent applies preliminary action by transmitting the downlink control channel (PDCCH/EPDCCH) first for the complete subframe duration before the limited maximum transmission duration expires. This ensures that critical control information is delivered completely, and then the base station transmits downlink data and reference signals for the remaining time. This preliminary transmission of control information maximizes resource utilization within the time constraint while avoiding interference.
3Reliability
If the UE receives downlink channel for the complete subframe duration, then the reception completeness is improved, but the resource wastage increases due to incomplete subframes on unlicensed bands
Solution Approach 1:
The patent implements dynamic reception timing where the UE adjusts its reception window based on the actual transmission duration. The UE receives the downlink control channel for the complete subframe duration and then receives downlink data and reference signals dynamically for the remaining time before the limited maximum transmission duration expires. This dynamic approach ensures complete reception of control information while avoiding wastage of resources on incomplete data transmissions.
Data Source
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AI summary
The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). The present disclosure provides a method of receiving downlink channel and/or downlink reference signal on an unlicensed band. An LTE user equipment (UE) receives control information of a cell operating on an unlicensed band, and receives downlink channel and/or downlink reference signal transmitted in the cell according to the control information. According to the present disclosure, data can be properly received on an unlicensed band.