Multi-subframe Grant Scheduling for Unlicensed Spectrum Coexistence
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Solution Overview
Problem
Wireless communication devices face challenges when operating in unlicensed radio spectrums due to coexistence issues with other technologies, such as Wi-Fi, leading to potential degradation of performance and limited spectrum efficiency.
Innovation Solution
Implementing a multi-subframe grant system that indicates specific data and control subframes for wireless devices to transmit in unlicensed radio spectrums, allowing for efficient scheduling and reduced interference with other systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LTE operates in unlicensed spectrum using traditional licensed spectrum scheduling methods, then wireless devices can access additional spectrum resources, but coexistence issues with Wi-Fi and other systems cause performance degradation
Solution Approach 1:
The patent segments the transmission opportunity into multiple subframes with different functions: some subframes are designated for data transmission while others are reserved for control channel transmissions. This segmentation allows the system to maintain both data throughput and control signaling reliability in the unlicensed spectrum, addressing the coexistence challenge by creating a structured transmission pattern that reduces random access conflicts with Wi-Fi
Solution Approach 2:
The patent implements preliminary action by sending control information in advance in designated control subframes before the actual data transmission subframes. This allows wireless devices to be pre-scheduled with grant information, reducing the need for repeated control signaling and minimizing channel access attempts that could interfere with Wi-Fi operations
2Adaptability or versatility
If multiple separate grants are used to schedule data and control channels in unlicensed spectrum, then scheduling flexibility is maintained, but control signaling overhead increases
Solution Approach 1:
The patent merges multiple grant indications into a single uplink grant message that simultaneously schedules both data subframes and control subframes. This consolidation reduces control signaling overhead by transmitting one unified grant instead of multiple separate grants, while maintaining scheduling flexibility through the grant's indication of different subframe types and their specific purposes
3Productivity
If LTE uses unlicensed spectrum without dedicated scheduling, then spectrum efficiency improves, but channel access conflicts with Wi-Fi increase
Solution Approach 1:
The patent implements periodic action by establishing a regular pattern of control subframes interspersed with data subframes. This periodic structure creates predictable transmission intervals that reduce random channel access conflicts with Wi-Fi, as the LTE system consistently uses the same subframe pattern rather than attempting random access in every subframe, thereby improving both spectrum efficiency and coexistence
Data Source
AI summary
A method implemented in a wireless device includes receiving an uplink grant from a network node indicating to the wireless device at least one data subframe and at least one control subframe. The at least one data subframe is one where the wireless device is scheduled to transmit a channel for carrying a data stream and optional control data, and the at least one control subframe is one where the wireless device is scheduled to transmit a channel for carrying control data only. The method further includes transmitting in at least one of the at least one data subframe and the at least one control subframe indicated by the uplink grant.