Modulation Order Adaptation for LTE Partial Subframe Transport Blocks
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Solution Overview
Problem
In LTE systems operating in unlicensed bands, the use of partial subframes due to listen before talk procedures results in unpredictable subframe lengths, leading to inefficiencies in data transmission as the transport block size may not fit within the available resources, limiting throughput and requiring fixed small block sizes that do not maximize resource utilization.
Innovation Solution
Implement modulation order adaptation for partial subframes by allowing higher modulation orders and adjusting transport block sizes dynamically based on the availability of subframes, indicated through additional signaling in the downlink control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If listen before talk procedure is employed in unlicensed bands, then channel access reliability is improved, but subframe length becomes unpredictable leading to resource utilization inefficiency
Solution Approach 1:
The patent applies dynamics by making the transport block size adaptive rather than fixed. The transport block size is dynamically adjusted based on the actual available resources in partial subframes, allowing the system to optimize resource utilization while maintaining reliable channel access through listen before talk procedures
Solution Approach 2:
The patent changes the parameter of transport block size from a fixed value to a variable that adapts to partial subframe conditions. By modifying this parameter based on actual resource availability, the system resolves the contradiction between maintaining reliability and improving productivity
2Reliability
If fixed small transport block sizes are used in partial subframes, then transmission reliability is improved, but throughput is limited due to underutilization of available resources
Solution Approach 1:
The patent makes transport block size dynamic rather than fixed. The system determines the appropriate transport block size based on the actual number of available resource elements in each partial subframe, enabling both reliable transmission and maximized throughput by adapting to varying channel conditions
Solution Approach 2:
The patent implements feedback mechanisms where the system monitors available resources in partial subframes and adjusts transport block sizes accordingly. This feedback loop ensures that transmission reliability is maintained while throughput is optimized based on actual resource availability
3Productivity
If transport block size is increased to maximize resource utilization, then productivity is improved, but the risk of not fitting within available partial subframe resources increases
Solution Approach 1:
The patent applies preliminary action by calculating and determining the appropriate transport block size before transmission based on the known available resources in partial subframes. This advance determination ensures that the transport block will fit within the allocated resources while maximizing resource utilization
Data Source
AI summary
The present disclosure relates to transmitting transport blocks in subframes of a predefined length within a wireless communication system. A downlink control information including a resource grant comprising a predetermined modulation and a predetermined transport block size is received (user equipment is the transmitter) or generated (base station is the transmitter). Then transport block including channel coded data to be transmitted in a subframe with the predetermined modulation and the predetermined transport block size is generated. Sensing is performed in the subframes and based thereon, it is determined whether a partial subframe or a complete subframe is available for transmission of the generated transport block. Finally, the transport block is transmitted with a modified modulation different from the predetermined modulation if the partial rather than complete subframe is available. Correspondingly, at the receiver, the grant is received (user equipment is receiver) or generated (base station is the receiver), the size of the subframe in which the reception is expected is determined and then the transport block is received with a modified modulation if only the partial subframe is available.