SIB Scheduling for Low Complexity UE in Coverage Enhancement
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Solution Overview
Problem
Existing communication systems face challenges in efficiently transmitting system information to Rel-13 low complexity user equipment due to limitations in bandwidth, power, and capabilities, leading to performance degradation and increased latency, especially in coverage enhancement modes.
Innovation Solution
An enhanced system information block scheduling scheme is introduced, including a new master system information block (M-SIB1) with predefined frequency allocation and periodicity, allowing Rel-13 low complexity user equipment to efficiently acquire system information without prior knowledge of bandwidth allocation, and incorporating a compact downlink control channel to indicate transport block size and transmission patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If system information block size is increased to improve information completeness, then the number of repetitions required increases, but transmission latency and power consumption increase
Solution Approach 1:
The system information is segmented into multiple types (Type0, Type1, Type2, Type3) with different repetition factors. Type0 has repetition factor 1, Type1 has repetition factor 2, Type2 has repetition factor 4, and Type3 has repetition factor 8. This segmentation allows the system to transmit different levels of information with appropriate repetition levels, balancing information completeness with transmission efficiency and reduced latency.
2Reliability
If repetition factor is increased to improve reliability in coverage enhancement mode, then system information transmission reliability improves, but downlink capacity is reduced
Solution Approach 1:
Different repetition factors are assigned to different system information types based on their specific reliability requirements. Type0 (master information) uses repetition factor 1 for high downlink capacity efficiency, while Type3 (dedicated MTC information) uses repetition factor 8 for maximum reliability in coverage enhancement mode. This local quality approach optimizes the balance between reliability and downlink capacity for each information type.
3Adaptability or versatility
If multiple small system information blocks are used to improve transmission flexibility, then scheduling flexibility improves, but acquisition latency increases
Solution Approach 1:
The system employs periodic transmission of system information blocks with predefined periodicity for each type. Type0 is transmitted every 80 radio frames, Type1 every 160 radio frames, Type2 every 320 radio frames, and Type3 every 640 radio frames. This periodic action provides scheduling flexibility while reducing acquisition latency compared to monitoring multiple small blocks, as UEs can efficiently acquire the information types they need at predictable intervals.
Data Source
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AI summary
Various communication systems may benefit from efficient communication of system information. For example, certain wireless communication systems may benefit from system information block enhancement for low complexity user equipment and/or user equipment in coverage enhancement mode. A method can include decoding a transport block size (TBS) index in a compact downlink control information. The method can also include monitoring for SIB based on the decoded TBS index. The method may optionally include monitoring for the SIB based on a predefined transmission pattern of physical downlink control channel for machine type communication. The method may also optionally include decoding of M-SI messages from a subframe according to a pattern indicated by an information element in M-SIB1.