Interleaving Transport Blocks Across TTIs for Wireless Reliability
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Solution Overview
Problem
In wireless communications, especially in 4G and 5G systems, communication devices often experience interference while receiving transport blocks, leading to unsuccessful decoding due to the lack of hybrid automatic repeat request (HARQ) feedback, particularly in multicast or broadcast transmissions where feedback is not configured.
Innovation Solution
The technique involves transmitting different parts of a transport block across multiple transmission time intervals (TTIs) with a scaling factor, applying a transport block allocation pattern to improve time diversity, and providing an indication of this pattern to the receiving device, allowing it to decode the transport block even if interference occurs in one TTI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If transport block is transmitted in a single TTI, then transmission speed is high, but reliability deteriorates due to interference
Solution Approach 1:
The transport block is divided into multiple segments and transmitted across different TTIs according to a transport block allocation pattern. This segmentation allows the receiver to combine information from multiple transmissions, improving reliability while maintaining throughput by distributing the data across time intervals where interference conditions may differ.
2Reliability
If transport block is transmitted across multiple TTIs, then reliability improves through time diversity, but transmission speed decreases
Solution Approach 1:
The system dynamically adapts the transport block allocation pattern based on channel conditions and interference characteristics. By adjusting the distribution of transport block segments across TTIs according to varying interference conditions, the system optimizes both reliability and transmission speed, achieving time diversity without excessive delay.
3Reliability
If HARQ feedback is used for retransmission, then decoding reliability improves, but device complexity increases due to feedback mechanisms
Solution Approach 1:
The system employs autonomous retransmission where the transmitting device automatically retransmits the transport block in subsequent TTIs based on the allocation pattern, without requiring explicit HARQ feedback from the receiving device. This self-service approach maintains high decoding reliability through repeated transmissions while significantly reducing the complexity of feedback mechanisms, especially beneficial in broadcast and multicast scenarios.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A base station may apply a scaling factor to a transport block of a first size, where the scaling factor may increase the transport block from the first size to a second size. The base station may interleave a set of parts of the transport block of the second size across a set of transmission time intervals (TTIs) in accordance with a transport block allocation pattern, where the set of TTIs may be contiguous or separated from each other by one or more intervening intervals. The base station may transmit, to a user equipment, an indication of the transport block allocation pattern applied to the transport block of the second size, and may transmit the set of parts of the transport block of the second size across the set of TTIs in accordance with the transport block allocation pattern.