ACK/NACK Bit Grouping for Balanced DFT-S-OFDM Reception
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Solution Overview
Problem
In LTE-A systems, the transmission of ACK/NACK messages using DFT-S-OFDM results in unbalanced receiving performance due to dependence on channel conditions of specific slots, leading to complex receiver algorithms and instability.
Innovation Solution
Divide information bits into groups and encode them separately, then modulate and reorder the coded bits to ensure balanced distribution across multiple slots, using techniques like alternately ordering modulation symbols to improve receiving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the first 24 coded bits are mapped onto slot 0 and the last 24 coded bits are mapped onto slot 1 using DFT-S-OFDM, then the transmission structure is simple and follows the standard format, but the receiving performance becomes unbalanced and depends heavily on channel conditions of specific slots
Solution Approach 1:
The 48 coded bits are divided into two groups of 24 bits each. The first group (b(0) to b(23)) is mapped to slot 0, and the second group (b(24) to b(47)) is mapped to slot 1. This segmentation allows independent channel condition dependence for each slot while maintaining overall system reliability through diversity.
Solution Approach 2:
The patent introduces time slot dimensionality by distributing coded bits across two different slots (slot 0 and slot 1) rather than concentrating them in one slot. This temporal distribution exploits time-varying channel conditions to improve receiving performance stability.
2Productivity
If the last symbol in slot 1 is occupied by SRS, then the extension length is shortened from 5 to 4, but the receiving performance of the last 24 coded bits deteriorates compared to the first 24 coded bits
Solution Approach 1:
The patent applies different extension lengths to different slots based on local conditions: slot 0 uses extension length 5 while slot 1 uses extension length 4 when SRS is present. This local adaptation maintains resource utilization efficiency while compensating for the performance loss in slot 1 through the robustness provided by slot 0.
3Ease of operation
If coded bits are independently mapped to specific slots, then the transmission process is straightforward, but the receiver requires complex algorithms to handle unbalanced performance
Solution Approach 1:
The receiver processes the two slots independently, decoding the first 24 coded bits from slot 0 and the last 24 coded bits from slot 1 separately. This segmentation simplifies the receiver algorithm by avoiding the need for complex joint processing across slots with different extension lengths.
Data Source
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AI summary
A method, an apparatus and a system for transmitting information bits are provided. The method for transmitting information bits includes: dividing the information bits to be transmitted into at least two groups; encoding the information bits to be transmitted in each group; modulating the coded bits obtained by the encoding to obtain modulation symbols, in which each modulation symbol is obtained by using the modulation of the coded bits in the same group; and mapping and transmitting the modulation symbols. In this way, the receiving end easily reduces the algorithm complexity, thereby ensuring the performance of the receiving end.