Soft Buffer Partition for Superposition Coding Interference
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Solution Overview
Problem
In LTE networks, the soft buffer sizes for receivers in superposition coding are not standardized, leading to inefficiencies in soft channel bits storage and decoding, particularly when codeword level interference cancellation is used, as the buffers are reserved only for desired signals, not accounting for interfering signals, which hampers the accumulation and combination of soft channel bits across multiple transmissions.
Innovation Solution
Implementing a method for rate matching and soft buffer partitioning that allows for flexible adjustment of soft buffer sizes for both desired and interfering transport blocks, ensuring that both types of signals are handled equally, and signaling the soft buffer size from the base station to user equipment for effective interference cancellation and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If soft buffer size is standardized per UE category, then buffer allocation is simplified, but superposition coding cannot be properly supported because receivers cannot accommodate interfering signals
Solution Approach 1:
The soft buffer is segmented into multiple partitions: a first soft buffer for desired transport blocks and a second soft buffer for interfering transport blocks. This segmentation allows the buffer to accommodate both desired and interfering signals simultaneously, enabling superposition coding support while maintaining standardized buffer allocation per UE category.
2Device complexity
If soft buffer is reserved only for desired signals, then buffer usage is simplified, but interfering signals cannot be stored and combined across multiple transmissions
Solution Approach 1:
The soft buffer is divided into separate partitions for desired and interfering signals. The second soft buffer specifically stores soft channel bits for interfering transport blocks, enabling accumulation across multiple transmissions for interference cancellation while maintaining manageable buffer management through structured partitioning.
Solution Approach 2:
The second soft buffer acts as an intermediary storage for interfering signals, allowing the receiver to store and combine soft channel bits from multiple transmissions of interfering transport blocks. This intermediary mechanism enables effective interference cancellation without complicating the overall buffer management structure.
3Productivity
If different soft buffer sizes are used for different UEs, then each UE gets optimized buffer size, but rate matching becomes problematic in superposition coding scenarios
Solution Approach 1:
The invention introduces a configurable parameter `firstCodeBlockSoftBufferSize` that can be signaled by the base station to user equipment. This parameter allows dynamic adjustment of the first soft buffer size for desired transport blocks, enabling optimized buffer allocation for different UE categories while maintaining compatibility with rate matching algorithms through base station configuration.
4Adaptability or versatility
If soft buffer partition is not standardized, then flexible buffer allocation is achieved, but base station and UE cannot coordinate properly for superposition coding
Solution Approach 1:
The base station signals the parameter `firstCodeBlockSoftBufferSize` to the user equipment, establishing a feedback mechanism for coordinate buffer allocation. This signaling ensures that both base station and UE use consistent buffer size parameters for rate matching, enabling reliable coordination in superposition coding while maintaining flexible buffer partitioning for different signal types.
Data Source
AI summary
When the codeword level interference cancellation (CW-IC) is used at the receiver in conjunction with the superposition coding scheme at the transmitter, it is helpful if the soft buffer at the receiver is reserved not only for the desired transport blocks (TBs) but also for the interfering TBs handled by the CW-IC. In so doing, the soft channel bits of interfering TBs at multiple (re)transmissions can be combined to enhance the success rate of data decoding. A soft buffer partition method for the soft channel bits of the desired and interfering TBs in the superposition coding scheme is proposed. The proposed method has a full flexibility in adjusting the soft buffer sizes for the desired and interfering TBs.