Sparse Codebook Encoding for Low-Interference mMTC Decoding
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Solution Overview
Problem
Existing coding and modulation methods for massive machine type communication (mMTC) short packet transmission services face challenges in reducing code error rates due to increased interference from superposition sequences as the number of groups in the codebook increases, particularly in scenarios with a large number of potential access users and specific latency requirements.
Innovation Solution
The proposed solution involves selecting K activation groups from a codebook of L groups and determining activation sequences based on specific mapping rules, reducing the number of superposition sequences and using a shared codebook across multiple users to minimize interference and complexity during decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of groups L in the codebook is increased to support more users, then the system capacity and user coverage are improved, but the interference from superposition sequences increases and code error rate worsens
Solution Approach 1:
The codebook is divided into L groups, and only K groups are selected as activation groups for superposition coding. This segmentation approach allows the system to support multiple users (large L) while limiting the actual number of superposed sequences (K) to control interference and maintain low code error rates during decoding.
2Productivity
If the number of superposition sequences is increased to support more simultaneous transmissions, then the system throughput is improved, but the decoding complexity and interference increase
Solution Approach 1:
Instead of using all L groups for superposition, the system selectively activates only K groups (where K < L) based on user scheduling requirements. This partial action approach maintains system throughput by supporting multiple users while reducing the number of superposed sequences to manage decoding complexity and interference levels.
Data Source
AI summary
A terminal device obtains coding information that includes a first information bit and a second information bit. The terminal device selects, based on the first information bit, K groups from a codebook having L groups as activation groups, where both L and K are positive integers, and K is less than L. The terminal device then selects, based on the second information bit, a sequence from each of the activation groups as an activation sequence, and obtains a first sequence by superimposing the K activation sequences.