SCMA Terminal Access Using Dynamic Signature Selection
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Solution Overview
Problem
The existing SCMA multi-terminal access mechanism experiences system performance degradation due to conflicts, leading to retransmissions and inefficiencies in massive access scenarios.
Innovation Solution
Each terminal determines a different signature using a random number seed and signature matrix for each transmission, reducing conflict probability and eliminating the need for random backoff processes, thereby improving system efficiency and reducing transmission delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If terminals use fixed signatures for data transmission in SCMA, then the access process is simple, but conflict probability increases causing system performance degradation
Solution Approach 1:
The patent applies dynamics by making the signature selection variable rather than fixed. Terminals dynamically select signatures from a codebook based on random number seeds that change with each transmission attempt. This dynamic signature selection reduces persistent conflicts while maintaining operational simplicity through automated random selection.
Solution Approach 2:
The patent changes the signature parameter over time by using different random number seeds for each transmission attempt. Instead of using a static signature assignment, the system varies the signature parameter dynamically, which reduces conflict probability while preserving the simplicity of the access mechanism.
2Reliability
If terminals perform random backoff process upon conflict, then conflict resolution is achieved, but transmission delay increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring a codebook containing multiple signatures for each terminal before transmission begins. When conflicts occur, terminals can immediately switch to alternative signatures from their pre-configured codebooks without performing time-consuming backoff procedures, thus resolving conflicts while minimizing transmission delays.
Solution Approach 2:
The patent maintains continuity of useful action by enabling terminals to continue transmission attempts using different signatures from their codebooks rather than pausing for random backoff. This allows the transmission process to continue without interruption, reducing overall transmission delay while still resolving conflicts effectively.
3Quantity of substance
If conventional multiple access mechanism is used for massive access, then each terminal can transmit large data amounts, but system efficiency decreases due to low access efficiency and high signaling overheads
Solution Approach 1:
The patent applies universality by designing a signature codebook that serves multiple functions: it enables conflict resolution through random selection, provides alternative signatures for retransmission without backoff, and supports massive access scenarios. This single codebook structure handles multiple access challenges simultaneously, improving system efficiency while maintaining the capability to transmit large data amounts.
Data Source
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AI summary
The present invention discloses a terminal access method and an apparatus, to resolve a problem in an existing SCMA multi-terminal access mechanism that a conflict causes system performance degradation and may cause system retransmission. The method is as follows: determining, by a terminal, to enter a contention-based access phase; and determining, by the terminal during each transmission of binary data, a first signature according to a random number seed and a signature matrix, and mapping, according to the first signature, the binary data to a multi-dimensional symbol for transmission, where first signatures used during different transmissions of binary data are different.