Complex Sequence Superposition for Multi-User Interference Control
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Solution Overview
Problem
Existing CDMA technology faces challenges with high interference and complex reception and detection processes when multiple users access the system, leading to degraded multi-user access communication performance, especially in overloaded conditions.
Innovation Solution
The method involves using N complex sequences, either orthogonal or non-orthogonal, of shorter length to process and superimpose data symbols, allowing for efficient control of receiver complexity and interference between users, thereby improving multi-user access communication performance and enabling multi-user overload and grant-free access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional CDMA technology with binary pseudo-noise sequences is used, then the system can support multiple users, but the interference between users increases and reception complexity increases when the system is overloaded
Solution Approach 1:
The patent changes the fundamental parameters of the spreading sequence from binary pseudo-noise sequences to complex sequences with optimized auto-correlation and cross-correlation properties. This parameter change enables better separation of user signals and reduces multi-user interference, allowing the system to support more users with improved performance even in overloaded conditions
2Quantity of substance
If traditional CDMA technology with binary pseudo-noise sequences is used, then the system can support multiple users, but the reception and detection process becomes more complex when the system is overloaded
Solution Approach 1:
The patent changes the spreading sequence parameters to complex sequences that maintain better orthogonality and correlation properties. This enables the receiver to separate user signals more easily through correlation-based detection, significantly reducing reception and detection complexity while supporting a larger number of users
3Object-affected harmful factors
If spreading sequences of longer length are used to reduce user interference, then the cross-correlation between sequences improves, but the transmission time increases and system efficiency decreases
Solution Approach 1:
The patent changes the sequence type from binary pseudo-noise to complex sequences that achieve low cross-correlation properties with shorter lengths. This parameter change allows the system to maintain good user separation performance while reducing the spreading factor and transmission time, thereby improving overall system efficiency
Solution Approach 2:
The patent uses complex sequences that combine multiple properties (orthogonality, low cross-correlation, good auto-correlation) into a single sequence design. This composite approach enables short sequences to achieve the interference reduction效果 that would otherwise require much longer binary sequences
Data Source
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AI summary
This document discloses a data transmission method and apparatus. The method includes: obtaining N data symbols to be sent; determining N complex sequences to be used; processing the N data symbols using the N complex sequences respectively to generate N data symbol sequences; superimposing the N data symbol sequences to generate a superimposed data symbol sequence; and sending the superimposed data symbol sequence; where N is an integer number greater than or equal to 2.