Non-Orthogonal Coded Multiple Access for 5G Massive Connectivity
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Solution Overview
Problem
Current wireless communication systems, particularly in the context of 5G technology, face challenges in achieving low latency and massive connectivity due to limitations in data transmission and reception methods, especially with the advent of real-time applications and increased user equipment (UE) connectivity requirements.
Innovation Solution
The implementation of a non-orthogonal coded multiple access (NCMA) scheme, which involves selecting and transmitting specific codebooks and codewords between user equipment (UE) and base stations, utilizing multi-user detection (MUD) to minimize interference and enhance communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal multiple access (OFDMA/TDMA) is used in LTE systems, then interference between users is minimized, but data transmission latency remains high (10ms) and connectivity density is limited
Solution Approach 1:
The patent combines multiple access schemes (orthogonal and non-orthogonal) into a unified framework. Specifically, it merges OFDMA for frequency resource allocation with non-orthogonal code division for user separation, allowing simultaneous orthogonal frequency multiplexing and non-orthogonal user multiplexing to achieve both low latency and interference management
Solution Approach 2:
The patent segments the multiple access function into distinct layers: orthogonal frequency division multiplexing handles frequency resource allocation to minimize inter-user interference, while non-orthogonal code division multiplexing handles user separation in the code domain. This segmentation allows each layer to optimize for its specific function
2Quantity of substance
If more user equipment (UE) are connected to support massive connectivity (1,000,000/km2), then network capacity increases, but interference management and detection complexity increase
Solution Approach 1:
The patent introduces a code domain dimension for user separation. Instead of relying solely on frequency and time resources, it adds a code dimension where each UE is assigned a unique non-orthogonal code. This additional dimension enables massive connectivity by providing another degree of freedom for user multiplexing without proportionally increasing detection complexity
Solution Approach 2:
The patent uses pre-defined non-orthogonal codebooks as intermediaries between users and the base station. These codebooks serve as a structured intermediary that facilitates user separation and signal detection, reducing the complexity of direct multi-user detection by providing a predetermined code structure for the base station to utilize
3Productivity
If non-orthogonal codebooks are used for user separation, then frequency usage efficiency improves, but codebook selection and codeword management complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-defining multiple non-orthogonal codebooks with specific properties (such as constant amplitude zero autocorrelation sequences) before actual communication occurs. These pre-configured codebooks are stored at both the base station and UE, eliminating the need for real-time codebook generation and reducing selection complexity during operation
Solution Approach 2:
The patent changes the parameter of code structure by using specific types of sequences (CAZAC sequences) with predetermined mathematical properties. This parameter change enables efficient frequency usage while simplifying management, as these sequences have inherent properties that reduce interference and simplify detection without requiring complex adaptive codebook selection
Data Source
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AI summary
A method for receiving, by a terminal, a signal on the basis of a non-orthogonal multiple access scheme in a wireless communication system comprises the steps of: receiving, from a base station, control information including information on a codebook selected for the terminal among pre-defined codebooks for non-orthogonal multiple access and information on a codeword selected from the selected codebook; receiving, from the base station, data for the terminal according to scheduling of the control information; and detecting data for the terminal by performing a multi-user detection (MUD) scheme on the basis of the information on the selected codebook and the information on the selected codeword.