Cyclic Orthogonal Code for Parallel OFDM-CDMA Processing
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Solution Overview
Problem
Existing OFDM-CDMA technologies face limitations in maximizing system performance and diversity gain due to the use of orthogonal codes that cannot be processed in parallel, leading to inefficient resource allocation and complex receiving units.
Innovation Solution
The introduction of a cyclic-shifted orthogonal code, known as the cyclic-OC code, which allows for parallel processing and maximizes diversity gain by generating multiple orthogonal codes through cyclic shifts, enabling efficient data transmission and reception with a simpler receiving unit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional orthogonal codes (Walsh Hadamard, PN code, Gold code, OVSF code) are used in OFDM-CDMA technology, then code division multiple access is achieved, but diversity gain cannot be maximized because these codes cannot be processed using parallel code perpendicular to each other
Solution Approach 1:
The invention segments the spreading code into multiple orthogonal sub-codes that can be processed in parallel. Each sub-code operates independently on different dimensions, enabling parallel processing while maintaining orthogonality. This segmentation allows the system to achieve maximum diversity gain by utilizing multiple perpendicular code dimensions simultaneously.
Solution Approach 2:
The invention introduces additional dimensional space for code processing by creating orthogonal codes that operate in perpendicular dimensions. This dimensional expansion enables parallel code processing where each dimension provides independent diversity, thereby maximizing diversity gain without increasing sequential processing complexity.
2Adaptability or versatility
If a single spread code is used to transmit data, then transmission is achieved, but resource application strategy (power and channel coding) cannot be flexibly applied according to channel state
Solution Approach 1:
The spreading sequence is segmented into multiple independent sub-spread sequences, each capable of having different resource application strategies applied. This allows flexible power allocation and channel coding across different sub-sequences based on channel conditions, while maintaining the overall spread structure for CDMA operation.
Solution Approach 2:
The invention enables dynamic resource allocation by allowing different resource application strategies to be applied to different sub-spread sequences based on real-time channel state. This dynamic adaptability allows the system to optimize performance by allocating resources differently across various spread sequences according to their respective channel conditions.
3Reliability
If related art orthogonal codes are used in OFDM-CDMA, then user signals can be separated, but the receiving unit complexity increases with code length making it difficult to embody an efficient receiving unit
Solution Approach 1:
The receiving unit processes signals by segmenting the correlation operation into parallel processing of multiple orthogonal sub-codes. This segmentation reduces the computational complexity at the receiver by distributing the processing load across multiple independent parallel channels rather than requiring a single complex sequential processor.
Solution Approach 2:
The invention replaces the mechanical complexity of long-code sequential processing with a parallel structure using shorter orthogonal sub-codes. This substitution reduces the computational burden on the receiving unit while maintaining the ability to separate user signals effectively through orthogonal correlation.
Data Source
AI summary
An orthogonal code including an orthogonal code set capable of a plurality of parallel processes through a cyclic shift method is provided. Moreover, a multiple access method of effectively using a new cyclic orthogonal complementary code (cyclic-OC) is provided.