SC-FDMA Transmission with Multiple Codewords and SIC
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Solution Overview
Problem
The SC-FDMA system faces challenges with high Peak to Average Power Ratio (PAPR) and interference between transmission symbols in frequency selective fading environments, limiting its performance.
Innovation Solution
The method involves dividing user data into multiple sub-streams, performing independent channel coding and QAM mapping, mapping signals to DFT indices, and transmitting multiple codewords using DFT and IFFT, while also incorporating successive interference cancellation (SIC) and adaptive power control based on channel state information feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If OFDMA system uses multiple carriers for high-speed data transmission, then data transmission speed is improved, but PAPR becomes high
Solution Approach 1:
The patent segments the single carrier signal into multiple sub-carriers through DFT spreading, transforming the time-domain signal into frequency-domain components. This segmentation allows the system to maintain single-carrier characteristics (low PAPR) while utilizing multiple frequency resources for high-speed transmission
Solution Approach 2:
The patent introduces DFT spreading as an intermediary processing step between the data stream and the OFDMA modulation. This intermediary transformation converts the time-domain signal into frequency-domain coefficients, enabling low PAPR single-carrier transmission while achieving multi-carrier transmission capabilities
2Use of energy by moving object
If SC-FDMA system uses single carrier to reduce PAPR, then PAPR is reduced, but interference between transmission symbols occurs in frequency selective fading environment
Solution Approach 1:
The patent segments the single carrier signal into multiple orthogonal sub-carriers through DFT spreading. This segmentation transforms the signal into frequency-domain components that can be independently processed, reducing inter-symbol interference in frequency selective fading channels while maintaining low PAPR characteristics
Solution Approach 2:
The patent transitions from time-domain single carrier transmission to frequency-domain multi-carrier transmission through DFT spreading. This dimensional transformation from time to frequency domain enables the system to exploit frequency diversity and reduce inter-symbol interference while maintaining single-carrier power efficiency
3Use of energy by moving object
If SC-FDMA system transmits only one stream, then PAPR is minimized, but performance is lowered due to interference between symbols
Solution Approach 1:
The patent segments the single data stream into multiple parallel sub-streams, each modulated onto separate orthogonal sub-carriers. This segmentation enables simultaneous transmission of multiple data streams with low PAPR, improving system reliability and throughput while maintaining power efficiency
Solution Approach 2:
The patent makes the SC-FDMA system multi-functional by enabling both single-stream and multi-stream transmission modes. The DFT spreading structure provides universal capability to handle multiple data streams while maintaining the low PAPR characteristic that defines SC-FDMA
Data Source
AI summary
The present invention relates a method and apparatus for transmitting/receiving data using multiple codewords in a communication system using SC-FDMA (single carrier frequency division multiple access). A transmitter generates the multiple codewords for user data and transmits the generated multiple codewords. A receiver receives the multiple codewords and sequentially performs decoding and SIC (successive interference cancellation) on the received multiple codewords. Therefore, this structure can minimize a PAPR (peak to average power ratio) and considerably reduces interference between symbols in a frequency selective fading environment.