Reverse Mapping for Subcarrier Phase Noise Reduction
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Solution Overview
Problem
In multi-carrier communication systems, synchronization impairments lead to significant issues such as inter-block interference, inter-carrier interference, and signal distortion due to symbol time-synchronization errors and frequency-synchronization errors, particularly affecting the OFDM scheme by causing carrier phase rotation and subcarrier phase shift noise proportional to the subcarrier index.
Innovation Solution
The method involves transmitting reverse mapping flag information to determine the direction of mapping data symbols to subcarriers within a resource block, either in a frequency-increasing or frequency-decreasing direction, depending on the transmission mode, to reduce subcarrier phase shift noise and enhance retransmission efficiency in wireless communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If OFDM scheme is used to extend transmission bandwidth, then transmission bandwidth is extended, but synchronization impairment causes carrier phase rotation and subcarrier phase shift noise
Solution Approach 1:
The patent applies reverse mapping for retransmitted data, inverting the normal frequency-increasing mapping direction. By mapping retransmitted data in a frequency-decreasing direction, the phase rotation caused by synchronization impairment is compensated, reducing subcarrier phase shift noise and improving retransmission performance.
2Reliability
If reverse mapping is applied to retransmitted data, then retransmission performance is improved, but mapping direction control complexity increases
Solution Approach 1:
The patent transmits reverse mapping flag information in advance through PDCCH before data transmission. This preliminary indication allows the receiving device to prepare the correct demapping direction, simplifying the control mechanism while ensuring proper synchronization between transmitter and receiver for both initial and retransmitted data.
Data Source
AI summary
An operation method of a transmitting apparatus in a wireless communication system includes transmitting, to a receiving apparatus, reverse mapping flag information indicating a direction of mapping data symbols to one or more subcarriers included in a resource block allocated to the receiving apparatus; mapping the data symbols to the one or more subcarriers of the resource block based on the reverse mapping flag information; and transmitting the resource block to the receiving apparatus. According to the embodiments of the present disclosure, the amount of subcarrier phase shift noises due to an SFO occurring in proportion to synchronization impairment and subcarrier index can be reduced in a multi-carrier communication system, thereby increasing data retransmission efficiency.