Radio Transmission Device Cyclic Shift Sequence Alignment
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Solution Overview
Problem
The accuracy of channel estimation using CAZAC sequences is compromised when the reference signal transmission band varies between local and nearby cells, leading to increased interference and reduced accuracy in channel estimation.
Innovation Solution
A radio transmitting apparatus and method that determines a pattern of CAZAC sequences based on the transmission band and bandwidth, ensuring that correlation value peaks align correctly across different cells by associating RS transmission bands with starting numbers of ZC sequences, thereby maintaining relative relationships between components of ZC sequences used in correlation calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If different cells use different transmission bands for reference signals, then frequency resource utilization is improved, but channel estimation accuracy deteriorates due to misalignment of correlation value peaks
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the starting number of the ZC sequence based on the transmission band. Specifically, the starting number is changed according to the subcarrier index of the transmission band to ensure that correlation value peaks align correctly across different cells. This parameter adjustment resolves the contradiction by maintaining channel estimation accuracy while allowing different transmission bands to be used.
2Reliability
If ZC sequences are used for reference signals, then good auto-correlation and cross-correlation characteristics are achieved, but interference increases when transmission bands vary between cells
Solution Approach 1:
The patent applies local quality by making the starting number of the ZC sequence location-dependent, i.e., specific to each transmission band. This means that while the ZC sequence maintains its good correlation characteristics globally, locally (in each cell with specific transmission band) the starting number is optimized to prevent interference. This resolves the contradiction by preserving correlation properties while reducing inter-cell interference through localized adaptation.
Data Source
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AI summary
It is possible to provide a radio transmission device and a radio transmission method which can avoid degradation of a channel estimation accuracy using a reference signal formed by a ZC sequence even when the RS transmission band of a local cell is different from that of an adjacent cell. A mobile station decides a cyclic shift sequence corresponding to RB allocation information from an RS table which correlates different frequency bandwidths from a reference point of respective transmission bands to a spectrum start number of the cyclic shift sequence so as to satisfy a particular relationship based on the sequence length and transmits the decided cyclic shift sequence as RS to a base station. The base station uses the same RS table as the RS table of the mobile station and performs correlation calculation of the RS transmitted from the mobile station, thereby performing channel estimation.