Multi-Antenna Synchronization Signal Allocation
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Solution Overview
Problem
In multi-antenna wireless communication systems, effectively transmitting a synchronization signal to allow for channel estimation for each transmit antenna is challenging, especially when the user equipment (UE) is initially synchronized with a base station (BS) and needs to distinguish between multiple transmit antennas without prior knowledge of their number.
Innovation Solution
An apparatus and method that utilize a synchronization signal generator to create a synchronization signal, allocate different subcarriers to each transmit antenna without overlapping, and perform inverse fast Fourier transformation (IFFT) to generate an orthogonal frequency division multiplexing (OFDM) symbol, while using control signals to manage codes and reduce interference, allowing the UE to estimate the channel for each antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a transparent multi-antenna scheme is used for initial synchronization, then the UE can receive the synchronization signal without knowing the number of Tx antennas, but the UE cannot estimate the channel for each Tx antenna
Solution Approach 1:
The patent segments the frequency resources (subcarriers) and assigns different segments to different Tx antennas. Each Tx antenna transmits synchronization signals on its allocated subcarrier segments, allowing the UE to identify and estimate channels for individual antennas while maintaining transparent operation during initial synchronization.
Solution Approach 2:
The patent applies local quality by assigning specific subcarrier segments to specific Tx antennas, creating distinct transmission characteristics for each antenna. This allows the UE to perform channel estimation for each antenna individually by processing signals from their respective subcarrier segments, while the overall system remains transparent during initial access.
2Measurement precision
If frequency resources are allocated to each Tx antenna in a divided manner (FSTD), then the UE can estimate the wireless channel for each Tx antenna, but channel interference increases
Solution Approach 1:
The patent applies preliminary action by pre-assigning specific subcarrier segments to each Tx antenna before transmission. This predetermined allocation allows the UE to know which subcarriers correspond to which antennas, enabling channel estimation while the orthogonal allocation structure prevents interference between antennas.
Solution Approach 2:
The patent resolves interference by moving the differentiation between antennas from the time or spatial domain to the frequency domain. By allocating different frequency segments (subcarriers) to different antennas, the system eliminates interference while maintaining the ability to estimate each antenna's channel independently.
3Productivity
If multiple Tx antennas transmit synchronization signals simultaneously, then data transfer capacity increases, but control information overhead increases
Solution Approach 1:
The patent merges the synchronization signal transmission from multiple antennas into a unified frequency-division structure. By allocating different subcarrier segments to different antennas and using a standardized allocation pattern, the system enables multi-antenna operation without requiring additional separate control information for each antenna, thus reducing overhead while maintaining high data transfer capacity.
Data Source
AI summary
An apparatus for transmitting a synchronization signal using a plurality of transmit (Tx) antennas is provided. The apparatus includes a synchronization signal generator for generating a synchronization signal used for tracking timing or frequency synchronization, a transmission processor for allocating different subcarriers to a plurality of Tx antennas without overlapping, mapping the synchronization signal to the subcarriers, and generating an orthogonal frequency division multiplexing (OFDM) symbol by performing inverse fast Fourier transformation (IFFT), a control signal coupler for controlling codes as a resource not to overlap among the plurality of Tx antennas, and the plurality of Tx antennas for transmitting the OFDM symbol.