Uplink Reference Signal Transmission via Cyclic Shift Allocation
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Solution Overview
Problem
Current LTE systems lack an effective method for transmitting reference signals that support MIMO systems using multiple antennas in uplink transmissions, which hampers channel estimation performance.
Innovation Solution
A method is proposed where different cyclic shift values are allocated to reference signal sequences, and these sequences are mapped onto OFDM symbols for transmission through multiple antennas, with the cyclic shift values determined based on parameters indicated by the cyclic shift field in the PDCCH, ensuring robust frequency selective channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference signals are transmitted in uplink MIMO systems using conventional methods, then transmission can be performed, but channel estimation performance is insufficient
Solution Approach 1:
The reference signal transmission is segmented across multiple antennas with different cyclic shift values applied to each antenna's reference signal sequence. This segmentation allows the receiver to estimate channels for each antenna independently and accurately, resolving the contradiction between achieving good channel estimation performance and maintaining reliable MIMO operation.
Solution Approach 2:
The invention changes the parameter of cyclic shift value for reference signal sequences transmitted on different antennas. By allocating different cyclic shift values to different antennas, the system enables precise channel estimation while maintaining robust MIMO functionality, thus resolving the technical contradiction.
2Measurement precision
If multiple reference signal sequences are transmitted through multiple antennas with different cyclic shift values, then channel estimation performance improves, but system complexity increases
Solution Approach 1:
Instead of using complex multi-dimensional orthogonal codes, the invention simplifies the system by changing only the cyclic shift value parameter for reference signals on different antennas. This approach maintains good channel estimation performance while significantly reducing transmission and reception complexity compared to other multi-antenna reference signal methods.
3Adaptability or versatility
If cyclic shift values are allocated based on PDCCH parameters, then adaptability to different transmission conditions improves, but processing complexity increases
Solution Approach 1:
The cyclic shift values are determined by changing parameters indicated in the PDCCH (such as the cyclic shift field). This allows the system to adapt to different transmission conditions and channel states while using simple parameter-based allocation rules that do not require complex processing logic at the transmitter or receiver.
Data Source
AI summary
A method and apparatus are described for transmitting a reference signal in a multi-antenna system. A terminal generates a plurality of reference signal sequences to which cyclic shift values different from each other are allocated, generates an orthogonal frequency division multiplexing (OFDM) symbol to which the plurality of reference signal sequences are mapped, and transmits the OFDM symbol to a base station through a plurality of antennas. The respective cyclic shift values allocated to the respective reference signal sequences are determined on the basis of a parameter n indicated by a cyclic shift field transmitted from a physical downlink control channel (PDCCH).