DFT-S-OFDM Reference Signal Allocation for Channel Estimation
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Solution Overview
Problem
In SC-FDMA communications, such as LTE uplink transmission, the fixed allocation of reference signals (RS) in two time-domain symbol locations leads to inefficient resource usage, as it cannot be dynamically adjusted based on varying channel conditions and service needs.
Innovation Solution
A method for transmitting DFT-S-OFDM signals with frequency domain reference symbols, involving determining null data symbols, performing DFT-spreading, puncturing the interleaved output, inserting reference symbols in the frequency domain, and transmitting the signal with these modifications to allow flexible RS insertion based on channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference signals are allocated in fixed time-domain symbol locations, then channel estimation can be performed, but resource usage efficiency deteriorates due to inability to dynamically adjust based on channel conditions
Solution Approach 1:
The patent applies dynamics by making the reference signal allocation flexible and adjustable based on channel conditions. The system dynamically determines the number and positions of reference signals according to the specific channel state and service requirements, transforming the fixed allocation into a dynamic adaptation mechanism that optimizes both channel estimation accuracy and resource efficiency
Solution Approach 2:
The patent changes the parameters of reference signal allocation (number of reference signals, their positions in time-domain symbols) based on channel conditions. By adjusting these parameters dynamically, the system achieves accurate channel estimation when needed while maximizing resource utilization when channel conditions are good
2Measurement precision
If more reference signals are inserted for poor channel conditions, then channel estimation accuracy improves, but resource overhead increases
Solution Approach 1:
The patent dynamically changes the number and distribution parameters of reference signals based on measured channel conditions. When channel quality is poor, the system increases reference signal density to improve estimation accuracy; when channel quality is good, it reduces reference signal overhead, achieving optimal balance between accuracy and resource consumption
3Productivity
If reference signal allocation is made flexible based on channel conditions, then resource efficiency improves, but system complexity increases
Solution Approach 1:
The patent implements dynamic reference signal allocation mechanisms in both transmitter and receiver that adapt to channel conditions. The transmitter dynamically determines reference signal positions and the receiver correspondingly adjusts its processing, creating a coordinated dynamic system that achieves resource efficiency through controlled complexity
Data Source
AI summary
A method for transmitting a discrete fourier transform (DFT) DFT-S-OFDM signal including frequency domain reference symbols is disclosed. The method comprises: determining to null a plurality of data symbols prior to DFT-spreading; performing DFT-spreading including the determined null data symbols; puncturing an interleaved output of the DFT-spreading; inserting reference symbols in a frequency domain of the punctured and interleaved DFT-S-OFDM signal; and transmitting the DFT-S-OFDM signal with inserted reference symbols to a receiver. The transmitted DFT-S-OFDM signal enables the receiver to apply zeros corresponding to the reference symbols to an interleaved input of DFT-despreading, and cancel interference due to the puncturing by using all outputs of the DFT-despreading.