DMRS Sequence Generation for pi/2 BPSK Modulation
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Solution Overview
Problem
Current wireless communication technologies face challenges in generating orthogonal or quasi-orthogonal demodulation reference signal (DMRS) sequences for pi/2 BPSK modulation, leading to increased peak-to-average power ratio (PAPR) and limited transmit power for user equipment (UE) at cell edges, especially when multiple UEs communicate simultaneously.
Innovation Solution
The implementation of techniques that allow UEs to determine and generate DMRS sequences based on assigned DMRS ports, using methods such as Gold sequences and computer-generated sequences, which are specific to each UE, enabling orthogonal or quasi-orthogonal DMRS transmissions and reducing PAPR, thereby allowing higher transmit power without violating maximum power constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMRS sequences are generated for pi/2 BPSK modulation using conventional methods, then orthogonal or quasi-orthogonal DMRS sequences can be obtained, but the peak-to-average power ratio (PAPR) increases and transmit power is limited
Solution Approach 1:
The patent changes the parameters of the base sequence by applying specific cyclic shifts (e.g., 0, 3, 6, 9 for normal cyclic prefix; 0, 2, 4, 6 for extended cyclic prefix) to generate orthogonal or quasi-orthogonal DMRS sequences. This parameter transformation maintains sequence orthogonality while controlling PAPR, allowing UEs to transmit at higher power levels without violating maximum power constraints.
2Productivity
If multiple UEs communicate simultaneously using the same uplink resources, then spectral efficiency improves, but interference between UEs increases
Solution Approach 1:
The patent segments the DMRS sequence space by assigning different cyclic shift values to different UEs. Each UE receives a specific cyclic shift assignment from the network, which segments the overall sequence space into orthogonal or quasi-orthogonal subspaces. This segmentation allows multiple UEs to share the same time-frequency resources without causing interference, thereby improving spectral efficiency.
Solution Approach 2:
The patent introduces an additional dimension for sequence differentiation by applying cyclic shifts in the time domain. Instead of only using frequency or time domain separation, the invention adds a cyclic shift dimension that creates orthogonal or quasi-orthogonal sequences. This dimensional expansion enables more UEs to share resources simultaneously while maintaining low interference levels.
3Reliability
If UEs at cell edges transmit at higher power, then communication performance improves, but maximum power constraints are violated
Solution Approach 1:
The patent transforms the DMRS sequence parameters through specific cyclic shifts that maintain orthogonality while controlling the amplitude characteristics. This parameter transformation reduces the peak-to-average power ratio, enabling UEs at cell edges to transmit at higher average power levels without exceeding maximum peak power constraints, thereby improving communication performance in challenging coverage scenarios.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive an indication of a demodulation reference signal (DMRS) port to be used by the UE for transmitting a DMRS communication; determine a base sequence based at least in part on the DMRS port; generate a DMRS sequence for the DMRS port based at least in part on the base sequence; and transmit the DMRS communication including the DMRS sequence via the DMRS port. Numerous other aspects are provided.