Orthogonal DMRS Port Generation for Pi/2 BPSK

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Solution Overview

Problem

Current techniques for orthogonal DMRS port generation in new radio (NR) systems using pi/2 binary phase shift keying (BPSK) modulation face challenges due to higher peak-to-average-power-ratio (PAPR) of demodulation reference signals (DMRS) sequences, leading to link budget loss and limited transmission power, especially when trying to support multi-user multiple input multiple output (MU-MIMO) scenarios.

Innovation Solution

Generating orthogonal DMRS ports based on a pi/2 BPSK DMRS base sequence using a frequency-domain comb structure and time-domain orthogonal cover code (OCC), which reduces PAPR and improves power allocation for data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional orthogonal DMRS port generation techniques are used in NR systems with pi/2 BPSK modulation, then multi-user MIMO scenarios can be supported, but the higher PAPR of DMRS sequences causes link budget loss and limited transmission power

Engineering Contradiction:

Improvemulti-user MIMO supportVSAvoidlink budget loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent changes the fundamental parameter of DMRS sequence generation by using pi/2 BPSK modulation instead of traditional QPSK or other modulations. This parameter change reduces the PAPR of the DMRS sequences, thereby reducing link budget loss while still supporting multi-user MIMO scenarios through orthogonal port generation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the DMRS sequence generation process into multiple orthogonal ports, where each port is generated independently using pi/2 BPSK modulation. This segmentation allows multiple users to be supported simultaneously while each user benefits from the lower PAPR characteristics of the pi/2 BPSK modulated sequence.

Inventive Principle:

Principle #1Segmentation

2Reliability

If traditional DMRS sequences are used, then orthogonality between ports can be maintained, but transmission power is limited due to higher PAPR

Engineering Contradiction:

Improveorthogonality maintenanceVSAvoidtransmission power

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

By changing the modulation parameter to pi/2 BPSK, the patent achieves both lower PAPR (improving transmission power) and maintains orthogonality between ports through the structured generation process that creates orthogonal sequences for different users while preserving the reliability of port differentiation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11196597B2Orthogonal demodulation reference signal (DMRS) port generation for pi/2 binary phase shift keying (BPSK)

Publication Date: 2021.12.07 QUALCOMM INC

AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may generate multiple orthogonal demodulation reference signal (DMRS) sequences associated with multiple orthogonal DMRS ports based at least in part on a pi/2 binary phase shift keying (BPSK) based DMRS base sequence and based at least in part on utilizing at least one of a frequency-domain comb structure or a time-domain orthogonal cover code (OCC), wherein the multiple orthogonal DMRS ports are associated with different UEs; determine a DMRS port, of the multiple orthogonal DMRS ports, to be used in association with a transmission of pi/2 BPSK modulated data; and transmit the pi/2 BPSK modulated data and a DMRS sequence, of the multiple orthogonal DMRS sequences, associated with the DMRS port. Numerous other aspects are provided.