Intra-symbol OCC for Uplink Control Channel Capacity

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Solution Overview

Problem

The New Radio (NR) unlicensed (NR-U) system faces reduced multiplexing capacity due to frequency domain interlacing, which affects the overall system capacity and user multiplexing, especially in unlicensed bands, where the signal needs to spread over more PRBs, leading to lower transmission power and coverage issues.

Innovation Solution

Applying intra-symbol cyclic shifts to demodulation reference signal (DMRS) subcarriers and intra-symbol or inter-symbol Orthogonal Cover Codes (OCCs) to data subcarriers, enhancing the multiplexing capacity by allowing multiple wireless devices (WDs) to share the same resource block, thereby increasing the number of WDs that can be multiplexed per physical resource block (PRB).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If frequency domain interlacing is used to spread signals over more PRBs in unlicensed bands, then compliance with regulatory requirements is improved, but multiplexing capacity and system throughput deteriorate

Engineering Contradiction:

Improveregulatory complianceVSAvoidmultiplexing capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies intra-symbol OCCs across multiple PRBs, transforming the multiplexing approach from traditional single-PRB methods to a multi-PRB dimensional extension. This allows the system to maintain regulatory compliance through frequency spreading while compensating for the capacity loss through code-domain multiplexing across the extended frequency range.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent modifies the multiplexing parameters by introducing intra-symbol OCCs that operate across multiple PRBs. This changes the multiplexing capacity calculation from a single-PRB basis to a multi-PRB basis, effectively doubling the number of simultaneously multiplexed users while maintaining compliance with unlicensed band regulations.

Inventive Principle:

Principle #35Parameter changes

2Power

If signals are spread over more PRBs in unlicensed bands, then transmission power distribution is improved, but coverage and signal strength deteriorate

Engineering Contradiction:

Improvetransmission power distributionVSAvoidsignal strength

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

The patent uses OCCs to create multiple copies of the signal across different PRBs with distinct code multiplexing. This allows the signal to be replicated across multiple frequency resources, maintaining overall signal strength while distributing power according to regulatory requirements for unlicensed band operation.

Inventive Principle:

Principle #26Copying

3Device complexity

If traditional FDM multiplexing is used for data and DMRS subcarriers, then implementation simplicity is maintained, but multiplexing capacity is limited

Engineering Contradiction:

Improveimplementation complexityVSAvoidmultiplexing capacity

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent nests the OCC structure within the existing FDM framework, placing code multiplexing inside the frequency domain structure. This nested approach allows the system to maintain the simplicity of FDM implementation while adding the capacity enhancement of code multiplexing without requiring a complete redesign of the multiplexing architecture.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS11838235B2Physical uplink control channel frequency division multiplexing with intra data subcarrier orthogonal cover codes

Publication Date: 2023.12.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method, wireless device, and network node for increasing the capacity on a control channel when using Frequency Division Multiplexing (FDM) of data and DMRS are disclosed. According to one aspect, a wireless device (WD) is configured to perform intra-symbol frequency division multiplexing of data subcarriers and demodulation reference signal, DMRS, subcarriers. The WD is also configured to apply intra-symbol orthogonal cover codes, OCCs, to the data subcarriers. The WD is further configured to apply intra-symbol cyclic shifts to the DMRS subcarriers.