CDMA Code Allocation for Walsh and QoF Interference

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Solution Overview

Problem

CDMA radio access networks face limitations in user capacity due to the insufficient allocation of Walsh codes, leading to high non-orthogonal interference when Quasi-orthogonal Functional (QoF) codes are not utilized, and recent advancements in 1×Advanced technology require a more efficient code allocation strategy to support increased user capacity.

Innovation Solution

A method and unit for allocating Walsh codes and QoF codes in CDMA systems, where AQLIC-capable mobile terminals receive QoF codes when Walsh codes are insufficient, and non-AQLIC-capable terminals are reserved with a threshold number of Walsh codes to minimize interference, optimizing user capacity and service quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If QoF codes are allocated to mobile terminals, then user capacity is increased, but non-orthogonal interference increases causing service quality degradation

Engineering Contradiction:

Improveuser capacityVSAvoidnon-orthogonal interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating code allocation strategies based on mobile terminal capabilities. AQLIC-capable terminals receive QoF codes to maximize capacity, while non-AQLIC terminals receive Walsh codes to maintain service quality. This localized differentiation resolves the contradiction by applying the appropriate code type to the appropriate terminal type.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of code allocation based on terminal capability parameters. By detecting whether a terminal supports AQLIC and adjusting the code allocation accordingly (QoF vs Walsh), the system dynamically adapts to resolve the interference-capacity tradeoff.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If Walsh codes are allocated to all mobile terminals, then service quality is maintained, but user capacity is limited

Engineering Contradiction:

Improveservice qualityVSAvoiduser capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements local quality by allocating different code types to different terminal groups. Walsh codes are allocated to non-AQLIC terminals to ensure service quality, while QoF codes are allocated to AQLIC terminals to expand capacity. This resolves the contradiction by maintaining quality where needed while enabling capacity expansion where possible.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the mobile terminal population into two groups based on AQLIC capability. This segmentation allows the system to apply different allocation strategies (Walsh for quality, QoF for capacity) to different segments, simultaneously achieving both service quality maintenance and user capacity expansion.

Inventive Principle:

Principle #1Segmentation

3Productivity

If the number of Walsh codes is increased, then user capacity is improved, but code resource efficiency decreases

Engineering Contradiction:

Improveuser capacityVSAvoidcode resource efficiency

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent makes the code allocation system multi-functional by supporting both Walsh code allocation (for quality-critical connections) and QoF code allocation ( for capacity expansion). This universality allows the same allocation mechanism to serve dual purposes: maintaining service quality and increasing user capacity without requiring additional physical code resources.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9019810B2Method of allocating walsh codes and quasi-orthogonal functional codes in a CDMA network

Publication Date: 2015.04.28 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method of allocating Walsh codes and Quasi-orthogonal Functional, QoF, codes in a CDMA system in which a finite number of Walsh codes are defined, and some mobile terminals operating in the CDMA system are capable of supporting Advanced Quasi-Linear Interference Cancellation, AQLIC, and some mobile terminals operating in the CDMA system are non-AQLIC-capable. Walsh codes are allocated to control channels. A code allocation unit then determines a threshold number of Walsh codes to reserve for non-AQLIC-capable mobile terminals. When a current Walsh code usage level is less than the threshold, the unit allocates Walsh codes to both the AQLIC-capable mobile terminals and the non-AQLIC-capable mobile terminals. When the current Walsh code usage level is greater than the threshold, the unit allocates QoF codes only to AQLIC-capable mobile terminals, and allocates Walsh codes to non-AQLIC-capable mobile terminals.