CCE Allocation States for LTE PDCCH Blocking

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Solution Overview

Problem

Priority-based resource allocation in LTE systems leads to inefficiencies such as blocking and priority inversion in PDCCH resource allocation, resulting in suboptimal use of control channel resources and increased intercell interference.

Innovation Solution

Introducing three CCE allocation states (used, unused, and alternate) and three availability states (available, unavailable, and contended) in the resource mapping process, allowing for flexible allocation of control channel resources without committing to a specific scheduling entity, especially when multiple candidate sets are available.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If priority-based resource allocation is used for PDCCH, then scheduling priority is maintained, but resource blocking and priority inversion occur

Engineering Contradiction:

Improvescheduling priorityVSAvoidresource allocation reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent segments the resource allocation process into multiple stages: initial priority-based allocation, followed by a blocking detection phase, and finally a reallocation phase for blocked users. This segmentation allows the system to maintain priority-based scheduling while providing a mechanism to resolve blocking situations, thereby improving resource allocation reliability without completely abandoning priority-based operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary allocation of CCE resources to users based on scheduling priority before finalizing the allocation. This preliminary action allows the system to identify potential blocking situations early and implement reallocation strategies before transmission, ensuring both priority maintenance and blocking prevention.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If CCEs are allocated in contiguous blocks based on aggregation level, then allocation simplicity is maintained, but blocking occurs even when sufficient CCEs are available

Engineering Contradiction:

Improveallocation simplicityVSAvoidPDCCH capacity

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent introduces dynamic reallocation mechanisms that allow the CCE allocation structure to adapt during the scheduling process. When blocking is detected, the system dynamically identifies alternative CCE sets and reallocates resources, transforming the static contiguous block allocation into a dynamic process that can overcome blocking while maintaining operational simplicity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the allocation parameters by allowing non-contiguous CCE sets in reallocation scenarios. Instead of strictly enforcing contiguous block allocation, the system modifies the allocation parameters to permit flexible CCE selection when blocking occurs, thereby increasing PDCCH capacity while maintaining allocation simplicity through standardized reallocation procedures.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If higher aggregation level is assigned to ensure reliability, then transmission reliability improves, but more CCEs are consumed leading to reduced system capacity

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidCCE consumption

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies partial reallocation by identifying and reallocating only the specific CCEs that cause blocking, rather than increasing the aggregation level for all users. This partial action allows the system to maintain the originally assigned aggregation levels and their associated reliability levels while consuming fewer total CCEs through targeted reallocation of problematic resources.

Inventive Principle:

Principle #16Partial or excessive action

4Productivity

If multiple users are scheduled in the same TTI, then system capacity increases, but PDCCH resource contention and blocking increase

Engineering Contradiction:

Improvesystem capacityVSAvoidresource allocation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the allocation process monitors for blocking conditions and triggers reallocation when blocking is detected. This feedback loop allows the system to handle multiple users in the same TTI effectively by automatically adjusting allocations to eliminate blocking, thereby maintaining high system capacity while managing resource allocation complexity through automated feedback-driven adjustment.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8830936B2Allocating control channel elements to downlink control channels

Publication Date: 2014.09.09 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method and apparatus is provided for allocating shared control channel resources. The control channel elements (CCEs) are allocated in units referred to as CCE sets. Each CCE set includes one or more control channel elements. Early commitment of control channel elements in a CCE set to a specific scheduling entity is avoided in situations where two or more candidate sets are available for the scheduling entity. In this case, the CCEs belonging to the candidate sets are designated as an alternate resource for a first scheduling entity. A CCE designated as an alternate may be allocated to another scheduling entity as long as such allocation does not block the first scheduling entity.