Coordinated Multipoint Cell Scheduling for Interference Minimization

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Solution Overview

Problem

Inter-cell interference remains a significant performance impairment in wireless cellular communication networks, particularly in Coordinated MultiPoint (CoMP) systems, where neighboring CoMP cells do not coordinate their transmissions, leading to interference at their boundaries, even with existing methods like Coordinated Scheduling.

Innovation Solution

Scheduling information for downlink and uplink transmissions is exchanged in advance between sets of geographically isolated CoMP cells to minimize intra-CoMP cell interference and inter-CoMP cell interference, allowing each set to schedule transmissions independently without causing interference to neighboring cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If CoMP cells coordinate transmissions internally to minimize inter-sub-cell interference, then intra-CoMP cell interference is reduced, but inter-CoMP cell interference increases at the boundaries between neighboring CoMP cells

Engineering Contradiction:

Improveinter-sub-cell interferenceVSAvoidinter-CoMP cell interference

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent segments the network into multiple CoMP cells, each independently coordinating its sub-cells. This segmentation allows localized interference management while pushing interference to boundaries, which is then addressed through selective scheduling information exchange between neighboring CoMP cells.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces scheduling information exchange as an intermediary mechanism between neighboring CoMP cells. By sharing scheduling information about border sub-cells, CoMP cells can coordinate their transmissions to avoid inter-CoMP cell interference while maintaining internal coordination benefits.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If all sub-cells are connected to a single central unit for network-wide coordination, then both intra-CoMP cell and inter-CoMP cell interference is minimized, but system complexity and implementation feasibility deteriorate

Engineering Contradiction:

Improveinter-CoMP cell interferenceVSAvoidcentralized coordination complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of a single centralized controller, the patent divides the coordination function into multiple distributed CoMP cell controllers. Each controller manages its own sub-cells and exchanges scheduling information only with neighboring controllers, reducing overall system complexity while achieving comparable interference mitigation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements partial coordination by having CoMP cells exchange scheduling information only with immediate neighbors rather than all cells in the network. This partial action achieves most of the interference mitigation benefits of full coordination while significantly reducing complexity.

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If CoMP cells independently schedule transmissions without coordination, then scheduling simplicity is maintained, but inter-CoMP cell interference at boundaries increases

Engineering Contradiction:

Improvescheduling simplicityVSAvoidboundary interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by having CoMP cells exchange scheduling information in advance before actual transmissions occur. This allows each CoMP cell to proactively adjust its scheduling decisions to avoid interfering with neighboring cells, maintaining simplicity while reducing boundary interference.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces feedback through the exchange of scheduling information between neighboring CoMP cells. Each cell receives feedback about neighboring transmissions and adjusts its own scheduling accordingly, maintaining operational simplicity while coordinating to reduce interference.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP2443761B1Network-wide inter-cell interference minimization via coordinated multipoint cell scheduling coordination

Publication Date: 2018.02.28 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

Network-wide inter-cell interference is reduced by aggregating cells (herein, sub-cells) into Coordinated Multipoint (CoMP) cells, each having a controller. The CoMP cells are divided into sets, similar to a frequency reuse plan. Scheduling information regarding transmissions, scheduled to and from UEs in one set of CoMP cells is transmitted to controllers in sets of neighboring CoMP cells, in advance of the transmissions. Controllers in the receiving sets of CoMP cells schedule transmission to minimize both inter-sub-cell interference and interference with the set of CoMP cells that transmitted the scheduling information, and assuming no interference from other CoMP cells. They then transmit scheduling information to subsequent set(s) of CoMP cells. The order of scheduling information transmission between sets of CoMP cells may be rotated for fairness The scheduling information may range from bare threshold data indicating at least one transmission, to detailed information such as estimated path gains to each UE.