Self-Organizing Coalitions for Conflict Evaluation and Resolution in Femtocells

Luis G. U. Garcia, Aalborg UniversityGustavo W. O. da Costa, Aalborg UniversityAndrea F. Cattoni, Aalborg UniversityKlaus I. Pedersen, Nokia Siemens NetworksPreben E. Mogensen, Aalborg University, Nokia Siemens Networks

Outline

Problem and solution overview

Supporting concepts

Coalition formation rules

Conclusions

Simulation scenario and results

Frequency planning / spectrum usage in cellular networks

Large macrocellswith sparseplannedplanned reuse

PastPast CurrentCurrent FutureFuture

Small macrocellswith tightplannedplanned reuse (1)

Heterogeneous networks includinguncoordinateduncoordinatedfemtocell deployment

ProblemProblem:

• Massive number of femtocells planning and optimization is too costly.

• High interference possible due to dense deployment and random HeNB and UE locations.

Proposed SolutionProposed Solution: Dynamic spectrum sharing using carrier aggregation.

Proposed framework

Low load – First-come, First served

High load – SSelf-OOrganizing CCoalitions for CConflict EEvaluation and RResolution (SOCCERSOCCER)

SOCCER in a nutshell

• Distributed dynamic method for spectrum sharing amongst femtocells no need for planning. Self-optimizingSelf-optimizing.

• Measurements determine incoming and outgoing SINR (BIM)• Evaluation of system capacity for different options

(reuse/orthogonal allocation).• Six simplesimple rules for formation of coalitions and

redistribution of resources (component carriers) on efficientefficient and fairfair way.

• Enabler: low capacity HeNB to HeNB communication link, as typically assumed for ACCS.

• Avoid reconfiguration storms: everything solved locally.

Outline

Problem and solution overview

Supporting concepts

Coalition formation rules

Conclusions

Simulation scenario and results

Evaluation of coalitions

)(1)(1)()( BreuseCAreuseCBcoalitionCAcoalitionC

Pair wise evaluation, based on sum system capacity

Strong interference bonding condition

SINRCell A

SINRCell B

Reuse isbetter

Orthogonal is better

Strong Interference Bonding Graph

MaximalClique-3

Clique 2

Maximal clique sizes define the optimal local frequency reuse!Maximal clique sizes define the optimal local frequency reuse!

Outline

Problem and solution overview

Supporting concepts

Coalition formation rules

Conclusions

Simulation scenario and results

Coalition formation rulesA coalition is a bilateral mutual agreement of having

an orthogonal allocation.

New coalitions are formed when HeNB needs more spectrum.

Optimized method for maximal cliques up to size 3 only 6 simple formation rules.

CFR CFA

Coalition formation

Outline

Problem and solution overview

Supporting concepts

Coalition formation rules

Conclusions

Simulation scenario and results

Simulated scenarioDual stripe, 6 floors, 40 apartments per floor *

25% and 75% deployment ratio

* 3GPP RAN 4, “Simulation assumptions and parameters for FDD HeNB

RF requirements,” Tech. Rep. R4-092042, May 2009.

What is the maximal clique distribution on this scenario?

25% deploymentratio

75% deploymentratio

Normalized Throughput at 25% deployment ratio

Normalized Throughput at 75% deployment ratio

Outline

Problem and solution overview

Supporting concepts

Coalition formation rules

Simulation scenario and results

Conclusions

Conclusions

Femtocell deployment should rely on self-organizing spectrum allocation

Proposal • At low traffic load simple threshold based selection.• At high traffic load interference management using

coalitions (SOCCER).

SOCCER has a lot of potential to become practical • Simple • Very effective method• Based on standardized measurements

Applicable to LTE-Advanced as well as other systems