wireless communications research seminar 2012, february 16th on stochastic modeling ... ·...

On Stochastic Modeling and Analysis of

Femtocell Networks

Wireless Communications Research Seminar 2012, February 16th

Carlos Lima

LOCON - Local connectivity and cross layer design for future broadband mobile systems

Introduction (1/2)

Putting into context…

• Short-range communications provide better link quality and higher spectral efficiency [1, 2]

• Unplanned deployment and uncoordinated operation cause harsh Co-Channel Interference (CCI) [3]

• Self-configuration and (re)organization of femtocells

[1] H. Claussen, L. Ho, and L. Samuel, “An overview of the femtocell concept,” Bell Labs

Tech. Journal, vol. 13, no. 1, pp. 221–245, 2008.

[2] V. Chandrasekhar, J. G. Andrews, and A. Gatherer, “Femtocell networks: a survey,”

IEEE Commun. Mag., vol. 46, no. 9, pp. 59–67, Sep. 2008.

[3] D. Lopez-Perez, A. Valcarce, G. de la Roche, and J. Zhang, “OFDMA femtocells: A

roadmap on interference avoidance,” IEEE Commun. Mag., vol. 47, no. 9, pp. 41–48,

Jun. 2009.

Introduction (2/2)

Putting into context…

• Practical deployment scenarios

• Network dynamics and channel variations

• Characterize the received signal and CCI

distribution

• Analytical framework based on Stochastic

Geometry (SG) and Higher-Order

Statistics (HOS)

Stochastic Framework (1/4)

Stochastic Geometry: Key words [1]

• Poisson process with constant intensity

• Slivnyak’s Theorem and Palm probability

• Campbell Theorem

• Marking Theorem

[1] D. Stoyan, W. S. Kendall, and J. Mecke, Stochastic Geometry and Its

Applications, 2nd ed. Wiley-Blackwell, 1995

Stochastic Framework (2/4)

Higher Order Statistics

• Cumulants concept

• Properties (additivity)

Stochastic Framework (3/4)

Approximations

• There’s no general closed-form expression for the PDF of the sum of log-normal RVs

• Positively skewed

• Case study: LN, SLN Approximations

• Are there any other alternatives?

Stochastic Framework (4/4)

Performance Evaluation

• SIR interference limited scenarios

• Outage probability

• Average spectral efficiency

Case Study: CM (1/10)

System Model

• Path loss attenuation with large- and

small-scale fading

• Shadowed fading channel [1]

• MPP

[1] M.-J. Ho and G. L. Stuber,

“Capacity and power control for

CDMA microcells,” ACM Journal

on Wireless Networks, vol. 1, no.

3, pp. 355–363, Oct. 1995.

F B S 1

F B S 2

F B S 3

F B S 4

F U 1

F U 2

F U 3

F U 4

M B S

M U

t ag

ged

l i nk

Case Study: CM (2/10)

Solution Description

Detecting

Non-detecting

Tagged receiver

Case Study: CM (3/10)

Solution Description

• Detection event

• Coordination

regions

Case Study: CM (4/10)

Uncoordinated Scenarios

• Full Interference activity

Case Study: CM (5/10)

Uncoordinated Scenarios

• Full Interference + PC Transmit power

Case Study: CM (6/10)

Coordinated Scenarios

• PC with discrete power levels Detecting femtos

Case Study: CM (7/10)

Coordinated Scenarios

• Dynamic Exclusion Regions (DER)

Exclusion region

Case Study: CM (8/10)

Coordinated Scenarios

• DER + PC Exclusion region

Power control

Case Study: CM (9/10)

Approximation

m=16 m=2

Case Study: CM (10/10)

Numerical Results

What’s next?

• Large DAS Vs. Massive MIMO

• Traffic effect

• Area spectral efficiency

• Cluster process