Joint Base Station and Relay Station Placement for IEEE 802.16j Networks

Hsiao-Chen Lu and Wanjiun LiaoDepartment of Electrical Engineering, National Taiwan University,Taiwan

IEEE GLOBECOM 2009

Outline Introduction System Model Problem Definition and Formulation The Two Stage BS and RS Deployment Algorithm Computational Experiments Conclusion

Introduction IEEE 802.16j

Network components Base station (BS) Subscriber Station (SS) Mobile station (MS) Relay station (RS)

BS

SS

SS

MS

RS

Transparent Model

RS

Non-Transparent Model

RS

Introduction IEEE 802.16j – Relay Station placement issue

Low cost Throughput enhancement Coverage extension

BS

MS

MS

Introduction-Motive and Goal Network planning problem

Deploying a number of BSs and RSs to serve mobile stations distributed arbitrarily in a given geographic area.

…

…Deployment

Let the cost is within the budget and the system capacity is maximized.

System Model

Demand Node (di)

Wi = The number of the MS.

Wi = 10

Other Assumption Only consider at most two-hop relaying. Transparent and non-Transparent model.

Candidate site for BS : bi

Candidate site for RS : ri

= 6

Problem Definition and Formulation The Joint BS and RS Deployment Problem (JBRDP)

Given the geographic area in which DNs are distributed, we want to determine the locations for a number of BSs and RSs, with the total cost within the pre-determined budget, such that each DN is covered by at least one BS or RS and the system capacity

can be maximized.

di

= 10 Mbps

60 Mbps

Problem Definition and Formulation Subject to constraints:

b1= 1 b2= 0 b3= 0

b4= 0 b5= 0 b6= 1

b7= 0 b8= 1 b9= 0

r1= 0 r2= 1 r3= 0

r5= 0 r6= 0 r7=0

r9= 0 r10= 1 r11= 0

r4= 0

r8= 1

r12= 1

r13= 1 b14= 0 r15=0 r16= 0

(1) (2)

= 1

Problem Definition and Formulation Subject to constraints:

(3)

(4)

dj

bi = 1

= 1ri = 1

Problem Definition and Formulation Subject to constraints:

ri = 1 rj = 1

(5)

The Two Stage BS and RS Deployment Algorithm To find the placement of BSs and RSs for a specific deployme

nt profile ( nB , nR ).

The number of BSs deployed in the network.

The number of RSs deployed in the network.

(3)

The Two Stage BS and RS Deployment Algorithm

First Stage : BS Deployment

Second Stage : RS Deployment

input

( nB , nR )

outputDeployment vector:B = [b1 b2 ... bN ] and R = [r1 r2 ... rM].

The Two Stage BS and RS Deployment Algorithm

First Stage : BS Deployment Second Stage : BS Deployment

First Stage : BS Deployment Determine a set of BS locations such that the longest distance between a DN and i

ts nearest BS is minimized . The number of BSs deployed is equal to nB .

The Two Stage BS and RS Deployment Algorithm

NP-complete problem: the k-supplier problem [9]

[9] “A unified approach to approximation algorithms for bottleneck problems,” Journal of the ACM, July 1986.

Vsup…

Vcust…

Weighti

= Distancei

bi

di

B = nB

The Two Stage BS and RS Deployment Algorithm Second Stage : RS Deployment

Achieve rate gain

Computational Experiments Simulator: The C++ program Simulation parameters

The coverage radius of a BS 7km

The coverage radius of a RS 4km

LI ( The interference threshold for RSs ) 3km

The deployment budget 80 units

The cost of a BS 10 units

The cost of a RS 3 units

25 km

25 km

1 km1 km

Computational Experiments

Computational Experiments The network aggregate data rate versus the number of BSs

and RSs deployed for the MS hotspot scenario

Computational Experiments The fairness index versus the number of BSs and RSs deplo

yed for the MS hotspot scenario.

Conclusion This paper Formulate the joint BS and RS deployment

problem under budget and coverage constraints as a capacity maximization problem.

Design a two-stage network deployment algorithm which considers both issues of capacity enhancement.

The numerical results indicate that deploying relay stations can enhance system capacity and fairness under the condition that the number of base stations deployed is not too small.

Thank you very much ~