Copyright © Chang Gung University. Permission required for reproduction or display.

On Femto Deployment Architecture and Macrocell Offloading Benefits in Joint Macro-Femto Deployments

IEEE Comm. Magazine, Jan. 2010Student: Mike

Advisor: J.h Chen

2

Outline

• Motivation• Introduction• Femtocell Deployment Architectures/Scenarios

– QoS Level Settings– Degradation

• Assessment of Macro-Offloading Benefits• Main Contribution• UMTS Case Study• WiMAX Case Study• Conclusion

3

Motivation

• Personal– Macro handover to femto– Understand femto

• Femto system settings• Deployment system design• Bandwidth sparing

• Author– Analysis of joint deployment

• Potential enhancement in quality of radio signals– Macro network– Joint macro-femto deployment

• Acquire better data rate (throughput)• Include more users

4

Introduction

• Femtocells– Low-power low-cost user-deployed base stations– Provide high quality cellular service

• Residential or enterprise

– Extensive auto-configuration– Self-optimization capability to enable simple plug-and-

play deployment– Automatically integrate in macro-cellular network– Reduce traffic of macro-cellular network

• Network operator as capital expenditures (CAPEX)

5

Femtocell Deployment Architectures/Scenario

• Standalone femtocell• Integrated femto

– Femtocell, home router and DSL modem are built within same physical device

• QoS level guarantee settings

6

QoS Level Settings

• Common Wireless and Wireline Operator– Same operator owns network path

• From femtocell to femto gateway

– Operator can manage wireline access network to guarantee QoS required for femto service

– QoS statically allocate bandwidth to femto traffic• Sufficient for low-bandwidth

– Voice, multimedia traffic, and dynamic bandwidth

– QoS management is necessary to achieve efficient network capacity usage for QoS-oriented wireless traffic with higher bandwidth requirements (Mobile video)

7

QoS Level Settings

• Separate wireless and wireline operators with a service level agreement– Wireline access provider different from wireless operator– Service level agreement (SLA)

• For femtocell QoS within access network

• Wireless and wireline operator with no SLAs– No QoS guarantee– All service served as best effort– Current over-the-top VoIP services– Access network < Network Capacity Good QoS– Access network > Network Capacity Degradation

8

Degradation

• Femtocell placement– Femto placed between Router and DSL modem– Femtocell provide its own traffic– Bottleneck

• Home to DSL access multiplexer (DSLAM)• Femtocell can shape traffic to fit access link capacity• Need to keep track of maximum available bandwidth

• Handover to macro network– Measure available bandwidth toward femto gateway– Available bandwidth < threshold

• Macro network handover to femto

9

Degradation

• Throttling femto data traffic– Voice packets are given priority over data packets– Femtocell data packets cause extra delay at bottleneck– Solved by throttling down femtocell data traffic when

voice quality degradate

• QoS-aware femto gateway selection– Multiple femto gateways available, femtocell can be

assigned to gateway with best path to femtocell– Femto gateway change dynamically– Don’t work well when gateway is congested

10

Assessment of Macro-Offloading Benefits

• User in buildings– Propagation losses are more significant– Result in poorer QoS in indoor– High impact on type of environment

• Deployment of femto– Improve usage of macrocell network

11

Main Contribution

• Analysis of qualitative and quantitative macrocell offloading benefits– Under which conditions can the macrocell capacity be

increased through offloading offloading of indoor users to femtocells

– By how much can be macrocell capacity be increased by increased by increasing the fraction of served indoor users through femtocells

12

UMTS Case Study (Simulation Scenario)

• Monitor the quantify the macrocell offloading gains• Simulation

– 7 macrocells with three sectors– Total of 5000 houses placed in uniform distribution – Two different types of house

• Detached house and terraced house

– Co-channel is possible with only minimal interference impact on macrocellular network

– System-level simulations perform to derive the resulting signal-to-interference-plus noise ratio (SINR)

– Different macrocell transmit signal-to-noise ration (SNR) from 0 to 30 dB

13

UMTS Case Study (Graphic)

14

UMTS Case Study (Mean throughput)

• Outdoor throughput reach a threshold at 10dB • Indoor throughput reach a threshold at 25 dB

– Caused by interference

15

UMTS Case Study (Offload capacity gain)

• Offloading gain disappear when SNR exceed 25dB

16

WiMAX Case Study

• Performed a quantitative assessment of macro offloading gain

• Simulation– Multicell simulation– Starting by using all users served by macro network– Comparing 6 scenarios– 10 users per sector (50% uses indoor)

17

Conclusion

• Advantage– Explaining the deployment of femtocell– Monitored throughput of performance

• Disadvantage– No particular handover is monitored– Femto and base station share same bandwidth

• I need to make it standalone femto