Integrated Support for Handoff Management and

Context Awareness in Heterogeneous Wireless Networks

ACM MPAC’05

Outline

• INTRODUCTION

• ARCHITECTURE DESIGN

• SMART AUDIO GUIDE CASE STUDY

• CONCLUSIONS AND FUTURE WORK

INTRODUCTION

• Mobile terminals, equipped with multiple wireless communication interfaces.

• Due to wireless medium volatile nature and device mobility

INTRODUCTION

• For these reasons, services are required to be context-aware(handoff).

• In this paper, the focus is on delay-sensitive services, e.g. multimedia streaming.

INTRODUCTION

• Proposed a middleware consisting of two layers.

• The proposed architecture has been implemented for BT and Wi-Fi wireless technologies.

INTRODUCTION

ARCHITECTURE DESIGN

ARCHITECTURE DESIGN

• Mechanism layer modules depend on the specific technology – encapsulate all the logic/knowledge necessary t

o control/monitor that particular wireless technology at datalink/ network layers.

ARCHITECTURE DESIGN

• Facility layer offers to the application level a set of common facilities, such as – the NCSOCKS and – the Mobility Awareness & Management

ARCHITECTURE DESIGN

ARCHITECTURE DESIGN

• Mechanisms Layer– includes one module for wireless technology.

• Each module is composed of two entities:– one to gather context information and

– another one to monitor and manage (when possible) the handoff process.

ARCHITECTURE DESIGN

• BT and Wi-Fi Context Awareness– The following context information is made available:

• a) connection status (e.g. connected, not connected, handoff), RSSI, bandwidth, and delay;

• b) location status, i.e., the current AP being used (in terms of its logical AP name, its IP address, its MAC address, its technology, and the local IP address); and

• c) static parameters, i.e., communication cost, battery consumption, and location granularity indicator.

ARCHITECTURE DESIGN

• BT Handoff Management– Last Second Soft Handoff (LSSH) scheme， based on the Receiv

er Signal Strength Indicator (RSSI).

– A handoff is triggered as soon as α(L) becomes greater than a certain threshold αT

ARCHITECTURE DESIGN

• Wi-Fi Handoff Management– Packet losses in particular to delay-sensitive ser

vices.– Received Signal Strength Indication-Grey Mod

el(RSSI-GM).• RSSI-GM technique can estimate future RSSI value

s by using the GM prediction model.

ARCHITECTURE DESIGN

ARCHITECTURE DESIGN

• Facilities Layer– Two common facilities

• the Mobility Awareness & Management and the NCSOCKS modules,

• Domain-specific facilityl： the Multimedia Streaming module.

ARCHITECTURE DESIGN

• Mobility Awareness & Management– Connection Monitor and Location Monitor– Connection Broker

• NCSOCKS(Nomadic Computing SOCKetS)– An object-oriented communication API.

ARCHITECTURE DESIGN

• Multimedia Streaming– are affected by handoffs.

• Middleware proxies receive and store incoming flows

SMART AUDIO GUIDE CASE STUDY

CONCLUSIONS AND FUTURE WORK

• A middleware architecture to ease the development of mobility-aware services in heterogeneous wireless networks.

• New technologies such as 3G cellular, can be integrated as new mechanism modules.