1. Integrated Support for Handoff Management and Context Awareness in Heterogeneous Wireless Networks ACM MPAC’05

2. Outline INTRODUCTION ARCHITECTURE DESIGN SMART AUDIO GUIDE CASE STUDY CONCLUSIONS AND FUTURE WORK

3. INTRODUCTION Mobile terminals, equipped with multiple wireless communication interfaces. Due to wireless medium volatile nature and device mobility

4. 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.

5. INTRODUCTION Proposed a middleware consisting of two layers. The proposed architecture has been implemented for BT and Wi-Fi wireless technologies.

6. INTRODUCTION

7. ARCHITECTURE DESIGN

8. Mechanism layer modules depend on the specific technology –encapsulate all the logic/knowledge necessary to control/monitor that particular wireless technology at datalink/ network layers.

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

10. ARCHITECTURE DESIGN

11. 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.

12. 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.

13. ARCHITECTURE DESIGN BT Handoff Management –Last Second Soft Handoff (LSSH) scheme ， based on the Receiver Signal Strength Indicator (RSSI). –A handoff is triggered as soon as α(L) becomes greater than a certain threshold αT

14. ARCHITECTURE DESIGN Wi-Fi Handoff Management –Packet losses in particular to delay-sensitive services. –Received Signal Strength Indication-Grey Model(RSSI-GM). RSSI-GM technique can estimate future RSSI values by using the GM prediction model.

15. ARCHITECTURE DESIGN

16. Facilities Layer –Two common facilities the Mobility Awareness & Management and the NCSOCKS modules, Domain-specific facilityl ： the Multimedia Streaming module.

17. ARCHITECTURE DESIGN Mobility Awareness & Management –Connection Monitor and Location Monitor –Connection Broker NCSOCKS(Nomadic Computing SOCKetS) –An object-oriented communication API.

18. ARCHITECTURE DESIGN Multimedia Streaming –are affected by handoffs. Middleware proxies receive and store incoming flows

19. SMART AUDIO GUIDE CASE STUDY

20. 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.