1. WAWC’05 Enhancing Mobile Peer-To-Peer Environment with Neighborhood Information Arto Hämäläinen - arto.hamalainen@lut.fi

2. 2 Outline Introduction to PeerHood - a Peer-to-Peer neighborhood –overall structure and detailed technical architecture Neighborhood Information exchange Usage Scenarios Evaluation

3. 3 PeerHood - Peer-to-peer neighborhood PeerHood is an environment consisting a number of personal trusted devices (PTDs), e.g. mobile phone, PDA, laptops PTDs sense their neighbors in the changing mobile environment using different network technologies PeerHood layer in PTD

4. 4 PTDs and their neighborhoods

5. 5 PeerHood - Peer-to-peer neighborhood Methods for searching depend on used network plug-in –In Bluetooth, its device and service discovery mechanisms are used, own methods in Wi-Fi and GPRS –Devices found are then stored in the local device database PeerHood provides a common network interface to connect to other PeerHood devices - independent from the underlying communications technology

6. 6 PeerHood components

7. 7 PeerHood class diagram

8. 8 PeerHood library interface Applications in PTD can send requests for the PeerHood daemon through the PeerHood library –Available functions include methods to list available devices and services, register and unregister local services offered by the application and to connect remote devices and services –Library interface also includes common read and write methods Same read and write methods for every network plugin

9. 9 Neighborhood information exchange Neighborhood information exchange is used to gather information about the neighboring devices from already discovered devices –Possibly revealing undiscovered devices and services –It can be used to speed up the device and service discovery and locate services not reachable with network technology currently in use –The neighborhood information exchange can either be enabled or disabled in devices, more detailed configuration is planned

10. 10 Neighborhood information exchange Neighborhood information exchange is carried out by the PeerHood daemon –It’s enabled or disabled using the configuration file or manually registering local neighborhood info service through the PeerHood library interface –If a remote device offers neighborhood information service, request is sent to the device and response is stored in local device database with the information about the offering device

11. 11 Neighborhood information exchange, usage scenarios Personal networking outside the immediate vicinity –interesting services found through neighborhood information exchange could be reached using longer range technology or via gateway device Exchange of detailed device information –Service-specific information offered Dedicated service discovery –Mobile device could use a dedicated device to carry out their device discovery (e.g. office/home PC) to save own batteries

12. 12 Neighborhood information exchange Device discoveries may fail, and neighborhood info can be used to get information about undiscovered devices

13. 13 Evaluation To evaluate the neighborhood information exchange, ten tests were carried out with and without it - in a situation corresponding to MSC in previous slide Fixed and mobile devices had different intervals in device discovery Time taken to find two other PeerHood devices was measured

14. 14 Conclusions and future work Neighborhood information exchange can be used to speed up device discovery in peer-to-peer environment and to find out devices outside the immediate vicinity or use alternative device discovery solutions Further work is still needed –the roles and nature of different devices needs to be defined and implemented –security and trust issues to be addressed as well as more detailed configuration of operation