Rewards-Based Negotiation for Providing Context Information

1. Rewards-Based Negotiation for Providing Context Information Bing Shi Nanjing University, Nanjing, P.R. China shibingtx@gmail.com

2. A story…… • Prepare my clothes before going to Australia • A travelagent help me make my plan • It needs context information about weather of Australia • Shanghai weather forecast and Nanjing weather forecast can provide these information under the QoC requirements (how many days it can predict, what accuracy it will reach, how long it will spend on getting weather information…) • The travelagent also tells the two providers that they can get proceeds when the user come back from Australia

3. A story…… • Prepare my clothes before going to Australia • Shanghai says to Nanjing “I provide it, you can get ¼ of the proceeds, and I also provide 1/10 extra portion in the future” • Nanjing evaluates Shanghai’s proposal, and compares it to its own. It can’t accept Shanghai’s proposal, then reject it, give its own proposal • Shanghai receives Nanjing’s proposal, also evaluates it to decide whether to accept it or give its own proposal • This process continues until they decide that “Shanghai provide weather information, Shanghai get 3/5 portion of proceeds, and Shanghai promise to provide extra 9/100 portion proceeds to Nanjing” • Travelagent gives an advice on clothes preparing according to weather information provided by Shanghai

4. A story…… • When I come back from Australia • I am satisfied with travelagent’s advice, I pay 100￥ to travelagent，and give it a good evaluation. • Travelagent pays 50￥ to Shanghai provider, and improves Shanghai provider’s reputation • Shanghai provider says to Nanjing “Here is your 20￥, and the extra portion of the proceeds will be paid in the future”

5. How to do? • A (i.e. Shanghai) and B (i.e. Nanjing) negotiate with each other to reach agreement on issues who provides weather information and how they allocate the proceeds.

7. Negotiation Model • Context manager gives A and B application’s QoC requirements • A initializes its proposal called offer o=(c, p) and reward ep, sends o and ep to B • c: who will provide weather information (Shanghai or Nanjing) • p: the portion of the whole proceeds A will get • ep: the extra portion A will require or promise

8. Negotiation Model • B receives A’s proposal o=(c, 1-p) and reward -ep, B evaluates A’s proposal and reward using utility function UB(o,ep,1), to compare it with its own initial offer and reward, greater then accept A’s proposal, negotiation finished • Otherwise B makes its own proposal, this negotiation process continues

9. Negotiation Model • At time t, A proposes offer o=(c,p) and reward ep to B, B use UB(o,ep,t) to evaluate o and ep. • Assume that at time t+1, the proposal from A can’t satisfy B, B proposes its own offer o’ and reward ep’ to A, then at time t+2, how A will do? Weight value Time discount function

10. Negotiation Model • At time t+2 • If UA(o,ep,t)<UA(o’,ep’,t+1) • Accepted • Else UA(o,ep,t)>=UA(o’,ep’,t+1) • Propose its own, but how to construct its own proposal?

11. Negotiation Model • First step: • A’s Conceded utility value at time t+2 Utility concession rate

12. Negotiation Model • Second step: determine offer (ct+2,pt+2) and ept+2 • ct+2 : ct or ct+1 • If then Ct+2=Ct The distance between the utility value of c at time T and the expected utility value at time T+2 The distance between the utility value of c at time T+1 and the expected utility value at time T+2

13. Negotiation Model • Else • Ct+2=Ct+1

14. Conclusion and discussions • Conclusion • A negotiation model for distributed providers to provide appropriate context information • Reduce the burden of middleware • Avoid the break down of “arbiter” • Guarantee providers’ interests • Discussions • Allow more providers to participate to the negotiation • Avoid deception and illusive promise of providers

15. Thank you! Any questions?