Paper #: Week 4 Paper 1
Title: Effects of power conservation, wireless coverage and cooperation on data dissemination among mobile devices

(1) Problems
This paper addresses a very real and current problem - the problem of people with mobile devices who have intermittent access to the internet but need more data availability. The authors contest that most mobile users run location dependent and news services. They propose a system called 7DS which will enable the exchange of relevant data among peers. 

(2) New Idea and Strengths
- I think the basis of the paper is very good. It tries to solve a very relevant problem. In today's world, we have a lot of devices which have the ability to connect to the net but the wireless infrastructure is not omnipresent enough to sustain continuous connection. To allow data dissemination even in this inhospitable environment is a very good idea.
- the idea of caching popular objects is appealing. Also 7DS organises and indexes this cache. Also using a GUI the user can set access permissions also. All these facilities are very handy.
- 7DS also provides security through encryption and decryption using public or private keys. This is an important feature to have.
- 7DS in its energy conservation mode offers 3 levels. This level hierarchy has been well thought out. Also, it supports the synchronous mode which is a nice strategy to conserve energy (compared to asynchronous). 


(3) Weaknesses and Extensions
- though a very nice idea - 7DS is still in prototype stage and its results have been possible ony through simulations.
- caching is nice for popular objects but reaching all the data that a particular user needs is still very difficult especially non static objects. For instance, if a user wants to check his mail this system does not make that possible.
- resolving inconsistencies among copies of a particular data object is a workable extension.



-- END --