A dynamic channel reservation method for multimedia streaming in Wi-Fi Mesh networks

To improve data transmission robustness in the Wi-Fi Mesh standard, a deterministic channel access method was added to the basic random access method, which enabled the stations to get a contention-free access in the previously reserved time intervals. This mechanism can be conveniently used for transmission of the real-time multimedia streams which require quality-of-service support. However, the packet transmission in the reserved time intervals is affected by random noise and interference, and the time-consuming reservation procedure does not allow one to change on-the-fly the amount of reserved channel resources. A method for dynamic channel reservation which takes into account these aspects of the deterministic channel access mechanism and meets the quality-of-service requirements was proposed.     

Universal Service-Providers for Private Information Retrieval

A private information retrieval scheme allows a user to retrieve a data item of his choice from a remote database (or several copies of a database) while hiding from the database owner which particular data item he is interested in. We consider the question of private information retrieval in the so-called ``commodity-based' model, recently proposed by Beaver for practically oriented service-provider Internet applications. We present simple and modular schemes allowing us to reduce dramatically the overall communication involving users, and substantially reduce their computation, using off-line messages sent from service-providers to databases and users. The service-providers do not need to know the database contents nor the future user's requests; all they need to know is an upper bound on the data size. Our solutions can be made resilient against collusions of databases with more than a majority (in fact, all-but-one) of the service-providers. Received 21 September 1998 and revised 21 December 1999 Online publication 19 May 2000