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A mobile environment is characterized by low communication bandwidth and poor network connectivity. Accessing web documents in a mobile environment is thus both inefficient and ineffective. To combat for the low bandwidth problem, we employ the multi-resolution transmission and browsing mechanism for web documents, in which a web document is partitioned into multiple units, to enable a mobile client to explore the more content-bearing portion earlier. To combat for the poor network connectivity problem, we utilize a mobile agent model in the distributed agent environment (DAE). A mobile agent has the capability of migrating to a base station that is currently serving a mobile client, establishing a virtual connection to the client. The agent, acting on behalf of the client, travels along the wired network to carry out its tasks and collect results, returning to the client at the end of its itinerary. We have implemented the DAE architecture, which supports mobile agent in a mobile environment, and demonstrated its usefulness in supporting our multi-resolution mechanism. We have also conducted experimental study, comparing performance between conventional mobile client/server model and different mobile agent models in accessing a database server through both wireless and wired networks.

We propose a multi-resolution transmission mechanism that allows various organizational units of a web document to be transferred and browsed according to the amount of information captured. We define the notion of information content for each individual organizational unit of a web document as an indication of its captured information. The concept of information content is used as a foundation for defining the notion of relative information content which determines the transmission order of various units. Our mechanism allows a web client to explore the more content-bearing portion of a web document earlier so as to be able to terminate browsing a possibly irrelevant document sooner. This scheme is based on our observation that different organizational units of a document contribute to different amount of information to the document. Such a multi-resolution transmission paradigm is particularly useful in mobile web where the wireless bandwidth is a scarce resource and browsing every document in detail would consume the bandwidth unnecessarily. This is becoming more serious when the size of a web document is getting large, such as technical documents. We then present a prototype of the system in Java and CORBA to illustrate its feasibility.

A mobile environment is weakly-connected, characterized by low communication bandwidth and poor connectivity. The conventional paradigm for surfing mobile Web documents is ineffective since portions of a document could be corrupted during transmission and it is expensive to re-transmit the whole document. It is important that the high content-bearing portions should be transmitted successfully so that a mobile client could at least obtain a high level content and determine if the corrupted portions need to be retransmitted. We have proposed a multi-resolution transmission paradigm which allows higher content-bearing portions of a Web document to be transmitted, by partitioning it into multiple organizational units and associating an information content with each unit. The client can explore the higher content-bearing portion earlier and terminate browsing an irrelevant document sooner. We extend our previous work and propose a fault-tolerant multi-resolution transmission scheme which allows units of higher information content to be recovered from transmission error. The client can obtain an overall content of a Web document and either terminate the transmission of the remaining portions or decide if the corrupted portions need to be retransmitted. We demonstrate its feasibility with a prototype and with simulation results.