Two-way communication with adaptive data acquisition

A bidirectional link between two nodes, Node 1 and Node 2, is studied in which Node 2 is able to acquire information from the environment, e.g., via access to a remote data base or via sensing. Information acquisition is expensive in terms of system resources, e.g., time, bandwidth and energy, and thus should be done efficiently. As a result of the forward communication from Node 1 to Node 2, the latter wishes to obtain information about the the data available at Node 1 and of the data obtained from the environment. The forward link is, however, also used by Node 1 to query Node 2 with the aim of retrieving information from the environment on the backward link. The problem is formulated using the concept of side information 'vending machine', and the optimal trade-off between communication rates, distortions of the estimates produced at the two nodes and costs for information acquisition at Node 2 is derived.