於行動環境中一個有效率處理k-NN的查詢方法

Abstract

藉由使用GPS，人們可以判斷自身的位址並產生其答案與這些位址相關的查詢。如果用戶端於自身儲存體中快取並重複使用這些查詢答案與其相對應的答案正確範圍(valid region)，將有效地降低其等待時間與能源消耗。然而，伺服器基於成本考量並不提供valid region予用戶端。因此，利用介於伺服器與客戶端的代理伺服器來提供valid region的方法應應而生。但是，這樣的方法仍有效率上的缺失。基於此我們提出改良的方法，並將這個方法延伸應用於k-NN查詢上。實驗結果證明我們的方法在縮短整體反應時間與減少網路資料量上有顯著的改良。

Using GPS, people can identify their locations and issue queries whose results depend on those locations. If clients cache and reuse valid regions in their local storage, this reduces response time and power consumption. However, servers may not provide valid regions to mobile clients for reasons of expense. Thus, another method of providing valid regions in proxy between database servers and clients has been proposed. However, this method still suffers from problems of efficiency. We propose an optimized proxy method that can learn valid regions faster than the original method. Moreover, our method can also service k-NN queries that the original cannot. The simulated results show that our method performs better than the existing proxy method in terms of response time and database workload.