This document describes a proxy-based approach for continuous location-based spatial queries in mobile environments. The proxy creates estimated valid regions (EVRs) for mobile clients to reduce the number of queries submitted and load on the servers. For nearest neighbor queries, the proxy uses two new algorithms to accelerate the growth of EVRs, allowing it to build effective EVRs even with small cache sizes. For window queries, the proxy represents EVRs as estimated window vectors to achieve larger valid regions. Separate index structures are used for the two query types. The experiments show the proposed approach significantly outperforms existing proxy-based approaches.