Heterogeneous networks require mechanisms for transparent protocol boosting in legacy systems and adaptive support for seamless interoperability between different wireless access methods. In this paper, we present an open performance enhancement protocol architecture that is developed to provide a generic protocol enhancing proxy (PEP) service for wireless access points and terminals. First, we describe the basic architecture and philosophy of our approach. Then some illustrative protocol boosting modules are presented with results. Finally, we describe the future work that is required in order to make the so-called wireless adaptation layer (WAL) useful in production quality environments.