Indexed on: 01 Jan '03Published on: 01 Jan '03Published in: Wireless Networks
Mobile and wireless network systems are characterized by a highly time varying and heterogeneous operational environment. For example, the wireless link bandwidth and bit error rate can change due to fading, mobile nodes may have different capabilities, and in the course of its movements a mobile node may visit base stations that provide different sets of services, protocols, and interfaces. Adaptability, in various forms and at various levels of the system, is a key to combating the inherent variability of a mobile environment. This paper describes our work on Active Base Stations and Active Mobile Nodes that use the general approach of active networking to allow run-time application-specific customization of communication processing done on packets at the base station and the mobile end-nodes. This is accomplished by a software-hardware architecture that allows application specified reconfigurable hardware datapaths as well as software functions to be inserted in the path of specified packet flows at the base station and the end-node. The reconfigurable hardware datapaths as well as software functions, called Packet Processing Filters (PPF), can be uploaded or downloaded across the network, and their behavior controlled via parameter adaptation. Examples of adaptive capabilities enabled by Active Base Stations and Active Wireless Nodes include: (i) flow-specific adaptation of coding/decoding and packet lengths at the two ends of a time varying wireless link; (ii) adaptation of encryption/decryption on the wireless link according to changing locale and security environment; (iii) downloading a new or proprietary MAC protocol from a base station to visiting foreign mobiles; and (iv) dynamically uploading mobile specified services to a base station of a different service provider. We present the basic architecture and implementation approach of our system, and description of the initial software/hardware prototype.