Power and spectrum are considered as the significantly resource in the satellite communication systems, recently multiple-input multiple-output (MIMO) precoding has been identified as an excellent choice for the multibeam satellite communication systems (MSCSs). In order to improve power and spectrum utilization while mitigate the intra-beam interference and inter-beam interference, the crucial challenge is joint precoding design for multiple terminals. This paper proposes a hybrid full frequency (HFF) joint precoding scheme and chooses transmit power minimization as the energy efficient optimization problem which can be formulated as an indefinite quadratic optimization program. An optimization algorithm based on semidefinite programming (SDP) is designed to obtain the optimal objective. Simulation results demonstrate the performance improvement of proposed HFF joint precoding outperforms conventional frequency reuse and existing algorithms with respect to per feed power on-board constrained.

Today's difficult business reality makes enterprises more and more resort to information technology to manage nearly everything within the enterprises and to conduct business activities. This puts forward high requirements on information systems and in turn, raises a great challenge to software vendors - how to develop systems according to the diverse requirements as quickly as possible while spending a cost as low as possible. To achieve this purpose, we argue a core infrastructure delivering some general functions is needed by software vendors. The paper proposes such an infrastructure and details its design philosophy. A scenario is also presented to illustrate the effectiveness and efficiency of the infrastructure proposed.

The emergence of e-commerce (EC) brings great challenges to both research community and industries. As an enabling technology, workflow is viewed as a good basis for EC solutions due to its immense power in dealing with complex tasks and integration of heterogeneous resources. However, there are many issues with existing workflow systems such as rigid process definition, lack of interoperability, limited support of transaction, to name a few. This paper details how to support EC applications by extending Cova, a meta-groupware with process management ability, to support Web services. Based on the ability of run-time process adjustment provided by Cova, the dynamics of EC applications can be well addressed, while the introduction of Web services facilitates the interaction between different organizations without violating their autonomy.