Liu Aijun

DiffServ-oriented On-board Switch

Based on the concept of DiffServ (Differentiated Service), an on-board switch framework is proposed, which satisfies QoS performance requirements and maintains a fairly low complexity. It applies the (m, k) model to the mapping between the terrestrial and satellite network traffic and uses the double-LB (Leak Bucket) model to control the traffic efficiently. Simulation results show that the scheme significantly improves the QoS performance, smoothes the burst traffic and saves the on-board buffer reservation.

A New Distance Property Analysis Algorithm for FTFs in DFH Systems

By considering the frequency transition as a coding process, a new state diagram based distance property analysis algorithm for frequency transition function (FTF) is derived in this paper. In this new algorithm the distance property can be quickly obtained by solving the state equations derived from the transition process of the state diagram. It is confirmed that the BER performances of DFH systems which are decided by the distance properties of FTFs can be easily and effectively acquired. The new algorithm provides an efficient distance property analysis tool for the construction of FTF, it can help to optimize the design of a DFH system. Numerical simulation results support the theoretical analysis result of our algorithm.

Performance improvement using beam diversity technique in GEO satellite communication system over correlated Nakagami-m fading channels

In GEO satellite communication with multi-beam antenna coverage, the decline of uplink performance will appear when the earth terminal near to the junction area of beams coverage. A method to solve the problem by beam diversity technique is studied in this paper. After presenting a new generation method of Nakagami-m fading channel simulation model, we build up a system model for the analysis of multi-beam diversity. In this model, terminal position, beam gain and channel fading level are taken into account. A number of results of simulation show that using beam diversity reception technique can effectively improve uplink performance of GEO satellite communication.