PERFORMANCE ANALYSIS AND SIMULATION OF VARIOUS BURST TIME PLAN GENERATION METHODS IN BROADBAND SATELLITE MULTIMEDIA SYSTEM

The Burst Time Plan(BTP) generation is the key for resource allocation in Broadband Satellite Multimedia(BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused by BTP generation as well as maintain the Quality of Service(QoS) and improve the channel utilization efficiency.Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm.Based on the analysis we find that Periodical BTP Generation(P-BTPG) method cannot guarantee the delay performance,channel utilization efficiency and QoS simultaneously,especially when the capacity requests arrived randomly.The Optimized BTP Generation(O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead.Finally,a novel Asynchronous BTP Generation(A-BTPG) method is proposed which is invoked according to users' requests.A BSM system application scenario is simulated.Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern.This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite(DVB-RCS) system or IP onboard routing BSM system in the future.

Cross-layer design of LT codes and LDPC codes for satellite multimedia broadcast/multicast services

According to large coverage of satellites, there are various channel states in a satellite broadcasting network. In order to introduce an efficient rateless transmission method to satellite multimedia broadcasting/multicast services with finite-length packets, a cross-layer packet transmission method is proposed with Luby transform （LT） codes for efficiency in the network layer and low density parity check （LDPC） codes for reliability in the physical layer jointly. The codewords generated from an LT encoder are divided into finite-length packets, which are encoded by an LDPC encoder subsequently. Based on noise and fading effects of satellite channels, the LT packets received from an LDPC decoder either have no error or are marked as erased, which can be mod- eled as a binary erasure channels （BECs）. By theoretical analysis on LT parameters and LDPC parameters, the relationships between LDPC code rates in the physical layer and LT codes word lengths in the network layer are investigated. With tradeoffs between the LT codes word lengths and the LDPC code rates, optimized cross-layer solutions are achieved with a binary search algorithm. Verified by simulations, the proposed solution for cross-layer parameters design can provide the best transmission mode according to satellite states, so as to improve throughput performance for satellite multimedia transmission.

Fairness based channel borrowing strategy in multimedia LEO satellite communications

A novel bandwidth allocation strategy along with a connection admission control technique was proposed to improve the utilization of network resources.It provides the network with better quality-of-service(QoS)guarantees,such as new call blocking probability(CBP)and handoff call drop-ping probability(CDP)in multimedia low earth orbit(LEO)satellite networks.Simulation results show that,compared with other bandwidth allocation schemes,the proposed scheme offers very low call dropping probability for real-time connections while,at the same time,keeping resource utilization high.Finally we discussed the fairness for the borrowed nonreal-time connections under three different channel borrowing methods.