Low Earth Orbit (LEO) satellites provide short round-trip delays and are becoming in- creasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algor...Low Earth Orbit (LEO) satellites provide short round-trip delays and are becoming in- creasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algorithms. To satisfy the QoS requirements of multimedia applications, satellite routing protocols should consider handovers and minimize their effect on the active connections. A distributed QoS routing scheme based on heuristic ant algorithm is proposed for satisfying delay bound and avoiding link congestion. Simulation results show that the call blocking probabilities of this al- gorithm are less than that of Shortest Path First (SPF) with different delay bound.展开更多
A new structure of next generation integrated communication system was proposed, which is composed of space segment based on satellites and terrestrial segment. Moreover, the characteristics of enhanced multiple acces...A new structure of next generation integrated communication system was proposed, which is composed of space segment based on satellites and terrestrial segment. Moreover, the characteristics of enhanced multiple access schemes based on orthogonal frequency division multiplexing (OFDM) technique were analyzed for satellite links. However, OFDM is a doubtful candidate as its higher peak-to-average power ratio (PAPR) that causes the distortion of high power amplifier (HPA). Furthermore, different schemes were evaluated and compared in terms of the HPA nonlinearity and the link level performance in detail. And the pilot-aided channel estimation and equalization techniques were also considered for analyzing the problem. Simulation results show that the bit error rate (BER) and block error rate (BLER) performance of orthogonal frequency division multiple access (OFDMA) outperforms that of single carrier-frequency division multiple access (SC-FDMA) for the satellite links in the proposed structure, though discrete Fourier transform-spread OFDM DFT-S OFDM has low PAPR, especially the BER performance of OFDMA is 3.6 dB larger than that of SC-FDMA at the target BER.展开更多
An effective spot beam handover trigger and channel allocation scheme is proposed for GEO mobile satellite communication based on its characteristic and application. By using both signal strength and terminal location...An effective spot beam handover trigger and channel allocation scheme is proposed for GEO mobile satellite communication based on its characteristic and application. By using both signal strength and terminal location information, necessary handover is triggered promptly and accurately to reduce the negative effect of long signaling delay. Then handover decision is made with the handover queuing and channel allocation strategy. An adaptive channel resource allocation scheme is considered to optimize resource utilization with guarantee of emergency communication, which is significant for emergency rescue and disaster relief. Simulation results show that the proposed scheme prevents unnecessary handover effectively and has favorable adaptability to emergent requirement of satellite communication.展开更多
基金Supported by the National Natural Science Foundation of China (No.60372013).
文摘Low Earth Orbit (LEO) satellites provide short round-trip delays and are becoming in- creasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algorithms. To satisfy the QoS requirements of multimedia applications, satellite routing protocols should consider handovers and minimize their effect on the active connections. A distributed QoS routing scheme based on heuristic ant algorithm is proposed for satisfying delay bound and avoiding link congestion. Simulation results show that the call blocking probabilities of this al- gorithm are less than that of Shortest Path First (SPF) with different delay bound.
基金Project(60532030) supported by the National Natural Science Foundation of China
文摘A new structure of next generation integrated communication system was proposed, which is composed of space segment based on satellites and terrestrial segment. Moreover, the characteristics of enhanced multiple access schemes based on orthogonal frequency division multiplexing (OFDM) technique were analyzed for satellite links. However, OFDM is a doubtful candidate as its higher peak-to-average power ratio (PAPR) that causes the distortion of high power amplifier (HPA). Furthermore, different schemes were evaluated and compared in terms of the HPA nonlinearity and the link level performance in detail. And the pilot-aided channel estimation and equalization techniques were also considered for analyzing the problem. Simulation results show that the bit error rate (BER) and block error rate (BLER) performance of orthogonal frequency division multiple access (OFDMA) outperforms that of single carrier-frequency division multiple access (SC-FDMA) for the satellite links in the proposed structure, though discrete Fourier transform-spread OFDM DFT-S OFDM has low PAPR, especially the BER performance of OFDMA is 3.6 dB larger than that of SC-FDMA at the target BER.
基金Supported by the High Technology Research and Development Programme of China （No. 2008AA011102） and the National Natural Science Foundation of China （ No. 60772112）.
文摘An effective spot beam handover trigger and channel allocation scheme is proposed for GEO mobile satellite communication based on its characteristic and application. By using both signal strength and terminal location information, necessary handover is triggered promptly and accurately to reduce the negative effect of long signaling delay. Then handover decision is made with the handover queuing and channel allocation strategy. An adaptive channel resource allocation scheme is considered to optimize resource utilization with guarantee of emergency communication, which is significant for emergency rescue and disaster relief. Simulation results show that the proposed scheme prevents unnecessary handover effectively and has favorable adaptability to emergent requirement of satellite communication.
