To improve the bit error rate(BER)performance of multi-user signal detection in satelliteterrestrial downlink non-orthogonal multiple access(NOMA)systems,an iterative signal detection algorithm based on soft interfere...To improve the bit error rate(BER)performance of multi-user signal detection in satelliteterrestrial downlink non-orthogonal multiple access(NOMA)systems,an iterative signal detection algorithm based on soft interference cancellation with optimal power allocation is proposed.Given that power allocation has a significant impact on BER performance,the optimal power allocation is obtained by minimizing the average BER of NOMA users.According to the allocated powers,successive interference cancellation(SIC)between NOMA users is performed in descending power order.For each user,an iterative soft interference cancellation is performed,and soft symbol probabilities are calculated for soft decision.To improve detection accuracy and without increasing the complexity,the aforementioned algorithm is optimized by adding minimum mean square error(MMSE)signal estimation before detection,and in each iteration soft symbol probabilities are utilized for soft-decision of the current user and also for the update of soft interference of the previous user.Simulation results illustrate that the optimized algorithm i.e.MMSE-IDBSIC significantly outperforms joint multi-user detection and SIC detection by 7.57dB and 8.03dB in terms of BER performance.展开更多
This paper presents a constructive discussion and inclusive review on advancements in the coded modulation free-space optical(FSO) communication system and corresponding techniques. These techniques mainly include cha...This paper presents a constructive discussion and inclusive review on advancements in the coded modulation free-space optical(FSO) communication system and corresponding techniques. These techniques mainly include channel model,forward error correction(FEC) and modulation schemes. Firstly,a complete view of FSO system is presented which contains the description,the current research situation along with the advantages over the traditional radio frequency(RF) wireless communication and fiber optical communications. Then,the channel model,FEC,modulation schemes and complete system of coded modulation FSO are analyzed successively. At last,the review work of coded modulation FSO system is summarized and further improvements are prospected.展开更多
Geography rectangle is used to reduce signaling overhead of the LEO satellite networks.Moreover,a multi-path routing algorithm based on an improved ant colony system(MPRA-AC) is proposed.Matrix indicating the importan...Geography rectangle is used to reduce signaling overhead of the LEO satellite networks.Moreover,a multi-path routing algorithm based on an improved ant colony system(MPRA-AC) is proposed.Matrix indicating the importance of the link between satellites is introduced into MPRA-AC in order to find the optimal path more quickly.Simulation results show that MPRA-AC reduces the number of iterations to achieve a satisfactory solution.At the same time,the packet delivery ratio of LEO satellite networks when running MPRA-AC and DSR-LSN(dynamic source routing algorithm for LEO satellite networks) is compared.The packet delivery ratio is about 7.9%lower when running DSR-LSN.Moreover,because of the mechanism of active load balancing of MPRA-AC,simulation results show that MPRA-AC outperforms DSR-LSN in link utilization when data packets are transmitted in the networks.展开更多
A novel trellis coded-4×8 overlapping amplitude and pulse position modulation(TC-4×8AOPPM) scheme is proposed to enhance bit error rate(BER) performance of free-space optical communication(FSO) system. In ad...A novel trellis coded-4×8 overlapping amplitude and pulse position modulation(TC-4×8AOPPM) scheme is proposed to enhance bit error rate(BER) performance of free-space optical communication(FSO) system. In addition, an uncoded AOPPM referential scheme is also designed. The schemes manage to decrease BER by designing gamma-gamma(GG) channel applicable decoding and demodulation methods. Simulation results of 8, 16 and 64-state TC-4×8AOPPM show 2.5-3.3 dB SNR gain against traditional TC-4×8AOPPM scheme respectively. Thus significant BER performance improvement is achieved and the reliability of the FSO system is also enhanced.展开更多
Based on the Schnorr signature scheme, a new signature scheme with non-repudiation is proposed. In this scheme, only the signer and the designated receiver can verify the signature signed by the signer, and if necessa...Based on the Schnorr signature scheme, a new signature scheme with non-repudiation is proposed. In this scheme, only the signer and the designated receiver can verify the signature signed by the signer, and if necessary, both the signer and the designated receiver can prove and show the validity of the signature signed by the signer. The proof of the validity of the signature is noninteractive and transferable. To verify and prove the validity of the signature, the signer and the nominated receiver needn＇t store extra information besides the signature. At the same time, neither the signer nor the designated receiver can deny a valid signature signed. Then, there is no repudiation in this new signature scheme. According to the security analysis of this scheme, it is found the proposed scheme is secure against existential forgery on adaptive chosen message attack.展开更多
An optical Amplitude and Pulse Position Modulation(APPM) mapping scheme for strong turbulent atmospheric channel is proposed to optimize Bit Error Rate(BER) performance.In this scheme,a nonequidifferent amplitude seri...An optical Amplitude and Pulse Position Modulation(APPM) mapping scheme for strong turbulent atmospheric channel is proposed to optimize Bit Error Rate(BER) performance.In this scheme,a nonequidifferent amplitude series is designed based on quantitative BER analysis of the specific A×M APPM demapping procedures containing time slot selection and amplitude decision in selected time slot,which are different from traditional ones.Simulation results of 4×4,4×8 and 4×16 APPM show 4,3.4 and 6.9 d B SNR gain against traditional APPM scheme respectively.Thus significant BER performance improvement is achieved which helps to enhance reliability of freespace optical communication systems.展开更多
An ant colony optimization （ACO） based load balancing routing and wavelength assignment （RWA） algorithm （ALRWA） was put forward for the sake of achieving a fairy load balancing over the entire optical satellite ...An ant colony optimization （ACO） based load balancing routing and wavelength assignment （RWA） algorithm （ALRWA） was put forward for the sake of achieving a fairy load balancing over the entire optical satellite networks. A multi-objective optimization model is established considering the characteristic of global traffic distribution. This not only employs the traffic intensity to modify the light path cost, but also monitors the wavelength utilization of optical inter-satellite links （ISLs）. Then an ACO algorithm is utilized to solve this model, leading to finding an optimal light path for every connection request. The optimal light path has the minimum light path cost under satisfying the constraints of wavelength utilization, transmission delay and wavelength-continuity. Simulation results show that ALRWA performs well in blocking probability and realizes efficient load balancing. Meanwhile, the average transmission delay can meet the basic requirement of real-time business transmission.展开更多
In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each＇ transmission can reduce the data collision rate. A...In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each＇ transmission can reduce the data collision rate. As classical random multiple access protocol, the slotted ALOHA （S-ALOHA） reduces the data collision rate through time slot allocation and synchronous measures. In order to improve the stability and throughput of satellite network, a backoff algorithm based on S-ALOHA will be effective. A new adaptive backoff algorithm based on S-ALOHA using grey system was proposed, which calculates the backofftime adaptively according to the network condition. And the network condition is estimated by each user terminal according to the prediction of the channel access success ratio using the model GM （1,1） in grey system. The proposed algorithm is compared to other known schemes such as the binary exponential backoff （BEB） and the multiple increase multiple decrease （MIMD） backoff. The performance of the proposed algorithm is simulated and analyzed. It is shown that throughput of the system based on the proposed algorithm is better than of system based on BEB and MIMD backoff. And there are also some improvements of the delay performance compared to using BEB. The proposed algorithm is especially effective for large number of user terminals in the satellite networks.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB2900602)the National Natural Science Foundation of China(No.61875230).
文摘To improve the bit error rate(BER)performance of multi-user signal detection in satelliteterrestrial downlink non-orthogonal multiple access(NOMA)systems,an iterative signal detection algorithm based on soft interference cancellation with optimal power allocation is proposed.Given that power allocation has a significant impact on BER performance,the optimal power allocation is obtained by minimizing the average BER of NOMA users.According to the allocated powers,successive interference cancellation(SIC)between NOMA users is performed in descending power order.For each user,an iterative soft interference cancellation is performed,and soft symbol probabilities are calculated for soft decision.To improve detection accuracy and without increasing the complexity,the aforementioned algorithm is optimized by adding minimum mean square error(MMSE)signal estimation before detection,and in each iteration soft symbol probabilities are utilized for soft-decision of the current user and also for the update of soft interference of the previous user.Simulation results illustrate that the optimized algorithm i.e.MMSE-IDBSIC significantly outperforms joint multi-user detection and SIC detection by 7.57dB and 8.03dB in terms of BER performance.
基金supported in part by the National NSFC with No. 61425022National High Technology 863 Program of China with No. 2013AA013403+5 种基金National Basic Research Program of China with No. 2010CB328300National NSFC (No. 60932004,61275074,61275158,& 61201151)National International Technology Cooperation with No.2012DFG1210Universities Ph.D. Special Research Funds with No. 20120005120007Beijing Excellent Ph.D. Thesis Guidance Foundation with No. 20121001302Open foundation of state key laboratory of optical communication technologies and networks(WRI)
文摘This paper presents a constructive discussion and inclusive review on advancements in the coded modulation free-space optical(FSO) communication system and corresponding techniques. These techniques mainly include channel model,forward error correction(FEC) and modulation schemes. Firstly,a complete view of FSO system is presented which contains the description,the current research situation along with the advantages over the traditional radio frequency(RF) wireless communication and fiber optical communications. Then,the channel model,FEC,modulation schemes and complete system of coded modulation FSO are analyzed successively. At last,the review work of coded modulation FSO system is summarized and further improvements are prospected.
基金Supported by the National High Technology Research and Development Programme of China(No.SS2013AA010503)the National Natural Science Foundation of China(No.61271281,61201151,61275158)the Fundamental Research Funds for the Central Universities(No.2482012PTB0004)
文摘Geography rectangle is used to reduce signaling overhead of the LEO satellite networks.Moreover,a multi-path routing algorithm based on an improved ant colony system(MPRA-AC) is proposed.Matrix indicating the importance of the link between satellites is introduced into MPRA-AC in order to find the optimal path more quickly.Simulation results show that MPRA-AC reduces the number of iterations to achieve a satisfactory solution.At the same time,the packet delivery ratio of LEO satellite networks when running MPRA-AC and DSR-LSN(dynamic source routing algorithm for LEO satellite networks) is compared.The packet delivery ratio is about 7.9%lower when running DSR-LSN.Moreover,because of the mechanism of active load balancing of MPRA-AC,simulation results show that MPRA-AC outperforms DSR-LSN in link utilization when data packets are transmitted in the networks.
基金supported in part by the National NSFC with No.61425022National High Technology 863 Program of China with No.2013AA013403+5 种基金National Basic Research Program of China with No.2010CB328300National NSFC(No.60932004,61275074,61275158,& 61201151)National International Technology Cooperation with No.2012DFG12110Universities Ph.D. Special Research Funds with No.20120005120007Beijing Excellent Ph.D. Thesis Guidance Foundation with No. 20121001302Open foundation of state key laboratory of optical communication technologies and networks(WRI)
文摘A novel trellis coded-4×8 overlapping amplitude and pulse position modulation(TC-4×8AOPPM) scheme is proposed to enhance bit error rate(BER) performance of free-space optical communication(FSO) system. In addition, an uncoded AOPPM referential scheme is also designed. The schemes manage to decrease BER by designing gamma-gamma(GG) channel applicable decoding and demodulation methods. Simulation results of 8, 16 and 64-state TC-4×8AOPPM show 2.5-3.3 dB SNR gain against traditional TC-4×8AOPPM scheme respectively. Thus significant BER performance improvement is achieved and the reliability of the FSO system is also enhanced.
基金Supported by the National Natural Science Foun-dation of China (60473028) the Science Foundation of ZhengzhouUniversity of Light Industry(2006XJJ17)
文摘Based on the Schnorr signature scheme, a new signature scheme with non-repudiation is proposed. In this scheme, only the signer and the designated receiver can verify the signature signed by the signer, and if necessary, both the signer and the designated receiver can prove and show the validity of the signature signed by the signer. The proof of the validity of the signature is noninteractive and transferable. To verify and prove the validity of the signature, the signer and the nominated receiver needn＇t store extra information besides the signature. At the same time, neither the signer nor the designated receiver can deny a valid signature signed. Then, there is no repudiation in this new signature scheme. According to the security analysis of this scheme, it is found the proposed scheme is secure against existential forgery on adaptive chosen message attack.
基金financial supports from National High Technology 863 Program of China(No.2012AA011304)National International Technology Cooperation(No.2012DFG12110)+5 种基金National NSFC(No.61275158/61201151/61275074)Beijing Nova Program( No.Z141101001814048)Beijing Excellent Ph.D.Thesis Guidance Foundation(No.20121001302)the Universities Ph.D.Special Research Funds(No.20120005110003)the Fundamental Research Funds for the Central Universities with No.2014RC0203Fund of State Key Laboratory of IPOC(BUPT)
文摘An optical Amplitude and Pulse Position Modulation(APPM) mapping scheme for strong turbulent atmospheric channel is proposed to optimize Bit Error Rate(BER) performance.In this scheme,a nonequidifferent amplitude series is designed based on quantitative BER analysis of the specific A×M APPM demapping procedures containing time slot selection and amplitude decision in selected time slot,which are different from traditional ones.Simulation results of 4×4,4×8 and 4×16 APPM show 4,3.4 and 6.9 d B SNR gain against traditional APPM scheme respectively.Thus significant BER performance improvement is achieved which helps to enhance reliability of freespace optical communication systems.
基金supported by the National Natural Science Foundation of China (61675033, 61575026, 61675233)National High Technical Research and Development Program of China (2015AA015504)
文摘An ant colony optimization （ACO） based load balancing routing and wavelength assignment （RWA） algorithm （ALRWA） was put forward for the sake of achieving a fairy load balancing over the entire optical satellite networks. A multi-objective optimization model is established considering the characteristic of global traffic distribution. This not only employs the traffic intensity to modify the light path cost, but also monitors the wavelength utilization of optical inter-satellite links （ISLs）. Then an ACO algorithm is utilized to solve this model, leading to finding an optimal light path for every connection request. The optimal light path has the minimum light path cost under satisfying the constraints of wavelength utilization, transmission delay and wavelength-continuity. Simulation results show that ALRWA performs well in blocking probability and realizes efficient load balancing. Meanwhile, the average transmission delay can meet the basic requirement of real-time business transmission.
文摘In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each＇ transmission can reduce the data collision rate. As classical random multiple access protocol, the slotted ALOHA （S-ALOHA） reduces the data collision rate through time slot allocation and synchronous measures. In order to improve the stability and throughput of satellite network, a backoff algorithm based on S-ALOHA will be effective. A new adaptive backoff algorithm based on S-ALOHA using grey system was proposed, which calculates the backofftime adaptively according to the network condition. And the network condition is estimated by each user terminal according to the prediction of the channel access success ratio using the model GM （1,1） in grey system. The proposed algorithm is compared to other known schemes such as the binary exponential backoff （BEB） and the multiple increase multiple decrease （MIMD） backoff. The performance of the proposed algorithm is simulated and analyzed. It is shown that throughput of the system based on the proposed algorithm is better than of system based on BEB and MIMD backoff. And there are also some improvements of the delay performance compared to using BEB. The proposed algorithm is especially effective for large number of user terminals in the satellite networks.
