Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have differen...Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have different Quality of Service(QoS)requirements.Hence,we study the power allocation in the downlink NCMA system in this paper,and propose a downlink Network-Coded Multiple Access with Diverse Power(NCMA-DP),wherein different amounts of power are allocated to different users.In terms of the Bit Error Rate(BER)of the multi-user decoder,and the number of packets required to correctly decode the message,the performance of the user with more allocated power is greatly improved compared to the Conventional NCMA(NCMA-C).Meanwhile,the performance of the user with less allocated power is still much better than NCMA-C.Furthermore,the overall throughput of NCMA-DP is greatly improved compared to that of NCMA-C.The simulation results demonstrate the remarkable performance of the proposed NCMA-DP.展开更多
将MC CDMA和空时分组编码相结合,构建出一种新的MC CDMA系统下行链路方案(ST MC CD MA)。该方案利用MC CDMA中固有的频率分集和空时分组码的空间分集来抵抗多径,提高系统性能。详细分析了该方案的信号变换形式和处理过程,从理论上给出...将MC CDMA和空时分组编码相结合,构建出一种新的MC CDMA系统下行链路方案(ST MC CD MA)。该方案利用MC CDMA中固有的频率分集和空时分组码的空间分集来抵抗多径,提高系统性能。详细分析了该方案的信号变换形式和处理过程,从理论上给出了系统采用最大比合并时的误码率性能。仿真结果表明,在瑞利衰落信道和较多用户条件下,该系统较传统MC CDMA具有明显的性能改善。展开更多
4-ary pulse amplitude modulation(4PAM) signals with 33% and 50% return-to-zero(RZ) clocks are generated for passive optical network(PON). We demonstrate that RZ-4PAM signals with duty cycles of 33% and 50% after trans...4-ary pulse amplitude modulation(4PAM) signals with 33% and 50% return-to-zero(RZ) clocks are generated for passive optical network(PON). We demonstrate that RZ-4PAM signals with duty cycles of 33% and 50% after transmission over 20-km-long single mode fiber(SMF) at 10 Gbit/s can be directly detected by using one photo detector,and the original data can also be restored by one M-ary threshold detector and one 4PAM sequence decoder. The optical spectra of 33% and 50% RZ-4PAM signals are measured,and their eye-diagrams before and after transmission are also analyzed. Simulation results show that 33% and 50% RZ-4PAM downlink signals can be received effectively,and the received power values are-15.1 d Bm and-13.8 d Bm when the bit error rate(BER) is 10^(-6). Moreover,33% RZ-4PAM optical signals have better reception performance than 50% RZ-4PAM optical signals.展开更多
文摘Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have different Quality of Service(QoS)requirements.Hence,we study the power allocation in the downlink NCMA system in this paper,and propose a downlink Network-Coded Multiple Access with Diverse Power(NCMA-DP),wherein different amounts of power are allocated to different users.In terms of the Bit Error Rate(BER)of the multi-user decoder,and the number of packets required to correctly decode the message,the performance of the user with more allocated power is greatly improved compared to the Conventional NCMA(NCMA-C).Meanwhile,the performance of the user with less allocated power is still much better than NCMA-C.Furthermore,the overall throughput of NCMA-DP is greatly improved compared to that of NCMA-C.The simulation results demonstrate the remarkable performance of the proposed NCMA-DP.
基金The National Key R&D Program of China(No.2022YFC38010000)the Key Research&Development Plan of Jiangsu Province(No.BE2020084-2)the Fundamental Research Funds for the Central Universities(No.2242022k60001).
文摘将MC CDMA和空时分组编码相结合,构建出一种新的MC CDMA系统下行链路方案(ST MC CD MA)。该方案利用MC CDMA中固有的频率分集和空时分组码的空间分集来抵抗多径,提高系统性能。详细分析了该方案的信号变换形式和处理过程,从理论上给出了系统采用最大比合并时的误码率性能。仿真结果表明,在瑞利衰落信道和较多用户条件下,该系统较传统MC CDMA具有明显的性能改善。
基金supported by the National Natural Science Foundation of China(No.61107064)the Chongqing University Innovation Team Founding(No.KJTD201320)+3 种基金the Natural Science Foundation of Chongqing Science & Technology Commission(Nos.cstc2014jcyj A40046 and cstc2016jcyj A1233)the Science and Technology Special Funds of Wanzhou District in Chongqing Citythe Chongqing Graduate Student Research Innovation Project(No.CYS15225)the Chongqing Three Gorges University Graduate Scientific Research Innovation Project
文摘4-ary pulse amplitude modulation(4PAM) signals with 33% and 50% return-to-zero(RZ) clocks are generated for passive optical network(PON). We demonstrate that RZ-4PAM signals with duty cycles of 33% and 50% after transmission over 20-km-long single mode fiber(SMF) at 10 Gbit/s can be directly detected by using one photo detector,and the original data can also be restored by one M-ary threshold detector and one 4PAM sequence decoder. The optical spectra of 33% and 50% RZ-4PAM signals are measured,and their eye-diagrams before and after transmission are also analyzed. Simulation results show that 33% and 50% RZ-4PAM downlink signals can be received effectively,and the received power values are-15.1 d Bm and-13.8 d Bm when the bit error rate(BER) is 10^(-6). Moreover,33% RZ-4PAM optical signals have better reception performance than 50% RZ-4PAM optical signals.
