With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA （S-ALOHA） using successive interference cancellation （SIC） technique to se...With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA （S-ALOHA） using successive interference cancellation （SIC） technique to separate collided packets and cooperative transmission to exploit the physical layer advantages. And a general theoretic analysis model is presented to obtain its throughput, which is also suitable for analyzing the performance of other protocols （such as S-ALOHA and S-ALOHA with cooperative transmission （C-ALOHA）） and is shown to be right and effective. Numerical results demonstrate that the proposed protocol can improve the maximal throughput by 190% and 132% over a Rayleigh fading channel, respectively, as compared with S-ALOHA and C-ALOHA. And the results show that our protocol can provide an effective random access method with high throughput for wireless transmission.展开更多
随着海洋资源的利用和开发,人们对高速率水下通信的需求也更加迫切。但水下环境的高频衰减特性和强噪声导致水下信号的传输带宽受限,信号传输速度较慢。同时现有的水下节点间通信通常采用碰撞避免的MAC协议,在一个时隙内只允许一个有效...随着海洋资源的利用和开发,人们对高速率水下通信的需求也更加迫切。但水下环境的高频衰减特性和强噪声导致水下信号的传输带宽受限,信号传输速度较慢。同时现有的水下节点间通信通常采用碰撞避免的MAC协议,在一个时隙内只允许一个有效用户发送数据,因而水声信道的利用率较低。针对上述问题,提出了一种同频时反水下协作通信系统的自信息干扰消除算法。在该水下协作通信系统中,节点可同时通过水下基站向对方发送数据,节点之间共用相同的上行频率和下行频率,实现频谱资源复用。该方法中通过在基站处进行主动时反,消除水声信道传输的多径效应,然后利用节点对自身发射信号已知的特点,消除基站转发信息中的自信息干扰。仿真结果表明,文中所提出方法的误码性能与现有的分时协作通信方法相当,在信噪比为11 d B时,误码率均可以达到10-3,但该方法的传输速度为分时水下协作通信方法的2倍。展开更多
在不完全信道状态信息和非理想连续干扰消除条件下对存在窃听者的非正交多址系统安全性能问题进行研究,提出一个存在窃听者的解码转发中继辅助非正交多址接入系统(Decode and Forward Cooperative Relay in Non-Orthogonal Multiple Acc...在不完全信道状态信息和非理想连续干扰消除条件下对存在窃听者的非正交多址系统安全性能问题进行研究,提出一个存在窃听者的解码转发中继辅助非正交多址接入系统(Decode and Forward Cooperative Relay in Non-Orthogonal Multiple Access System with Eavesdropper,DFCR-E-NOMA)。在该系统中,分析了在不完全的信道状态信息和非理想连续干扰消除同时存在的条件下系统的安全性能,利用中断概率和截获概率表征系统的安全性能,通过蒙特卡罗模拟仿真分析了功率分配系数、信道估计误差对所提系统性能的影响。验证结果表明,在信道条件一定的情况下,可通过设置较高的数据传输速率,在基站或中继处选择合适的功率分配系数能够有效降低窃听者的截获概率。展开更多
The transmission antennas of cooperative systems are spatially distributed on multiple nodes, so the received signal can be asynchronous due to propagation delays. A receiving scheme for cooperative relay networks is ...The transmission antennas of cooperative systems are spatially distributed on multiple nodes, so the received signal can be asynchronous due to propagation delays. A receiving scheme for cooperative relay networks is proposed, multiple asynchronous signals are reconstructed at the receiver by forward and backward interference cancellation, which can obtain gains of cooperative transmission diversity with obvious delay and with no requiring timing synchronization or orthogonal channelization between relays. Analysis and simulation show that the bit error rate（BER） of the proposed scheme is similar to Alamouti code, and the scheme has the diversity order of orthogonal transmission scheme accompanied by minimal BER losses. It is demonstrated that the performance can be further improved by adding an error correcting code（ECC）.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 60672079)the open research fund of National Mobile Communications Research Laboratory, Southeast University (Grant No. N200814)the Project of Natural Science Foundation of Jiangsu Province(Grant No. BK2007002)
文摘With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA （S-ALOHA） using successive interference cancellation （SIC） technique to separate collided packets and cooperative transmission to exploit the physical layer advantages. And a general theoretic analysis model is presented to obtain its throughput, which is also suitable for analyzing the performance of other protocols （such as S-ALOHA and S-ALOHA with cooperative transmission （C-ALOHA）） and is shown to be right and effective. Numerical results demonstrate that the proposed protocol can improve the maximal throughput by 190% and 132% over a Rayleigh fading channel, respectively, as compared with S-ALOHA and C-ALOHA. And the results show that our protocol can provide an effective random access method with high throughput for wireless transmission.
文摘随着海洋资源的利用和开发,人们对高速率水下通信的需求也更加迫切。但水下环境的高频衰减特性和强噪声导致水下信号的传输带宽受限,信号传输速度较慢。同时现有的水下节点间通信通常采用碰撞避免的MAC协议,在一个时隙内只允许一个有效用户发送数据,因而水声信道的利用率较低。针对上述问题,提出了一种同频时反水下协作通信系统的自信息干扰消除算法。在该水下协作通信系统中,节点可同时通过水下基站向对方发送数据,节点之间共用相同的上行频率和下行频率,实现频谱资源复用。该方法中通过在基站处进行主动时反,消除水声信道传输的多径效应,然后利用节点对自身发射信号已知的特点,消除基站转发信息中的自信息干扰。仿真结果表明,文中所提出方法的误码性能与现有的分时协作通信方法相当,在信噪比为11 d B时,误码率均可以达到10-3,但该方法的传输速度为分时水下协作通信方法的2倍。
文摘在不完全信道状态信息和非理想连续干扰消除条件下对存在窃听者的非正交多址系统安全性能问题进行研究,提出一个存在窃听者的解码转发中继辅助非正交多址接入系统(Decode and Forward Cooperative Relay in Non-Orthogonal Multiple Access System with Eavesdropper,DFCR-E-NOMA)。在该系统中,分析了在不完全的信道状态信息和非理想连续干扰消除同时存在的条件下系统的安全性能,利用中断概率和截获概率表征系统的安全性能,通过蒙特卡罗模拟仿真分析了功率分配系数、信道估计误差对所提系统性能的影响。验证结果表明,在信道条件一定的情况下,可通过设置较高的数据传输速率,在基站或中继处选择合适的功率分配系数能够有效降低窃听者的截获概率。
基金supported by the National Science&Technology Major Projects(2012ZX03001031-004)the Fundamental Research Funds for the Central Universities(2012RC0105)
文摘The transmission antennas of cooperative systems are spatially distributed on multiple nodes, so the received signal can be asynchronous due to propagation delays. A receiving scheme for cooperative relay networks is proposed, multiple asynchronous signals are reconstructed at the receiver by forward and backward interference cancellation, which can obtain gains of cooperative transmission diversity with obvious delay and with no requiring timing synchronization or orthogonal channelization between relays. Analysis and simulation show that the bit error rate（BER） of the proposed scheme is similar to Alamouti code, and the scheme has the diversity order of orthogonal transmission scheme accompanied by minimal BER losses. It is demonstrated that the performance can be further improved by adding an error correcting code（ECC）.
