Current Issue : January - March Volume : 2016 Issue Number : 1 Articles : 7 Articles
Channels of mobile satellite communications are affected by multipath fading and shadowing attenuation. At the same time,\ndiversity gains are believed to improve the transmission reliability in fading channels. Considering that the traditional Space-Time\nCoding (STC) is not suitable for the cooperative mobile satellite communication, in this paper, a new cooperative mobile satellite\ncommunication system is proposed based on the Dynamic Space-Time Coding (D-STC). The transmitting energy of the proposed\nscheme is saved by avoiding forwarding erroneous signals in cooperative users.Meanwhile, this system benefits from diversity gains\nand the transmission is robust. Additionally, a closed-form expression of the outage probability for the proposed scheme is derived,\nand then it is demonstrated that this scheme is much better than the existing non cooperative scheme and schemes with traditional\nSTCs in the outage performance. Finally, the analytical result is supported and validated by numerical simulations....
Delay and throughput are important metrics for network performance.We analyze the end-to-end delay of cognitive radio ad hoc\nnetworks for two traffic models: backlogged and geometric, respectively. By modelling the primary users as a Poisson point process\nand the secondary network deploying multi hop transmissions, we derive the closed-form expression for the end-to-end delay in\nsecondary networks. Furthermore, we optimize the end-to-end delay in terms of the hop number and the secondary transmission\nprobability, respectively.The range of the optimal hop number and the equation satisfied by the optimal transmission probability\nare obtained for backlogged source models.The equation met by the optimal hop number is presented for geometric source models....
The Mobile and wireless communications Enablers for the Twenty-twenty Information Society (METIS) project is laying\nthe foundations of Fifth Generation (5G) mobile and wireless communication system putting together the point\nof view of vendors, operators, vertical players, and academia. METIS envisions a 5G system concept that efficiently\nintegrates new applications developed in the METIS horizontal topics and evolved versions of existing services and\nsystems. This article provides a first view on the METIS system concept, highlights the main features including\narchitecture, and addresses the challenges while discussing perspectives for the further research work....
Superconducting nanowire single photon detectors\nare rapidly emerging as a key infrared photon-counting\ntechnology. Two front-side-coupled silver dipole nanoantennas,\nsimulated to have resonances at 1480 and 1525 nm, were\nfabricated in a two-step process. An enhancement of 50 to\n130% in the system detection efficiency was observed when\nilluminating the antennas. This offers a pathway to increasing\nabsorption into superconducting nanowires, creating larger\nactive areas, and achieving more efficient detection at longer\nwavelengths....
Named data networking (NDN) is a newly proposed paradigm for future Internet, in which communication among nodes is based\non data names, decoupling from their locations. In dynamic and self-organized cognitive radio ad hoc networks (CRAHNs), it is\ndifficult to maintain end-to-end connectivity between ad hoc nodes especially in the presence of licensed users and intermittent\nwireless channels. Moreover, IP-based CRAHNs have several issues like scalability, inefficient-mapping, poor resource utilization,\nand location dependence. By leveraging the advantages of NDN, in this paper,we propose a new cross layer fine-grained architecture\ncalled named data networking for cognitive radio ad hoc networks (NDN-CRAHNs). The proposed architecture provides distinct\nfeatures such as in-networking caching, security, scalability, and multipath routing. The performances of the proposed scheme\nare evaluated comparing to IP-based scheme in terms of average end-to-end delay and packet delivery ratio. Simulation results\nshow that the proposed scheme is effective in terms of average contents download time and packet delivery ratios comparing to\nconventional cognitive radio ad hoc networks....
A multiuser communication scheme which is a hybrid of Walsh code with DCSK and CDSK is proposed to improve low data\ntransmission rate of Differential Chaos Shift Keying (DCSK), poor bit error ratio (BER) performance of Correlation Delay Shift\nKeying (CDSK), and disadvantage of orthogonality in traditional multi user DCSK. It not only overcomes the disadvantages of\nDCSK and CDSK, but also has better performance than CDSK and higher transmission data rate than DCSK. It has been proved\nthat the novel multiuser CDSK-DCSK has better properties than traditional Multiple Input Multiple Output-Differential Chaos\nShift Keying (MIMO-DCSK) and Modified-Differential Chaos Shift Keying (M-DCSK). Also the multiuser interference is greatly\nsuppressed due to the orthogonality of Walsh code....
In this work, we studied the behavior and mobility of telecom subscribers into a train for now and predict a future telecom movement subscriber and have a perfect resources data signal of an operator mobile telecom, we used a deterministic and a probabilistic method. the train in our model example travels through a cellular network and passed into four zones (Z1, Z2, Z3 and Z4), each one is characterized by: topography, numbers of the cellular network, types of network (GSM, GPRS, UMTS ...), numbers of subscribers, types of subscribers(staffs, students, workers and others), numbers of operators (Operator 1, Operator 2 and Operator 3). We have studied statistics in deterministic and probabilistic vision of traffic telecom; the model used is approach to vehicular traffic model....
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