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Cooperative diversity systems rely on using relay nodes to relay copier of transmitted information to the destination such that each copy experiences different channel fading, hence increasing the diversity of the system. In this letter, we proposed a novel distributed cooperative beamforming scheme for decode-and-forward relay networks without channel state information (CSI) feedback. We further...
Congestion in computer network happens when the number of transmission requests exceeds the transmission capacity at a certain network point (called a bottle-neck resource) at a specific time. Congestion usually causes buffers overflow and packets loss. The purpose of congestion management is to maintain a balance between the transmission requests and the transmission capacity so that the bottle-neck...
Based on free probability theory, a new scheme for frequency band sensing of spreading communication system is proposed. Unlike previous studies in the field, the new scheme does not require the knowledge of the spreading sequences of users and is related to the asymptotic free behavior of random matrices. Simulation result shows that the convergence characteristic holds true even for a small number...
Spectrum sensing is a crucial technology for cognitive radio networks. In this paper, we develop a novel spectrum sensing method for secondary users to sense the idle spectrum. The key idea of the proposed method is combining multiple slots energy detection. Firstly, we establish the probability model regarding the appearance of the primary user at each slot of a secondary user slots window structure...
The closed form expression for the sum of composite Nakagami-lognormal distributions is hard to obtain. Numerical integration approximation to the sum distribution provides sufficient accuracy but is too complicated to apply into further analysis. In this paper we investigate a simple analysis approach based on the least square method, which achieves the accuracy of numerical integration and has a...
Using directional antennas in wireless ad hoc networks offers many benefits. However, utilizing this antennas with IEEE 802.11 MAC protocol which is introduced for omni-directional antennas can cause new problems like hidden node, exposed node and deafness problems. In this paper we propose an auxiliary tone-based DMAC (ATB-DMAC) scheme to tackle all of these problems and give an analytical model...
Power allocation with relay selection with incomplete channel state information is considered. Particularly, the utility function is based on the rate and adds the different pricing schemes to reflect the cost of each node according to the different status of each node. We decide if and which relay node to take part in cooperative communication based on the SNR of each node. Then the source and the...
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