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Based on IEEE 802.15.4, a contention-free period (CFP) adopts guarantee time slot (GTS) mechanism to ensure each device can access the radio channel. However, it is hard to get the authority to access the radio channel due to more competitors access the radio channel simultaneously. To cope with this issue, we proposed a guarantee time slot mechanism to enhance the performance and utilization of using...
Tactical data links are an essential contribution to automatic "real-time" communication. In the current tactical environment, most users are pre-allocated a fixed amount of bandwidth. As a result, there should be bandwidth wastes and no guarantee of QoS. If the network is flooded, delaying of important messages may happen. So We need proper network management framework in TDL system. And...
The recently standardized IEEE 802.15.4 protocol is emerging as a basic building block for wireless sensor network applications by providing many appealing features, such as low power, low cost, low data-rate, and simplicity. However, when treating applications with strict timeliness, energy, and bandwidth requirements several problems arise, triggering the need of a solution for an efficient twinning...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
This correspondence demonstrates the significant gains that multiple-access users can achieve from sharing a single amplify-forward relay in slow-fading environments. The proposed protocol, namely, multiple-access amplify-forward (MAF), allows for a low-complexity relay and achieves the optimal diversity-multiplexing tradeoff (DMT) at high multiplexing gains. Analysis of the protocol further reveals...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
Three applications in wireless networks where model-free stochastic learning is applicable, are discussed. The learning based optimization problems are formulated and simulation results are presented. Some open issues are also discussed.
As Grid networks grows, the complexity of resource management in Grid networks dramatically increases. To manage the Grid resources efficiently, policy based resource management system is suitable. However, the policy which made at a moment could not be appropriate to other time because the condition of the grid resources with time space changes. Thus, in this paper, we propose asynchronous policy-based...
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