Sihai Zhang

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—Though cooperative relaying is believed to be a promising technology to improve the energy efficiency of cellular networks, the relays' static power consumption might worsen the energy efficiency therefore can not be neglected. In this paper, we focus on whether and how the energy efficiency of cellular networks can be improved via relays. Based on the(More)
Practical mobile communication systems suffer from time-variant channel fading and co-channel interference, both of which give rise to challenges on strategy design and performance analysis in wireless relay networks. Although these two aspects have gained concerns in recent studies, most researchers still focused on dealing with single problem and avoided(More)
In this paper, we consider resource allocation with proportional fairness in the downlink orthogonal frequency division multiple access relay networks, in which relay nodes operate in decode-and-forward mode. A joint optimization problem is formulated for relay selection, subcarrier assignment and power allocation. Since the formulated primal problem is(More)
For opportunistic networks, we propose a new routing protocol named PPSW, which exploits the benefit of the polynomial interpolation prediction of mobile nodes positions. This scheme can deliver the message faster with appropriate opportunities. Specifically, in wait phase, relay can forward message to another one moving closer to destination, instead of(More)
Current satellite coverage architectures generally assumes uniform traffic distribution among all beams, giving rise to uniform beam coverage pattern along with equal beam bandwidth allocation. However, the uniform coverage is not suitable for the unbalanced traffic scenarios, e.g. the metropolis region and emergency communication during disaster, which is(More)
In this paper, we study energy-efficient channel aggregation problem in cognitive radio networks, where a secondary user senses multiple channels simultaneously or sequentially in the sensing period and subsequently aggregate those channels sensed free. We aim at designing the optimal sensing time and power allocation to achieve the maximum energy(More)
Though opportunistic relaying coded cooperation is known as an efficient cooperation scheme for cooperative multi-relay networks, the existing works have the disadvantage of low resource utilization or high system complexity. In this paper, we focus on how to achieve a balance between resource utilization and system complexity by proposing an novel(More)