Recently the Cognitive Radio (CR), in particular the CR Ad-Hoc Network (CRAHN) technology appears as a burgeoning area in wireless communication that enables utilization of limited network resources in more efficient ...Recently the Cognitive Radio (CR), in particular the CR Ad-Hoc Network (CRAHN) technology appears as a burgeoning area in wireless communication that enables utilization of limited network resources in more efficient and intelligent way;studies indicate that opportunistic utilization of the available radio frequency spectrum, without interfering the licensed primary user (PU) could be made. This paper presents some simulation based performance of the Multi-Channel Hidden Terminal (MCHT) problem on CRAHNs;new observations on the effect of the number of channels on certain PU-activity metrics, e.g., delay and throughput, are described.展开更多
In this paper,we study cross-layer scheduling scheme on multimedia application which considers both streaming traffic and data traffic over cognitive ad hoc networks.A cross-layer design is proposed to optimize SU'...In this paper,we study cross-layer scheduling scheme on multimedia application which considers both streaming traffic and data traffic over cognitive ad hoc networks.A cross-layer design is proposed to optimize SU's utility,which is used as an approach to balance the transmission efficiency and heterogeneous traffic in cognitive ad hoc networks.A framework is provided for utility-based optimal subcarrier assignment,power allocation strategy and corresponding modulation scheme,subject to the interference threshold to primary user(PU) and total transmit power constraint.Bayesian learning is adopted in subcarrier allocation strategy to avoid collision and alleviate the burden of information exchange on limited common control channel(CCC).In addition,the M/G/l queuing model is also introduced to analyze the expected delay of streaming traffic.Numerical results are given to demonstrate that the proposed scheme significantly reduces the blocking probability and outperforms the mentioned single-channel dynamic resource scheduling by almost 8%in term of system utility.展开更多
In Cognitive radio ad hoc networks （CRAHNs）, the secondary users （SUs） or cognitive radio nodes （CRs） are always equipped with limited energy and have a high error probability of data transmission. To address th...In Cognitive radio ad hoc networks （CRAHNs）, the secondary users （SUs） or cognitive radio nodes （CRs） are always equipped with limited energy and have a high error probability of data transmission. To address this issue, we first describe the network utility under energy constraint as a max-min model, where the re-transmission strategy with network coding is employed. Additionally, the expression of retransmission probability is presented in terms of power and bit error rate （BER）. Moreover, since the max-min model is non-convex in both objective and constraints, we use a normal- form game to find a near-optimal solution. The simulation results show that the proposed approach could achieve a higher network utility than the compared approaches.展开更多
One critical issue for routing in cognitive radio ad hoc networks (CRAHNs) is how to select a reliable path for forwarding traffic. This is because mobility may cause radio links to break frequently. The reliability o...One critical issue for routing in cognitive radio ad hoc networks (CRAHNs) is how to select a reliable path for forwarding traffic. This is because mobility may cause radio links to break frequently. The reliability of a path depends on the availability of those links that constitutes the path. In this letter, we present a novel approach to predict the probability of the availability of the link between two cognitive radio nodes. The prediction is achieved by estimating the link activation and spectrum activation probabilities. Our prediction is verified by simulation and proved to be accurate. This study can provide reliability assurance on dynamic routing for cognitive radio ad hoc networks.展开更多
We study the problem of frequency and power allocation and scheduling at a time-slotted cognitive ad-hoc wireless network, where cognitive nodes share a number of frequency bands and frequency reuse is allowed. In suc...We study the problem of frequency and power allocation and scheduling at a time-slotted cognitive ad-hoc wireless network, where cognitive nodes share a number of frequency bands and frequency reuse is allowed. In such a network the throughput maximization problem generally results in a mixed zero-one nonlinear non-convex problem. Interestingly, in the low-SINR regime, the power allocation policy that maximizes the total throughput follows an “on/off” strategy with maximum power usage in the “on” state. In this paper we show that the on/off strategy in the low-SINR regime is also optimal with respect to throughput when scheduling users over time and frequency subject to minimum SINR requirements. We show that these additional constraints will not change the optimum strategy, but may affect the set of “on” or “off” transmitters. Also we present an approach that transforms the mixed zero-one nonlinear problem to an equivalent mixed zero-one linear problem at the expense of extra variables.展开更多
针对避免广播冲突的CR Ad Hoc网络的分布式广播协议广播成功率低和基于选择性广播信道集的低延迟广播算法广播冲突率高的问题,提出基于中继节点选择的多跳CR Ad Hoc网络广播算法。根据节点可用信道集的大小和基于邻居度的转发概率选取...针对避免广播冲突的CR Ad Hoc网络的分布式广播协议广播成功率低和基于选择性广播信道集的低延迟广播算法广播冲突率高的问题,提出基于中继节点选择的多跳CR Ad Hoc网络广播算法。根据节点可用信道集的大小和基于邻居度的转发概率选取中继节点,并对相应中继节点的可用信道集随机左移,在保证一定广播成功率、广播时延和广播冲突率的前提下,降低节点转发率,减少网络中的冗余信息;建立综合评价函数对广播算法的综合性能进行了定量分析;给出广播冲突概率推导。仿真结果表明,该算法与分布式广播协议相比,提高了广播成功率,降低了广播时延;与低延迟广播算法相比,降低了节点转发率和广播冲突概率。根据综合评价函数,该广播算法的综合性能更好。展开更多
认知无线Ad hoc网络(cognitive wireless ad hoc networks)是由一组具有认知决策能力的节点以多跳无线方式组成的智能网络.网络容量的求解与网络吞吐量的优化是该类网络研究的难点.作者首先推导了混叠模式下认知无线Ad hoc网络容量上界...认知无线Ad hoc网络(cognitive wireless ad hoc networks)是由一组具有认知决策能力的节点以多跳无线方式组成的智能网络.网络容量的求解与网络吞吐量的优化是该类网络研究的难点.作者首先推导了混叠模式下认知无线Ad hoc网络容量上界的闭合表达式,并指出该上界只与用户空间分布特性相关;然后提出了一种新的基于遗传算法的跨层优化算法,通过联合优化邻居选择与功率分配实现网络吞吐量的最大化;最后仿真验证了该算法的有效性,结果表明网络吞吐量能较好地逼近网络容量上界.展开更多
文摘Recently the Cognitive Radio (CR), in particular the CR Ad-Hoc Network (CRAHN) technology appears as a burgeoning area in wireless communication that enables utilization of limited network resources in more efficient and intelligent way;studies indicate that opportunistic utilization of the available radio frequency spectrum, without interfering the licensed primary user (PU) could be made. This paper presents some simulation based performance of the Multi-Channel Hidden Terminal (MCHT) problem on CRAHNs;new observations on the effect of the number of channels on certain PU-activity metrics, e.g., delay and throughput, are described.
基金This work was supported by the National Natural Science Foundations of China （Grant No. 61201143）, the Fundamental Research Fund for the Central Universities （Grant No. HIT. NSRIF. 2010091）, the National Science Foundation for Post-doctoral Scientists of China （Grant No. 2012M510956）, and the Post-doc- toral Fund of Heilongjiang Province （GrantNo. LBHZ11128）.
文摘In this paper,we study cross-layer scheduling scheme on multimedia application which considers both streaming traffic and data traffic over cognitive ad hoc networks.A cross-layer design is proposed to optimize SU's utility,which is used as an approach to balance the transmission efficiency and heterogeneous traffic in cognitive ad hoc networks.A framework is provided for utility-based optimal subcarrier assignment,power allocation strategy and corresponding modulation scheme,subject to the interference threshold to primary user(PU) and total transmit power constraint.Bayesian learning is adopted in subcarrier allocation strategy to avoid collision and alleviate the burden of information exchange on limited common control channel(CCC).In addition,the M/G/l queuing model is also introduced to analyze the expected delay of streaming traffic.Numerical results are given to demonstrate that the proposed scheme significantly reduces the blocking probability and outperforms the mentioned single-channel dynamic resource scheduling by almost 8%in term of system utility.
基金This work was supported in part by the Research Fund for the Doctoral Program of Higher Education of China under Grant 20122304130002,the Natural Science Foundation in China under Grant 61370212,the Fundamental Research Fund for the Central Universities under Grant HEUCFZ1213 and HEUCF100601
文摘In Cognitive radio ad hoc networks （CRAHNs）, the secondary users （SUs） or cognitive radio nodes （CRs） are always equipped with limited energy and have a high error probability of data transmission. To address this issue, we first describe the network utility under energy constraint as a max-min model, where the re-transmission strategy with network coding is employed. Additionally, the expression of retransmission probability is presented in terms of power and bit error rate （BER）. Moreover, since the max-min model is non-convex in both objective and constraints, we use a normal- form game to find a near-optimal solution. The simulation results show that the proposed approach could achieve a higher network utility than the compared approaches.
文摘One critical issue for routing in cognitive radio ad hoc networks (CRAHNs) is how to select a reliable path for forwarding traffic. This is because mobility may cause radio links to break frequently. The reliability of a path depends on the availability of those links that constitutes the path. In this letter, we present a novel approach to predict the probability of the availability of the link between two cognitive radio nodes. The prediction is achieved by estimating the link activation and spectrum activation probabilities. Our prediction is verified by simulation and proved to be accurate. This study can provide reliability assurance on dynamic routing for cognitive radio ad hoc networks.
文摘We study the problem of frequency and power allocation and scheduling at a time-slotted cognitive ad-hoc wireless network, where cognitive nodes share a number of frequency bands and frequency reuse is allowed. In such a network the throughput maximization problem generally results in a mixed zero-one nonlinear non-convex problem. Interestingly, in the low-SINR regime, the power allocation policy that maximizes the total throughput follows an “on/off” strategy with maximum power usage in the “on” state. In this paper we show that the on/off strategy in the low-SINR regime is also optimal with respect to throughput when scheduling users over time and frequency subject to minimum SINR requirements. We show that these additional constraints will not change the optimum strategy, but may affect the set of “on” or “off” transmitters. Also we present an approach that transforms the mixed zero-one nonlinear problem to an equivalent mixed zero-one linear problem at the expense of extra variables.
文摘针对避免广播冲突的CR Ad Hoc网络的分布式广播协议广播成功率低和基于选择性广播信道集的低延迟广播算法广播冲突率高的问题,提出基于中继节点选择的多跳CR Ad Hoc网络广播算法。根据节点可用信道集的大小和基于邻居度的转发概率选取中继节点,并对相应中继节点的可用信道集随机左移,在保证一定广播成功率、广播时延和广播冲突率的前提下,降低节点转发率,减少网络中的冗余信息;建立综合评价函数对广播算法的综合性能进行了定量分析;给出广播冲突概率推导。仿真结果表明,该算法与分布式广播协议相比,提高了广播成功率,降低了广播时延;与低延迟广播算法相比,降低了节点转发率和广播冲突概率。根据综合评价函数,该广播算法的综合性能更好。
文摘认知无线Ad hoc网络(cognitive wireless ad hoc networks)是由一组具有认知决策能力的节点以多跳无线方式组成的智能网络.网络容量的求解与网络吞吐量的优化是该类网络研究的难点.作者首先推导了混叠模式下认知无线Ad hoc网络容量上界的闭合表达式,并指出该上界只与用户空间分布特性相关;然后提出了一种新的基于遗传算法的跨层优化算法,通过联合优化邻居选择与功率分配实现网络吞吐量的最大化;最后仿真验证了该算法的有效性,结果表明网络吞吐量能较好地逼近网络容量上界.
