A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video tra...A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video transmission consisted of a series of shortterm transmissions, the optimization problem in the video transmission was a composite optimization process. Firstly,considering some factors like primary user's( PU's) collision limitations,non-synchronization between SU and PU,and SU's limited buffer size, the short-term optimization problem was formulated as a mixed integer non-linear program( MINLP) to minimize the block probability of video packets. Secondly,combining the minimum packet block probability obtained in shortterm optimization and SU's constraint on hardware complexity,the partially observable Markov decision process( POMDP) framework was proposed to learn PU's statistic information over DCRNs.Moreover,based on the proposed framework,joint optimization strategy was designed to obtain the minimum packet loss rate in long-term video transmission. Numerical simulation results were provided to demonstrate validity of our strategies.展开更多
This paper analyzes fault-tolerance over the entire design life of a class of multiple-hop wireless networks, where cooperative transmission schemes are used. The networks are subject to both node failure and random c...This paper analyzes fault-tolerance over the entire design life of a class of multiple-hop wireless networks, where cooperative transmission schemes are used. The networks are subject to both node failure and random channel fading. A node lifetime distribution is modeled with an increasing failure rate, where the node power consumption level enters the parameters of the distribution. A method for assessing both link and network reliabilities projected at the network's design life is developed. Link reliability is enhanced through use of redundant nodes. The number of redundant nodes is restricted by the cooperative transmission scheme used. The link reliability is then used to establish a re-transmission control policy that minimizes an expected cost involving power, bandwidth expenditures, and packet loss. The benefit and cost of feedback in network operations are examined. The results of a simulation study under specific node processing times are presented. The study quantifies the effect of loop closure frequency, acknowledgment deadline, and nodes' storage capacity on the performance of the network in terms of network lifetime, packet loss rate, and false alarm rate. The study concludes that in a network where energy is severely constrained, feedback must be applied judiciously.展开更多
An improved spectrum-efficient and fair resource scheduling algorithm for multimedia broadcast multicast service(MBMS)in long term evolution(LTE)systems is proposed in this paper.By jointly considering the channel con...An improved spectrum-efficient and fair resource scheduling algorithm for multimedia broadcast multicast service(MBMS)in long term evolution(LTE)systems is proposed in this paper.By jointly considering the channel conditions of all the users,the average packet loss rate,and the fairness of users in the MBMS group,the transmission data rate of the MBMS group is first selected according to the link adaptation and the average packet loss rate of users.Then,the resource blocks are allocated to MBMS groups according to the scheduling priority.Such a resource scheduling algorithm further balances the system throughput and user fairness.Theoretical analysis and simulation results show that the proposed algorithm can achieve a good tradeoff between system throughput and user fairness in comparison with traditional scheduling algorithms.展开更多
In this paper,a utility-based feedback delay-aware and buffer status-aware( FABA) scheduling scheme is proposed for downlink multiuser multiple-input multiple-output orthogonal frequency-division multiple-access( MIMO...In this paper,a utility-based feedback delay-aware and buffer status-aware( FABA) scheduling scheme is proposed for downlink multiuser multiple-input multiple-output orthogonal frequency-division multiple-access( MIMO-OFDMA) systems. The FABA scheme allocates subcarriers to multiusers with an objective of not only maximizing the total system capacity but reducing the system packet loss rate as well. We design a utility function which consists of a feedback estimate module,a proportional fairness module and a buffer monitoring module. The feedback estimate module is used to improve the system throughput by utilizing the Automatic Repeat-reQuest( ARQ) feedback information to combat the fast time-varying fading condition. The proportional fairness module can guarantee the scheduling fairness among users,and the buffer monitoring module can utilize the transmitting buffer status information to avoid high packet loss rate of the system caused by the system congestion. The FABA scheme then formulates the scheduling problem into a problem of overall system utility maximization. We solve the problem by using a heuristic algorithm with low computational complexity. The simulation results show that the proposed FABA scheme outperforms the existing algorithms in terms of the system throughput and the packet loss rate and can also guarantee the fairness demand among users.展开更多
A dynamic network Qo S control mechanism was proposed based on traffic prediction. It first predicts network traffic flow and then dynamically distributes network resources, which makes full use of network flow self-s...A dynamic network Qo S control mechanism was proposed based on traffic prediction. It first predicts network traffic flow and then dynamically distributes network resources, which makes full use of network flow self-similarity and chaos. So it can meet changing network needs very well. The simulation results show that the dynamic Qo S control mechanism based on prediction has better network performance than that based on measurement.展开更多
Wireless sensor network(WSN)nodes exchange information via wireless signals,whose power can attenuate at different levels according to the propagation environment.The branches and leaves of young apple trees are much ...Wireless sensor network(WSN)nodes exchange information via wireless signals,whose power can attenuate at different levels according to the propagation environment.The branches and leaves of young apple trees are much sparser than that of adult apple trees.Propagation rules such as propagation distance and attenuation rate are the parameters necessary to know before applying a WSN to a young apple orchard.Field tests were performed,and propagation distance and packet loss rate(PLR)were computed and compared under the two cases:a young apple orchard in fruit period and an open space to find the effect of the apple trees on radio propagation.A model of antenna height and propagation distance was created to forecast the extra path loss caused by the young trees.Validation experiments were performed in a different young apple orchard,and the validation results showed that 70% of R^(2) were higher than 0.7,while the smallest being 0.65;80% RMSE were smaller than 5.The new model was also compared with some classical models such as Cost 235,FITU,ITU-R,and Weissberger model,and the new model was proved to be the best.展开更多
How to reduce interference among neighbor nodes in wireless mesh networks is still an important and key issue nowa- days. In this paper, an optimized channel assignment algorithm (OCA) is proposed to solve this prob...How to reduce interference among neighbor nodes in wireless mesh networks is still an important and key issue nowa- days. In this paper, an optimized channel assignment algorithm (OCA) is proposed to solve this problem based on link throughput and node priority. The effects of the numbers of network interface cards and channels on the network throughput are analyzed and evaluated, When there are seven of the numbers of both network interface cards and channels, the efficiency of utilizing network interface card and channel reaches highest. Compared with cen- tralized channel assignment algorithm (CCA), the proposed algo- rithm has less packet loss rate and more network throughput sig- nificantly.展开更多
基金National Natural Science Foundation of China(No.61301101)
文摘A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video transmission consisted of a series of shortterm transmissions, the optimization problem in the video transmission was a composite optimization process. Firstly,considering some factors like primary user's( PU's) collision limitations,non-synchronization between SU and PU,and SU's limited buffer size, the short-term optimization problem was formulated as a mixed integer non-linear program( MINLP) to minimize the block probability of video packets. Secondly,combining the minimum packet block probability obtained in shortterm optimization and SU's constraint on hardware complexity,the partially observable Markov decision process( POMDP) framework was proposed to learn PU's statistic information over DCRNs.Moreover,based on the proposed framework,joint optimization strategy was designed to obtain the minimum packet loss rate in long-term video transmission. Numerical simulation results were provided to demonstrate validity of our strategies.
基金This work was partly supported by the US AFOSR (No. FA9550-06-0456 and FA9550-06-10249).
文摘This paper analyzes fault-tolerance over the entire design life of a class of multiple-hop wireless networks, where cooperative transmission schemes are used. The networks are subject to both node failure and random channel fading. A node lifetime distribution is modeled with an increasing failure rate, where the node power consumption level enters the parameters of the distribution. A method for assessing both link and network reliabilities projected at the network's design life is developed. Link reliability is enhanced through use of redundant nodes. The number of redundant nodes is restricted by the cooperative transmission scheme used. The link reliability is then used to establish a re-transmission control policy that minimizes an expected cost involving power, bandwidth expenditures, and packet loss. The benefit and cost of feedback in network operations are examined. The results of a simulation study under specific node processing times are presented. The study quantifies the effect of loop closure frequency, acknowledgment deadline, and nodes' storage capacity on the performance of the network in terms of network lifetime, packet loss rate, and false alarm rate. The study concludes that in a network where energy is severely constrained, feedback must be applied judiciously.
文摘An improved spectrum-efficient and fair resource scheduling algorithm for multimedia broadcast multicast service(MBMS)in long term evolution(LTE)systems is proposed in this paper.By jointly considering the channel conditions of all the users,the average packet loss rate,and the fairness of users in the MBMS group,the transmission data rate of the MBMS group is first selected according to the link adaptation and the average packet loss rate of users.Then,the resource blocks are allocated to MBMS groups according to the scheduling priority.Such a resource scheduling algorithm further balances the system throughput and user fairness.Theoretical analysis and simulation results show that the proposed algorithm can achieve a good tradeoff between system throughput and user fairness in comparison with traditional scheduling algorithms.
基金Sponsored by the National High Technology Research and Development Program of China(863 Program)(Grant No.2012AA01A508)the National Natural Science Funds of China for Young Scholar(Grant No.61302080)the Central Universities Research and Innovation Program of China for Young Scholar(Grant No.2013RC0112)
文摘In this paper,a utility-based feedback delay-aware and buffer status-aware( FABA) scheduling scheme is proposed for downlink multiuser multiple-input multiple-output orthogonal frequency-division multiple-access( MIMO-OFDMA) systems. The FABA scheme allocates subcarriers to multiusers with an objective of not only maximizing the total system capacity but reducing the system packet loss rate as well. We design a utility function which consists of a feedback estimate module,a proportional fairness module and a buffer monitoring module. The feedback estimate module is used to improve the system throughput by utilizing the Automatic Repeat-reQuest( ARQ) feedback information to combat the fast time-varying fading condition. The proportional fairness module can guarantee the scheduling fairness among users,and the buffer monitoring module can utilize the transmitting buffer status information to avoid high packet loss rate of the system caused by the system congestion. The FABA scheme then formulates the scheduling problem into a problem of overall system utility maximization. We solve the problem by using a heuristic algorithm with low computational complexity. The simulation results show that the proposed FABA scheme outperforms the existing algorithms in terms of the system throughput and the packet loss rate and can also guarantee the fairness demand among users.
基金Funded by the National Natural Science Foundation of China(No.41301084)the Scientific Research Project of Hunan Province Education Department,China(No.13C713)the Natural Science Foundation of Hunan Province,China(No.13JJ6075)
文摘A dynamic network Qo S control mechanism was proposed based on traffic prediction. It first predicts network traffic flow and then dynamically distributes network resources, which makes full use of network flow self-similarity and chaos. So it can meet changing network needs very well. The simulation results show that the dynamic Qo S control mechanism based on prediction has better network performance than that based on measurement.
基金financially supported by the National High Technology and Development Program of China(863):Model-based digital management platform for orchard and rape plants(2013AA102405).
文摘Wireless sensor network(WSN)nodes exchange information via wireless signals,whose power can attenuate at different levels according to the propagation environment.The branches and leaves of young apple trees are much sparser than that of adult apple trees.Propagation rules such as propagation distance and attenuation rate are the parameters necessary to know before applying a WSN to a young apple orchard.Field tests were performed,and propagation distance and packet loss rate(PLR)were computed and compared under the two cases:a young apple orchard in fruit period and an open space to find the effect of the apple trees on radio propagation.A model of antenna height and propagation distance was created to forecast the extra path loss caused by the young trees.Validation experiments were performed in a different young apple orchard,and the validation results showed that 70% of R^(2) were higher than 0.7,while the smallest being 0.65;80% RMSE were smaller than 5.The new model was also compared with some classical models such as Cost 235,FITU,ITU-R,and Weissberger model,and the new model was proved to be the best.
基金Supported by the Scientific Research Fund of Liaoning Province(L2013433)
文摘How to reduce interference among neighbor nodes in wireless mesh networks is still an important and key issue nowa- days. In this paper, an optimized channel assignment algorithm (OCA) is proposed to solve this problem based on link throughput and node priority. The effects of the numbers of network interface cards and channels on the network throughput are analyzed and evaluated, When there are seven of the numbers of both network interface cards and channels, the efficiency of utilizing network interface card and channel reaches highest. Compared with cen- tralized channel assignment algorithm (CCA), the proposed algo- rithm has less packet loss rate and more network throughput sig- nificantly.