In order to mitigate the interference for macrocell users caused by deploying femtocells （home base-station） in a long term evolution （LTE） system, a hybrid spectrum access model is proposed by means of applying t...In order to mitigate the interference for macrocell users caused by deploying femtocells （home base-station） in a long term evolution （LTE） system, a hybrid spectrum access model is proposed by means of applying the cognitive radio technology to the femtocell. The femtocell periodically senses the radio environment and opportunistically accesses the usable frequency band so that the frequency spectrum resource is used intelligently. The sensing process is performed in two stages, which are principal sensing in the downlink and assisted sensing in the uplink, respectively. Based on the information obtained from the sensing results, the frequency spectrum can be used flexibly in underlay or overlay modes in the femtocell. Simulation results show that by using the proposed model, the throughput of a femtocell is greatly improved with tolerable interference to macrocell users.展开更多
为了实现超密集网络中的绿色通信,提出一种基于能效最优的资源分配算法。首先,在考虑用户服务质量(quality of service,QoS)需求和干扰容限的情况下,建立最大化网络能效的优化问题。其次,为了降低求解原问题的计算复杂度,采用柯西不等...为了实现超密集网络中的绿色通信,提出一种基于能效最优的资源分配算法。首先,在考虑用户服务质量(quality of service,QoS)需求和干扰容限的情况下,建立最大化网络能效的优化问题。其次,为了降低求解原问题的计算复杂度,采用柯西不等式将原优化问题进行松弛,从而转化为非合作博弈问题。进而,在满足最大最小公平(max-min fairness,MMF)准则的情况下,提出一种分布式能效最优算法(distributed EE maximization algorithm,DEMA)。仿真结果表明,所提算法较传统算法可以更好地兼顾系统的能效和吞吐量性能。展开更多
For wireless sensor networks, a simple and accurate coordinate-free k-coverage hole detection scheme is proposed. First, an algorithm is presented to detect boundary cycles of 1-coverage holes. The algorithm consists ...For wireless sensor networks, a simple and accurate coordinate-free k-coverage hole detection scheme is proposed. First, an algorithm is presented to detect boundary cycles of 1-coverage holes. The algorithm consists of two components, named boundary edge detection and boundary cycle detection. Then, the 1-coverage hole detection algorithm is extended to k-coverage hole scenarios. A coverage degree reduction scheme is proposed to find an independent covering set of nodes in the covered region of the target field and to reduce the coverage degree by one through sleeping those nodes. Repeat the 1-coverage hole detection algorithm and the higher order of coverage holes can be found. By iterating the above steps for k-1 times, the boundary edges and boundary cycles of all k-coverage holes can be discovered. Finally, the proposed algorithm is compared with a location-based coverage hole detection algorithm. Simulation results indicate that the proposed algorithm can accurately detect over 99% coverage holes.展开更多
基金The National Science and Technology Major Project(No.2012ZX03004005-003)the National Natural Science Foundation of China(No.61171081,61201175)the Innovation Technology Fund of Jiangsu Province(No.BC2012006)
文摘In order to mitigate the interference for macrocell users caused by deploying femtocells （home base-station） in a long term evolution （LTE） system, a hybrid spectrum access model is proposed by means of applying the cognitive radio technology to the femtocell. The femtocell periodically senses the radio environment and opportunistically accesses the usable frequency band so that the frequency spectrum resource is used intelligently. The sensing process is performed in two stages, which are principal sensing in the downlink and assisted sensing in the uplink, respectively. Based on the information obtained from the sensing results, the frequency spectrum can be used flexibly in underlay or overlay modes in the femtocell. Simulation results show that by using the proposed model, the throughput of a femtocell is greatly improved with tolerable interference to macrocell users.
文摘为了实现超密集网络中的绿色通信,提出一种基于能效最优的资源分配算法。首先,在考虑用户服务质量(quality of service,QoS)需求和干扰容限的情况下,建立最大化网络能效的优化问题。其次,为了降低求解原问题的计算复杂度,采用柯西不等式将原优化问题进行松弛,从而转化为非合作博弈问题。进而,在满足最大最小公平(max-min fairness,MMF)准则的情况下,提出一种分布式能效最优算法(distributed EE maximization algorithm,DEMA)。仿真结果表明,所提算法较传统算法可以更好地兼顾系统的能效和吞吐量性能。
基金The National Natural Science Foundation of China(No.61601122,61471164,61741102)
文摘For wireless sensor networks, a simple and accurate coordinate-free k-coverage hole detection scheme is proposed. First, an algorithm is presented to detect boundary cycles of 1-coverage holes. The algorithm consists of two components, named boundary edge detection and boundary cycle detection. Then, the 1-coverage hole detection algorithm is extended to k-coverage hole scenarios. A coverage degree reduction scheme is proposed to find an independent covering set of nodes in the covered region of the target field and to reduce the coverage degree by one through sleeping those nodes. Repeat the 1-coverage hole detection algorithm and the higher order of coverage holes can be found. By iterating the above steps for k-1 times, the boundary edges and boundary cycles of all k-coverage holes can be discovered. Finally, the proposed algorithm is compared with a location-based coverage hole detection algorithm. Simulation results indicate that the proposed algorithm can accurately detect over 99% coverage holes.
