认知OFDM系统中基于能耗受限的频谱感知方法

针对传统频谱感知方法没有考虑能耗受限对认知系统的影响,以认知正交频分复用(OFDM)系统为背景,提出一种基于能耗受限的联合优化频谱感知方法。该方法基于传统能量检测方法,以最大化吞吐量性能为目标,将频谱感知问题建模为一个优化问题,联合多个频带选取最优感知时间和判决门限参数,使其在能耗受限的情况下,总吞吐量达到最大。仿真结果表明,与传统使用能耗均分的检测方法相比,该方法具有更大的吞吐量,能够更好地节约能耗。     

能量受限的软件预取优化问题

在移动设备和嵌入式设备中,能量的供给是十分有限的,它受限于能量供给设备的容量和节电能力的大小.在能量受限的环境下,电池所提供的能量不足以使系统达到最优的性能目标.因此,提出了一种能量受限环境下最优化预取性能的方法.该方法通过软件控制的手段,能在有限的能量供给条件下达到最优的性能.该方法是基于动态频率可调的CPU和存储器的.根据CPU和存储器的忙闲情况,通过插入频率调节指令,指导调节CPU和存储器的频率,使得预取优化的两个性能指标(一是时间,二是处理器收益)在一定的能量约束条件下达到最优.对该问题建立了详细的模型及模拟环境,并通过一组以数组访问为主的测试程序验证了该方法的有效性.模拟结果表明,该方法对能量受限预取优化问题是有效的.     

Energy-constrained ferry route design for sparse wireless sensor networks

In recent years, using message ferries as mechanical carriers of data has been shown to be an effective way to collect information in sparse wireless sensor networks. As the sensors are far away from each other in such highly partitioned scenario, a message ferry needs to travel a long route to access all the sensors and carry the data collected from the sensors to the sink. Typically, practical constraints （e.g., the energy） preclude a ferry from visiting all sensors in a single tour. In such case, the ferry can only access part of the sensors in each tour and move back to the sink to get the energy refilled. So, the energy-constrained ferry route design （ECFRD） problem is discussed, which leads to the optimization problem of minimizing the total route length of the ferry, while keeping the route length of each tour below a given constraint. The ECFRD problem is proved to be NP-hard problem, and the integer linear programming （ILP） formulation is given. After that, efficient heuristic algorithms are proposed to solve this problem. The experimental results show that the performances of the proposed algorithms are effective in practice compared to the optimal solution.