Adaptive contact probing mechanisms for delay tolerant applications
Adaptive contact probing mechanisms for delay tolerant applications
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DOI：
10.1145/1287853.1287882
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发表时间：
2007-09
期刊：
影响因子：
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通讯作者：
Wen Wang;V. Srinivasan;M. Motani
中科院分区：
文献类型：
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作者：
Wen Wang;V. Srinivasan;M. Motani
在许多延迟容忍应用中，信息在彼此相遇的移动设备之间机会性地交换。为了实现这种信息交换，移动设备必须了解其附近的其他设备。我们考虑没有基础设施且设备必须探测其环境以发现其他设备的情况。这可能是一个非常耗能的过程，并突出了对能量敏感的接触探测机制的需求。如果设备探测非常不频繁，它们可能会错过许多联系人。另一方面，频繁的联系探测可能会降低能源效率。在本文中，我们研究了丢失联系的概率和联系探测频率之间的权衡。首先，通过理论分析，刻画了平稳过程中遗漏接触概率与接触探测间隔之间的权衡关系。其次，对于时变的接触到达率，我们提供了一个优化框架来计算作为到达率的函数的最优接触探测间隔。我们通过蓝牙手机联系记录实验来表征真实世界的联系模式，并表明联系到达过程是自相似的。设计了一种适应接触到达过程的接触探测算法STAR。通过对实验数据的轨迹驱动模拟，我们发现，与恒定接触探测间隔方案相比，STAR的能量消耗减少了三倍。
In many delay tolerant applications, information is opportunistically exchanged between mobile devices who encounter each other. In order to effect such information exchange, mobile devices must have knowledge of other devices in their vicinity. We consider scenarios in which there is no infrastructure and devices must probe their environment to discover other devices. This can be an extremely energy consuming process and highlights the need for energy conscious contact probing mechanisms. If devices probe very infrequently, they might miss many of their contacts. On the other hand, frequent contact probing might be energy inefficient. In this paper, we investigate the trade-off between the probability of missing a contact and the contact probing frequency. First, via theoretical analysis, we characterize the trade-off between the probability of a missed contact and the contact probing interval for stationary processes. Next, for time varying contact arrival rates, we provide an optimization framework to compute the optimal contact probing interval as a function of the arrival rate. We characterize real world contact patterns via Bluetooth phone contact logging experiments and show that the contact arrival process is self-similar. We design STAR, a contact probing algorithm which adapts to the contact arrival process. Via trace driven simulations on our experimental data, we show that STAR consumes three times less energy when compared to a constant contact probing interval scheme.