Optimal channel probing and transmission scheduling for opportunistic spectrum access

Optimal channel probing and transmission scheduling for opportunistic spectrum access
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DOI：
10.1145/1287853.1287858
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发表时间：
2007-09
期刊：
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影响因子：
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通讯作者：
N. Chang;M. Liu
N. Chang;M. Liu
中科院分区：
其他
文献类型：
--
作者：
N. Chang;M. Liu

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在这项研究中，我们认为最佳的机会频谱接入（OSA）政策的发射机在多信道无线系统中，其中一个信道可以在多个国家之一。每个信道状态与传输成功的概率或传输速率相关联。在这样的系统中，发射机通常具有关于信道状态的部分信息，但是可以通过探测各个信道（例如，通过在信道中发送控制分组）来推断出更多信息，这是以某些资源为代价的，例如，能量和时间。这项工作的主要目标是获得最佳的策略，以确定哪些通道探测（在什么顺序），并使用哪个通道进行传输。在此背景下，我们考虑两个问题，所有的常数数据时间（CDT）和常数访问时间（CAT）的问题。对于这两个问题，我们推导出相应最优策略的关键结构性质。特别是，我们表明，它有一个阈值结构，可以描述的索引政策。我们进一步表明，最佳的CDT策略只能采取三种结构形式之一。利用这些结果，我们提出了一个两步前瞻CDT（CAT）的战略。这种策略被证明是最佳的一些情况下的实际利益。我们研究其性能下的一类实际的信道模型，通过数值研究。
In this study we consider optimal opportunistic spectrum access (OSA) policies for a transmitter in a multichannel wireless system, where a channel can be in one of multiple states. Each channel state is associated with either a probability of transmission success or a transmission rate. In such systems, the transmitter typically has partial information concerning the channel states, but can deduce more by probing individual channels, e.g. by sending control packets in the channels, at the expense of certain resources, e.g., energy and time. The main goal of this work is to derive optimal strategies for determining which channels to probe (in what sequence) and which channel to use for transmission. We consider two problems within this context,allthe constant data time (CDT) and the constant access time (CAT) problems. For both problems, we derive key structural properties of the corresponding optimal strategy. In particular, we show that it has a threshold structure and can be described by an index policy. We further show that the optimal CDT strategy can only take on one of three structural forms. Using these results we present a two-step lookahead CDT (CAT) strategy. This strategy is shown to be optimal for a number of cases of practical interest. We examine its performance under a class of practical channel models via numerical studies.