Transmission Policies for Time Varying Channels with Average Delay Constraints
Transmission Policies for Time Varying Channels with Average Delay Constraints
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发表时间：
1999
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通讯作者：
B. Collins;R. Cruz
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作者：
B. Collins;R. Cruz
本文考虑在一个特性随时间变化的离散时间信道上传输具有固定可靠性的数据的问题，该信道的平均时延受数据的约束，峰值发射功率受约束。我们假设，信道状态是已知的发射机在每个时隙的开始，并寻求传输策略，最大限度地减少发射机所消耗的平均功率。使用一个动态规划公式加上一个对偶参数，我们发现，良好的传输策略一般会采取行动，根据有多少数据排队在发射机，以及根据信道状态。特别地，如果积压非常大，则即使信道处于“坏”状态，发射机也应该使用该信道，并且如果积压非常小，则发射机应该仅在信道处于“好”状态时使用该信道。然而，我们发现，相对于最大可容忍的平均延迟的信道中的变化的时间尺度是一个至关重要的因素，在uencing的最优传输策略的定性特征。
We consider the problem of transferring data with a xed level of reliability over a discrete time channel whose characteristics vary with time, with a constraint on the average delay su ered by the data and a constraint on peak transmitter power. We assume that the channel state is known to the transmitter at the beginning of each slot, and seek transmission policies that minimize the average power expended by the transmitter. Using a dynamic programming formulation coupled with a duality argument, we nd that good transmission policies will in general take action in accordance with how much data is queued at the transmitter, as well as in accordance with the channel state. In particular, if the backlog is su ciently large the transmitter should use the channel even if it is in a \bad" state, and if the backlog is su ciently small the transmitter should only use the channel when it is in a \good" state. However, we nd that the time scale of the variations in the channel relative the maximum tolerable average delay is a crucial factor in uencing the qualitative features of the optimal transmission policy.