Characterizing Energy–Delay Tradeoff in Hyper-Cellular Networks With Base Station Sleeping Control
Characterizing Energy–Delay Tradeoff in Hyper-Cellular Networks With Base Station Sleeping Control
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DOI：
10.1109/jsac.2015.2393494
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发表时间：
2015-01
影响因子：
16.4
通讯作者：
Z. Niu;Xueying Guo;Sheng Zhou;P. Kumar
中科院分区：
文献类型：
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作者：
Z. Niu;Xueying Guo;Sheng Zhou;P. Kumar
基站休眠是蜂窝网络节能的有效途径之一，但它可能会给用户带来较长的时延。于是就出现了一个根本问题：在一个可容忍的延迟时间内，可以消耗多少能量？在本文中，我们描述了基本的权衡之间的总能量消耗和总延迟的BS与睡眠模式操作的睡眠模型。这里，BS总能耗不仅包括发射功率，还包括基本功率（用于基带处理、功率放大器等）。以及BS工作模式的切换功率，总时延不仅包括传输时延，还包括切换时延。具体地说，BS被建模为M/G/1休假队列的建立和关闭时间，其中BS进入睡眠模式，如果没有客户到达关闭（滞后）时间后，队列变空。当睡眠时，BS保持在睡眠模式，直到在睡眠时段期间队列建立到N个客户（N-Policy）。通过改变关闭时间、建立时间和参数N，得到了不同唤醒策略下的能量消耗和平均延迟之间的折衷关系。结果表明，系统能耗与平均延迟之间的关系与平均关闭时间成线性关系，与N成非线性关系。从理论上分析了不同服务速率下总功耗和平均时延之间的显式关系，指出牺牲时延并不总是能换取能量节省。换句话说，较大的N可能导致较低的能量消耗，但存在最优N*，其同时最小化平均延迟和能量消耗。我们还研究了特定服务百分比的最大延迟（延迟界限），并发现在测试的情况下，延迟界限与平均延迟几乎呈线性关系。因此，在能量消耗和延迟界限之间存在类似的权衡。总之，封闭形式的能量延迟权衡对设计BS休眠和唤醒控制策略有启发，该策略旨在节省能量同时保持可接受的服务质量。
Base station (BS) sleeping operation is one of the effective ways to save energy consumption of cellular networks, but it may lead to longer delay to the customers. The fundamental question then arises: How much energy can be traded off by a tolerable delay? In this paper, we characterize the fundamental tradeoffs between total energy consumption and overall delay in a BS with sleep mode operations by queueing models. Here, the BS total energy consumption includes not only the transmitting power but also basic power (for baseband processing, power amplifier, etc.) and switch-over power of the BS working mode, and the overall delay includes not only transmission delay but also queueing delay. Specifically, the BS is modeled as an M/G/1 vacation queue with setup and close-down times, where the BS enters sleep mode if no customers arrive during the close-down (hysteretic) time after the queue becomes empty. When asleep, the BS stays in sleep mode until the queue builds up to N customers during the sleep period ( N-Policy) . Several closed-form formulas are derived to demonstrate the tradeoffs between the energy consumption and the mean delay for different wake-up policies by changing the close-down time, setup time, and the parameter N. It is shown that the relationship between the energy consumption and the mean delay is linear in terms of mean close-down time, but non-linear in terms of N. The explicit relationship between total power consumption and average delay with varying service rate is also analyzed theoretically, indicating that sacrificing delay cannot always be traded off for energy saving. In other words, larger N may lead to lower energy consumption, but there exists an optimal N* that minimizes the mean delay and energy consumption at the same time. We also investigate the maximum delay (delay bound) for certain percentage of service and find that the delay bound is nearly linear in mean delay in the cases tested. Therefore, similar tradeoffs exist between energy consumption and the delay bound. In summary, the closed-form energy-delay tradeoffs cast light on designing BS sleeping and wake-up control policies that aim to save energy while maintaining acceptable quality of service.