Elsevier

Information Sciences

Volume 283, 1 November 2014, Pages 79-93
Information Sciences

On the throughput-energy tradeoff for data transmission between cloud and mobile devices

https://doi.org/10.1016/j.ins.2014.06.022Get rights and content

Abstract

Mobile cloud computing has recently emerged as a new computing paradigm promising to improve the capabilities of resource-constrained mobile devices. As the data processing and storage are moved from mobile devices to powerful cloud platforms, data transmission has become an important issue affecting user experiences of mobile applications. One of the challenges is how to optimize the tradeoff between system throughput and energy consumption, which are potentially conflicting objectives. Inspired by the feasibility of transmission scheduling for prefetching-friendly or delay-tolerant applications, we mathematically formulate this problem as a stochastic optimization problem, and design an online control algorithm to balance such an energy-performance tradeoff based on the Lyapunov optimization framework. Our algorithm is able to independently and simultaneously make control decisions on admission and transmission to maximize a joint utility of the average application throughput and energy cost, without requiring any statistical information of traffic arrivals and link bandwidth. Rigorous analysis and extensive simulations have demonstrated both the system stability and the utility optimality achieved by our control algorithm.

Introduction

Mobile devices, such as smartphone, PDA, and tablet-PC, are gradually becoming an important part of human life as the most convenient communication tools unbounded by time and space. However, mobile devices are facing severe challenges in resources (e.g., computation, storage and energy) and communications (e.g., bandwidth and mobility), which greatly impede the improvement of user experiences. In recent years, the paradigm of mobile cloud computing has been introduced to extend capabilities of mobile devices, by taking advantage of high-speed wireless communications and high-performance cloud platforms [7], [21] to help gather, store and process data for the mobile devices [22], [14]. In this new paradigm, the cloud-based mobile applications usually require frequent data exchanges between mobile devices and cloud platforms [44]. With the surging popularity of mobile cloud computing, it has been found that traffic from mobile devices grows three times faster than that from wired devices, and will exceed the latter by year 2016 [8]. Unlike wired devices, current mobile devices and their daily use are seriously constrained by the energy capacity of batteries [23], [17]. Hence, the data transmission strategy for mobile devices has to take into account not only providing sufficient system throughput to satisfy application requirements, but also conserving precious battery energy to prolong operational lifetime.

This paper explores such a throughput-energy trade-off for prefetching-friendly or delay-tolerant applications on mobile devices having multiple types of network interfaces. To support pervasive Internet access, current mobile devices are increasingly being equipped with more than one wireless interfaces [9], such as WiFi, 3G-HSDPA, and 4G-LTE [3], [13], that have substantially different characteristics. Firstly, the availability of these types of networks can vary significantly at different places [32], [35]. At least as of now, the coverage and penetration capabilities of 3G and 4G are much higher than those of WiFi. Secondly, the achievable data rates of these interfaces can vary considerably over time, and are sometimes far less than the nominal values specified by the technical standards [13], [35]. For example, it is reported in [13] that the downlink bandwidth measured in U.S. range from 0.35Mbps to 19.27 Mbps for 802.11g WiFi (up to 54 Mbps), and from 2.08 Mbps to 30.80 Mbps for LTE (up to 100 Mbps). Thirdly, the energy costs for transmitting a given amount of data over these wireless interfaces could differ by an order of magnitude [13], [30]. It has been revealed by empirical studies in [13] that the radio power level has a linear relationship with link transmission bandwidth, while the power coefficients are distinct for different types of interfaces. Based on above-mentioned reasons, the selection of available wireless interfaces for data transmission has direct impacts on system throughput and energy consumption of mobile devices.

Fortunately, many of the mobile applications are naturally prefetching-friendly or delay-tolerant, to different degrees, so that it is possible to switch among multiple radio interfaces to achieve energy-efficient data transfer. For example, mobile users may rely on the online map service when visiting new places. When they use the mobile client to request online maps, the cloud could pre-push some potentially useful maps (e.g., historic sites) to the device during periods of good connectivity of a lower-energy link. On the other hand, delay-tolerant applications such as online social networking can be set to fetch the content update at specific intervals. This create opportunities for energy saving by deferring the transmission of the latest data until a satisfactory link connection becomes available. However, one-sided pursuit of energy saving may degrade system throughput and application performance.

To address the challenges above, we propose a new online control algorithm, MOTET, for Mobile device Optimization on the Throughput-Energy Tradeoff using the Lyapunov optimization framework [27]. MOTET maximizes a joint utility of the sum throughput of applications and the energy costs of device, by independently and simultaneously making online decisions to control admission and transmission behaviors [11], [20]. It is associated with two control parameters, i.e., throughput-energy parameter and stability-utility parameter, which can be appropriately tuned to provide a desired performance tradeoff among application throughput, energy cost and service delay. Specifically, a non-negative parameter θ is used to normalize the values of throughput and energy to make them comparable in the utility function. Meanwhile, MONET can obtain a time-average utility within a deviation of O(1/V) from optimality, while bounding the traffic queue length and the traffic service delay by O(V), where V is a non-negative control parameter representing a design knob of the stability-utility tradeoff (i.e., how much we emphasize utility maximization compared to system stability). MOTET operates without requiring any statistical knowledge of traffic arrivals and link conditions, and is computationally efficient for implementing on resource-constrained mobile devices. We thoroughly analyze the performance of our new proposed online control algorithm with rigorous theoretical analysis. To complement the analysis, we conduct a simulation study to evaluate MOTET using datasets from real-world measurements on wireless link bandwidth and transmission energy consumption of mobile devices [13]. Experimental results demonstrate that MOTET can approach a time-average utility that is arbitrarily close to the optimum, while still maintaining strong stability and low congestion. Furthermore, with an appropriate throughput-energy parameter, MOTET can significantly reduce the energy expenditure while only incurring a marginal sacrifice in the system throughput. To our knowledge, prior work has not explored such a tradeoff issue on mobile devices, and our use of the Lyapunov optimization framework for solving this issue is also novel.

The rest of this paper is organized as follows: Section 2 reviews some related work. Section 3 describes the theoretical model for throughput-energy tradeoff, and also formulates the objective problem. Section 4 presents the optimal control algorithm, and Section 5 provides an analysis on performance bounds of our algorithm. Section 6 shows the performance evaluation results. Finally, Section 7 concludes the paper.

Section snippets

Related work

The contribution of our work lies in the intersection of the following two important cutting-edge research topics.

Basic throughput-energy tradeoff model

As shown in Fig. 1, we consider a mobile device user who has M heterogeneous applications m{0,1,2,,M} running on a cloud platform [34]. The whole system operates in discrete time with unit time slots t{0,1,2,}. The data (i.e., content) generated by each application is processed in a corresponding queue, denoted as Q(t)(Q1(t),,QM(t)), in which Qm(t) represents the queue backlog of application m’s data to be transmitted from the cloud to the mobile device at the beginning of time slot t. In

Problem transformation

To solve problem (6), we need to transform it to a solvable form. The Lyapunov optimization framework has provided the “auxiliary variables” to transform the problem into a new one involves only time averages rather than functions of time averages, and hence can be solved by the drift-plus-penalty framework [27]. Since the utility function g(rm) is concave and non-linear, we introduce auxiliary variables γm for each admitted traffic stream Rm(t),m{1,,M}, as follows:maxm=1Mg(γm)-θps.t.γmrm,

Algorithm analysis

In this section, we analyze the performance bound of our MOTET algorithm.

Theorem 2

(Algorithm Performance) Implementing the MOTET algorithm in every time slot for any fixed control parameter V0, yields the following performance bounds:(1) The worst case queue backlog for each queue Qm is upper bounded by a finite constant Qmmax for all t:Qm(t)QmmaxV+2Ammax(2) Assuming FIFO service, and Qm(t)Qmmax,Zm(t)Zmmax for all t{0,1,2,}. Then, the worst-case delay for data in Qm is upper bounded by the

Performance evaluation

In this section, we evaluate the proposed MOTET algorithm using datasets from real-world measurements on wireless link bandwidth and transmission energy consumption of mobile devices.

Conclusion

To reduce energy consumption for cloud-based mobile applications and prolong operational lifetime for energy-constrained mobile devices, we design and analyze an optimal online control algorithm, MOTET, to balance the tradeoff between the system throughput and the energy consumption in mobile cloud scenarios. By applying rigorous Lyapunov optimization framework, MOTET is able to independently and simultaneously make the control decisions on traffic admission and data transmission for the mobile

Acknowledgment

We would like to thank Dr. Junxian Huang (University of Michigan) for providing us the UMICH dataset from 4GTest measurement [13]. We are also grateful to Dr. Yunlu Liu (China Mobile Research Institute) for useful discussions. This work was supported by the National Natural Science Foundation of China under Grants 61202430 and 61303245, the State Key Lab of Astronautical Dynamics of China under Grant 2014ADL-DW0401, and the Science and Technology Foundation of Beijing Jiaotong University under

References (44)

  • AT&T, AT&T high speed internet access, AT&T Inc., 2013....
  • N. Balasubramanian, A. Balasubramanian, A. Venkataramani, Energy consumption in mobile phones: a measurement study and...
  • A. Chakraborty, S. Das, Adapp: an adaptive network selection framework for smartphone applications, in: Proceeding of...
  • Cisco, Cisco visual networking index: forecast and methodology, 2012–2017, Cisco Systems Inc., 2013....
  • Y. Guo et al.

    Optimal power management of residential customers in the smart grid

    IEEE Trans. Parallel Distrib. Syst.

    (2012)
  • F. Gustavo et al.

    Qos-oriented admission control in hsdpa networks

    Netw. Protocols Algor.

    (2009)
  • I.-H. Hou, P.R. Kumar, Utility-optimal scheduling in time-varying wireless networks with delay constraints, in:...
  • J. Huang, F. Qian, A. Gerber, Z.M. Mao, S. Sen, O. Spatscheck, A close examination of performance and power...
  • K. Kumar et al.

    A survey of computation offloading for mobile systems

    Mob. Netw. Appl.

    (2013)
  • H.A. Lagar-Cavilla, K. Joshi, A. Varshavsky, J. Bickford, D. Parra, Traffic backfilling: subsidizing lunch for...
  • K. Lee et al.

    Mobile data offloading: how much can wifi deliver?

    IEEE/ACM Trans. Netw.

    (2013)
  • F. Liu et al.

    Gearing resource-poor mobile devices with powerful clouds: architectures, challenges, and applications

    IEEE Wireless Commun.

    (2013)
  • Cited by (77)

    • Meta-analytical comparison of energy consumed by two sorting algorithms

      2022, Information Sciences
      Citation Excerpt :

      In the same manner, information accessed and processed by mobile phones has dramatically increased over the years. This dramatic growth unfortunately call for an increased power supply or alternatively highly optimised energy efficient algorithms [16]. Sorting algorithms are used to arrange elements in a specific order [17].

    • Design and analysis of a decision intelligent system based on enzymatic numerical technology

      2021, Information Sciences
      Citation Excerpt :

      Hence, enzymatic numerical P systems (ENPSs) were proposed as membrane computing systems in which enzyme-like variables allow the existence of different production functions for each membrane and let the P system be more flexible in calculating [13,14]. Although an ENPS is powerful in different applications [9], it still cannot form an effective theory to support the decisional evolution process [15,16], because its attributes and mechanisms are mainly designed to handle the numerical values. In many studies, decisional theory has shown its importance [17,18] and we want to combine membrane computing with decisional theory.

    View all citing articles on Scopus
    View full text