OKRA: optimal task and resource allocation for energy minimization in mobile edge computing systems

To cope with the computational and energy constraints of mobile devices, Mobile Edge Computing (MEC) has recently emerged as a new paradigm that provides IT and cloud-computing services at mobile network edge in close proximity to mobile devices. This paper investigates the energy consumption problem for mobile devices in a multi-user MEC system with different types of computation tasks, random task arrivals, and unpredictable channel conditions. By jointly considering computation task scheduling, CPU frequency scaling, transmit power allocation and subcarrier bandwidth assignment, we formulate it as a stochastic optimization problem aiming at minimizing the power consumption of mobile devices and to maintain the long-term stability of task queues. By leveraging the Lyapunov optimization technique, we propose an online control algorithm (OKRA) to solve the formulation. We prove that this algorithm is able to provide deterministic worst-case latency guarantee for latency-sensitive computation tasks, and balance a desirable tradeoff between power consumption and system stability by appropriately tuning the control parameter. Extensive simulations are carried out to verify the theoretical analysis, and illustrate the impacts of critical parameters to algorithm performance.

     

A Survey of Green Mobile Networks: Opportunities and Challenges

The explosive development of Information and Communication Technology (ICT) has significantly enlarged both the energy demands and the CO ₂ emissions, and consequently contributes to make the energy crisis and global warming problems worse. However, as the main force of the ICT field, the mobile networks, are currently focusing on the capacity, variety and stability of the communication services, without paying too much severe concerns on the energy efficiency. The escalating energy costs and environmental concerns have already created an urgent need for more energy-efficient “green” wireless communications. In this paper, we survey and discuss various remarkable techniques toward green mobile networks to date, mainly targeting mobile cellular networks. We also summarize the current research projects related to green mobile networks, along with the taxonomy of energy-efficiency metrics. We finally discuss and elaborate future research opportunities and design challenges for green mobile networks.     

EcoPlan: energy-efficient downlink and uplink data transmission in mobile cloud computing

Mobile cloud computing (MC2) is emerging as a new computing paradigm that seeks to augment resource-constrained mobile devices for executing computing- and/or data-intensive mobile applications. Nonetheless, the energy-poverty nature of mobile devices has become a stumbling block that greatly impedes the practical application of MC2. Fortunately, for delay-tolerant mobile applications, energy conservation is achievable via two means: (1) dynamic selection of energy-efficient links (e.g., WiFi interface); and (2) deferring data transmission in bad connectivity. In this paper, we study the problem of energy-efficient downlink and uplink data transmission between mobile devices and clouds. In the presence of unpredictable data arrival, network availability and link quality, our objective is to minimize the time average energy consumption of a mobile device while ensuring the stability of both device-end and cloud-end queues. To achieve this goal, we propose an online control framework named EcoPlan under which mobile users can make flexible link selection and data transmission scheduling decisions to achieve arbitrary energy-delay tradeoffs. Real-world trace-driven simulations demonstrate the effectiveness of EcoPlan, along with its superior energy-efficiency over alternative WiFi-prioritized, minimum-delay and SALSA schemes.     

Energy Optimisation for Mobile Device Power Consumption: A Survey and a Unified View of Modelling for a Comprehensive Network Simulation

The need for the analysis of energy consumption has become greater due to the constrained resources of mobile devices afforded by the increased usage of mobile devices and the environmental footprint of large-scale, distributed systems. Energy usage has previously been modelled for a variety of use cases in order to optimise its consumption, through both simulation and real-world use. As computing devices become ubiquitous, more mobile, and highly varied in their components and use; the networks which interconnect them have become highly dynamic in tandem. This is partly due to the mobility of devices and the constantly fluctuating resource requirements. Whilst simulation of energy consumption within networks has been conducted for specific use cases (e.g. Cloud and wireless networks), it is often not examined from a unified view. This paper attempts to review the state-of-the-art in network energy consumption, modelling, and simulation from the perspective of heterogeneous networks but with a focus upon mobile devices, and then propose a gap in which a unified view is needed. Such views will assist in understanding more about the complex relationships between varied, synergistic device types, such as those which compose mobile cloud networks.     

移动通信电源系统可靠性提升策略

随着移动通信技术的快速发展,移动通信电源的功能也得到了不断的创新和完善,当前的移动通信电源系统已经具备了较好的安全性和稳定性,但随着移动通信用户要求的不断提高,和移动通信业务的快速发展,移动通信电源系统的可靠性得到了更为广泛的重视,如何通过技术手段或管理手段实现移动通信电源系统可靠性的提升,已经成为广大技术人员所关注的重要课题。本文在介绍移通信电源系统构成的基础上,对其可靠性的内涵进行了阐述,并就如何通过合理的技术与管理手段来提升移动通信电源系统可靠性提出了一些可行的方法,以供参考。     

LIDAR: a protocol for stable and energy-efficient clustering of ad-hoc multihop networks

Clustering has been proposed as a promising method for simplifying the routing process in mobile ad hoc networks (MANETs). The main objective in clustering is to identify suitable node representatives, i.e. cluster heads (CHs) to store routing and topology information; CHs should be elected so as to maximize clusters stability, that is to prevent frequent cluster re-structuring. Since CHs are engaged on packet forwarding they are prone to rapidly drop their energy supplies, hence, another important objective of clustering is to prevent such node failures. Recently proposed clustering algorithms either suggest CH election based on node IDs (nodes with locally lowest ID value become CHs) or take into account additional metrics (such as energy and mobility) and optimize initial clustering. Yet, the former method is biased against nodes with low IDs (which are likely to serve as CHs for long periods and therefore run the risk of rapid battery exhaustion). Similarly, in the latter method, in many situations (e.g. in relatively static topologies) re-clustering procedure is hardly ever invoked; hence initially elected CHs soon suffer from energy drainage. Herein, we propose LIDAR, a novel clustering method which represents a major improvement over alternative clustering algorithms: node IDs are periodically re-assigned so that nodes with low mobility rate and high energy capacity are assigned low ID values and, therefore, are likely to serve as CHs. Therefore, LIDAR achieves stable cluster formations and balanced distribution of energy consumption over mobile nodes. Our protocol also greatly reduces control traffic volume of existing algorithms during clustering maintenance phase, while not risking the energy availability of CHs. Simulation results demonstrate the efficiency, scalability and stability of our protocol against alternative approaches.     

Trust-Aware Fuzzy Evaluation Method for Preventive Route Generation in Mobile Network

The existence of a non-cooperative or black hole node as an intermediate node in a mobile network can degrade the performance of the network and affects the trust of neighbor nodes. In this paper, a trust-aware routing protocol is defined for improving the routing reliability against black hole attacks. A new Trust aware and fuzzy regulated AODV (TFAODV) protocol is investigated in this work as an improvement over the existing AODV protocol. The session-driven evaluation of stability, communication-delay, and failure-ratio parameters are conducted for evaluating the trust of nodes. The fuzzy rules apply to these parameters for computing the degree of trust. This trust vector isolates the attack-suspected and trustful nodes. The proposed TFAODV protocol used the trustful mobile nodes as the intermediate path nodes. The proposed protocol has been experimented with in the NS2 simulation environment. The analytical results are obtained in terms of PDR ratio, Packet Communication, Loss rate parameters. The comparative results are derived against the AODV, Probabilistic AODV, PDS-AODV, PSAODV, and Juneja et al. protocols. The analysis is performed on different scenarios varied in terms of network density, degree of stability, and the number of attackers. The simulation results ensured the proposed TFAODV protocol has improved the PDR ratio and reduced the communication loss significantly against these state-of-art protocols.

     

On the Trade-Off between Energy and Multicast Efficiency in 802.16e-Like Mobile Networks

In this paper, we define a new problem that has not been addressed in the past: the trade-off between energy efficiency and throughput for multicast services in 802.16e or similar mobile networks. In such networks, the mobile host can reduce its energy consumption by entering the sleep mode when it is not supposed to receive or transmit information. For unicast applications, the tradeoff between delay and energy efficiency has been extensively researched. However, for mobile hosts running multicast (usually push- based) applications, it is much more difficult to determine when data should be transmitted by the base station and when each host should enter the sleep mode. In order to maximize the channel throughput while limiting the energy consumption, a group of hosts needing similar data items should be active during the same time intervals. We define this as an optimization problem and present several algorithms for it. We show that the most efficient solution is the one that employs cross-layer optimization by dividing the hosts into groups according to the quality of their downlink physical (PHY) channels.     

一种自组网功率控制算法及分析

无线自组网中的移动节点大多依靠电池提供能量,因此能量是影响无线自组网性能的一个很大的瓶颈,作为事实上的无线自组网媒体接入协议,802.11并没有动态调整传输功率的能力,大大限制了网络的生存时间。采用功率控制可以提高节点的功率使用效率,减少相邻节点间的干扰,改善网络的性能。在802.11基础上提出一种基于信噪比的动态传输功率控制算法。通过进行计算机仿真,与802.11协议相比,在保持吞吐量性能的前提下,大大减少了节点的功率消耗,提高了节点的能量利用率。     

Power Consumption Based Simulation Model for Mobile Ad-hoc Network

Mobile ad-hoc network has limited battery power. Power consumption control is the main issue in mobile ad-hoc network. Node battery power is a precious resource that should be used in order to avoid the early termination of nodes. Energy management model and power consumption control flow chart is proposed to control power consumption by reducing data transmit time in mobile ad-hoc network. Simulation model has been used to analysis the energy consumption of a node. This has been achieved by estimating the time spent in transmission of data by node. The proposed model has been simulated using OMNET \(++\) simulator. Simulation results show significant energy savings after applying the proposed model and flow chart.     

A Novel Modelling Technique for Tracing Mobile Users in a Cellular Mobile Communication System

Mobility of users in a cellular mobile communication system has been formulated mathematically under generalized conditions. Based on this model a computer simulation has been developed. This mobility model is used to examine cell residence time distribution in cellular environments defined by different cell sizes and mobility parameters. It is shown that cell residence time can be described by the generalized gamma distribution.     

Decentralized and energy‐balanced algorithms for maintaining temporal full‐coverage in mobile WSNs

Coverage is one of the most important issues in Wireless Sensor Networks (WSNs). However, full coverage only can be achieved when surplus mobile sensors contribute a coverage area larger than the hole size. When there is no surplus mobile sensor to cover a big hole, previous studies have utilized mobile sensors by moving the hole from one location to another, therefore achieving temporal full‐coverage, where each location on the monitoring region has been ever covered by mobile sensors during a fixed time interval. However, with only some mobile sensors participating in the hole‐movement task, this results in an energy‐imbalance WSN. This paper considers a mobile WSN that contains a big hole where there exists no redundant mobile sensor to heal the hole. Three distributed algorithms, called Basic, Forward‐Only, and Any‐Direction movement mechanisms, are proposed to achieve the purpose of temporal full‐coverage in a way that the total energy consumption is minimized or that the energy consumption of all mobile sensors that participate in the hole‐movement task are balanced. Simulation results reveal that the proposed hole‐movement mechanisms enhance the coverage of WSNs and balance the energy consumption of mobile sensor nodes. Copyright © 2010 John Wiley & Sons, Ltd.     

移动Sink传感网中基于IEEE 802.15.4的拓扑控制与路由

针对查询驱动的移动Sink无线传感器网络,基于IEEE 802.15.4标准,提出了一个联合簇树组网和移动路由的跨层协议设计方案。以能耗、网络连通度、负载均衡和子树深度等指标为评价因子,在多目标优化模型下定义了一个拓扑综合评价函数,构建稳定的最优簇树网络结构;改进了IEEE 802.15.4 MAC中基于信标帧调度的分布式睡眠同步算法,维护较低占空比下的网络同步与拓扑修正;利用拓扑形成过程中依"最早信标帧"、"最好链路"、"最小层次"3种准则确立的父子关系,建立移动Sink与N-Hop范围内节点的双向路由路径。最终将上述MAC层的拓扑控制方案与网络层的查询路由方法完整实现于TinyOS协议栈中。实验结果表明,评价函数能够有效地反映组网质量,N-Hop后验式路由结合睡眠同步机制,在"最好链路"拓扑下表现出较高的能量效率。     

Evaluation of energy efficiency of fifth generation mobile systems

There has been active research worldwide to develop the next generation, i.e., fifth generation, wireless network. Next generation mobile communication networks are broadening their spectrum to higher frequency bands (above 6 GHz) to support a high data rate up to multigigabits per second. This work examines how to substantially improve energy efficiency for next fifth generation mobile communication systems. It is depicted how by limited exchange of information between neighboring base stations it is possible to maintain quality of service, over a range of traffic loads, while enabling inactive base stations to sleep. Performance of distributed energy efficient topology management schemes are compared against the system without topology management. Performance evaluation is examined using both analytical and simulation based models. Extensive numerical results show that the schemes deliver a significant energy reduction in energy consumption in the mobile network systems.     

A Survey of Energy Efficient Network Protocols for Wireless Networks

Wireless networking has witnessed an explosion of interest from consumers in recent years for its applications in mobile and personal communications. As wireless networks become an integral component of the modern communication infrastructure, energy efficiency will be an important design consideration due to the limited battery life of mobile terminals. Power conservation techniques are commonly used in the hardware design of such systems. Since the network interface is a significant consumer of power, considerable research has been devoted to low-power design of the entire network protocol stack of wireless networks in an effort to enhance energy efficiency. This paper presents a comprehensive summary of recent work addressing energy efficient and low-power design within all layers of the wireless network protocol stack.     

移动互联网业务对基站能耗的影响

快速发展的移动互联网业务,为运营商带来了诸多挑战,业务特性与网络能耗之间的映射关系尚属空白。为了准确评估业务对网络资源的影响以及网络设备由此产生的能耗,深入物理层资源粒度,提出一种改进的“二次线性映射”模型及四步建模思路,同时选取了11种典型业务场景,定量评估数据、信令分别消耗的网络资源和能耗大小,便于业务能耗的精细化管理和运营管控,为降低端到端资源开销和业务能耗打下基础。     

A bandwidth allocation and energy-optimal transmission rate scheduling scheme in multi-services wireless networks

The energy-saving of mobile devices during their application offloading process has always been the research hotspot in the field of mobile cloud computing (MCC). In this paper, we focus on the scenario where multiple mobile devices with MCC and non-MCC services coexist. A bandwidth allocation and the corresponding transmission rate scheduling schemes are proposed with the objectives of simultaneously maximizing the overall system throughput and minimizing the energy consumption of individual mobile device with MCC service. To allocate the bandwidth to all mobile devices, two different algorithms are proposed, i.e., 0–1 integer programming algorithm and Lagrange dual algorithm. The transmission rate scheduling scheme for mobile device with MCC service is presented based on reverse order iteration method. The numerical results suggest that energy consumed by individual mobile device with MCC service can be remarkably saved while the overall system throughput can also be maximized. Moreover, the results show that 0–1 integer programming algorithm can get greater system throughput but has higher computational complexity, which means the algorithm is more suitable for small-scale systems, whereas Lagrange dual algorithm can achieve a good balance between the performance and computational complexity.     

Performance evaluation of packet aggregation scheme for VoIP service in wireless multi-hop network

In a wireless multi-hop network environment, energy consumption of mobile nodes is an important factor for the performance evaluation of network life-time. In Voice over IP (VoIP) service, the redundant data size of a VoIP packet such as TCP/IP headers is much larger than the voice data size of a VoIP packet. Such an inefficient structure of VoIP packet causes heavy energy waste in mobile nodes. In order to alleviate the effect of VoIP packet transmission on energy consumption, a packet aggregation algorithm that transmits one large VoIP packet by combining multiple small VoIP packets has been studied. However, when excessively many VoIP packets are combined, it may cause deterioration of the QoS of VoIP service, especially for end-to-end delay. In this paper, we analyze the effect of the packet aggregation algorithm on both VoIP service quality and the energy consumption of mobile nodes in a wireless multi-hop environment. We build the cost function that describes the degree of trade-off between the QoS of VoIP services and the energy consumption of a mobile node. By using this cost function, we get the optimum number of VoIP packets to be combined in the packet aggregation scheme under various wireless channel conditions. We expect this study to contribute to providing guidance on balancing the QoS of VoIP service and energy consumption of a mobile node when the packet aggregation algorithm is applied to VoIP service in a wireless multi-hop networks.     

FUCEM: futuristic cooperation evaluation model using Markov process for evaluating node reliability and link stability in mobile ad hoc network

The cooperation between the nodes is one of the potential factor for successful routing in mobile ad hoc networks. The non-cooperative behaviour of the node disturbs the routing as well as degrades network performances. The non-cooperativeness is due to the resource constraint characteristics of a mobile node. The battery energy is an important constraint of a node because it exhausts after some period. On the other side, the mobility of nodes also affects routing performances. Hence, this work concentrates on evaluating cooperation of a node by probing future node energy and mobility. This paper proposes a futuristic cooperation evaluation model (FUCEM) for evaluating node reliability and link stability to establish effective routing. The FUCEM model examines influencing factors of cooperation and state transition of nodes using Markov process. Node reliability and link stability manipulated through the Markov process. The Markov process helps in fixing the upper and lower bounds of the cooperation and calculates the cooperation factor. The NS2 simulator simulates the proposed work and evaluates performance results with different scenarios. The result indicates that the proposed FUCEM has 13–21% higher packet delivery ratio than other algorithms. The remaining energy of the nodes increases to 6–7% as compared with the existing algorithms in a higher mobility scenario. Further, it significantly improves the results of routing overhead and average end-to-end delay than the existing models.

     

Future Cooperative Communication Systems Driven by Social Mobile Networks

In this work we are underlining the importance of social mobile networks for upcoming cooperative communication systems. The assumption of this work is that future mobile communication systems will incorporate user cooperation, i.e. a combination of cellular access in parallel with ongoing short range links to the neighboring devices. It has been shown that user cooperation enables higher data rates, better spectral efficiencies, and reduces the energy consumption of the mobile unit. In this work the social mobile networks are identified to be a fertile ground to facilitate the cooperative use cases. By the example of the Gedda-Headz gaming community, possible links between cooperative mobile communication and social mobile networks are shown.