Credit-based slot allocation for multimedia mobile ad hoc networks

This paper studies resource management for multimedia mobile ad hoc networks (MANET). In particular, we focus on providing fair scheduling with quality-of-service (QoS) support for MANET. We consider two types of flows: guaranteed and best effort flows. The goal is to satisfy the QoS requirements of guaranteed flows and to provide global fairness for best effort flows. In this paper, a credit-based fair scheduling mechanism called credit-based slot allocation protocol (CSAP) is proposed. In CSAP, nodes are logically grouped into clusters, each with a scheduler. Each scheduler assigns time slots to nodes in its cluster based on the first tier algorithm. The node scheduled to send at the next time slot then in turn assigns the time slot to a relayed flow determined by the second-tier algorithm. Each multihop flow is treated as multiple single-hop flow segments. These segments are then correlated such that a downstream segment will not be allocated a slot unless the upstream segments have all been allocated. We evaluate the performance of CSAP by simulations. The results show that CSAP meets the QoS requirements of guaranteed flows, provides global fairness for best effort flows, and improves overall system throughput.     

任务迁移的移动边缘计算系统中资源分配和任务卸载策略

针对在任务卸载时由于设备的移动而导致任务迁移这一问题,将任务卸载过程建模为马尔科夫决策过程,并通过优化资源分配和任务卸载策略,解决基于联合时延和能耗的损耗函数最小的优化问题。首先将问题转化为最小化损耗函数之和,并在决策前对每个任务的传输功率采用二分法进行优化,然后基于获得的传输功率提出一种QLBA（Q-learning Based Algorithm）来完成卸载决策。仿真结果证实所提方案优于传统算法。     

面向MANET环境的动态自适应副本放置算法研究

移动自组网环境给数据复制技术带来了新的挑战。本文提出了一种分布式动态自适应副本放置算法,算法以数据访问的通信开销作为目标函数,每个副本节点从其邻居节点收集读写请求的局部信息,动态地调整副本放置方案以适应访问请求和网络拓扑的变化。本文还提出了基于稳定邻居的副本放置算法以减小由于节点移动给副本放置带来的振荡。模拟实验表明,在移动自组网环境中,本文提出的算法有效地减少了数据访问的通信开销,提高了数据访问的效率。     

Joint optimization of energy and delay for computation offloading in cloudlet-assisted mobile cloud computing

Wireless Networks - In the mobile cloud computing (MCC), although offloading requests to the distant central cloud or nearby cloudlet can reduce energy consumption at the mobile devices (MDs), it...     

Deep reinforcement learning-based joint task offloading and bandwidth allocation for multi-user mobile edge computing

The rapid growth of mobile internet services has yielded a variety of computation-intensive applications such as virtual/augmented reality. Mobile Edge Computing (MEC), which enables mobile terminals to offload computation tasks to servers located at the edge of the cellular networks, has been considered as an efficient approach to relieve the heavy computational burdens and realize an efficient computation offloading. Driven by the consequent requirement for proper resource allocations for computation offloading via MEC, in this paper, we propose a Deep-Q Network (DQN) based task offloading and resource allocation algorithm for the MEC. Specifically, we consider a MEC system in which every mobile terminal has multiple tasks offloaded to the edge server and design a joint task offloading decision and bandwidth allocation optimization to minimize the overall offloading cost in terms of energy cost, computation cost, and delay cost. Although the proposed optimization problem is a mixed integer nonlinear programming in nature, we exploit an emerging DQN technique to solve it. Extensive numerical results show that our proposed DQN-based approach can achieve the near-optimal performance.     

Future trust management framework for mobile ad hoc networks [security in mobile ad hoc]

In mobile ad hoc networks nodes should collaborate with each other to support the functions of the network. The trust management framework, which evaluates the trust of participating nodes, is used to force nodes to cooperate in a normal way. We make an effort to design a robust and attack-resistant trust management framework for the future. In this article we describe the vulnerabilities of and possible attacks on existing frameworks. An objective trust management framework is proposed to overcome these vulnerabilities. We provide a theoretical basis and skeleton for this framework. The performance evaluation and security analysis are provided showing the effectiveness and robustness of the OTMF compared with existing frameworks.     

Distributed game theoretic approach for offloading in ad hoc cloud

An ad hoc mobile cloud had been proposed to offload workload to neighboring mobile devices for resource sharing.The issues that whether to offload or not was addressed,how to select the suitable mobile device to offload,and how to assign workload.Game theoretic approach was used to formulate this problem,and then,a distributed scheme was designed to achieve the optimal solution.The experimental results validate the rightness and effectiveness of proposed scheme.     

Distributed resource allocation with fairness for cognitive radios in wireless mobile ad hoc networks

Both spectrum sensing and power allocation have crucial effects on the performance of wireless cognitive ad hoc networks. In order to obtain the optimal available subcarrier sets and transmission powers, we propose in this paper a distributed resource allocation framework for cognitive ad hoc networks using the orthogonal frequency division multiple access (OFDMA) modulation. This framework integrates together the constraints of quality of service (QoS), maximum powers, and minimum rates. The fairness of resource allocation is guaranteed by introducing into the link capacity expression the probability that a subcarrier is occupied. An incremental subgradient approach is applied to solve the optimization problems that maximize the weighted sum capacities of all links without or with fairness constraints. Distributed subcarrier selection and power allocation algorithms are presented explicitly. Simulations confirm that the approach converges to the optimal solution faster than the ordinary subgradient method and demonstrate the effects of the key parameters on the system performance. It has been observed that the algorithms proposed in our paper outperform the existing ones in terms of the throughput and number of secondary links admitted and the fairness of resource allocation.     

Contention-based forwarding for mobile ad hoc networks

Existing position-based unicast routing algorithms which forward packets in the geographic direction of the destination require that the forwarding node knows the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages each node sends out periodically.

Due to mobility, the information that a node receives about its neighbors becomes outdated, leading either to a significant decrease in the packet delivery rate or to a steep increase in load on the wireless channel as node mobility increases. In this paper, we propose a mechanism to perform position-based unicast forwarding without the help of beacons. In our contention-based forwarding scheme (CBF) the next hop is selected through a distributed contention process based on the actual positions of all current neighbors. For the contention process, CBF makes use of biased timers. To avoid packet duplication, the first node that is selected suppresses the selection of further nodes. We propose three suppression strategies which vary with respect to forwarding efficiency and suppression characteristics. We analyze the behavior of CBF with all three suppression strategies and compare it to an existing greedy position-based routing approach by means of simulation with ns-2. Our results show that CBF significantly reduces the load on the wireless channel required to achieve a specific delivery rate compared to the load a beacon-based greedy forwarding strategy generates.     

Scalable routing protocols for mobile ad hoc networks

The growing interest in mobile ad hoc network techniques has resulted in many routing protocol proposals. Scalability issues in ad hoc networks are attracting increasing attention these days. We survey the routing protocols that address scalability. The routing protocols included in the survey fall into three categories: flat routing protocols; hierarchical routing approaches; GPS augmented geographical routing schemes. The article compares the scalability properties and operational features of the protocols and discusses challenges in future routing protocol designs     

Rethinking information theory for mobile ad hoc networks

The subject of this article is the long standing open problem of developing a general capacity theory for wireless networks, particularly a theory capable of describing the fundamental performance limits of mobile ad hoc networks. A MANET is a peer-to-peer network with no preexisting infrastructure. MANETs are the most general wireless networks, with single-hop, relay, interference, mesh, and star networks comprising special cases. The lack of a MANET capacity theory has stunted the development and commercialization of many types of wireless networks, including emergency, military, sensor, and community mesh networks. Information theory, which has been vital for links and centralized networks, has not been successfully applied to decentralized wireless networks. Even if this was accomplished, for such a theory to truly characterize the limits of deployed MANETs it must overcome three key roadblocks. First, most current capacity results rely on the allowance of unbounded delay and reliability. Second, spatial and timescale decompositions have not yet been developed for optimally modeling the spatial and temporal dynamics of wireless networks. Third, a useful network capacity theory must integrate rather than ignore the important role of overhead messaging and feedback. This article describes some of the shifts in thinking that may be needed to overcome these roadblocks and develop a more general theory.     

Self-organized public-key management for mobile ad hoc networks

In contrast with conventional networks, mobile ad hoc networks usually do not provide online access to trusted authorities or to centralized servers, and they exhibit frequent partitioning due to link and node failures and to node mobility. For these reasons, traditional security solutions that require online trusted authorities or certificate repositories are not well-suited for securing ad hoc networks. We propose a fully self-organized public-key management system that allows users to generate their public-private key pairs, to issue certificates, and to perform authentication regardless of the network partitions and without any centralized services. Furthermore, our approach does not require any trusted authority, not even in the system initialization phase.     

Capacity and delay tradeoffs for ad hoc mobile networks

We consider the throughput/delay tradeoffs for scheduling data transmissions in a mobile ad hoc network. To reduce delays in the network, each user sends redundant packets along multiple paths to the destination. Assuming the network has a cell partitioned structure and users move according to a simplified independent and identically distributed (i.i.d.) mobility model, we compute the exact network capacity and the exact end-to-end queueing delay when no redundancy is used. The capacity-achieving algorithm is a modified version of the Grossglauser-Tse two-hop relay algorithm and provides O(N) delay (where N is the number of users). We then show that redundancy cannot increase capacity, but can significantly improve delay. The following necessary tradeoff is established: delay/rate/spl ges/O(N). Two protocols that use redundancy and operate near the boundary of this curve are developed, with delays of O(/spl radic/N) and O(log(N)), respectively. Networks with non-i.i.d. mobility are also considered and shown through simulation to closely match the performance of i.i.d. systems in the O(/spl radic/N) delay regime.     

A mobility measure for mobile ad hoc networks

A mobility measure for mobile ad hoc networks is proposed that is flexible because one can customize the definition of mobility using a remoteness function. The proposed measure is consistent because it has a linear relationship to the rate at which links are established or broken for a wide range of mobility scenarios, where a scenario consists of the choice of mobility model, the physical dimensions of the network, the number of nodes. This consistency is the strength of the proposed mobility measure because the mobility measure reliably represents the link change rate regardless of network scenarios.     

Spanning-tree based autoconfiguration for mobile ad hoc networks

In order to allow truly spontaneous and infrastructureless networking, autoconfiguration algorithm is needed in the practical usage of most mobile ad hoc networks (MANETs). This paper presents spanning-tree based autoconfiguration for mobile ad hoc networks, a novel approach for the efficient distributed address autoconfiguration. With the help of the spanning tree, the proposed scheme attempts to distribute address resources as balanced as possible at the first beginning. Since each node holds a block of free addresses, a newly joining node can obtain a free address almost immediately. Subnet partitioning and merging are well supported. Finally, analysis and simulation demonstrate that our algorithm outperforms the existing approaches in terms of both communication overhead and configuration latency.     

ATCP: TCP for mobile ad hoc networks

Transport connections set up in wireless ad hoc networks are plagued by problems such as high bit error rates, frequent route changes, and partitions. If we run the transmission control protocol (TCP) over such connections, the throughput of the connection is observed to be extremely poor because TCP treats lost or delayed acknowledgments as congestion. We present an approach where we implement a thin layer between Internet protocol and standard TCP that corrects these problems and maintains high end-to-end TCP throughput. We have implemented our protocol in FreeBSD, and we present results from extensive experimentation done in an ad hoc network. We show that our solution improves the TCP's throughput by a factor of 2-3     

Energy-efficient location services for mobile ad hoc networks

Location-based routing protocols are stateless since they rely on position information in forwarding decisions. However, their efficiency depends on performance of location services which provide the position information of the desired destination node. Several location service schemes have been proposed, but the most promising among them, hierarchical hashing-based protocols, rely on intuitive design in the published solutions. In this paper, we provide full analysis of the efficiency of routing in hierarchical hashing-based protocols as a function of the placement of the routers. Based on the theoretical analysis of the gain and costs of the query and reply routing, we propose a novel location service protocol that optimizes the distance traveled by the location update and query packets and, thus, reduces the overall energy cost. These gains are further increased in the second presented protocol by the optimal location of servers that we established through analysis of geometrical relationships between nodes and location servers. Simulation results demonstrate that the proposed protocols achieve around 30–35% energy efficiency while improving or maintaining the query success rate in comparison to the previously proposed algorithms.     

Stable routing algorithm for mobile ad hoc networks using mobile agent

Wireless ad hoc networks are growing important because of their mobility, versatility, and ability to work with fewer infrastructures. The mobile ad hoc network is an autonomous system consisting of mobile nodes connected with wireless links. Establishing a path between two nodes is a complex task in wireless networks. It is still more complex in the wireless mobile ad hoc network because every node is no longer as an end node and an intermediate node. In this paper, it focuses on design of connectionless routing protocol for the wireless ad hoc networks based on the mobile agent concept. The proposed model tries to discover the best path taking into consideration some concerns like bandwidth, reliability, and congestion of the link. The proposed model has been simulated and tested under various wireless ad hoc network environments with the help of a different number of nodes. The results demonstrate that the proposed model is more feasible for providing reliable paths between the source and destination with the minimum control message packets over the network. It has delivered more number of packets to the destination over the network. Copyright © 2012 John Wiley & Sons, Ltd.