Replica Allocation Methods in Ad Hoc Networks with Data Update

In ad hoc networks, since mobile hosts move freely, network division occurs frequently, and thus data accessibility is lower than that in conventional fixed networks. In this paper, assuming an environment where each data item is periodically updated, we propose three replica allocation methods to improve data accessibility by replicating data items on mobile hosts. In these three methods, we take into account the access frequency from mobile hosts to each data item, the status of the network connection, and the time remaining until each item is updated next. We also show the results of simulation experiments regarding the performance evaluation of our proposed methods. We further extend the proposed methods to adapt to an environment where aperiodic data updates occur.     

Preference-aware coding data broadcast in delay tolerant networks

Traditional data broadcasting schemes in delay tolerant networks assume that mobile users can only retrieve one data item in each time slot. In this paper, we propose a novel data broadcasting framework in the delay tolerant networks that exploits the concept of network coding to mix the delivered data items according to the user’s stored data items. Our approach enables a user to encode multiple data items dynamically in each time slot, and allows each user with a mobile device to retrieve a data item by using locally stored data items to decode the encoding data. Specifically, we design an algorithm called Preference-Aware Coding (PAC) to select the data items to be encoded in each time slot. The objective is to serve the maximal number of mobile users with the encoding data and minimize the access time required for data broadcasting in the delay tolerant networks. The algorithm avoids encoding unnecessary data in each time slot to reduce the access delay. We empirically implement the framework in the real delay tolerant networks, and simulation results show that the PAC algorithm can reduce the access time of the traditional scheme by 42 % on average.     

Traffic load metrics for multihomed mobile IP and global connectivity

Support for host mobility an essential and necessary feature for roaming users who connect to wireless networks via access points. Access points may have different capabilities, be connected to different networks and be installed by different providers. A mobile host will discover multiple access points in this environment. In such an environment, a mobile host should be able to use the best available connection to communicate with a correspondent host and perhaps use multiple connections for different hosts. In areas with wireless local area network access, pockets with limited or no coverage could exist. Such restricted connectivity could be compensated by neighbor hosts who form an ad hoc network and relay packets until they reach an access point. This paper describes and discusses a proposed solution towards enabling and supporting connectivity in wireless networks. In the proposed solution the network layer software will evaluate and decide which wireless network connections to use. A Running Variance Metric (RVM) and a Relative Network Load(RNL) are used to measure the traffic load of access points in wireless access networks. RVM and RNL can be efficiently used for both infrastructure networks and ad hoc networks. Multihomed Mobile IP (M-MIP) is an extension of Mobile IP that enables mobile hosts to use multiple care-of addresses simultaneously. The extension enhances network connectivity by enabling the mobile host, the home agent and correspondent hosts to evaluate and select the best connection. A proposed gateway architecture using M-MIP that integrates wired IP networks with ad hoc networks is described. The M-MIP and gateway architecture using the RVM and RNL metrics have been validated with simulation studies and results are presented.     

Distributed Mapping Management of Identifiers and Locators in LISP-based Mobile Networks

The Locator Identifier Separation Protocol (LISP) has been proposed as an identifier-locator separation scheme for scalable Internet routing. However, LISP was originally designed in the fixed network environment rather than in the mobile network environment. In particular, the existing LISP mobility schemes are based on a centralized map server that is used as an anchor point for mobile nodes, and thus intrinsically subject to some limitations in mobile environment. In this paper, we propose a distributed mapping management of Endpoint Identifiers (EIDs) and Locators (LOCs) in mobile LISP networks. We use Routing LOC (RLOC) and Local LOC (LLOC) as locators for mobile hosts. RLOC represents the IP address of the domain gateway, and LLOC is the IP address of the access router that a host is currently attached to. For EID-LOC mapping management, each network domain has a Distributed Map Server (DMS) over its gateway. Each DMS keeps track of the EID-LOC mapping information for mobile hosts in the distributed way. The proposed scheme is also a network-based approach, in which each access router, instead of a host, performs the mapping management operations. From the performance analysis, we can see that the proposed distributed scheme can give better performance than the existing schemes in terms of the signaling delays required for EID-LOC mapping update and query operations.     

Data replication protocols for mobile ad-hoc networks: a survey and taxonomy

In mobile ad-hoc networks, frequent network partitioning and the failure of mobile nodes due to exhaustion of their battery power can considerably decrease data availability. In addition, the increase in network size and node mobility cause the performance of data access to degrade. To deal with these issues, a number of data replication protocols have been proposed in the recent years. This paper surveys the existing data replication protocols in mobile ad-hoc networks and proposes a classification scheme that categorizes the protocols into various classes, with respect to the issues they address. Network partitioning, energy consumption, and scalability are the three issues that are identified in this paper, and which have not been previously considered in the fixed networks. The paper also provides a comparison of the protocols and investigates opportunities for future research.     

Optimized D-RAN Aware Data Retrieval for 5G Information Centric Networks

The evolution of wireless network services has enabled consumers and intelligent devices to freely exchange information with each other. Mobile users frequently exchange popular contents, resulting in massive increase in the mobile traffic. The redundant mobile traffic can be reduced by archiving the frequently accessed data within a 5G core network or radio access network, and demands for the same content can be readily met without relying on remote servers. In this paper, we propose an eNB/gNB aware data retrieval algorithm along with Liveliness and Size based data Replacement algorithm to refine, rank, and cache the data items efficiently. Data items are selected based on their popularity and cached in D-RAN for efficient data replacement. We have also included a cost-optimized Radar-Based data Retrieval algorithm that helps to find the data nearness in the neighbouring eNBs. In our proposed technique, unique contents are maintained at each end of the cluster to aid in extending content diversity within the cluster. The experimental analysis shows that the proposed model achieves lower latency, lower congestion, and higher cache hit ratio in 5G networks.

     

Exploiting In-Zone Broadcasts for Cache Sharing in Mobile Ad Hoc Networks

The problem of cache sharing for supporting data access in mobile ad hoc networks is studied in this paper. The key to this problem is to discover a requested data item in an efficient manner. In the paper, we propose two caching protocols, IXP and DPIP, which distinguish themselves from the existing ones in that they fully exploit in-zone broadcasts to facilitate cache sharing operation. In particular, the DPIP protocol offers an implicit index push property, which is highly useful for enhancing cache hit ratio in the neighborhood of a data requester node. Moreover, our protocols also exploit the broadcasts to facilitate the design of a simple but efficient count-based cache replacement scheme. Performance study shows that the proposed protocols can significantly improve the performance of data access in a mobile ad hoc network.     

Data Broadcast with Adaptive Network Coding in Heterogeneous Wireless Networks

In this paper, we propose a new data broadcast mechanism with network coding in heterogeneous wireless networks. Our mechanism adaptively clusters the mobile hosts in fewer cells to minimize the bandwidth consumption. In addition, we adaptively code the data according to the data temporarily stored in each mobile host with a distributed manner. Our mechanism allows each delivered message to be coded from only a subset of data to further reduce the number of required messages. We formulate the cell selection and broadcast coding problem with integer programming and prove that the problem is NP-hard. We design a distributed algorithm based on Lagrangean relaxation. Our algorithm needs no server to record the location, queried, and stored information of receivers. Moreover, our algorithm is adaptive to the dynamic group membership, mobility, queried, and stored data of receivers.     

Data collection in future mobile networks

Future mobile networks will be increasingly heterogeneous. Already today, wireless LAN is used by many mobile network operators as an addition to traditional technologies like GSM and UMTS; WiMax and 3GPP Long Term Evolution (LTE) will be added. Having heterogeneous wireless networks, one challenging research question needs to be answered: Which user should be served by which access network and when to conduct a handover? For such decisions, information on the state of networks and terminals is required. In this publication, we simulate mobile networks in which a central entity called Network Resource Management (N-RM) gives handover recommendations to mobile terminals. Based on these recommendations and local knowledge on link qualities, the terminals choose the cell to switch to. The N-RM should have a global view on the networks to give best recommendations. We designed the Generic Metering Infrastructure (GMI), a publish/subscribe system to collect information about access networks and terminals efficiently. We investigate the tradeoff between the signalling overhead caused by data collection and the quality of the handover decisions and show, how smart monitoring can reduce the amount of measurement data while ensuring the efficient use of heterogeneous networks. In addition, our simulation results show that combined local and central handover decisions significantly increase the capacity of the networks as compared to only local decisions.     

基于Jaccard的移动终端自动识别并行算法及其MapReduce实现

The ability of accurate and scalable mobile device recognition is critically important for mobile network operators and ISPs to understand their customers’ behaviours and enhance their user experience. In this paper, we propose a novel method for mobile device model recognition by using statistical infor-mation derived from large amounts of mobile network traffic data. Specifically, we create a Jaccard-based coefficient measure method to identify a proper keyword representing each mobile device model from massive unstruc-tured textual HTTP access logs. To handle the large amount of traffic data generated from large mobile networks, this method is designed as a set of parallel algorithms, and is imple-mented through the MapReduce framework which is a distributed parallel programming model with proven low-cost and high-efficiency features. Evaluations using real data sets show that our method can accurately recognise mobile client models while meeting the scalability and pro-ducer-independency requirements of large mobile network operators. Results show that a 91.5% accuracy rate is achieved for rec-ognising mobile client models from 2 billion records, which is dramatically higher than existing solutions.     

A Two-Tier Heterogeneous Mobile Ad Hoc Network Architecture and Its Load-Balance Routing Problem

The mobile ad hoc network (MANET) has attracted a lot of interest recently. However, most of the existing works have assumed a stand-alone MANET. In this paper, we propose a two-tier, heterogeneous MANET architecture which can support Internet access. The low tier of the network consists of a set of mobile hosts each equipped with a IEEE 802.11 wireless LAN card. In order to connect to the Internet and handle the network partitioning problem, we propose that the high tier is comprised of a subset of the mobile hosts, called gateways, which can access to cellular/infrastructure networks. The high tier is heterogeneous in the sense that the network interfaces in the gateway hosts could be IEEE 802.11 cards, PHS handsets, or GPRS handsets characterized by different bandwidths and latencies. Observing that the gateways could become the bottlenecks of the two-tier network, we propose a set of solutions, namely boundary-moving, host-partitioning, and probabilistic solutions, to solve the load-balance routing issue. Implementation issues/concerns of these schemes are discussed. Simulation results are presented to compare these load-balance routing schemes.     

An Efficient Multicast Routing Protocol in Wireless Mobile Networks

Providing multicast service to mobile hosts in wireless mobile networking environments is difficult due to frequent changes of mobile host location and group membership. If a conventional multicast routing protocol is used in wireless mobile networks, several problems may be experienced since existing multicast routing protocols assume static hosts when they construct the multicast delivery tree. To overcome the problems, several multicast routing protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, overheads resulting from frequent reconstruction of a multicast tree, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast routing protocol based on IEFT mobile IP in wireless mobile networks. The proposed protocol introduces a multicast agent, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent may start multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases the amount of duplicate copies of multicast datagrams. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals.     

A Random Access Protocol with Multi-Packet Reception for Infrastructure-Less Wireless Autonomic Networks

A random access protocol with multi-packet reception (MPR) capability for infrastructure-less wireless autonomic networks is introduced and analyzed. In these networks mobile nodes may communicate with each other directly without a central entity (base station), where each mobile node either will be in a transmitting mode or in a receiving mode or in an idle mode. The throughput per node and the packet retransmission probability depend exclusively on the MPR capability and the ratio of the transmission probability and the receiving probability of each mobile node. For a given ratio of the transmission probability and the receiving probability of each mobile node, throughput-delay performance increases with the increase of MPR capability. In the proposed infrastructure-less networks, mobile nodes can control the network traffic very precisely by controlling the three parameters. These three parameters are transmission probability, receiving probability and idle mode probability of each mobile node. Since each mobile node can control the network traffic very precisely to obtain the maximum throughput, the network is autonomic, i.e., self-optimizing. The optimum transmission probability of each mobile node to obtain the maximum throughput is evaluated. The throughput utility increases with the increase of MPR capability. On the other hand, the cost per mobile node also increases with the increase of MPR capability. Therefore the MPR capability should be optimized to provide reasonable trade-off between the throughput per node and the cost per mobile node. The results of this study may be used for a system design of an infrastructure-less contention-based multiple access schemes with MPR capability.     

Benefit-Based Data Caching in Ad Hoc Networks

Data caching can significantly improve the efficiency of information access in a wireless ad hoc network by reducing the access latency and bandwidth usage. However, designing efficient distributed caching algorithms is nontrivial when network nodes have limited memory. In this article, we consider the cache placement problem of minimizing total data access cost in ad hoc networks with multiple data items and nodes with limited memory capacity. The above optimization problem is known to be NP-hard. Defining benefit as the reduction in total access cost, we present a polynomial-time centralized approximation algorithm that provably delivers a solution whose benefit is at least 1/4 (1/2 for uniform-size data items) of the optimal benefit. The approximation algorithm is amenable to localized distributed implementation, which is shown via simulations to perform close to the approximation algorithm. Our distributed algorithm naturally extends to networks with mobile nodes. We simulate our distributed algorithm using a network simulator (ns2) and demonstrate that it significantly outperforms another existing caching technique (by Yin and Cao [33]) in all important performance metrics. The performance differential is particularly large in more challenging scenarios such as higher access frequency and smaller memory.     

Mobility support across hybrid IP-based wireless environment: review of concepts, solutions, and related issues

The 4G or Beyond 3G wireless networks is consist of IP-based heterogeneous access networks from 3G cellular, WiFi, WiMAX to other emerging access technologies such as mesh networks. The key objective of designing the next generation wireless networks is to support of mobile subscribers. To support the mobile host in the hybrid wireless access technologies, many solutions based on network protocol stack have been proposed in the literature. In this article, after review of mobility concepts, a special attention is given to some of the mobility management methods as well as handover techniques across various wireless access networks. We have also compared the major mobility protocols in each layer for their features. Finally, some of the open issues that needed to be addressed in mobility management protocol in the next generation wireless networks are outlined.     

On the effect of group mobility to data replication in ad hoc networks

The growth in wireless communication technologies attracts a considerable amount of attention in mobile ad hoc networks. Since mobile hosts in an ad hoc network usually move freely, the topology of the network changes dynamically and disconnection occurs frequently. These characteristics make it likely for a mobile ad hoc network to be separated into several disconnected partitions, and the data accessibility is hence reduced. Several schemes are proposed to alleviate the reduction of data accessibility by replicating data items. However, little research effort was elaborated upon exploiting the group mobility where the group mobility refers to the phenomenon that several mobile nodes tend to move together. In this paper, we address the problem of replica allocation in a mobile ad hoc network by exploring group mobility. We first analyze the group mobility model and derive several theoretical results. In light of these results, we propose a replica allocation scheme to improve the data accessibility. Several experiments are conducted to evaluate the performance of the proposed scheme. The experimental results show that the proposed scheme is able to not only obtain higher data accessibility, but also produce lower network traffic than prior schemes.     

Energy and Spatial Reuse Efficient Network-Wide Real-Time Data Broadcasting in Mobile Ad Hoc Networks

In this paper, we present NB-TRACE, which is an energy-efficient network-wide voice broadcasting architecture for mobile ad hoc networks. In the NB-TRACE architecture, the network is organized into overlapping clusters through a distributed algorithm, where the clusterheads create a nonconnected dominating set. Channel access is regulated through a distributed TDMA scheme maintained by the clusterheads. The first group of packets of a broadcast session is broadcast through flooding, where each data rebroadcast is preceded by an acknowledgment to the upstream node. Nodes that do not get an acknowledgment for a predetermined time, except the clusterheads, cease to rebroadcast, which prunes the redundant retransmissions. The connected dominating set formed through this basic algorithm is broken in time due to node mobility. The network responds to the broken links through multiple mechanisms to ensure the maintenance of the connected dominating set. We compare NB-TRACE with four network layer broadcast routing algorithms (Flooding, Gossiping, Counter-based broadcasting, and Distance-based broadcasting) and three medium access control protocols (IEEE 802.11, SMAC, and MH-TRACE) through extensive ns-2 simulations. Our results show that NB-TRACE outperforms other network/MAC layer combinations in minimizing energy dissipation and optimizing spatial reuse, while producing competitive QoS performance.     

Auction–Stackelberg game framework for access permission in femtocell networks with multiple network operators

With the explosive growth of indoor data traffic in forthcoming fifth generation cellular networks, it is imperative for mobile network operators to improve network coverage and capacity. Femtocells are widely recognized as a promising technology to address these demands. As femtocells are sold or loaned by a mobile network operator (MNO) to its residential or enterprise customers, MNOs usually employ refunding scheme to compensate the femtocell holders (FHs) providing indoor access to other subscribers by configuring the femtocell to operate in open or hybrid access mode. Due to the selfishness nature, competition between network operators as well as femtocell holders makes it challenging for operators to select appropriate FHs for trading access resources. This inspires us to develop an effective refunding framework, with aim to improve overall network resource utilization, through promoting FHs to make reasonable access permission for well-matched macro users. In this paper, we develop a two-stage auction–Stackelberg game (ASGF) framework for access permission in femtocell networks, where MNO and mobile virtual network operator lease access resources from multiple FHs. We first design an auction mechanism to determine the winner femtocell that fulfils the access request of macro users. We next formulate the access permission problem between the winner femtocell and operators as a Stackelberg game, and theoretically prove the existence of unique equilibrium. As a higher system payoff can be gained by improving individual players’ payoff in the game, each player can choose the best response to others’ action by implementing access permission, while avoiding solving a complicated optimization problem. Numerical results validate the effectiveness of our proposed ASGF based refunding framework and the overall network efficiency can be improved significantly.     

Data aggregation in sensor networks using learning automata

One way to reduce energy consumption in wireless sensor networks is to reduce the number of packets being transmitted in the network. As sensor networks are usually deployed with a number of redundant nodes (to overcome the problem of node failures which is common in such networks), many nodes may have almost the same information which can be aggregated in intermediate nodes, and hence reduce the number of transmitted packets. Aggregation ratio is maximized if data packets of all nodes having almost the same information are aggregated together. For this to occur, each node should forward its packets along a path on which maximum number of nodes with almost the same information as the information of the sending node exist. In many real scenarios, such a path has not been remained the same for the overall network lifetime and is changed from time to time. These changes may result from changes occurred in the environment in which the sensor network resides and usually cannot be predicted beforehand. In this paper, a learning automata-based data aggregation method in sensor networks when the environment’s changes cannot be predicted beforehand will be proposed. In the proposed method, each node in the network is equipped with a learning automaton. These learning automata in the network collectively learn the path of aggregation with maximum aggregation ratio for each node for transmitting its packets toward the sink. To evaluate the performance of the proposed method computer simulations have been conducted and the results are compared with the results of three existing methods. The results have shown that the proposed method outperforms all these methods, especially when the environment is highly dynamic.