QoS provisioning for multiple non‐real‐time services in cellular wireless networks

Future mobile services are expected to include various non‐voice oriented services. One important category of non‐voice oriented mobile services is non‐real‐time services. When a mobile user establishes a connection to access non‐real‐time service, the mobile user usually cares about whether the total time to complete its data transfer is within its time tolerance. In addition, different mobile users may have different bandwidth requirements and different tolerances in the total completion time. It is essential for wireless systems to provide various mobile users with different total completion times. In this paper, two quality‐of‐service (QoS) metrics, called stretch ratio and eligibility percentage, are employed at a connection level to present the degree of the length of the total completion time. We devise a measurement based call admission control scheme that provides multiple QoSs for various mobile users which have different requirements of stretch ratios, eligibility percentages, and bandwidths. Extensive simulation results show that the measurement based call admission control scheme not only provides various satisfactory QoSs for mobile users but also produces high throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

Towards generalized ID‐based user authentication for mobile multi‐server environment

With the popularity of Internet and wireless networks, more and more network architectures are used in multi‐server environment, in which mobile users remotely access servers through open networks. In the past, many schemes have been proposed to solve the issue of user authentication for multi‐server environment and low‐power mobile devices. However, most of these schemes have suffered from many attacks because these schemes did not provide the formal security analysis. In this paper, we first give a security model for multi‐server environment. We then propose an ID‐based mutual authentication and key agreement scheme based on bilinear maps for mobile multi‐server environment. Our scheme can be used for both general users with a long validity period and anonymous users with a short validity period. Under the presented security model, we show that our scheme is secure against all known attacks. We demonstrate that the proposed scheme is well suitable for low‐power mobile devices. Copyright © 2011 John Wiley & Sons, Ltd.     

Secure CAS‐based authentication scheme for mobile pay‐TV systems

Pay‐television has become a popular added‐value service in mobile systems. Recently, Yeh and Tsaur proposed an authentication scheme for mobile pay‐television based on Sun and Leu's scheme. However, we found that Yeh and Tsaur's scheme has some security flaws, ie, impersonation attack with knowing mobile set's identity card, the adversary impersonates the head‐end system attack, the replay attack, the denial‐of‐service attack, and collusion attack. To overcome these problems, in this paper, we propose an improved scheme by storing a head‐end system signature and using a password. In addition, our proposed scheme keeps all the merits of Yeh and Tsaur's scheme. Furthermore, the performance analysis shows that the computation cost and the communication cost of our scheme are decreased dramatically compared to Yeh and Tsaur's scheme.     

Capacity optimizing channel allocation schemes for multi‐service cellular systems with mobile users

In this paper, we study the blocking and dropping probability of mobile users in the multi‐service cellular systems with mobile users. Based on the idea that different services may require different signal‐to‐interference ratios and different reuse factors, we proposed a channel allocation scheme called channel partitioning to support different services using different reuse factors. Under channel partitioning scheme, the channels in each cell are divided into two or more sets of channels and each set of the channels supports certain service, depending on the required reuse factor of the service. We first apply this channel partitioning with fixed channel allocation scheme called fixed channel partitioning (FCP), where a three‐dimensional Markov chain is developed to analyze the impact of the mobile user. After that a simpler model, which can estimate the numeric result from the closed‐form solution, is presented to make the analysis easier. In order to cater for the traffic variation between services and between cells, a dynamic channel partitioning with flexible channel combination scheme, called FDCP, is proposed to support multiple services. This FDCP tries to minimize the effect of assigned channels on the availability of channels for use in the interfering cells. The analysis and the simulation results show that for equal arrival rate of two services, the proposed FCP and FDCP scheme can provide about 32% and 54% improvement, respectively, in terms of grade of service as compared with conventional FCA scheme using a single reuse factor to support two services for the mobile users. Copyright © 2006 John Wiley & Sons, Ltd.     

Fair end‐to‐end window‐based congestion control in time‐varying data communication networks

Communication networks are time varying and, hence, fair sharing of network resources among the users in such a dynamic environment is a challenging task. In this context, a time‐varying network model is designed, and the shortest user's route is found. In the designed network model, an end‐to‐end window‐based congestion control scheme is developed with the help of internal nodes or router, and the end user can get implicit feedback (throughput). This scheme is considered as fair if the allocation of resources among users minimizes overall congestion or backlog in the networks. Window update approach is based on a multi‐class fluid model and is updated dynamically by considering delays (communication, propagation, and queuing) and the backlog of packets in the user's routes. Convergence and stability of the window size are obtained using a Lyapunov function. A comparative study with other window‐based methods is also provided.     

Space‐time block coding in millimeter wave large‐scale MIMO‐NOMA transmission scheme

In this paper, we introduce a new wireless system architecture using space‐time block coding schemes (STBC) and non‐orthogonal multiple access (NOMA) in millimeter wave (mmWave) large‐scale MIMO systems. The proposed STBC mmWave large‐scale MIMO‐NOMA system utilizes two MIMO subarrays, transmitting data over two channel vectors to mobile users. To reduce the communication overhead and latency in the system, we utilize random beamforming with optimal coefficients at the base station and random‐near random‐far user pairing in implementing the NOMA scheme. Our results show that the proposed STBC mmWave large‐scale MIMO‐NOMA technique significantly outperforms the previous counterparts.     

A PTD‐based transaction protocol for public transportation

Advances in wireless network technology and the increasing number of users of the personal trusted device (PTD) make the PTD an ideal channel for offering personalized services to mobile users. In this paper, we propose using a PTD as a payment tool in a mobile transaction system for public transportation. To overcome the inherent weakness of computing resources in a PTD, we use a trusted observer to coordinate the mobile transaction and to integrate cryptology (such as a digital signature and a one‐way hash function). The proposed scheme satisfies the requirements for mobile transactions. These requirements include fairness, non‐repudiation, anonymity, off‐line capability, no forgery, efficient verification, simplicity, and practicability. Because a PTD is more portable and personal than a personal computer and because the public transportation can be a necessity in our daily lives, our scheme proposes a novel use of PTDs in mobile commerce. Copyright © 2008 John Wiley & Sons, Ltd.     

Efficient three‐party password‐based key exchange scheme

In three‐party password‐based key exchange protocol, a client is allowed to share a human‐memorable password with a trusted server such that two clients can negotiate a session key to communicate with each other secretly. Recently, many three‐party password‐based key exchange protocols have been developed. However, these proposed schemes cannot simultaneously achieve security and efficiency. Based on elliptic curve cryptography (ECC), this paper will propose a new simple three‐party password‐based authenticated key exchange scheme. The proposed method not only reduces computation cost for remote users and a trusted server but also is more efficient than previously proposed schemes. It is better suited for resource constrained devices, such as smart cards or mobile units. Copyright © 2010 John Wiley & Sons, Ltd.     

A heterogeneous‐network aided public‐key management scheme for mobile ad hoc networks

A mobile ad hoc network does not require fixed infrastructure to construct connections among nodes. Due to the particular characteristics of mobile ad hoc networks, most existing secure protocols in wired networks do not meet the security requirements for mobile ad hoc networks. Most secure protocols in mobile ad hoc networks, such as secure routing, key agreement and secure group communication protocols, assume that all nodes must have pre‐shared a secret, or pre‐obtained public‐key certificates before joining the network. However, this assumption has a practical weakness for some emergency applications, because some nodes without pre‐obtained certificates will be unable to join the network. In this paper, a heterogeneous‐network aided public‐key management scheme for mobile ad hoc networks is proposed to remedy this weakness. Several heterogeneous networks (such as satellite, unmanned aerial vehicle, or cellular networks) provide wider service areas and ubiquitous connectivity. We adopt these wide‐covered heterogeneous networks to design a secure certificate distribution scheme that allows a mobile node without a pre‐obtained certificate to instantly get a certificate using the communication channel constructed by these wide‐covered heterogeneous networks. Therefore, this scheme enhances the security infrastructure of public key management for mobile ad hoc networks. Copyright © 2006 John Wiley & Sons, Ltd.     

Mitigating file‐sharing misbehavior with movement synchronization to increase end‐to‐end availability for delay sensitive streams in vehicular P2P devices

When dealing with wireless connectivity in a mobile peer‐to‐peer (MP2P) environment, there are many concerns about the offered efficiency and availability of the requested resources and concerns about practicality considerations. These considerations deal with the movement and deployment of continuous connectivity. The intermittent connectivity is a major factor for object sharing misbehavior because it aggravates the connectivity and reliability. MP2P environments are in need of specialized placement algorithms where structured index‐centric solutions will be able to provide efficiency and object location determination over intermittent connectivity and communication. Replication of any requested object and redundancy face the requests' failures because they create severe duplications, and aggravate the capacity of the end‐to‐end path. This work proposes a framework that enables mitigation between the file sharing misbehavior in contrast to the movement synchronization, and it quantifies the parameters that affect the end‐to‐end efficient transmission by taking into consideration the synchronization between moving peers to assign the requested resources in the end‐to‐end path. Resilience metrics are introduced to enable reliability in cooperative file sharing procedure. The proposed scheme considers synchronization and assignment of the moving mobile Infostation peer with certain object indices to a certain vehicle via a synchronized cooperative scheme where the file sharing process is performed through the message ferry mobile peer. In addition, a resource assignment cooperation engine is developed taking into consideration the social cooperation model and the end‐to‐end capacity of the relay path. The proposed resource exchange apparatus for file chunks' migration is performed to enable delay sensitive streaming. The proposed model is evaluated through experimental simulation taking measures for the throughput and the reliability offered and for the robustness for sharing resources of any capacity in dynamically changing MP2P wireless environments under synchronized movements. Copyright © 2012 John Wiley & Sons, Ltd.     

Efficient device‐to‐device discovery and access procedure for 5G cellular network

A large number of new data‐consuming applications are emerging, and many of them involve mobile users. In the next generation of wireless communication systems, device‐to‐device (D2D) communication is introduced as a new paradigm to offload the increasing traffic to the user equipment. Before the traffic transmission, D2D discovery and access procedure is the first important step which needs to be completed. In this paper, our goal is to design a device discovery and access scheme for the fifth generation cellular networks. We first present two types of device discovery and access procedures. Then we provide performance analysis based on the Markov process model. In addition, we present numerical simulation on the Vienna Matlab platform. The simulation results demonstrate the viability of the proposed scheme. Copyright © 2015 John Wiley & Sons, Ltd.     

Managing QoS requirements for video streaming: from intra‐node to inter‐node

Streaming video over IP networks has become increasingly popular; however, compared to traditional data traffic, video streaming places different demands on quality of service (QoS) in a network, particularly in terms of delay, delay variation, and data loss. In response to the QoS demands of video applications, network techniques have been proposed to provide QoS within a network. Unfortunately, while efficient from a network perspective, most existing solutions have not provided end‐to‐end QoS that is satisfactory to users. In this paper, packet scheduling and end‐to‐end QoS distribution schemes are proposed to address this issue. The design and implementation of the two schemes are based on the active networking paradigm. In active networks, routers can perform user‐driven computation when forwarding packets, rather than just simple storing and forwarding packets, as in traditional networks. Both schemes thus take advantage of the capability of active networks enabling routers to adapt to the content of transmitted data and the QoS requirements of video users. In other words, packet scheduling at routers considers the correlation between video characteristics, available local resources and the resulting visual quality. The proposed QoS distribution scheme performs inter‐node adaptation, dynamically adjusting local loss constraints in response to network conditions in order to satisfy the end‐to‐end loss requirements. An active network‐based simulation shows that using QoS distribution and packet scheduling together increases the probability of meeting end‐to‐end QoS requirements of networked video. Copyright © 2005 John Wiley & Sons, Ltd.     

Dynamic region‐based mobile multicast

Traditional mobile multicast schemes have higher multicast tree reconfiguration cost or multicast packet delivery cost. Two costs are very critical because the former affects the service disruption time during handoff while the latter affects the packet delivery delay. Although the range‐based mobile multicast (RBMoM) scheme and its similar schemes offer the trade‐off between two costs to some extent, most of them do not determine the size of service region, which is critical to the network performance. Hence, we propose a dynamic region‐based mobile multicast (DRBMoM) to dynamically determine the optimal service region for reducing the multicast tree reconfiguration and multicast packet delivery costs. DRBMoM provides two versions: (i) the per‐user version, named DRBMoM‐U, and (ii) the aggregate‐users version, named DRBMoM‐A. Two versions have different applicability, which are the complementary technologies for pursuing efficient mobile multicast. Though having different data information and operations, two versions have the same method for finding the optimal service region. To that aim, DRBMoM models the users' mobility with arbitrary movement directional probabilities in 2‐D mesh network using Markov Chain, and predicts the behaviors of foreign agents' (FAs') joining in a multicast group. DRBMoM derives a cost function to formulate the average multicast tree reconfiguration cost and the average multicast packet delivery cost, which is a function of service region. DRBMoM finds the optimal service region that can minimize the cost function. The simulation tests some key parameters of DRBMoM. In addition, the simulation and numerical analyses show the cost in DRBMoM is about 22∼50% of that in RBMoM. At last, the applicability and computational complexity of DRBMoM and its similar scheme are analyzed. Copyright © 2010 John Wiley & Sons, Ltd.     

Supporting dependable group‐oriented mobile transactions: redundancy‐based architecture and performance

Several of the emerging mobile commerce services, such as mobile auctions, mobile financial services, and multi‐party interactive games, will require support for dependable transactions. This is a difficult challenge because of both intermittent connectivity and potential failures in wireless infrastructure. In this paper, we present a multi‐network access‐based wireless architecture and related protocols to support dependable transactions. The key idea is to allow group users to utilize access to one or more wireless networks to complete different steps of a transaction. This allows for transactions to be completed even under time‐ and location‐dependent connectivity problems and network failures. The performance results show that access to multiple wireless networks leads to very high transaction completion probability even when individual wireless networks do not offer continuous and/or highly available access. The transaction completion probability is found to be dependent on the group size and number of steps in a transaction, and the same level of dependable performance for transactions can be achieved by increasing the number of wireless networks or improved access to individual networks. The overhead for multi‐network access can be further reduced by creating preferred wireless networks and by reducing the number of critical users in different transaction stages. Copyright © 2006 John Wiley & Sons, Ltd.     

X‐Region: A framework for location privacy preservation in mobile peer‐to‐peer networks

While enjoying various LBS (location‐based services), users also face the threats of location privacy disclosure. This is because even if the communications between users and LBS providers can be encrypted and anonymized, the sensitive information inside LBS queries may disclose the exact location or even the identity of a user. The existing research on location privacy preservation in mobile peer‐to‐peer (P2P) networks assumed that users trust each other and directly share location information with each other. Nonetheless, this assumption is not practical for most of the mobile P2P scenarios, for example, an adversary can pretend to be a normal user and collect the locations of other users. Aiming at this issue, this paper presents x‐region as a solution to preserve the location privacy in a mobile P2P environment where no trust relationships are assumed amongst mobile users. The main idea is to allow users to share a blurred region known as x‐region instead of their exact locations so that one cannot distinguish any user from others inside the region. We propose a theoretical metric for measuring the anonymity property of x‐region, together with three algorithms for generating an x‐region, namely, benchmark algorithm, weighted expanding algorithm, and aggressive weighted expanding algorithm. These algorithms achieve the anonymity and QoS requirements with different strategies. Our experiments verify the performance of the algorithms against three key metrics. Copyright © 2013 John Wiley & Sons, Ltd.     

Routing protocol development for quality of service optimization of video‐on‐demand system over mobile ad hoc networks

A video‐on‐demand (VoD) application system over mobile ad hoc networks typically requires particular quality of service (QoS) parameters to be achieved. In this paper, we have proposed a novel QoS‐based routing protocol called as mobile VoD protocol. This protocol has been developed for improving the QoS of the mobile VoD system (normal Mobi_VoD approach). The protocol uses customer caching scheme for storing the first fragment of the entire video in the mobile customers and thereafter broadcast them when the new mobile customers missed the portion of the already transmitted first fragment for reducing the service delay of the customer, consequently optimizing QoS parameters. Various scenarios have been studied, and the efficacy of simulation results proves that the proposed system architecture in which the mobile customers use an ad hoc network caching scheme (mobile VoD protocol) is more efficient and performs better than the existing system (ad hoc on‐demand distance vector protocol) when compared in terms of QoS parameters such as the end‐to‐end delay, energy consumption, packet delivery ratio, throughput, and overhead.     

CAPR: context‐aware participant recruitment mechanism in mobile crowdsourcing

With the advances of sensing, wireless communication, and mobile computing, mobile crowdsourcing has become a new paradigm for data collection and retrieval that has attracted considerable attention. This paper addresses the fundamental research issue in mobile crowdsourcing: Which participants should be selected as winners in each time slot with the aim of maximizing the total utility of the service provider in the long term? First, a double‐sided combinatorial auction model is introduced to describe the relationships between the mobile users and requesters from the perspective of supply and demand at a given time. Then, the coupling between the utility values of the system in different time slots is investigated. Based on the aforementioned analyses, this paper proposes a context‐aware participant recruitment mechanism, in which the mobile crowdsourcing system dynamically adjusts the participant recruitment mechanism depending on the ratio between the numbers of mobile users and requesters. Context‐aware participant recruitment consists of two main components: (1) a heuristic algorithm based on the greedy strategy to determine the winning participants and (2) a critical payment scheme, which guarantees the rationality of the proposed mechanism. Finally, extensive simulations demonstrate that the proposed mechanism achieves high system utility in the long term. Copyright © 2016 John Wiley & Sons, Ltd.     

Distributed Routing Based on Minimum End‐to‐End Delay for OFDMA Backhaul Mobile Mesh Networks

In this paper, an orthogonal frequency division multiple access (OFDMA)‐based minimum end‐to‐end delay (MED) distributed routing scheme for mobile backhaul wireless mesh networks is proposed. The proposed scheme selects routing paths based on OFDMA subcarrier synchronization control, subcarrier availability, and delay. In the proposed scheme, OFDMA is used to transmit frames between mesh routers using type‐I hybrid automatic repeat request over multipath Rayleigh fading channels. Compared with other distributed routing algorithms, such as most forward within radius R, farthest neighbor routing, nearest neighbor routing, and nearest with forwarding progress, simulation results show that the proposed MED routing can reduce end‐to‐end delay and support highly reliable routing using only local information of neighbor nodes.     

Second‐order statistics of multiuser relay cooperation systems over Nakagami‐m fading channels

To attain overall recognition of the effect of Nakagami‐m channel parameters on the second‐order statistics and to present a guide to the design and configuration of systems, we investigate the average level crossing rate (LCR) and average fading duration (AFD) of multiuser single relay cooperation wireless communications, in which the multiple mobile users communicate with base station under the help of single relay. On the basis of the statistical channel state information (CSI) between mobile users and relay, a single user is selected to communicate with base station. For the multiuser relay cooperation communications, we first present the integral expressions to the LCR and AFD of equivalent end‐to‐end envelope by using strict mathematical proof. Then with appropriate approximation, we obtain the closed‐form solutions to the upper and lower bounds of average LCR and AFD as well as the ones of Laplace approximation. Finally, on the basis of the derivations, we validate the approximations to LCR and AFD, and investigate the effect of the system parameters on LCR and AFD. The comparison results show that the derivations match well the simulations, and the exact values can be bounded by the obtained upper and lower bounds. Copyright © 2013 John Wiley & Sons, Ltd.     

Network‐coded MIMO‐NOMA systems with FEC codes in two‐way relay networks

This paper assumes two users and a two‐way relay network with the combination of 2×2 multi‐input multi‐output (MIMO) and nonorthogonal multiple access (NOMA). To achieve network reliability without sacrificing network throughput, network‐coded MIMO‐NOMA schemes with convolutional, Reed‐Solomon (RS), and turbo codes are applied. Messages from two users at the relay node are network‐coded and combined in NOMA scheme. Interleaved differential encoding with redundancy (R‐RIDE) scheme is proposed together with MIMO‐NOMA system. Quadrature phase‐shift keying (QPSK) modulation technique is used. Bit error rate (BER) versus signal‐to‐noise ratio (SNR) (dB) and average mutual information (AMI) (bps/Hz) versus SNR (dB) in NOMA and MIMO‐NOMA schemes are evaluated and presented. From the simulated results, the combination of MIMO‐NOMA system with the proposed R‐RIDE‐Turbo network‐coded scheme in two‐way relay networks has better BER and higher AMI performance than conventional coded NOMA system. Furthermore, R‐RIDE‐Turbo scheme in MIMO‐NOMA system outperforms the other coded schemes in both MIMO‐NOMA and NOMA systems.