Space-air-ground integrated networks (SAGINs) hold great promise in delivering ubiquitous aerial access, effectively meeting the demands for large-coverage on-demand services. Moreover, in 6G networks, the integration of Communication, Computation, Caching, and Control (4C) enables seamless connectivity, efficient data processing, optimized content delivery, and intelligent decision-making for next-generation services. However, various components like unmanned aerial vehicles (UAVs), high-altitude platforms (HAPs), satellites, and terrestrial networks each face distinct limitations. In this demo, we first showcase a SAGIN-4C-6G platform capable of establishing a high-capacity backhaul link to the core network while ensuring stable and continuous coverage. Experiments demonstrate that the proposed platform can deliver high-speed, on-demand air-to-ground (A2G) coverage with wireless backhaul, extending over an area of up to 100 km2. Beyond communication enhancement and optimization control, we also illustrate the potential for computation and caching services by deploying the proposed SAGIN platform.

In an era of increasing data cap constraints, optimizing video streaming quality while adhering to user-defined data caps remains a significant challenge. This paper introduces Bitrate-Adaptive Limit-Aware Netcast Content Enhancement (BALANCE), a novel Quantum framework aimed at addressing this issue. BALANCE intelligently pre-selects video segments based on visual complexity and anticipated data consumption, utilizing the Video Multimethod Assessment Fusion (VMAF) metric to enhance Quality of Experience (QoE). We compare our method against traditional bitrate ladders used in Adaptive Bitrate (ABR) streaming, demonstrating a notable improvement in QoE under equivalent data constraints. We compare the Slack variable approach with the Dynamic Penalization Approach (DPA) by framing the bitrate allocation problem through Quadratic Unconstrained Binary Optimization (QUBO) to effectively enforce data limits. Our results indicate that the DPA consistently outperforms the Slack Variable Method, delivering more valid and optimal solutions as data limits increase. This new quantum approach significantly enhances streaming satisfaction for users with limited data plans.

To address the explosive growth of number of mobile users in future generations of wireless networks, Non-Orthogonal Multiple Access (NOMA) has received significant attention. In this work, we propose an incentive driven content shifting framework to reward users which push multimedia data content from an Orthogonal Multiple Access (OMA) link to a NOMA link. The objective of the framework is to benefit both the user and the base station by simultaneously improving the user’s Quality of Experience (QoE) and the base station’s profits. The key issue of strategically splitting the data among the available NOMA and OMA links are studied to attain the best possible service. According to our study, OMA could be leveraged for transmission of important frames while NOMA is suitable for frames with lesser importance. Using game theoretic methods, we develop a method to attain the Nash Equilibrium of the solution. Simulation studies showcase the merits and potentials of the proposed incentive mechanism to encourage users transmitting certain data through NOMA links.

Non-Orthogonal Multiple Access (NOMA) is one of the promising solutions for next-generation wireless multimedia services to mitigate traffic congestion and reduce latency. Orthogonal Multiple Access (OMA) on the other hand has been used over the years to transmit content wirelessly. The merits offered by OMA would make it co-exist along with NOMA in the upcoming years. The key idea of this paper is to leverage Uber/Lyft ride-share philosophy to design the wireless access pricing model to be "orthogonality-centric"; being aware of the shared NOMA and exclusive OMA access price differences in wireless networks. The efficacy of the developed pricing model is then studied on a hybrid network which supports both NOMA and OMA resource blocks. The utility definitions for both the base station and the mobile user are mathematically modeled and the profit maximization interplay between the two parties is analyzed using game theoretic methods. An algorithm to derive Nash Equilibrium solution is presented. The simulations showcase the efficacy of the developed orthogonality driven pricing framework developed in this paper. Furthermore, the results indicate that the non-uniform orthogonality-centric pricing yields better utilities for both the base station and the end user.

Intelligent Reflecting Surface (IRS) has been demonstrated as a promising and innovative technology for next-generation wireless communications. It can be utilized to flexibly re-configure the fundamental communication environment to realize low-cost, energy-saving, and low-interference wireless communications. On the other hand, malicious users may also utilize the powerful capability of the IRS to re-configure the communication environment to achieve an advantageous position to launch security attacks such as eavesdropping and jamming wireless networks. Therefore, while the integration of IRS into wireless communications brings promising new opportunities, it also raises significant concerns from the security perspective. This issue has not been thoroughly studied in the literature. In this paper, we first introduce the recent works of using IRS in wireless communications by grouping them into two categories: 1) securing communication via IRS and 2) launching attacks using IRS. We then derive a critical performance metric, the Signal-to-Noise Ratio (SNR), for evaluating IRS-assisted wireless communication systems. Next, we present four typical scenarios of utilizing IRS for security or threats to wireless communications. At last, we evaluate the IRS-assisted system with regard to the SNR performance affected by the IRS in those four scenarios toward a deeper understanding of the potential of IRS-assisted wireless communication systems in terms of security and threats.

Wireless multimedia communications is one of the most rapidly growing technologies of the decade. With explosive growth in network traffic, the service providers struggle to provide satisfactory Quality of Experience (QoE) to the users and increase revenue. Non-Orthogonal Multiple Access (NOMA) has been proposed to cater multiple users simultaneously in each resource block by exponentially increasing the network capacity. However, the strategic allocation and trading of NOMA resource blocks are still open issues. In this work, we treat a NOMA resource block as a commodity representing its channel quality and the importance of data it carries. We then chalkup the innovative and appealing QoE-price interplay to promote NOMA resource block trading as a suitable candidate for future-generation wireless mobile networks. The proposed framework benefits both the utilities of users and service providers. The proposed approach is solved by deriving the Nash Equilibrium of the network interactions using a best-response game. Simulations suggests further exploration of the potentials to the adaptation of proposed framework for NOMA wireless multimedia communications.

With increasing number of mobile users, leveraging economics in communications has been envisioned as a new paradigm to boost the network performance. However, the issues such as incentivizing offloading devices and improving end-user Quality of Experience (QoE) are still open challenges. The philosophy of the proposed algorithmic protocol lies in encouraging end-users to scavenge multimedia data from the neighbors (offloading users), and by doing so, maximize their QoE by taking advantage of shorter communication distance. The protocol also facilitates the wireless carriers to lower the network traffic congestion and to improve profits by setting up cache delegation communication among the offloading users and end-user for a nominal commission fee. Steadiness of the proposed game theoretic algorithmic protocol has been achieved by formulating the interaction between the service provider, offloading user and the end-user as a game. An algorithm has been developed to determine the Nash Equilibrium solution of the game which maximizes the utilities of all the parties. Simulation studies conducted using H.265 encoded multimedia data indicate a significance raise in end-user QoE and decrease in network congestion.

Non-Orthogonal Multiple Access (NOMA) is one of the promising solutions for next-generation wireless services to mitigate traffic congestion and reduce latency. However, the issues such as regulating network revenue and ameliorating end-user Quality of Experience (QoE) are still open challenges. In this work, we propose the concept of Non-Orthogonal Multiple Access Pricing (NOMAP), to bridge the gap between price and QoE in NOMA resource allocation. The framework was then applied to a NOMA network scenario, and the problems of power allocation and resource block selection were investigated. The main contribution of this paper is to show that higher utilities can be achieved by dynamically pricing the NOMA resource blocks and by allowing the users to have a choice in resource management. In addition, an algorithm to achieve optimality in terms of Nash equilibrium is provided as an implementation example. The simulations carried out using MATLAB showcase the efficacy of the developed NOMAP framework. Furthermore, the results indicate that the proposed pricing significantly outperforms the traditional uniform pricing schemes.

Abstract Relaying multimedia with decent Quality of Experience (QoE) is paramount for future wireless networks. In this paper, the problem of multimedia cache relay delegation with device‐to‐device (D2D) communication interference is studied. A solution with gametheoretic cached multimedia relay is proposed considering the mutual interference between the downlink relay and the succeeding uplink communications. The interference between D2D and uplink is modelled in the game competition. In the proposed solution, the base station (BS) and relay device (RD) are treated as two rational game players, where the BS acts as the leader, and RD acts as the follower. The utilities of BS, and RD are modelled using the expected QoE of the user equipment (UE). Analytical modeling shows that the system achieves the desirable state by acquiring the Stackelberg game equilibrium between the BS, and RD. The models show that the RD gets positive incentives for relaying, the UE experiences better QoE through D2D communication, and BS achieves higher payoff. Various cases are quantitatively analysed whether the Nash Equilibrium exists with numerical discussion. Various relay to uplink ratios, amount of relay traffic, transmission distances between relay and uplink, as well as various numbers of interference uplinks are also studied.

With the unification of modern wireless services of Mixed Reality and Tactile Internet, providing Quality of Experience (QoE) with ultra low latency become critical challenges in edge resource allocation. In this paper we propose a reinforcement learning-based economic pricing model for wireless multimedia QoE, leveraging economic theories and machine intelligence. In the proposed approach, the QoE pricing model considers the User Equipment (UE)'s perceived QoE, the amount of purchased data, the wireless channel conditions, and the user's subjective multimedia content preference. In addition, the QoE gain of UE, cost of three entities in wireless networks Content Provider (CP), Wireless Carrier (WC), and UE, are integrated in the economic concept of social utility. The social utility would be affected by all system factors such as unit data price, multimedia quality requirement, and wireless channel conditions. The proposed reinforcement learning method improves the social utility performance by maximizing the accumulated utility through obtaining the optimal factors set up. At last, through numerical simulations we show the impacts of different system parameters on UE's QoE gain and the improvement of social utility performance by using the proposed reinforcement learning approach.

The transmission scheduling is a critical problem in radio frequency (RF) energy harvesting communications. Existing transmission strategies are mainly based on a conventional model, in which the amount of harvested energy is modeled as predetermined random variables and the data transmission is arranged in a fixed feasible energy tunnel. In this paper, we show through the theoretical analysis and experimental results that due to the nonlinear battery charging characteristics, the harvested energy will largely depend on the transmission strategy. The bounds of feasible energy tunnel become dynamic. To describe a practical ambient energy harvesting process more accurately, a new nonlinear recursive model is proposed by adding a feedback loop that reflects the real-time influence of the data transmission on the energy harvesting process. In addition, to improve communication performance, we redesign the optimal transmission scheduling strategy based on the new model. In order to cope with the challenge of the endless loop in the new model, a recursive algorithm is developed. The simulation results reveal that the new transmission scheduling strategy can balance the efficiency of energy harvest and energy utilization regardless of the length of energy packets, thus improving the throughput performance of RF energy harvesting wireless communications.

How to jointly provide Quality of Experience (QoE) to mobile multimedia users and simultaneously address the profit maximization issue of Content Provider (CP) - Wireless Carrier (WC) is a new economic challenge in wireless multimedia communications. In this paper, we consider leveraging the Smart Media Pricing (SMP) concept and develop a generalized best-response game theoretical model to determine the consumed data traffic from users and the media price charged by CPWC alliance. Based on the SMP utility models of user and CPWC alliance, a generalized game theoretical best-response game model is proposed to solve the non-cooperative selfish competition between the two players, which does not require concavity of the utility function at all. In the proposed Best Response Nash Equilibrium (BRNE) algorithm, both pure strategy and mixed-strategy schemes are developed for attaining the equilibrium solutions of the CP-WC's data price and user's amount of data consumption. Simulation study demonstrates the efficiency of the proposed BRNE algorithm that both user and CP-WC alliance get better utility when the system takes the Nash Equilibrium solutions.

Improving Quality of Experience (QoE) of User Equipment (UE) in wireless multimedia services is a critical challenge. In this paper we study the joint design of high level dynamic video Quantization Parameter (QP) and the low level power control in QoE-driven downlink wireless multimedia services. Furthermore, we study QoE performance with new Non-Orthogonal Multiple Access (NOMA) schemes in the Base Station (BS) - UE multimedia downlink, and discuss the performance in comparison with conventional Orthogonal Multiple Access (OMA). We mathematically model UE's QoE gain (also known as utility) by considering UE's perceived data quality and the corresponding data cost. Then we show that there exists an optimal data consumption option for UE to achieve utility maximization based on different cost coefficients. In addition, the power allocation strategies and their associated constraints are investigated in both OMA and NOMA transmission schemes. Finally, through numerical simulations, we quantitatively analyze the impact of low level power allocation and high level QP control on UEs' utility gain and the system throughput performance.

With the advances in wireless multimedia communication technologies and the rise in end- user experience expectations, meeting the Quality of Experience (QoE) requirements of the mobile multimedia user has become challenging for content providers and wireless carriers. In this research, we chalk up a QoE-sensitive multimedia data pricing economic model, by pricing the quality of the data rather than the quantity of the data. Utility maximization problem between the content provider (sells multimedia content), wireless carrier (provides transmission service) and the mobile user (requests multimedia data) is modeled using the proposed framework. We then formulate the aforementioned problem as a two-stage Stackelberg game and derive the Nash Equilibrium using backward induction method. Simulation study show that each player can obtain optimal strategy where the Stackelberg equilibrium exists stably. Finally, the proposed smart pricing mechanism was tested against the traditional uniform pricing scheme and the results indicate that better utilities can be achieved by leveraging the proposed scheme.

In Non-Orthogonal Multiple Access (NOMA) downlink the Base Station (BS) transmits to multiple User Equipments (UEs) at the same time and the same frequency with different power levels. However making full use of the promising NOMA technology to relay multimedia contents for UEs in wireless media service is an open issue. In this paper, a Quality of Experience (QoE)-centric multimedia relaying scheme is proposed, where the NOMA is not only applied at the downlinks between the BS and UEs, but also at the Device-to-Device (D2D) relay links among UEs during the relaying phase. By mathematically analyzing the Signal to Interference plus Noise Ratio (SINR) model in downlinks and D2D relay links, we show that the new QoE-centric relay scheme would significantly improve the multimedia QoE of UEs, especially for the UEs with low SINR. In addition, the QoE and energy consumption models are developed in order to comprehensively analyze the system performance. Finally, through numerical simulation we quantitatively analyze the energy efficiency and QoE performance of UEs in different NOMA systems with various numbers of UEs.

In this paper, we propose a price-driven Nash Bargaining game solution to maximize Quality of Experience (QoE) with cache content optimization in wireless multimedia communications. By leveraging the cached multimedia content and the Smart Media Pricing (SMP) concept through device-to-device (D2D) communications, the economic-quality equilibrium is established between Service Provider (SP) and End Devices (EDs). The contribution of this paper is as follows. First, referring to the importance of multimedia packets, we develop a price-driven method to allocate cached multimedia resource on the seller EDs. Then a Nash Bargaining game is formulated between the seller and buyer EDs considering multimedia packet importance and content popularity. Referring to the two-player Nash Bargaining game theoretic model, a buying-caching-reselling strategy for multimedia content is proposed by deriving the Nash Bargaining Solution (NBS). Simulation results demonstrate that the proposed SMP cache allocation method has high efficiency and fairness in quality-driven wireless multimedia communications, leading to desirable utilities towards Pareto optimality.

The consideration of multimedia Quality of Experience (QoE) has largely been ignored in emerging Non-Orthogonal Multiple Access (NOMA) research. In order to address the wireless video transmission challenge in NOMA wireless networks, a QoE-optimized communication power allocation approach for downlink wireless video service is proposed in this paper. By jointly analyzing and exploring the power budget of the Base Station (BS), the physical channel constraint, and the video packet quality influence, we connect the QoE to the optimal NOMA power allocation to various video packets. In particular, an analytical QoE model is established by taking transmission rate, packet size, and video content quality into consideration. Then we prove the concavity of the QoE objective function, such that the QoE maximization problem can be solved by finding the optimal power allocation array for all User Equipments (UEs) in the system. An optimized power allocation algorithm is proposed in the spectrum- shared power domain NOMA system based on a light- weighted binary search scheme. Numerical simulation results demonstrate that comparing with the conventional Orthogonal Multiple Access (OMA) scheme, the proposed QoE-optimized power allocation method in spectrum-shared NOMA can drastically improve the system QoE performance regardless of the number of UEs in the service. Furthermore, the proposed method also provides desirable QoE when UEs have different video compression rate-distortion requirements.

The transmission scheduling is a critical problem in radio frequency (RF) energy harvesting communications. Existing transmission strategies are mainly designed based on a classic model, in which the harvested energy is assumed pre-determined and considered as prior knowledge in offline approaches. In this extended abstract, we challenge this assumption showing that the harvested energy is affected by the transmission scheduling and becomes unknown and not pre-determined. In the new model, we add a feedback line from the data transmission to the harvested energy. It properly indicates the interplay between the energy harvest and the data transmission but challenges the transmission scheduling in the meantime. We formulated the optimal transmission scheduling based on the new model and advocate a recursive solution.

During the past decades, we have witnessed significant research and development efforts related to Sensor Networks (SN) with both wired and wireless technologies. Those efforts resulted in the development of benchmark application paradigms for SNs with applications in both safety-critical and non-safety-critical fields, including environmental monitoring, military apps, tactics, smart sensing, underwater sensing, pollution sensing, fire alarms, and other hundreds of applications to improve our lifestyles. Similarly, the Internet of Things (IoT) has been promoting the emergence of various networking technologies with standardization efforts being carried out by the IEEE community. SNs have been proven to be the most investigated topic for enabling IoT applications. For example, sensors installed in a house may update the owner on his/her cell phone about any medical or security threat. However, to support such applications, SNs and IoT come up against several constraints, like low capacity processing capabilities, battery operated devices, limited transmission ranges, and limited data transmission capacity. One of the key issues in IoT and SNs is the efficient data forwarding in terms of energy consumption, multi-hop data retrieval, safety/emergency message dissemination, etc. The goal of this special issue is to present and highlight the novel advances, emerging technologies, and applications targeting the efficient data collection is the internet of things and sensor networks. This special issue contains thirteen regular papers which can be organized into three groups: data forwarding in SNs, energy efficiency in wireless body area networks, secure data forwarding in SNs.

Millimeter wave (mmWave) communication has been a promising technology of future fifth generation (5G) cellular networks. Due to the tremendous propagation loss of mmWave communication, device-to-device (D2D) communications are widely used over directional mmWave networks to improve the network throughput. In this paper, a new time resource sharing scheme is proposed based on Stackelberg game for interference D2D links to further enhance the network throughput. The D2D links causing interference can access to the time resource by paying higher price, while the D2D links causing no interference can also be scheduled in the scheme. Concurrent transmission scheduling between D2D links causing interference is formulated as a non-cooperative game, which achieves a distributed transmission power control solution among the interference D2D links. Moreover, the price strategy can be adjusted by setting the interference threshold such that the transmission quality can be guaranteed. The simulation results show that the proposed scheme can achieve significant network throughput gain compared with traditional concurrent transmission scheme.

Massive trust assessment (MTA) in an Online Social Network (OSN), i.e., computing the trustworthiness of all users in the network, is crucial in various OSN-related applications. Existing solutions are either too slow or inaccurate in addressing the MTA problem. We propose the OpinionWalk algorithm that accurately and efficiently conducts MTA in an OSN. OpinionWalk models trust by the Dirichlet distribution and uses a matrix to represent the direct trust relations among users. From the perspective of a user, other users' trustworthiness are stored in a column vector that is iteratively updated when the algorithm “walks” through the network, in a breadth-first search manner. We identify the overlapping subproblems property in MTA and prove OpinionWalk is a more efficient solution. The accuracy and execution time of OpinionWalk are evaluated and compared to benchmark algorithms including EigenTrust, TrustRank, MoleTrust, TidalTrust and AssessTrust, using two real-world datasets (Advogato and Pretty Good Privacy). Experimental results indicate that OpinionWalk is an efficient and accurate solution to MTA, compared to previous algorithms.

Efficient use of available energy resources for real‐time multimedia communication with a quality guarantee is one of the main challenges for future mobile computing systems. To meet the high quality‐of‐experience (QoE) demand of multimedia services, we propose a novel quality‐driven joint source‐channel coding (JSCC) scheme with an unequal error protection (UEP) technique that allocates bits by optimising source intra refreshing rates and channel correction coding rates. The key contribution of this work is that the frame importance diversity at the application layer is jointly considered with the error correction techniques and resource constraints at lower layers. For any given bit budget, the JSCC model is capable of allocating adaptive bits between source coding and channel coding among media streams. The source‐aware UEP scheme is capable of dynamically allocating the error correction bits among frames, achieving the maximum overall QoE. Simulation results demonstrated that significant improvement in multimedia quality and remarkable energy/time conservation can be achieved by deploying the proposed group‐based JSCC strategy, although the complexity is limited.

Multicast routing that meets multiple quality of service constraints is important for supporting multimedia communications in the Internet of Things (IoT). Existing multicast routing technologies for IoT mainly focus on ad hoc sensor networking scenarios; thus, are not responsive and robust enough for supporting multimedia applications in an IoT environment. In order to tackle the challenging problem of multicast routing for multimedia communications in IoT, in this paper, we propose two algorithms for the establishing multicast routing tree for multimedia data transmissions. The proposed algorithms leverage an entropy-based process to aggregate all weights into a comprehensive metric, and then uses it to search a multicast tree on the basis of the spanning tree and shortest path tree algorithms. We conduct theoretical analysis and extensive simulations for evaluating the proposed algorithms. Both analytical and experimental results demonstrate that one of the proposed algorithms is more efficient than a representative multiconstrained multicast routing algorithm in terms of both speed and accuracy; thus, is able to support multimedia communications in an IoT environment. We believe that our results are able to provide in-depth insight into the multicast routing algorithm design for multimedia communications in IoT.

With the popularity of multimedia sensing at cloud edges and the reducing cost of the Internet of Things (IoT) fog devices and systems, new challenges have been posed to efficiently deal with the big data multimedia traffic generated from IoT sensing units. Specifically, in this paper we introduce the concept of multimedia sensing as a service (MSaaS), and propose a generalized premium prioritization-based quality of experience paradigm for wireless big-volumes-of-data (BVDs) multimedia communications, with significant energy saving potentials for future multimedia IoT devices and systems. The key contribution of this new framework is its data diversity flexibility at the application layer, which could be flexibly adopted by future multimedia communication systems. Data dependencies in spatial, frequency and temporal domains are analyzed, and interaction with uplink resource allocation optimization are investigated with regards to wireless communication energy cost estimation. Extensive simulation results demonstrate that the proposed prioritization-based communication paradigm has significant energy saving potentials for BVD MSaaS wireless multimedia communications at cloud edges and fogs.

As Internet-of-Things (IoT) and its applications are increasingly popular, where diverse multi-scale sensors and devices are seamlessly blended for ubiquitous communication infrastructure, broadcast operation still plays an essential role in scalable information dissemination to enhance information accessibility and availability. A unit-disk signal propagation model has been implicitly assumed and extensively applied to prior broadcast protocols, but we need to relax this assumption in reality. In this paper, we propose a transitional region aware broadcast protocol, called TCast, in variable wireless link qualities due to the signal propagation effects and non-uniform radiation pattern from the omni-directional antenna. The TCast is a stateless protocol and consists of two major operations, forwarder search and probabilistic rebroadcast. A sender neither maintains any neighbor information nor searches for a set of forwarders, but broadcasts a set of Beacon packets followed by a single Data packet. The sender repeatedly conducts the broadcast operations depending on the number of rebroadcasted packets overheard. Each receiver independently makes its own rebroadcast decision based on the number of received Beacon packets. A network-level random backoff mechanism is also proposed to avoid any packet contentions and collisions. The transitional region and its corresponding probability of packet reception are further investigated through a simple mathematical analysis. Extensive simulation experiments are also conducted using the OMNeT++, and simulation results indicate that the TCast shows competitive and scalable performance and is deployable in time-varying packet reception rates at receivers.

Multimedia broadcasting applications become increasingly popular in future user-centric 5G networks. However, traditional multimedia data broadcasting scheme from the base station to devices is hard to satisfy the highly diversified Quality of Experience (QoE) requirement from users' perspectives. In this paper we propose a user-centric multimedia rebroadcasting scheme leveraging the device-to- device (D2D) communication model with strict energy constraint. Our method first optimizes the transmission energy of each rebroadcasting user device at physical layer, by taking modulation rate scaling under power limitation. Then we propose a cross-layer optimal method to improve the multimedia QoE for user applications by jointly considering the physical layer parameters and different channel information factors. The simulation results show the proposed rebroadcasting resource allocation approach achieves significant multimedia quality gain by allocating optimal transmission power and modulation rate under strict energy limitation. Performance gain of QoE is further enhanced when the differences of channel information between transmitting and receiving devices are available and leveraged.

This study proposes a quality‐driven approach that jointly selects the frequency reuse mode of device‐to‐device (D2D) links at lower layers, the video coding mode of frames, and multiple paths at higher layers for multimedia transmission in a cellular network with multi‐antenna relays placed at the intersection of adjacent cells. Based on power control of the shared relay, the user‐centered mode selection problem is formulated by maximising the quality of service (QoS) with total energy consumption constrained. Underlay mode and overlay mode are both considered. For each frame, one coding mode (I, P, or B) and multiple paths (cellular links and/or D2D links with/without relays) are selected to optimise the received video quality expectation. Different retransmission polices are considered to give higher protection levels to paths with higher transmission rates. The authors’ evaluation shows that the proposed unified power allocation and mode control scheme could enhance the perceived QoS as changing the energy constraint and the distances of different paths. The underlay mode is optimal in most cases. It provides evidences that it is not always the best to code all frames as I‐frames, to initialise the relay transmission power as the maximum, or to select one single path for video transmission.

Due to the deployment limitations of global positioning system (GPS), a pseudo geometric broadcast approach is investigated in resource constrained wireless sensor networks (WSNs). Without relying on the GPS support, a set of nodes closely located in a strategic position is judiciously searched and identified as a forwarding node. In this paper, we first propose both enhanced ad hoc broadcast protocol (AHBP) with target forwarding nodes (EBP(|Nƒ|)) and node distribution sensitive broadcast (NDS) to maximize the network coverage while minimizing the number of broadcasts. Second, we revisit prior AHBP and approximating neighbor nodes based broadcast protocol (Approx) for investigation in terms of network coverage. For performance comparison study, we modify the AHBP and broadcast protocol for sensor networks (BPS), denoted as BPS*. We conduct extensive simulation experiments using OMNeT++ and analyze the performance of protocols. Extensive simulation results indicate that the proposed EBP(|Nƒ|) and NDS protocols achieve competitive performance and can be a viable approach in WSNs.

Cloud computing has emerged as a new computing paradigm and its economics has opened up a new research area. Though progress has been made toward address competitions among Cloud service providers (CSPs) or among network service providers (NSPs), few studies have focused on the relationship between CSPs and NSPs. In this paper, we investigate this problem and present a new economic model to characterize the competition between CSPs and NSPs. We then conduct thorough theoretical analysis and numeric experiments to validate the proposed model. The results show that the replacement coefficient, connection rate, service coefficient, the equilibrium will affect the market share and the profit of CSPs and NSPs. Through this study, we believe that the developed economic model is general and practical, thus it is applicable to model the Cloud computing market.

In this paper, the mode selection (underlay or overlay) for device-to-device (D2D) links at low layers is jointly analyzed with the video coding mode selection and multiple transmission path selection at high layers. For each packet, three video coding modes (I, P, and B) and three transmission paths (cellular link with/without the shared relay and D2D link) are considered to optimize the received video quality expectation. The cross-layer mode selection problem is formulated by maximizing the Quality of Service (QoS) with total energy consumption constrained. Our evaluation shows that the proposed joint mode selection strategy could enhance the perceived QoS with less energy consumption as changing the channel conditions and transmitting power of different paths in a single sector. The coding mode selection is mainly decided by the energy constraint and the path selection mostly depends on the channel conditions.

For scalable information routing and dissemination, broadcast has been gaining tremendous interests of research in Wireless Sensor Networks (WSNs), where each sensor node has inherent resource constraints in terms of battery energy, and computing and communication capabilities. Since a blind broadcast can cause the broadcast storm problem, diverse broadcast strategies have been explored to increase the network coverage but to minimize the redundant rebroadcasts. In this paper, we propose a geometric broadcast scheme in dense WSNs. This scheme deploys a sender-initiated broadcast approach, where a sender approximates the location of its neighbor nodes without using an on-board global positioning system (GPS). Then the sender selects a set of forwarding candidate nodes located at the closest to the strategic positions based on a virtual hexagon-based coverage. A simple random backoff mechanism is also proposed to reduce the packet contentions and collisions. We develop a customized discrete-event driven simulator using the OMNeT++ to conduct our experiments. Two well-known broadcast schemes are modified to work in dense WSNs: Flooding and Ad Hoc Broadcast Protocol (AHBP). We conduct an extensive performance comparison study and the proposed scheme achieves a competitive and scalable performance in dense WSNs.

Software Defined Network (SDN) may significantly enhance network and service management by enabling separated control and data planes. The centralized OpenFlow controller with a global vision of network states offers a promising approach to realizing flow-based admission control for supporting Quality of Service (QoS) provisioning in SDN. However, per-flow process brings in challenges to scalability of OpenFlow-based SDN. Flow aggregation has been explored as an effective method to address this issue. In this paper, we investigate admission control with flow aggregation for QoS provisioning in SDN. Specifically we propose a model for admission control with flow aggregation and develop the analysis techniques for determining the required amounts of bandwidth and buffer space at OpenFlow-enabled switches for meeting performance requirements in delay and packet loss. Network calculus is applied in our modeling and analysis; which makes our method applicable to general OpenFlow-based SDNs with various implementations. Numerical experiment results are also provided to evaluate effectiveness of the developed modeling and analysis techniques.

This paper addresses the problem that devices are reluctant to participate in local device-to-device (D2D) communications in the purpose of improving the data transmission quality. We propose a novel game-theoretic approach of joint source selection and power control, which enhances the multimedia transmission quality with latency constraint. The proposed approach first analyzes the interactions between the base station (BS) and the devices using a Stackelberg game model. The optimal transmission power and price are obtained for each source device through deriving Stackelberg equilibrium off-line, in which the BS and the device both achieve maximum utilities. Second, the BS schedules the devices according to its equilibrium of signal-to-interference-and-noise ratios in D2D links. Finally, the selected best source devices complete the multimedia transmission with their power controlled. Simulations demonstrate that our proposed scheme can significantly improve multimedia transmission quality with low complexity.

Spectrum sensing is an essential process in cognitive radio networks. The majority of existing sensing approaches aim to detect the existence of a signal on a busy channel without differentiating whether a signal originates from a primary user or not. In this paper, we address this issue and propose to employ an Angle of Arrival (AoA) based sensing approach to effectively distinct a primary user's signal from a secondary user' signal. Multiple Signal Classification (MUSIC), a classical AoA algorithm, is selected due to easy implementation and high resolution. Unlike the previous works on AoA based sensing, we thoroughly investigate its sensing performance based on a practical model which captures typical characteristics in cognitive radio networks. Two performance metrics named false alarm probability and miss detection probability are theoretically analyzed. Closed-form analytical expressions are derived for both metrics. Extensive simulations are carried out under various scenarios to evaluate AoA based sensing approach.

To ease the burdens on the hospitalization capacity, an emerging swallowable-capsule technology has evolved to serve as a remote gastrointestinal (GI) disease examination technique with the aid of the wireless body sensor network (WBSN). Secure multimedia transmission in such a swallowable-capsule-based WBSN faces critical challenges including energy efficiency and content quality guarantee. In this paper, we propose a joint resource allocation and stream authentication scheme to maintain the best possible video quality while ensuring security and energy efficiency in GI-WBSNs. The contribution of this research is twofold. First, we establish a unique signature-hash (S-H) diversity approach in the authentication domain to optimize video authentication robustness and the authentication bit rate overhead over a wireless channel. Based on the full exploration of S-H authentication diversity, we propose a new two-tier signature-hash (TTSH) stream authentication scheme to improve the video quality by reducing authentication dependence overhead while protecting its integrity. Second, we propose to combine this authentication scheme with a unique S-H oriented unequal resource allocation (URA) scheme to improve the energy-distortion-authentication performance of wireless video delivery in GI-WBSN. Our analysis and simulation results demonstrate that the proposed TTSH with URA scheme achieves considerable gain in both authenticated video quality and energy efficiency.

In multimedia communication, various data rates, security strategies, and data qualities are required for different content forms such as text, audio, images, video, and interactivity content forms. In this paper, we propose a secure and robust approach to achieve the multimedia multiple access (MA) communication using self-encoded spread spectrum (SESS). In this proposed system, SESS multiple access (SESS-MA) is a novel approach to multimedia system due to its unique secure and flexible spreading nature. Iterative detection is applied for an improved multimedia quality of service (QoS) at the receiver. The number of iterations needed is evaluated separately according to different multimedia contents. Simulation studies demonstrate that the proposed scheme ensures satisfactory data quality, security, and robustness.

Providing end-to-end reliability for data transmission is still an intractable challenge for delay-sensitive wireless multimedia networks. This paper deals with an unequal error protection (UEP) scheme for scalable video delivery over packet-lossy networks using forward error correction (FEC). The proposed cross-layer approach allows the wireless multimedia networks to jointly optimize the application layer and the error protection strategies available at the lower layers. The redundancy is tuned in accordance with both the wireless channel condition (as indicated by symbol error rate) and the time limit (as indicated by parity budget). Simulations demonstrate that the proposed cross-layer grouping scheme can significantly improve video transmission quality by allocating more correction bits to the vital frames, while the time constraint is satisfied and the complexity associated with performing this group allocation algorithm is reduced.

Extreme physical conditions in the deep space environment result in the severe challenge of unreliable deep-space data communications. Moreover, high data rate services such as Earth-Mar multimedia communication in space exploration applications consume significant amount of energy, while the limited battery energy storage forms another communication bottleneck. To overcome these challenges, we propose an algorithm to adaptively control transmission power in a two-hop relay Mars-Earth communication link, to improve end-to-end throughput performance while minimizing the energy consumption at different transmission stations. In the proposed approach, transmission power of each communication station is adaptively adjusted according the energy storage leftover at each node. To achieve such optimal power adaptation, energy budget constraint is considered in the overall optimization process. Simulation results demonstrate the proposed power control methodology can bring significant improvement of throughput performance to support traffic intensive multimedia applications by exploring the limited energy budget.

In this paper, an Alamouti space time based cooperative wireless cellular network for multimedia transmission is proposed. According to various requirements of text, voice, image, video or medical signal transmissions, this multiplexing-diversity balanced structure is provided for such comprehensive multimedia transmission in wireless cellular networks. Simulation results of this Alamouti based cooperative network have been compared with Maximum Ratio Combining (MRC) method. Simulation results show the BER performance of proposed scheme outperforms several other spatial modulation methods.

Using harvestable energy in Wireless Sensor Networks (WSNs) has gained considerable popularity recently. However, how to utilize the unstable power supply to achieve quality performance is still a challenge. In this paper, we propose a Weight-Optimized Source Rate Optimization (WOSRO) approach which allows the WSN system to adaptively control source coding rates by choosing the most valuable data packets to transmit. In this approach, the packet selection strategy is optimized by considering multimedia distortion reduction, energy cost, energy neutrality constraint and power saving efficiency. Simulation results show that the proposed data packet selecting strategy significantly improves data transmission quality by exploring harvesting-storage energy neutrality and multimedia data packet importance.

In this paper, an Alamouti based cooperative wireless networks for multimedia transmission is proposed. According to various requirements of video, image, voice or medical signal transmissions, the multiplexing-diversity balanced structure is provided for such comprehensive multimedia network. Simulation results of this Alamouti based cooperative network have been compared with Maximum Ratio Combining (MRC) method. Simulation results show the BER performance of proposed schedule outperforms several other spatial modulation methods.

This paper investigates the resource allocation problem in a relay-aided cognitive radio (CR) system under the orthogonal frequency division multiplexing (OFDM) transmission. Different from the conventional CR resource allocation problem, the relay node here is capable of performing subcarrier permutation over two hops such that the signal received over a particular subcarrier is forwarded on a different subcarrier. The objective is to maximize the throughput of the CR network subject to a limited power budget at the secondary source and relay node, as well as the interference constraints at the primary receiver. The optimization is performed under a unified framework where the power allocation at the source node, power allocation at the relay node, and subcarrier pairing at the two hops are optimized jointly. Finally, numerical examples are provided to corroborate the proposed studies.

There is a strong need to explore green and harvestable energy in computer communications. However, adapting wireless network performance to harvested energy has largely been ignored in literature. In this paper, we propose a new resource allocation scheme to improve data delivery quality in energy harvesting enabled wireless networks. In the proposed approach, packet Automatic Repeat reQuest (ARQ) limit of each wireless node is adaptively adjusted according to harvested energy. To achieve such optimal retry adaptation, energy neutrality constraint is considered in the overall optimization process. Simulation results show that the proposed retry adaptation approach significantly improves packet delivery ratio by exploring the harvested energy.

In this paper, we present a cooperative transmission approach to reduce the end-to-end delay in the context of AODV based multi hop wireless networks. The underneath idea is to effectively increase the average reach of each hop so that data packets can arrive at the destination in less number of hops with lower end-to-end delay. The existing approaches of increasing transmitted power are not effective while they increase the network interferences. Unlike them, we exploit the concept of cooperative beamforming to reduce the end-to-end delay by increasing the effective communication distances and reducing the communication interferences in wireless ad-hoc networks.

Explosive growth in Information Technology has enabled many innovative application areas such as large-scale outdoor vehicular networks for vehicle-to-vehicle communications. By providing time-sensitive and location-aware information, vehicular networks can contribute to a safer and more efficient driving experience. However, the performance of vehicular networks requires robust and real-time data communications and is impacted by high mobility, intermittent connectivity, and unreliability of the wireless channel. In this paper, a novel adaptive distributed cooperative medium access control (ADC-MAC) protocol is proposed in order to address the inherent problems in the IEEE 802.11 standard when employed in vehicular networks. ADC-MAC exploits spatial diversities to maximize the system throughput as well as the service range of vehicular networks. This is accomplished through adaptively selecting the most suitable helper and transmission mode for transmit/receive pairs among direct transmission (DT), cooperative relay (CR) transmission and two-hop relay (TR) transmission, in accordance with the channel quality and the positioning of relay nodes. Both our Markov Chain modeling based theoretical analysis and ns-2 simulation experiments show that our ADC-MAC protocol outperforms existing schemes under the same network scenarios and maximizes the achieved system throughput and service distance.

Joint exploration of intra/inter-video coding versatility in signal processing domain and signature/hash diversity in the information security domain has not been well investigated in the literature. In this paper, we show multimedia stream authentication quality can be improved significantly by exploring these diversities. Specifically, we propose a new rate distortion framework by considering intra/inter-signature/hash diversity to simultaneously provide video service quality, communication rate efficiency and video content integrity for wireless video streaming. This research aims to provide a unique fusion of inter/intra video coding versatility and signature/hash authentication diversity to provide video authentication and traffic control. The results based on simulations demonstrate the effectiveness of the proposed scheme in achieving video robust authentication quality with limited rate constraint.

Some theoretical and experimental models have been considered for the prediction of the path loss in mobile communication systems. This paper presents an alternative method to model the path loss characteristics, taking into account data analytical methods to discover dependency pattern among propagation model parameters. We applied the concept of nonlinear multi-regression to predict path losses from the collected data, such as considering carrier frequency, path loss exponent, and distance between transmitter and receiver. Based on this information, the pseudo gradient search approach is adopted to determine the optimal search direction, build propagation knowledge, and accurately estimate the path loss. Finally, the free space path loss is adopted in order to validate our approach. The results are found to be well in agreement with theoretical results.

IEEE 802.16e-based Mobile WiMAX has gained considerable popularity recently. However, there is no current simulation model that provides feature completeness and performance accuracy. In this paper we propose the design and implementation methodology of a complete, accurate, realistic and versatile simulation model to support Mobile WiMAX for the NS-2 simulation platform. In the proposed simulation model design, all major mandatory as well as many optional features in the IEEE 802.16e standard are implemented based on the enhancement of an open-source WiMAX model published by NIST. The major contributions of this work are: 1) the additional features integrated to the NIST model including OFDMA physical layer, 2) periodical ranging and Adaptive Modulation and Coding (AMC) for robust link adaptation, 3) multi-hop support for large-scale test-bed simulation, as well as 4) the simulation model validation using WiMAX Forum certified devices. Versatile simulation scenarios are also designed to validate the implemented features.

In this paper, we propose an innovative low-cost biometric authentication scheme based on uniformed Gaussian mixture model (GMM) for secure communications within wireless body area sensor networks (WBASNs), to obviate the cost-prohibitive key exchange problem. In this approach, the sender Inter Pulse Interval (IPI) information is selected as the biometric key for authentication, and a statistical based signing scheme is developed using the uniformed GMM. Experimental analysis shows that the proposed approach effectively protects the communication channels in WBASN with a low computational complexity, significantly removing the need for secret key exchange and critical time synchronization overheads.

Wireless multimedia sensor networks (WMSNs) support many acoustic applications for audio surveillance, animal tracking/vocalization, human health monitoring, etc. However, resource constraints in sensor networks (such as limited battery power, bandwidth/computation capability, etc.) pose challenges for the quality and security of audio data transmission and processing. The security is a critical issue since audio information can be accessed or even manipulated in WMSNs. In order to ensure security, audio quality and energy efficiency, we propose an index-based selective audio encryption scheme for WMSNs. The scheme protects data transmissions by incorporating both resource allocation and selective encryption based on modified discrete cosine transform (MDCT). In this proposed scheme, the audio data importance is leveraged using the MDCT audio index, and wireless audio data transmission proceeds with energy efficient selective encryption. The simulation results show that the proposed approach offers a significant gain in terms of energy efficiency, encryption performance and audio transmission quality.

Selective encryption for video streaming was proposed for efficient multimedia content protection. However, the issues on joint optimization of video quality, content protection, and communication energy efficiency in a wireless sensor network (WSN) have not been fully addressed in the literature. In this paper, we propose a scheme to optimize the energy, distortion, and encryption performance of video streaming in WSNs. The contribution of this work is twofold. First, a channel-aware selective encryption approach is proposed to minimize the extra encryption dependency overhead at the application layer. Second, an unequal error protection (UEP)-based network resource allocation scheme is proposed to improve the communication efficiency at the lower layers. Simulation experiments demonstrate that the proposed joint selective encryption and resource allocation scheme can improve the video transmission quality significantly with guaranteed content protection and energy efficiency.

Media integrity, transmission quality, and energy efficiency are critical for secure wireless image streaming in a wireless multimedia sensor network (WMSN). However, conventional data authentication and resource allocation schemes cannot be applied directly to WMSN due to the constraints on limited energy and computing resources. In this paper, we propose a quality-driven scheme to optimize stream authentication and unequal error protection (UEP) jointly. This scheme can provide digital image authentication, image transmission quality optimization, and high energy efficiency for WMSN. The contribution of this research is two-fold as summarized below. First, a new resource allocation-aware greedy stream authentication approach is proposed to simplify the authentication process. Second, an authentication-aware wireless network resource allocation scheme is developed to reduce image distortion and energy consumption in transmission. The scheme is studied by unequally protected image packets with the consideration of coding and authentication dependency. Simulation results demonstrate that the proposed scheme achieves a performance gain of 3 ~ 5 dB in terms of authenticated image distortion.

This paper presents a novel passive measurement approach to accurately evaluate the performance of outdoor multi- hop 802.11 networks from the wireless side directly. Our approach employs five processing steps to evaluate per-hop system performances. Firstly, reference packets are identified from multiple independent packet traces. Secondly, multiple packet traces in one channel are merged together using the identified reference packets. Thirdly, redundant packets are filtered from the merging packet traces. To adjust for propagation differences between access points and monitors, the status of each packet is then corrected according to its context packets. Finally, an inference approach based on finite state machines (FSM) is designed to infer missing packets which are not recorded in any of the monitor traces but known to have existed in the real traffic. The unique features in our approach include propagation delay evaluation and FSM designs for existing packet status correction and missing packet inference. The measurement results collected from our outdoor multi-hop 802.11 testbed are used to validate the accuracy of our approach.

A cross layer Unequal Error Protection (UEP) scheme based upon the multimedia position-value (P-V) partitioning has been recently proposed to only improve energy-distortion performance in Wireless Multimedia Sensor Networks (WMSN). There is also a great potential to adapt this UEP scheme into multimedia stream integrity protection. However, performance gains in multimedia transmissions with considerations of energy, distortion, and authentication in WMSN is a challenge. This difficulty results from the media codec dependency on both the content of multimedia stream authentication and protection on the integrity process itself. In this article, we propose a novel scheme which optimally matches the application layer multimedia codec dependency to both lower layer resource allocation requirements and the upper layer stream authentication. The goal of this scheme is to optimize the integrity and quality performance gain within energy constraint. The contribution of the proposed approach is two folds. Firstly, a stream authentication scheme matched with P-V codec dependency is proposed which significantly reduces additional authentication dependency overhead. Secondly, a new resource allocation scheme is proposed to improve energy-distortion-authentication performance with regard to codec dependency. Simulation studies demonstrate that the proposed scheme significantly impacts achieving multimedia transmission quality with energy efficiency and authentication assurance.

Current propagation models used in network simulations neglect obstacles of a propagation environment and employ over-simplified assumptions that the received signal strength is a simple function of distance and the transmission area of a node is circular. These assumptions are in contradiction with the actual tests and the measurement results. To run reasonable simulations for evaluating the performance of a specific outdoor wireless testbed, a novel multipath propagation framework is proposed in this paper, which is based on the ray tracing technique and uses site-specific geographic data of the analyzed area. It provides accurate propagation predictions, and it does not significantly prolong the simulation duration.

While the development of Mobile WiMAX devices is still an ongoing process, complete and accurate simulations become more important in order to study the performance of Mobile WiMAX based broadband wireless access networks. To further improve network simulation models for Mobile WiMAX, we have theoretically modeled the Hybrid Automatic Retransmission reQuest (HARQ) mechanism and evaluated its performance and accuracy. In this paper, we present the design and implementation methodology of the Mobile WiMAX HARQ simulation model in system-level network simulators in order to gain the benefit of link quality improved by enabling HARQ. Our results show that HARQ achieves higher throughput even at low signal strength which can be considered as non-line-of-sight (NLOS) environments. We believe the implementation of HARQ in the network simulation model and its evaluation studies will provide profound understanding to Mobile WiMAX field test studies.

Accurate network planning is critical with deployments of large outdoor wireless networks. Propagation and path loss considerations are key factors in predicting performance of wireless networks. We are currently studying large-scale wireless networks for US railway environments. In this study, both theoretical and measurement based propagation models indicate that the average received signal power decreased logarithmically with distance. The average large-scale path loss is expressed as a function of distance between the transmitter and the receiver by using a path loss exponent n and the close-in reference distance d0. However it is very important to select a suitable space reference distance that is appropriate for a specific propagation environment. In this paper, a deterministic approach is proposed to select an appropriate reference distance for a given propagation environment. Also a Minimum Mean Square Error (MMSE) based method is introduced to compute path loss exponents. Furthermore the comparison between the site specific measurement data collected from our testbed and the estimated values verifies the accuracy of our proposed method.

It is widely believed that IEEE 802.11 standard is aimed mainly for fixed indoor wireless local area networks and is not suited for mobile applications, even though the IEEE 802.11b systems may work in either infrastructure mode or ad hoc mode. The impact of node mobility on ad hoc network performance has already been studied intensively, but these studies mostly do not consider temporal fluctuations of the mobile wireless channel due to the Doppler shift. An investigation of the mobility impact on the performance of IEEE 802.11b ad hoc systems with Rician/Rayleigh fading under different node velocities is presented. A comprehensive and in-depth analysis of the impacts of a multitude of different signal distortions on an IEEE 802.11b system performance is also presented. Specifically, the authors study the bit-error rate performances with respect to node velocities for different modulation schemes. The simulation results show that, owing to its extremely low implementation and deployment cost, the current IEEE 802.11b standard has its potential to be deployed in a mobile ad hoc environment if the line-of-sight path between transmitter and receiver exists.

Transmissions of large sized images can be a bottleneck for a wireless sensor network (WSN) due to its limited resources. Security can be another concern. This paper proposes a collaborative transmission scheme for image sensors to utilize inter-sensor correlations to decide the transmission and security sharing patterns based on the path diversities. Our proposed approach for secret image sharing on multiple node-disjoint paths for image delivery is to achieve high security without any key distribution and management, and thus the key management related problems do not exist. The energy efficiency is another major contribution made in this paper. This scheme does not only allow each image sensor to transmit optimal fractions of overlapped images through appropriate transmission paths in an energy-efficient way, but also provides unequal protection to overlapped image regions by path selections and adaptive bit error rate (BER) requirement. The simulation results show that the proposed scheme can achieve considerable gains in terms of network lifetime extension, image transmission security enhancement, image quality improvement, and energy efficiency for wireless sensor networks.

Distributed Source Coding (DSC) is an effective means in reducing data redundancy in Wireless Sensor Networks (WSNs). However, the issues on designing multirate DSC with multirate transmission in WSNs have not been well addressed in the literature. In this paper, we propose a cross-layer approach to achieve optimal DSC data quality while assuring energy efficiency and latency requirement through adjusting multirate DSC data dependencies and network multirate transmission parameters jointly. Specifically, the DSC coding dependency among multirate source coding sensors are fine-tuned to balance compression efficiency and transmission robustness. Transmission rate and retransmission limit on each wireless link are optimized accordingly to achieve Unequal Error Protection (UEP) among inter-dependent DSC streams. Simulation studies demonstrate that the proposed scheme ensures satisfactory DSC data quality and energy efficiency.

Abstract In this paper, we propose an innovative adaptive secure image delivery approach, to achieve effective and efficient image encryption based on an optimal transmission rate in terms of energy efficiency in wireless sensor networks (WSN). Our contribution is three folds—First, the proposed component based selective encryption scheme achieves high image security, while incurring little encryption overhead; furthermore, the proposed adaptive encryption scheme achieve the best security effort within delay bound; finally, the proposed transmission rate optimization improves energy efficiency, and feeds back effective path capacity parameters for adaptive encryption. Simulation results show a significant gain in both energy efficiency and security based on the proposed approach for image secure transmissions in WSN. Copyright © 2007 John Wiley & Sons, Ltd.

Biological systems exhibit remarkable adaptation and robustness in the face of widely changing environments. Currently speaking, we often imitate the properties of biological systems. Based on this thought, it also exists the analogous situation in the WSNs (Wireless Sensor Networks). Survivability is the ability to provide essential services in the presence of attacks and failures, and recover full services in timely manner. The conventional security technologies for WSNs only focus on confidentiality, integrity and authentication and can not provide survival services. The WSNs survivability depends most critically on base station that attaches WSN to outside networks including Internet. Thus, to increase the survivability, one Survivable model for base station in WSNs is presented with rejuvenation technology, where it is designed to provide continued useful services in face of attacks, failure or accidents and to prevent the intruders’ attempts in their attack. This model is described and analyzed by semi-Markov Process for survivability. Finally, according to the experimental results, current model has the feasibility to enhance the survivability level for WSNs.

Multimedia delivery over Wireless Sensor Networks (WSNs) is energy critical. In this paper, we study an energy constrained cross layer optimization scheme to improve digital image quality in cross polarization discrimination (XPD) based Multiple Input Multiple Output (MIMO) WSNs. The contribution of this research can be summarized in three parts. First, link layer energy consumption and packet loss ratio in multirate XPD based MIMO WSN are modeled. Secondly, XPD based modulation optimization cross link and physical layer is proposed, achieving considerable energy efficiency. Finally, a new Position-Value (P- V) based Unequal Error Protection (UEP) scheme is studied and discussed in XPD MIMO WSNs, with more efficient resource allocation compared to traditional approaches. Simulation results show the proposed modulation optimization scheme improves energy efficiency considerably, and position based UEP achieves significant distortion-energy gain compared with traditional layer based resource allocation schemes in XPD MIMO WSNs.

A secure image transmission mechanism is necessary when malicious intruders intend to access and modify content delivery over wireless networks. To assure data integrity, authentication is required for multimedia data delivered over wireless image sensor networks. Watermarking technique is an effective vehicle to assert and assure the image data authentications. There have been recent works reported on watermarking, but few with the consideration of energy cost in terms of the data communication and processing, which is a key constraint to many embedded systems and wireless sensor networks. Most watermarking systems only target at minimizing watermarked image distortion and increasing robustness at the source coding site for lossy image processing. The watermarked image distortion caused by error-prone wireless environments during transmission has not been fully considered. In this paper, an innovative energy-aware adaptive watermarking scheme for realtime image delivery is proposed in wireless multimedia sensor networks. This new scheme allocates network resource to protect the watermarked image transmission while embedding watermark coding redundancies into the images. Dynamic watermark thresholds are applied to be adaptive to the network condition (packet loss ratio) and the inter-frame correlation is exploited to reduce processing delay. The simulation results show that the proposed adaptive watermark system can achieve considerable energy efficiency and assure the data integrity.

With the steady development of WiMAX based broadband wireless access networks, complete and accurate simulation studies become crucial. In an effort to further improve our ns-2 simulation model for mobile WiMAX, we have implemented a Selective Repeat Automatic Retransmission reQuest (SR-ARQ) mechanism into our model and evaluated its performance and accuracy. In this paper, we present the design and implementation methodology of the WiMAX SR-ARQ simulation model in ns-2 and discuss its accuracy via extensive simulation studies. Our evaluation clearly shows that SR-ARQ achieves increased successful packet delivery ratio and goodput, which is true for both non-saturated channels and saturated channels. In each case a cost of increased bandwidth consumption and latency overhead for received packets is also quantitatively analyzed. We believe the implementation of SRARQ in the ns-2 simulation model and its evaluation studies will provide profound empirical values to WiMAX field test studies.

Throughput vs. distance analysis and coverage requirements are critical issues in planning wireless network deployments. With the recent availability of IEEE 802.16e and its promise of larger coverage areas for high-speed data communication, evaluating it in a real-world environment is very important to us in our ongoing study of standards based wireless technologies for the Federal Railroad Administration (FRA). In this paper, we present results obtained with our IEEE 802.16e module for NS-2, particularly throughput vs. distance performance, and its consideration for designing a real-world multi-hop IEEE 802.16e testbed. Firstly, a quantitative analysis of throughput vs. distance performance is conducted via extensive simulation, and the optimal modulation and coding scheme as well as channel bandwidth profiles are identified for specific distances. Secondly, we present a real-world multi-hop IEEE 802.16e testbed design intended for installation along BNSF Railway track in Nebraska. We apply our findings towards selecting various base station deployment locations and their appropriate communications parameters in order achieve best possible multi-hop throughput performance. We also provide a client access coverage analysis for the various locations.

In this paper, we analyze the performance of mobile real time services in a large-scale IEEE 802.11 multi-hop network. We present our field measurements with discussion of performance bottlenecks for VoIP services under mobile scenarios. We utilized our test bed which is located in Nebraska and supported by the University of Nebraska-Lincoln (UNL), US Federal Railroads Administrations (FRA), and major US railroad companies. Our UNL-FRA test bed consists of 8 outdoor access point towers, which are deployed along 3.5 mile of BNSF railroad. Passive measurement approaches are taken to ensure the integrity of collected data and multi-layer stream based packet analyzer has been implemented to provide a global view of the entire performance of the monitored network from the physical layer to the application layer. Based on our analysis of collected data, we conclude that in a typical outdoor 802.11 environment similar to our UNL-FRA test bed, uncertain handoff latencies and lack of Quality of Service guarantee are main performance bottlenecks for real-time applications. Furthermore, we discuss the enhancement strategies to support mobility in high-speed railway networks. We believe our work is one of the initial efforts in wireless mobile network field measurement in terms of scale, methodology, and analysis.

Joint consideration of energy efficiency, multimedia quality and media authenticity has largely been overlooked in the studies of secure wireless multimedia streaming. In this paper, we propose an authentication - resource allocation framework for secure transmission of multimedia streaming over energy constrained wireless networks. The contributions of this research can be summarized in three aspects. Firstly, a hash chain based stream level authentication scheme compatible for JPEG2000 compression standard is proposed. Secondly, link layer energy- distortion is modeled, and the energy-distortion convex hull is efficiently identified, which significantly reduces optimization complexity. Finally, an authentication oriented resource allocation scheme is proposed based on the proposed authentication scheme and link layer energy-distortion convex hull, where the authenticated image quality is optimized according to energy budget constraints.

Because of the wide deployment of 802.11 equipments in the past decade, current applications are not limited anymore to only single Access Points (AP) deployments for indoor usage, but have been extended to multi-hop networks to fulfill the need of high speed connectivity in mobile environments, where the analysis of multi-hop networks is extremely complicated. The behavior of an AP is dependent not only on its neighbors’ behavior, but also on the behavior of other hidden nodes. In this paper, we provide an accurate and verified multi-hop wireless backhaul analysis for performance of IEEE 802.11 DCF in terms of the channel throughput using a static channel error rate. The model is based on analysis of a single hop communications for evaluating the multi-hop wireless backhaul networks. We utilized our existing 3.5-mile Federal Railroad Administration (FRA) test bed on the BNSF railroad track in Nebraska to validate the model. Our field measurements and simulation results show that our proposed model is accurate.

Image transmissions in Wireless Multimedia Sensor Networks (WMSNs) are often energy constrained. They also have requirement on distortion minimization, which may be achieved through Unequal Error Protection (UEP) based communication approaches. In related literature with regard to wireless multimedia transmissions, significantly different importance levels between image-pixel-position information and image-pixel-value information have not been fully exploited by existing UEP schemes. In this paper, we propose an innovative image-pixel-position information based resource allocation scheme to optimize image transmission quality with strict energy budget constraint for image applications in WMSNs, and it works by exploring these uniquely different importance levels among image data streams. Network resources are optimally allocated cross PHY, MAC and APP layers regarding inter-segment dependency, and energy efficiency is assured while the image transmission quality is optimized. Simulation results have demonstrated the effectiveness of the proposed approach in achieving the optimal image quality and energy efficiency. The performance gain in terms of distortion reduction is especially prominent with strict energy budget constraints and lower image compression ratios.

The advancement in Distributed Source Coding (DSC) for mission-driven wireless sensor networks (WSNs) has opened a new vista for its wide applications in multiple correlated sensor networks such as real time target tracking and environment monitoring. The features of the DSC applications offer many potential opportunities for sensor networks to utilize multirate transmissions for network performance enhancement. In this paper, we propose a methodology for cross-layer optimization between routing and DSC in WSNs, and we introduce a multirate based routing scheme for mission-driven DSC applications that can considerably extend network lifetime. The proposed scheme adopts the rate assignment based on residual energy and employs a joint rate and energy scheduling mechanism to meet the end-to-end transmission rate demand, information precision requirement, and energy constraints in the networks adopting DSC. This approach is different from the traditional multirate research in link adaptation, where the focus was to increase channel throughput based on rate adaptation from variable channel conditions. The objective of this work is not to utilize multirate for increasing channel throughput, but to exploit multirate capability for routing optimization in DSC based applications with consideration for energy consumption. We also introduce the concept of "Energy Usage Scheduling (EUS)" to optimize the energy usage based on the rate constraints and DSC application needs. Simulation results show that the proposed scheme can achieve a significantly longer network lifetime than that reported in the literature.

Many Sensor applications such as monitoring and surveillance may require image sensor array to conduct collaborative image transmissions in Wireless Sensor Network (WSN). The large size image transmission in WSN is a bottleneck due to the limited energy resources. In this paper, we propose an optimal scheme for image sensors to utilize inter-sensor correlations to decide transmission patterns based on a Multi-Rate Least Cost Path (MRLCP) routing scheme, which achieves high energy efficiencies and longer network lifetime. This optimization scheme allows each image sensor to transmit optimal fractions of the overlapped images through appropriate ratebased routing paths. A specific genetic algorithm is designed to solve such discrete optimization problem. The simulation results show that the proposed image transmission scheme can achieve considerable gains in terms of the WSN energy efficiency and network lifetime extension.

Nowadays, smart spaces occupy an essential part of ubiquitous computing environment. The spaces integrated with wireless sensors networks, actuators and context-aware services become part of our daily life. Smart spaces are equipped with a large number of wireless sensors that aim to collect large quantities of context information, during the process, there exists a large amount of collisions and energy consumption. Therefore, this paper provides a novel multi-rate based local framing pre-schedule scheme to further reduce collisions and improve energy efficiency in CSMA/TDMA hybrid MAC layer of wireless sensor network. This MAC combines CSMA and TDMA functionalities together while obviates their shortcomings. Having been assigned, slot 0 is preserved as the pre-schedule slot, to inform neighbor nodes the schedule of the senders. During the pre-schedule slot, each node knows exactly the schedule of other neighbor nodes. Multi-rate and power scaling are applied to achieve further energy saving by adpoting an acceptable rate rather than maximum rate. Data rate is dynamically adjusted according to the traffic load of sending nodes, in an energy efficient data rate, to save energy. Being compared with Z-MAC in terms of performances, local framing pre-schedule and multi-rate in this experiment achieved further energy efficiency. Index Terms--MAC, CSMA, TDMA, Mult-Rate, Wireless Sensor Networks

Many sensor applications such as monitoring and surveillance may require image sensor array to conduct collaborative image transmissions in wireless sensor networks (WSN). The large size image transmissions cause bottlenecks in WSN due to the limited energy resources and network capacity. In this paper, we propose a collaborative transmission scheme for image sensors to utilize inter-sensor correlations to decide transmission patterns based on transmission path diversities, which achieves minimal energy consumption, balanced sensor lifetime and required image quality. This optimization scheme not only allows each image sensor to transmit optimal fractions of the overlapped images through appropriate transmission paths in energy-efficient way, but also provides unequal protection on the overlap image regions through path selections and resource allocations to achieve good transmission image quality. The simulation results show that the proposed image transmission scheme can achieve considerable gains in terms of the network lifetime extension, image distortion reduction, and energy efficiency.

In image transmission applications over wireless sensor networks (WSN), energy efficiency and image quality are both important factors for joint optimization. In this paper, we propose a new position-value (P-V) oriented cross layer optimization approach to minimize energy consumption with distortion bounds for image transmission applications in WSN, by exploring importance level diversity for position-magnitude information. To put more effort on transmitting important position information and relatively less effort on unimportant magnitude information, desirable BER, ARQ retry limit, transmission rate and distortion reduction of image are jointly optimized cross PHY, MAC and APP layers, and image quality is assured while energy consumption is minimized. Simulation results demonstrate the effectiveness of the proposed approach in achieving energy efficiency while maintaining image quality.

Recent advances in distributed source coding (DSC) for mission-driven wireless sensor networks (WSN) are related to the coding for multiple correlated sensors in applications such as real time target tracking and environment monitoring. The characteristic of these DSC applications provides significant potential opportunities in the associated sensor network to utilize multirate transmissions for enhancing network performance. In this paper, we study a methodology for interplay optimization between routing and DSC in WSN, and propose a novel multirate based routing scheme for mission-driven DSC applications that considerably extends network lifetime. The proposed scheme adopts the rate assignment based on the residual energy, and employs a joint rate and energy scheduling mechanism to meet the end-to-end transmission rate constraint, information precision requirement, and the energy constraints in the network for DSC. Simulation results show that this multirate based routing scheme achieves significantly longer network lifetime compared to other existing research in WSN for DSC applications.

Many Sensor applications such as monitoring and surveillance may require image sensor array to conduct collaborative image transmissions in Wireless Sensor Network (WSN). The large size image transmission in WSN is a bottleneck due to the limited energy resources. In this paper, we propose an optimal scheme for image sensors to utilize inter-sensor correlations to decide transmission patterns based on a Multi-Level Rate-Oriented routing (MLRR) routing scheme, which achieves high energy efficiencies and longer network lifetime. This optimization scheme allows each image sensor to transmit optimal fractions of the overlapped images through appropriate multiple Rate-Oriented routing paths. The simulation results by using GA algorithm show that the proposed image transmission scheme can achieve considerable gains in terms of the WSN energy efficiency and network lifetime extension.

Selective encryption for secure image transmission is an important ongoing research area which aims to scramble the critical information correlation and inter-dependency within final image compression bit streams. However, how to take Unequal Error Protection (UEP) method for transmitting partially encrypted image data in error-prone communication channels is still an open research problem in Wireless Sensor Networks (WSN). In this paper, we propose a new cross layer optimization approach for energy efficient delivery of selectively encrypted images in WSN while assuring image quality. In the proposed approach, identified importance levels of diversity for encrypted procession blocks as well as position-value (P-V) information are extensively explored within image compression and encryption bit streams. Desirable BER, ARQ retry limit, transmission rate are jointly optimized across PHY, MAC and APP layers regarding the image distortion reduction bound and communication energy efficiency. Both image quality and security are assured while energy consumption is minimized. Simulations results have shown significant gain in image security assurance and transmission quality achievement with energy efficient communications in WSN.

Image sensors' digital transmissions are significant challenge to the Wireless Sensor Networks (WSN) due to resource constraints. In this paper, we propose a novel position-value (P-V) oriented multirate image transmissions approach called Image Component Multirate Transmissions (ICMT) over WSN. This method adapts different reliable levels of transmissions to various P-V segmented components within the compressed image bit stream. Simulation results show that the proposed scheme achieves high energy efficiency in WSN while enhancing the image transmission quality.

Signal processing applications such as Distributed Source Coding (DSC) in Wireless Sensor Network (WSN) are often multirate in nature, which provide additional significant opportunities in WSN design for achieving energy efficiency. In this paper, we analyze the DSC traffic for signal processing applications in multirate WSN and propose a novel rate oriented approach with MAC and PHY cross layer utilization to achieve high energy efficiency. Simulation results show that the proposed approach achieves significant energy efficiency by a factor of three while maintaining the transmission quality in WSN. This approach can be easily extended to other WSN MAC and PHY designs, providing multirate service to application layer to allow achieving higher energy efficiency

Distributed source coding (DSC) based signal processing applications involve data transmissions at multirates in wireless sensor network (WSN). In this paper, we propose a novel cross layer approach in WSN to achieve energy efficiency using multirates desirable for the DSC based signal processing applications and current network conditions. Our approach can be summarized into two parts: first, energy efficient multirate MAC-PHY supporting DSC applications; and second, rate oriented interaction of MAC-PHY and DSC applications. Multirate MAC-PHY utilizes desirable bit error rate (BER), channel attenuation, corresponding modulation schemes, and multirate requirements, to determine the minimum desirable transmission power. Rate oriented interaction provides optimal transmission rates feedback to interact with DSC applications, making DSC applications adaptively adjust information coding rate according to network conditions. This interactive approach achieves further energy saving significantly by making the DSC application aware of WSN conditions. Besides DSC, this work can be easily extended to other multirate signal processing applications in WSN.