110 research outputs found
Recommended from our members
Cooperative smartphone relay selection based on fair power utilization for network coverage extension
This paper presents a relay selection algorithm based on fair battery power utilization for extending mobile network coverage and capacity by using a cooperative communication strategy where mobile devices can be utilized as relays. Cooperation improves the network performance for mobile terminals, either by providing access to out-of-range devices or by facilitating multi-path network access to connected devices. In this work, we assume that all mobile devices can benefit from using other mobile devices as relays and investigate the fairness of relay selection algorithms. We point out that signal strength based relay selection inevitably leads to unfair relay selection and devise a new algorithm that is based on fair utilization of power resources on mobile devices. We call this algorithm Credit based Fair Relay Selection (CF-RS) and in this paper show through simulation that the algorithm results in fair battery power utilization, while providing similar data rates compared with traditional approaches. We then extend the solution to demonstrate that adding incentives for relay operation adds clear value for mobile devices in the case they require relay service. Typically, mobile devices represent self-interested users who are reluctant to cooperate with other network users, mainly due to the cost in terms of power and network capacity. In this paper, we present an incentive based solution which provides clear mutual benefit for mobile devices and demonstrate this benefit in the simulation of symmetric and asymmetric network topologies. The CF-RS algorithm achieves the same performance in terms of achievable data rate, Jain's fairness index and utility of end devices in both symmetric and asymmetric network configurations
Recommended from our members
Patient privacy protection using anonymous access control techniques
Objective: The objective of this study is to develop a solution to preserve security and privacy in a healthcare environment where health-sensitive information will be accessed by many parties and stored in various distributed databases. The solution should maintain anonymous medical records and it should be able to link anonymous medical information in distributed databases into a single patient medical record with the patient identity. Methods: In this paper we present a protocol that can be used to authenticate and authorize patients to healthcare services without providing the patient identification. Healthcare service can identify the patient using separate temporary identities in each identification session and medical records are linked to these temporary identities. Temporary identities can be used to enable record linkage and reverse track real patient identity in critical medical situations. Results: The proposed protocol provides main security and privacy services such as user anonymity, message privacy, message confidentiality, user authentication, user authorization and message replay attacks. The medical environment validates the patient at the healthcare service as a real and registered patient for the medical services. Using the proposed protocol, the patient anonymous medical records at different healthcare services can be linked into one single report and it is possible to securely reverse track anonymous patient into the real identity. Conclusion: The protocol protects the patient privacy with a secure anonymous authentication to healthcare services and medical record registries according to the European and the UK legislations, where the patient real identity is not disclosed with the distributed patient medical records
Recommended from our members
A Cross Layer Solution to Address TCP Intra-flow Performance Degradation in Multihop Ad hoc Networks
Incorporating the concept of TCP end-to-end congestion control for wireless networks is one of the primary concerns in designing ad hoc networks since TCP was primarily designed and optimized based on the assumptions for wired networks. In this study, our interest lies on tackling the TCP instability and in particular intra-flow instability problem since due to the nature of applications in multihop ad hoc networks, connection instability or starvation even for a short period of time can have a negative impact on the Quality of Service and may not be acceptable for the end user. Through a detailed analysis, it will be shown that the main causes of TCP intra-flow instability lies in overloading the network by sending more packets than the capacity of the channel. Based on this, the paper proposes a novel cross layer solution called “TCP Contention Control” that dynamically adjusts the amount of outstanding data in the network based on the level of contention experienced by packets as well as the throughput achieved by connections. The simulation results show TCP Contention Control can drastically improve TCP stability over 802.11 multihop ad hoc networks
Recommended from our members
Credit-Based Relay Selection Algorithm Using Stackelberg Game
Public wireless networks usually comprise of self-interested users who are reluctant to cooperate with other users of the network unless and until they are provided with some incentives. This paper presents a new incentive-based relay selection algorithm, which motivates the self-interested in-range mobile users to act as relays providing network access to the out-of-range users, thus extending the coverage range of a wireless network. The new Credit-based Relay Selection (CRS) algorithm uses Stackelberg game employing a credit-based incentive mechanism, providing instantaneous as well as long-term benefit to the selfish in-range users. In addition to this, the CRS algorithm takes into account both the achievable data rate at the out-of-range user and fair consumption of battery power of in-range user as the relay selection criteria. Simulation results presented in this paper show that when the CRS algorithm is used for relay selection, it is advantageous even for the self-interested in-range users to participate in the relaying process to earn some benefit to utilize it when they move outside the transmission range of access point and need to buy assistance from other users. The CRS algorithm also provides better data rate to the out-of-range users as well as fair utilization of battery power of the in-range users compared to a default algorithm which uses Signal to Interference and Noise Ratio (SINR) as relay selection criterion
Recommended from our members
Location Aware Data Aggregation for Efficient Message Dissemination in Vehicular Ad Hoc Networks
An intelligent location-aware data aggregation mechanism for real-time observation, estimation, and efficient dissemination of any kind of traffic information in vehicular ad hoc networks (VANETs) is presented in this paper. The mechanism introduces a location awareness algorithm, enabling spatiotemporal database indexing and providing the location context of the messages without the use of advanced positioning systems such as satellite navigation and digital maps. Intelligent passive clustering and adaptive broadcasting are used to minimize the number of messages exchanged, packet collisions, and network load. The incoming messages are fused by a Kalman filter, allowing the description of the traffic-related information as a system characterized by as many variables as needed, depending on the application design. The scheme allows the comparison of aggregates and single observations, which enables their merging and better overall accuracy. Old information in aggregates is removed by real-time database refreshing, thus leaving only newer relevant information for the driver to make real-time decisions in traffic. The mechanism is generic and can be used for any kind of VANET information. It is evaluated by extensive simulations to show the efficiency and accuracy
Recommended from our members
Alternative Topology Construction for Cooperative Data Distribution in Mobile Ad Hoc Networks
Ad hoc networks of mobile nodes can be used to extend or improve connectivity, and cooperative data distribution represents the basis of this approach. Cooperation in such networks can be improved by providing nodes with information on network dynamics and topology changes. This paper proposes a proactive approach to handling mobility-induced network topology changes. The approach uses signal strength trends to predict the future locations and connectivity between the network nodes. Our research is aimed towards the creation of an alternative topology in each node, where a node would keep other nodes suitability for cooperation in the data distribution. In this paper we present the initial algorithm and test the prediction method using a simulation. The algorithm is then applied in an experimental testbed where its performance was tested using real moving nodes executing a real data distribution process. The performance results show a significant improvement in terms of file transfer delay
Recommended from our members
Distributed Road Traffic Congestion Quantification Using Cooperative VANETs
The well-known traffic congestion problem in urban environments has negative impact on many areas including economy, environment, health and lifestyle. Recently, a number of solutions based on vehicle-to-vehicle communications were proposed for traffic congestion detection and management. In this paper we present an algorithm designed to enable each vehicle in the network to detect and quantify the level of traffic congestion in completely distributed way, independent of any supporting infrastructure and additional information such as traffic data from local authorities. Based on observations of traffic congestion by every vehicle, and by adapting the broadcast interval, it enables dissemination of the traffic information to other vehicles. The algorithm also makes every vehicle aware about the congestion level on the streets that are spatially separated from their current location by several streets. Its robustness keeps the vehicle's overall knowledge about congestion consistent, despite the short-term changes in vehicle's motion. Since the quantification of congestion is based on per-vehicle basis, the algorithm is able to operate even when only 10% of vehicles in the network are VANET enabled. Data aggregation and adaptive broadcasting are used to ensure that vehicles do not send redundant information about the traffic congestion. The simulations are conducted in Veins framework based on OMNeT++ network simulator and SUMO vehicular mobility simulator
Recommended from our members
Joint rate control and scheduling for providing bounded delay with high efficiency in multihop wireless networks
We consider the problem of supporting traffic with elastic bandwidth requirements and average end-to-end delay constraints in multihop wireless networks, with focus on source rates and link data rates as the key resource allocation decisions. The network utility maximization-based approaches to support delay-sensitive traffic have been predominantly based on either reducing link utilization, or approximation of links as M/D/1 queues, which lead to inefficient link utilization under optimal resource allocation, and mostly to unpredictable transient behavior of packet delays. On the contrary, we present an alternative formulation where the delay constraint is omitted and sources' utility functions are multiplied by a weight factor. The alternative optimization problem is solved by a scheduling algorithm incorporating a duality-based rate control algorithm at its inner layer, where link prices correlate with their average queueing delays. We then present an alternative strategy where the utility weight of each source is adjusted to ensure its desired optimal path prices, and hence the desired average path delays. Since the proposed strategy is based on solving a concave optimization problem for the elastic traffic, it leads to maximal utilization of the network capacity. The proposed approach is then realized by a scheduling algorithm that runs jointly with an integral controller whereby each source independently regulates the queueing delay on its paths at the desired level, using its utility weight factor as the control variable. The proposed algorithms are shown, using theoretical analysis and simulation, to achieve asymptotic regulation of end-to-end delay with good performance
Recommended from our members
Integrated mobility and resource management for cross-network resource sharing in heterogeneous wireless networks using traffic offload policies
The problem of efficient use of resources in wireless access networks becomes critical today with users expecting continuous high-speed network access. While access network capacity continues to increase, simultaneous operation of multiple wireless access networks presents an opportunity to increase the data rates available to end-users even further using intelligent cross-network resource sharing. This paper introduces a new integrated mobility and resource management (IMRM) framework for automatic execution of policies for cross-network resource sharing using traffic offload and pre-emptive resource reservation algorithms. The presented framework enables both mobile-initiated and network-initiated resource sharing policies to be executed. This paper presents the framework in detail and analyses its performance using extensive ns-2 simulations of the operation of a set of static policies based on measured signal strength, and dynamic pre-emptive network-initiated policies in a WiFi/WiMAX scenario. The detailed evaluation of the static policies clearly shows that the quality of voice applications shows large deviation, mostly due to very different levels of delay in access networks. Based on these conclusions, this paper presents a design of two new dynamic policies and shows that such policies, when efficiently implemented using the new IMRM framework can greatly improve the capacity of the network to serve voice traffic with a minimal impact on the data traffic and with a very low signalling overhead
Recommended from our members
Hybrid Radio Resource Management with Co-scheduling for Relay Extended OFDMA Networks
In orthogonal frequency division multiple access networks buffer aided non-transparent in-band half duplex decode and forward relay nodes aim to improve coverage and capacity under fairness considerations. Existing centralized radio resource management and inter cell interference coordination schemes achieve these goals at the cost of heavy signalling overhead. Especially for frequency division duplex downlink transmission this is an critical issue. Fully decentralized schemes often focus on different types of frequency reuse schemes with less amount of necessary feedback. Here, it is often overseen that in a practical deployment, the backhaul link quality is the bottleneck of the two hop transmission and needs to be taken into account. Moreover, it is often modelled way too optimistic and necessary co-scheduling with single hop UE further limits the possible data rate. In order to minimize the required overhead this work proposes a hybrid radio resource management (RRM) scheme. The RRM includes synchronous adapted two-hop proportional frequency selective resource scheduling as the decentralized part. Asynchronous subband power allocation scheme with very limited feedback is proposed to maximize the wireless backhaul link quality with no loss for single hop UE. Comprehensive system level simulation results show stable fairness and throughput when minimizing the required feedback and improvements for the backhaul links based on the centralized adapted power allocation including no losses in the overall system. In addition possible energy savings for the shared channel are presented when applying the proposed scheme
- …