On the efficient use of multiple channels by single‐receiver clients in wireless data broadcasting

This letter proposes an adaptive wireless push system for wireless data broadcasting environments, where multiple channels are available for broadcasting data from a broadcast server to a large number of mobile clients. We address the general case where the client demands are not dependent on client locations. The efficiency of the proposed system lies in the fact that it offers significant performance improvements to the system clients with the need of only one receiver at each client device. Copyright © 2012 John Wiley & Sons, Ltd.     

Cooperative user–network interactions in next generation communication networks

Next Generation Communication Networks employ the idea of convergence, where heterogeneous access technologies may coexist, and a user may be served by anyone of the participating access networks, motivating the emergence of a Network Selection mechanism. The triggering and execution of the Network Selection mechanism becomes a challenging task due to the heterogeneity of the entities involved, i.e., the users and the access networks. This heterogeneity results in different and often conflicting interests for these entities, motivating the question of how they should behave in order to remain satisfied from their interactions. This paper studies cooperative user–network interactions and seeks appropriate modes of behaviour for these entities such that they achieve own satisfaction overcoming their conflicting interests.     

A security protocol for D2D communications in 5G networks using elliptic curve cryptography

International Journal of Information Security - Advancements in the field of wireless and mobile communication motivate academia, industry, and standardisation organisations to explore new...     

A multilevel optimal control approach to dynamic bandwidth allocation in broadband ISDN

In this paper a novel scheme for the dynamic allocation of bandwidth at the virtual path level in B-ISDNs is presented. A fluid flow model is developed to describe the time varying mean behaviour of a virtual path and serves as a state variable model. A multilevel optimal control theoretic approach is used in conjunction with the state model to derive a coordinated decentralised algorithm for virtual path bandwidth allocation. The integration of the virtual path bandwidth controller into a hierarchically organised network control scheme is incorporated in the problem formulation. The performance of the proposed scheme is evaluated using simulation.A version of this paper appears in the proceedings of INFOCOM'95.     

Biotelemetry of cardiovascular hemodynamic measurements inminiswine

A three-channel biotelemetry system has been designed and implemented for use in a chronically instrumented animal model of cardiovascular disease. A dual-channel ultrasonic transit-time micrometer allows monitoring of left-ventricular wall motion for the regions perfused by the left circumflex and left anterior descending coronary arteries. A third channel provides left ventricular blood pressure obtained from a high-fidelity blood pressure transducer implanted in the left ventricle. The biotelemetry system features a high voltage dc-dc converter for improved ultrasonic signal strength, a time-to-voltage converter that is highly immune to synchronization frequency variations, low power consumption (approx. 100 mW), small size (4 x 6 x 12 cm), and low weight (approx. 200 g). This three-channel system has enabled our laboratory to continuously monitor untethered animals for 24-h periods. Data obtained from this miniature biotelemetry system can be utilized to quantify myocardial oxygen demand and regional left-ventricular wall thickening.     

Computational intelligence in management of ATM networks

Designing effective control strategies for asynchronous transfer mode (ATM) networks is known to be difficult because of the complexity of the structure of networks, nature of the services supported, and variety of dynamic parameters involved. Additionally, the uncertainties involved in identification of the network parameters cause analytical modeling of ATM networks to be almost impossible. This renders the application of classical control system design methods (which rely on the availability of these models) to the problem even harder. Consequently, a number of researchers are looking at alternative non-analytical control system design and modeling techniques that have the ability to cope with these difficulties to devise effective, robust ATM network management schemes. Those schemes employ artificial neural networks, fuzzy systems and design methods based on evolutionary computation. In this survey, the current state of ATM network management research employing these techniques as reported in the technical literature is summarized. The salient features of the methods employed are reviewed.     

Adaptive nonlinear congestion controller for a differentiated-services framework

The growing demand of computer usage requires efficient ways of managing network traffic in order to avoid or at least limit the level of congestion in cases where increases in bandwidth are not desirable or possible. In this paper we developed and analyzed a generic Integrated Dynamic Congestion Control (IDCC) scheme for controlling traffic using information on the status of each queue in the network. The IDCC scheme is designed using nonlinear control theory based on a nonlinear model of the network that is generated using fluid flow considerations. The methodology used is general and independent of technology, as for example TCP/IP or ATM. We assume a differentiated-services network framework and formulate our control strategy in the same spirit as IP DiffServ for three types of services: Premium Service, Ordinary Service, and Best Effort Service. The three differentiated classes of traffic operate at each output port of a router/switch. An IDCC scheme is designed for each output port, and a simple to implement nonlinear controller, with proven performance, is designed and analyzed. Using analysis performance bounds are derived for provable controlled network behavior, as dictated by reference values of the desired or acceptable length of the associated queues. By tightly controlling each output port, the overall network performance is also expected to be tightly controlled. The IDCC methodology has been applied to an ATM network. We use OPNET simulations to demonstrate that the proposed control methodology achieves the desired behavior of the network, and possesses important attributes, as e.g., stable and robust behavior, high utilization with bounded delay and loss, together with good steady-state and transient behavior.     

Calvarial and limb bone cells in organ and monolayer culture do not show the same early responses to dynamic mechanical strain

Responses to mechanical strain in calvaria and limb bone organ cultures were compared by measuring cellular glucose 6-phosphate dehydrogenase (G6PD) activity in situ and prostaglandin release. Normal functional strains were recorded in the ulnae (1000 mu epsilon) and calvarium (30 mu epsilon) in vivo in 110 g rats. Organ cultures of ulnae and calvaria from similar animals were loaded to produce dynamic strains (600 cycles, 1 Hz) of 1000 mu epsilon in the ulna, and 100 or 1000 mu epsilon in calvaria. In ulnae, both PGE2 and PGI2 were released and resident osteocytes and osteoblasts showed increased G6PD activity. Neither response was seen in calvaria. However, exogenous PGI2 (10(-5)-10(-9) M) stimulated G6PD activity in osteocytes and osteoblasts in organ cultures of both calvaria and ulnae. In ulnar cells the response was linear, in calvarial cells it was biphasic with maximum activity at 10(-7) M. Osteoblasts derived from ulnae and cultured on plastic plates subjected to dynamic strain (600 cycles, 1 Hz, 4000 mu epsilon) showed increased G6PD activity. There was no such response in similarly treated calvarial-derived cells. Calvarial bone cells differ from those of the ulna in that they do not respond to physiological strains in their locality with increased prostanoid release or G6PD activity either in situ or when seeded onto dynamically strained plastic plates. Cells from both sites in organ culture show increased G6PD activity in response to exogenous PGI2, but their dose:responses differ in shape. These differences may reflect the extent to which functional loading influences bone architecture in these two sites.     

Fuzzy explicit marking: A unified congestion controller for Best-Effort and Diff-Serv networks

This paper, proposes a generic active queue management (AQM) control methodology in TCP/IP networks, based on Fuzzy logic control principles. A simple, effective and efficient non-linear control law is built, using a linguistic model of the system, rather than a traditional mathematical model, which is easily adapted in different network environments (e.g. Best-Effort and Differentiated-Services architectures). We demonstrate, via extensive simulative evaluation, that the proposed Fuzzy control methodology offers inherent robustness with effective control of the system under widely differing operating conditions, without the need to (re)tune any parameters. As demonstrated, this is in contrast with its well-known conventional counterparts A-RED, REM, PI, AVQ for Best-Effort, and two-level PI, RIO for Differentiated-Services based networks, where the proposed approach outperforms all of them both in Best-Effort and Differentiated-Services architecture application scenarios. Furthermore, the proposed approach is applied without any retuning for the two architectures using the same Fuzzy logic controller for both, with the only difference being in the setting of the target queue lengths for different precedence levels in Differentiated-Services.