QoS support using SWAN model in mobile ad-hoc networks

Mobile Ad-Hoc Network (MANET) is a collection of mobile nodes, dynamically forming a temporary network without pre-existing network infrastructure or centralized administration. Due to the bandwidth constraint and dynamic topology of MANETs, supporting quality of Service (QoS) in MANETs is a challenging task. MANETs have certain unique characteristics that pose several difficulties in provisioning QoS. Most routing protocols for MANETs are designed without explicitly considering QoS of the routes. QoS-aware routing requires to find a route that satisfies the end-to-end QoS requirement. QoS in MANETs is a rapidly growing area of research interest. In this report, the challenges of QoS support for MANETs are discussed first.Then the current research on QoS support in MANETs is reviewed, followed by extensive discussion and analysis of QoS models and QoS routing. Finally, one of the QoS models - SWAN is studied to provide a qualitative assessment of the applicability of the model.

QoS support using SWAN model in mobile ad-hoc networks

Mobile Ad-Hoc Network (MANET) is a collection of mobile nodes, dynamically forming a temporary network without pre-existing network infrastructure or centralized administration. Due to the bandwidth constraint and dynamic topology of MANETs, supporting quality of Service (QoS) in MANETs is a challenging task. MANETs have certain unique characteristics that pose several difficulties in provisioning QoS. Most routing protocols for MANETs are designed without explicitly considering QoS of the routes. QoS-aware routing requires to find a route that satisfies the end-to-end QoS requirement. QoS in MANETs is a rapidly growing area of research interest. In this report, the challenges of QoS support for MANETs are discussed first.Then the current research on QoS support in MANETs is reviewed, followed by extensive discussion and analysis of QoS models and QoS routing. Finally, one of the QoS models - SWAN is studied to provide a qualitative assessment of the applicability of the model.

Navigation Signal Design and Ranging Performance Evaluation of Cn Band Based on Satellite-to-Ground Link

As the only priority frequency band for navigation services except L protected by ITU, the Cn band could provide navigation services to solve problems of spectrum congestion and vulnerability to interference faced in L using global navigation satellite systems. However, Cn band navigation still faces some problems such as limited-bandwidth and link uncertainty. To solve these problems, an orthogonal MSK signal is designed in this paper under Cn limited bandwidth constraint. The analysis results show that although it’s ranging performance of narrow correlation spacing has been deteriorated, the performance of wide correlation spacing has been improved, and it can reduce 98.7% power interference to adjacent radio astronomy band. On the other hand, the Cn band navigation signal test based on the satellite-to-ground link is carried out in this paper. The test results show that the trend of designed signals’ ranging performance is consistent with the simulation results and its rain attenuation is 0.5–1dB.

Distributed Primal-Dual Optimization for Online Multi-Task Learning

Conventional online multi-task learning algorithms suffer from two critical limitations: 1) Heavy communication caused by delivering high velocity of sequential data to a central machine; 2) Expensive runtime complexity for building task relatedness. To address these issues, in this paper we consider a setting where multiple tasks are geographically located in different places, where one task can synchronize data with others to leverage knowledge of related tasks. Specifically, we propose an adaptive primal-dual algorithm, which not only captures task-specific noise in adversarial learning but also carries out a projection-free update with runtime efficiency. Moreover, our model is well-suited to decentralized periodic-connected tasks as it allows the energy-starved or bandwidth-constraint tasks to postpone the update. Theoretical results demonstrate the convergence guarantee of our distributed algorithm with an optimal regret. Empirical results confirm that the proposed model is highly effective on various real-world datasets.

Attitude stabilization of flexible spacecraft under limited communication with reinforced robustness

This paper proposes a robust event-driven control for attitude regulation in flexible spacecraft affected by inertial parametric uncertainties and external disturbances. The bandwidth constraint of the communication channel between controller and system requires an event-based control design. Under the action of proposed control law, the system trajectories are ensured to be uniformly ultimately bounded (UUB) in a small vicinity of their equilibrium points. Apart from the boundedness of states, the proposed event-triggered controller also satisfies bandwidth restrictions by achieving a substantially low control usage. The results obtained from numerical simulations are indeed encouraging. It demonstrates the proposed controller as a potential alternative to the periodically sampled data controllers. Moreover, the proposed control strategy successfully eludes the unwanted unwinding phenomenon encountered in quaternion based attitude control of the spacecraft.