The highest NIC bonding performance is achieved by the round-robin scheduling mode. However, we found that the performance was much lower than the theoretical limit due to out-of-order TCP packet delivery. So our work proposes a load-balanced NIC bonding scheduling approach as a significant improvement over the current state-of-the-art. We pro- pose that the outgoing packets should be queued on interfaces with the least amount of packets waiting to be sent. This allows the load to be well balanced over all interfaces thereby reducing the probability of packets arriving out-of-order at their destination. This work presents an analysis of all currently available NIC bonding modes in terms of perfor- mance. A new bonding simulation framework was developed to facilitate the development of alternate scheduling algorithms and compare their performance. This helped us analyze and propose load-based scheduling as a better alternative to the most popularly used round-robin scheduling mode.

Path planning for an autonomous vehicle in a dynamic environment is a challenging problem particularly if the vehicle has to utilize its complete maneuvering abilities, perceive its environment with a high degree of accuracy and react to unsafe conditions. Trajectory planning in an environment with stationary and moving obstacles has been the topic of considerable interest in robotics communities and much of the work focuses on holonomic and non-holonomic kinematics. Optimal path planning has been approached using numerical optimization techniques planning the navigation of ground and aerial navigation producing realistic results in spite of computational complexity. Most of the previous work discussed uses static obstacles and autonomous vehicles moving in closed indoor environments involving prior knowledge of its environment using map based localization and navigation. The work that has focused on dynamic environments with moving obstacles having assumptions of completely known velocities don't account for uncertainty during obstacle motion prediction. Estimation based approaches use grid-based environment representation of the state space, discretized velocities and linear motion models. This simulation aims at finding an optimal trajectory by obtaining the optimal longitudinal and lateral maneuvers using the vehicle's sensing and predictive capabilities for path planning in continuous 2-D space. The focus is on specific scenarios using spatial and temporal constraints while navigating and it involves timed maneuvering in between periods of straight line motion as for a typical unmanned ground vehicle. It also combines tracking obstacles independently and relative localization with targets to achieve its objective. The parametric space of longitudinal and lateral velocities is generated for the host vehicle aiming to reach a goal state configuration within a pre-specified time threshold. This considers independently the cases for completely known trajectories of obstacles and motion under uncertainty. The results of constrained non-linear optimization allow the vehicle to trace its trajectory given its known initial and destination configuration along with known velocity profiles, noise models and range-bearing measurements to the targets in its vicinity. Simulation results show that the proposed scenario-specific approaches produce reasonable maneuvers within the admissible velocity ranges.

The proceedings of the second international workshop on reliable networks design and modeling, which was held in Moscow, Oct. 19 and 20, 2010.

Recent work on cooperative communications has demonstrated benefits in terms of improving the reliability of links through diversity and/or increasing the reach of a link

compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide such benefits using space-time coding. In a multi-hop sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node, which will use its neighbors and so on to reach the destination. For the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions.

However, the presence of malicious or compromised nodes in

the network impacts the use of cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions may fare better or worse than SISO transmissions.

In this paper, we develop a performance modeling technique for analyzing the time varying network layer queueing behavior of multihop wireless networks with constant bit rate traffic. Our approach is a hybrid of fluid flow queueing modeling and a time varying connectivity matrix. Network queues are modeled using fluid-flow based differential equation models which are solved using numerical methods, while node mobility is modeled using deterministic or stochastic modeling of adjacency matrix elements. Numerical and simulation experiments show that the new approach can provide reasonably accurate results with significant improvements in the computation time compared to standard simulation tools. © 2010 IEEE.

Simple calibration-free localization techniques using proximity to multiple monitoring stations are cost-effective and avoid the need for laborious measurements, calibration, and large search spaces for RF fingerprints. Proximity-based localization does not suffer from multi-path problems associated with localization that employs time, time difference, or angle of arrival measurements. We propose Sub-Area Localization (SAL) that uses the sub-areas created by the overlapping ranges of monitoring stations (MoSs) to estimate the location of a mobile node. We investigate the relationship between localization accuracy (that depends on the number and sizes of sub-areas) and the monitoring ranges of MoSs when they are placed on a virtual grid in a given workspace. We present analytical and simulation results that allow us to determine the "best" range of monitoring stations, and understand the limits on the accuracy performance of SAL. © 2010 ACM.

Core networks are increasingly supporting overlay networks on top of an IP-WDM network. As network reliability is a growing concern, a major challenge in the survivable layered network design is the crosslayer survivable mapping problem that deals with QoS parameters such as availability, lightpath length, and many others. This work directly studies this problem and proposes matrix formulations of the NP-hard mapping problem, giving a detailed insight into the structure of the layered network as well as relationships between and among links, and some potential mapping extensions. Numerical experiments show availability gains at no expense, occasionally, to the routing cost. ©2010 IEEE.

The unifying network architecture has contributed to a wave of work on layered network evolution. The undertaking of this paper is twofold: This paper's first-of-its-kind examination of the problems of logical link mapping and traffic flow routing unveils that backhaul traffic, a flow loop that occurs at any lower link layer below the traffic layer except its own, could happen in the traffic flow routing even when no backhaul occurs in the link mapping, prompting our discussion on the investigation of crosslayer survivable link mapping when traffic layers are explicitly considered and survivability is required. In addition to the theoretical treatment on the connection among and between link and traffic layers, a forbidden link matrix is also identified masking part of the network for use in situations where some physical links are reserved exclusively for a designated service, mainly for the context of providing multiple levels of differentiation on the network use. The masking effect is then evaluated on two metrics using two practical approaches in a sample real-world network, showing that both efficiency and practicality can be achieved. ©2010 IEEE.

We propose a novel technique called dimming to improve the energy efficiency of cellular networks by reducing the capacity, services, and energy consumption of cells without turning off the cells. We define three basic methods to dim the network: coverage, frequency, and service dimming. We construct a multi-time period optimization problem to implement frequency dimming and extend it to implement both frequency and service dimming together. We illustrate the ability of dimming techniques to adapt the capacity and network services in proportion to the dynamic spatial and temporal load resulting in significant energy savings through numerical results for a sample network. ©2010 IEEE.

This paper considers the problem of where a survivability technique should be deployed in a network based on managing risk given a limited financial budget. We formulate three novel risk management resilient network design techniques: (1) minimize the maximum damage that could occur in the network, (2) minimize the maximum risk in the network and (3) minimize the root mean squared damage. The first two approaches try to minimize the damage/risk from the worst case failure scenario, where as the third technique minimizes the variability of damage across all failure scenarios. Numerical results for a sample network show the tradeoffs among the schemes. ©2010 IEEE.

Channel Bonding (CB) combines two adjacent frequency bands to form a new, wider band to facilitate high data rate transmissions in MIMO-based 802.11n networks. However, the use of a wider band with CB can exacerbate interference effects. Furthermore, CB does not always provide benefits in interference-free settings, and can even degrade performance in some cases. We conduct an in-depth, experimental study to understand the implications of CB. Based on this study we design an auto-configuration framework, ACORN, for enterprise 802.11n WLANs. ACORN integrates the functions of user association and channel allocation, since our study reveals that they are tightly coupled when CB is used. We show that the channel allocation problem with the constraints of CB is NP-complete. Thus, ACORN uses an algorithm that provides a worst case approximation ratio of [EQUATION] with • being the maximum node degree in the network. We implement ACORN on our 802.11n testbed. Our experiments show that ACORN (i) outperforms previous approaches that are agnostic to CB constraints; it provides per-AP throughput gains from 1.5x to 6x and (ii) in practice, its channel allocation module achieves an approximation ratio much better than [EQUATION]. © 2010 ACM.

802.11n has made a quantum leap over legacy 802.11 systems by supporting extremely higher transmission rates at the physical layer. In this paper, we ask whether such high rates translate to high qual- ity links in a real deployment. Our experimental investigation in an indoor wireless testbed reveals that the highest transmission rates advertised by the 802.11n standard typically produce losses (or even outages) even in interference-free environments. Such losses become more acute and persist at high SNR values, even at low interference intensity. We find that these problems are partly due to bad configurations that do not allow exploitation of spatial di- versity, partly due to the wider 802.11n channels that expose these sensitive high rates to more interference. We show that these prob- lems can be alleviated using the 802.11n MAC layer enhancements jointly with packet size adaptation. Copyright 2010 ACM.

Spectrum trading markets are of growing interest to many spectrum management agencies. They are motivated by their desire to increase the use of market based mechanisms for spectrum management and reduce their emphasis on command and control methods. Despite the liberalization of regulations on spectrum trading in some countries, spectrum markets have not yet emerged as a key spectrum assignment component. The lack of liquidity in these markets is sometimes cited as a primary factor in this outcome. This work focuses on determining the conditions for viability of spectrum trading markets by considering scenarios with different market structures, number of trading participants and amount of tradable spectrum. We make use of Agent-Based Computational Economics (ACE) to analyze each market scenario and the behaviors of its participants. Our models indicate that spectrum markets can be viable in a service if sufficient numbers of market participants exist and the amount of tradable spectrum is balanced to the demand. We use the results of this analysis and the characteristics of the viable markets found to make recommendations for the design of spectrum trading markets. Further work will explore more complicated scenarios. ©2010 IEEE.

The cognitive radio literature generally assumes that the functions required for non-cooperative secondary DSA are integrated into a single radio system. It need not be so. In this paper, we model cognitive radio functions as a value chain and explore the implications of different forms of organization of this value chain. We initially explore the consequences of separating the sensing function from other cognitive radio functions. ©2010 IEEE.

This paper analyses optimal pricing of two different platforms of broadband mobile internet access where one provider uses third generation (3G) and the other WiFi. The authors utilised a game theoretic competition model considering population density, user's preference for bandwidth and coverage, user's willingness-to-pay, the number of hot-spots, cost structure of deployment, and market penetration rate. The authors used both simulation and computation methods to find the market equilibrium point. Through the equilibrium analysis, the authors found that the 3G network is more profitable as WiFi coverage percentage increases, and 3G is more favourable in higher density areas. Copyright © 2010 Inderscience Enterprises Ltd.