Energy has always been one of the fundamental elements in the growth of human society. It is crucial that we improve our energy management due to the ever-growing imbalance in demand-supply. The new wave in the energy sector is characterized by the three D's of decarbonization, decentralization, and digitalization. For a sustainable life, it is necessary that energy is tapped from alternative sources that are renewable to leave a minimal carbon footprint. To integrate different sources with the main power grid, we require two-way communication among them. This makes it indispensable that consumers are empowered to protect their privacy and make them the sole owners of their data. A good access control scheme would ensure security of data, and an efficient trading platform would ensure judicious use of the resources. Here, we propose a framework URJA with an access control scheme and an energy trading platform based on blockchain for a smart grid. The locally available renewable sources of energy are connected to the grid such that demand-supply is managed effectively without loss of efficiency and privacy. A customized consensus scheme based on trust ensures a quick operation in real-time.

As the extend of IoT is spreading to more domains, the human intervention in their operation is becoming minimal to none. Many a times, IoT devices have to interact with an unknown entity, outside their domain. It is difficult for them to identify if the device they are connecting to is authentic or counterfeit. In these circumstances, hardware authentication techniques especially PUF, which is unalterable and unclonable, have a lot of relevance. We propose a PUF-based authentication and key exchange scheme with the challenge response pairs stored in secret share distributed form. This helps to counter a possible ML-based modelling attack and a case of curious intermediaries. Using ECC and a federated identity management makes it applicable for resource-constrained devices too. The results indicate that the scheme proposed is an elastic authentication and key exchange scheme with less computation intensive mechanism for resource constrained end devices whereas intensive and more secure mechanism for others.

In this paper, we consider the inefficiency of distributed routing in a network of parallel links with class-based traffic. Network link behavior is modeled by the M/M/1-GPS queue (i.e. when links use General Processor Sharing(GPS) scheduling scheme to serve packets). Each traffic type is guaranteed a minimum capacity rate on each link using GPS scheduling. We show under specific demand conditions that, among multiple equilibria the worst-case Nash equilibrium occurs when each class dispatcher utilizes all the links to fulfill its demand. Using this fact, we give an upper bound on the Price of Anarchy (PoA). Our results also indicate that, while the price of selfish behavior can be unbounded in a specific demand setting, there exist demand regimes where the bound on PoA is reasonable. These results also apply to the resource allocation or load balancing applications in the processor sharing systems.

In this paper we consider the problem of minimizing delay variance amongst paths utilized for concurrent multi-path routing. We will assume that we are provided with a polynomial size set of paths. Minimizing the variance in the delay will reduce out-of-sequence packets and hence reduce jitter in the received stream. We assume a network with edge delays as well as edge capacities. The edge delays are modelled using constant, affine (including linear) and queueing delays. We show that the problem is NP-hard (even in the case when polynomial-size paths are given and there is no capacity constraint). We also propose a practical heuristic approach and present experimental results on network topologies mimicking large backbone networks.

One of the most important problems in the field of performance optimization for data networks is the problem of routing to achieve delay minimization. This becomes extremely important in the context of providing Quality of Service while satisfying demand. The problem is classical and was considered three decades ago by a number of authors primarily Gallagher, Bertsekas and Garcia-Luna-Aceves. The models attempt to find multiple flow paths to satisfy demands while minimizing the total delay in the network. Over the years it has become clear that in order to reduce congestion, a multipath approach to routing is needed. Moreover to provide explicit guarantee on QoS the routing needs to provide explicit delay bounds on each flow path. In fact the emergence of voice and video services has highlighted the need for explicit delay bounds. In this paper we propose an iterative algorithm that minimizes the maximum delay for individual flows while meeting demand requirements for multiple source-sink pairs. We assume that the delay on links is a convex function of the demand. We also propose to minimize the gap between the maximum and minimum delay paths so that the buffer required at the destination will be small.

How much information can one send through a random ad hoc network of n nodes, if overlaid with a cellular architecture of m base stations? This network model is commonly referred to as hybrid wireless networks and our paper analyzes the above question by characterizing its throughput capacity. Although several research efforts related to throughput capacity exist in the area of hybrid wireless networks, most of these solutions under-explore the capacity analysis. Their results particularly indicate that one can realize only a less than log or no gain on capacity, as compared to pure ad hoc networks, when m scales slower than some threshold. This unsatisfying capacity gain is due to the fact that the base stations were not properly exploited while formulating the capacity analysis. Moreover, these research efforts also assume an one-hop wireless uplink between a node and its associated base station. Nevertheless, with those power-constrained wireless nodes, this assumption clearly indicates an unrealistic scenario. In this paper, we establish the bounds on capacity and delay by resolving the issues in existing efforts and at the heart of our analysis lies a simple routing policy known as same cell routing policy. Our findings particularly stipulate that whether m = O(n/log n) or Ω(n/log n), each node can realize a throughput that scales, sublinearly or linearly, with m. This is in fact a significant result as opposed to previous efforts which claims that if m grows slower than some threshold, the benefit of augmenting those base stations to the original ad hoc network is insignificant. Our analysis also shows that for a maximum per node throughput Λ(n, m), the average end-to-end delay in a hybrid network can be bounded by Θ(Λ(n, m)n/m), which has an inverse relationship to m.

One of the crucial challenges in practical wireless networks is how to provide robust communication over fading channels. Recently, cooperative communications have emerged as a promising approach to achieve spatial diversity and thereby reduce the negative effects of fading on wireless channels. Nevertheless, a few existing works indicate that deploying cooperative relays in large-scale wireless networks can lead to an elevated level of interference which in turn leads to degraded throughput and higher packet losses. It is also well-known that the use of multiple frequency channels can mitigate the wireless interference to a greater extent and thus improve the overall performance of a wireless network. Therefore, it is interesting and important to design and evaluate protocols that can provide the combined potential of both cooperation communication and multiple channels. In this paper, we propose a novel cooperative multi-channel MAC protocol that integrates the capabilities of both multiple channels and cooperative communications at the MAC layer to improve the performance of wireless networks. The performance improvement of our proposed solution is further evaluated by extensive simulations.

In this paper we address the issue of designing multi-path routing algorithms. Multi-path routing has the potential of improving the throughput but requires buffers at the destination. Our model assumes a network with capacitated edges and a delay function associated with the network links (edges). We consider the problem of establishing a specified throughput from multiple source to destination pairs in the network, given bounds on the buffer sizes available at the network intermediate nodes and a bound on the maximum delay that the paths are allowed to have. We formulate the problem using a linear programming model. We also present practical heuristics and present the experimental results on an existing network topology. The results are promising and demonstrate the effectiveness of simultaneous multipaths in the multi-commodity scenario.

The existence of channel variations (or fading) is one of the crucial challenges that affects the capacity of wireless networks. Recently, cooperative communications have emerged as a promising approach to achieve spatial diversity and thereby reduce the negative effects of fading on wireless channels. On the other hand, in addition to channel variations, it is well-known that interference among concurrent transmissions also severely limits the network capacity particularly in multi-hop settings. Recent studies indicate that the use of multiple channels can reduce the wireless interference and thus greatly improve the overall network capacity. In this paper, we propose a model termed as CoopMC which employs multiple channels in cooperative networks to mitigate the impact of interference. This work primarily investigates the capacity of CoopMC in multi-hop settings and derive the asymptotic capacity bounds under random placements of nodes. Our analysis reveals the important insights on when a network can benefit from cooperative communications and how multi-channel networking can further improve the network capacity.

Transmission power plays a crucial role in the design and performance of wireless networks. The issue is therefore complex since an increase in transmission power implies that a high quality signal is received at the receiver and hence an increase in channel capacity. Conversely, due to the shared nature of the wireless medium an increase in transmission power also implies high interference in the surrounding region and hence a quadratic reduction in the capacity of wireless networks. Recent literatures indicate that employing multiple channels can mitigate the negative effects of wireless interference and thus greatly improve the overall network capacity. Therefore, it is worth investigating the effect of exploiting power on the capacity of multi-channel multi-radio (MC-MR) wireless networks. Specifically, in this paper we address the following questions: (a) Can we maximize the capacity of MC-MR wireless networks by exploiting power? (b) Under what criteria can we increase the transmission power of the nodes in a MC-MR network? When n nodes each with m half-duplex interfaces are optimally deployed in a torus of unit area, traffic patterns are optimally assigned, each transmission's range is optimally chosen and in the presence of c channels, we show that in contrast to the setting where nodes transmit at minimum power level Po the transport capacity, measured in bit-meters per second, of MC-MR network exploiting power is increased by Θ(cmin) in region cmin0(c/cmin)α/2and P0nα/2respectively-where cminis the minimum number of channels required to achieve conflict-free transmissions in a network. Our analysis also sheds light into several insights that designers may want to consider to improve the performance of energy-efficient bandwidth-constrained wireless networks.

In this paper we address the issue of designing multi-path routing algorithms. Multi-path routing has the potential of improving the throughput but requires buffers at the destination. Our model assumes a network with capacitated edges and a delay function associated with the network links (edges). We consider the problem of establishing a specified throughput from source to destination in the network, given bounds on the buffer size available at the destination and a bound on the maximum delay paths are allowed to have. A related problem which we consider is to establish bounds on the delay variance (which we call jitter) amongst the paths chosen for the multi-path routing scheme. We show that the problems are NP-complete and present pseudo-polynomial algorithms based on linear programming. We also propose practical heuristics and present the experimental results on an existing network topology. The results are promising.

The issue of efficiently selecting the best available wireless network by a mobile device is an area of active research. Many researchers have proposed several strategies and policies for selecting the appropriate network. These policies differ among each other due to various reasons. The state and load of networks, number and types of wireless networks considered, and preferences of users are some of the reasons that attribute to differences in those proposed policies. As a result, the applicability and efficiency of those policies depend upon certain situations and circumstances. We propose, in this paper, a new concept that will help in utilizing these various policies in a manner that will give better results in a longer run and in various kinds of situations. We have a pool of policies available, and our proposed method will select the policy that is most appropriate according to the current state of user. We modeled this problem as a Markov Decision Process. In the end we provide some heuristics to support our work.

In this paper, we consider a special case of denial of service (DoS) attack in wireless mesh networks (WMNs) known as selective forwarding attack (a.k.a gray hole attacks). With such an attack, a misbehaving mesh router just forwards a subset of the packets it receives but drops the others. While most of the existing studies on selective forwarding attacks focus on attack detection under the assumption of an error-free wireless channel, we consider a more practical and challenging scenario that packet dropping may be due to an attack, or normal loss events such as medium access collision or bad channel quality. Specifically, we develop a channel aware detection (CAD) algorithm that can effectively identify the selective forwarding misbehavior from the normal channel losses. The CAD algorithm is based on two strategies, channel estimation and traffic monitoring. If the monitored loss rate at certain hops exceeds the estimated normal loss rate, those nodes involved will be identified as attackers. Moreover, we carry out analytical studies to determine the optimal detection thresholds that minimize the summation of false alarm and missed detection probabilities. We also compare our CAD approach with some existing solutions, through extensive computer simulations, to demonstrate the efficiency of discriminating selective forwarding attacks from normal channel losses.

Gray hole attacks (a.k.a selective forwarding attacks) are a special case of denial of service (DoS) attack, where a misbehaving mesh router just forwards a subset of the packets it receives but drops the others. In wireless networks, it is particularly hard to detect the presence of such attackers because a packet loss over the wireless link can be due to bad channel quality, medium access collisions, or intentional dropping. In contrast to existing studies, we propose a more practical algorithm known as channel aware detection (CAD) that adopts two strategies, hop-by-hop loss observation and traffic overhearing, to detect the mesh nodes subject to the attack. We derive the optimal detection thresholds by analyzing the false alarm and missed detection probabilities of CAD. We also compare our approach to existing solutions and demonstrate that CAD detects the attackers effectively even in harsh channel conditions.

It is desirable to allow packets with the same source and destination to take more than one possible path. This facility can be used to ease congestion and overcome node failures. One approach toward deploying multipath routing in the networks is by creating virtual paths, e.g. using MPLS. There are however costs associated with establishing and maintaining such virtual connections. In this paper, we present the formulation and an approximate solution for the problem of modeling, creation and optimization of the multiple paths in the networks. The aim is to minimize the cost of operating the network and maximize the utilization, using multiple paths. The polynomial-time approximation algorithm presented is based on mixed and linear programming formulation. This approximate solution has a constant approximation ratio; more precisely the throughput of the paths output by our algorithm is at least 0.14 of the optimum throughput, without exceeding the cost of the optimal solution.

This paper presents a novel medium access control (MAC) protocol intended to provide multi-hop wireless mesh networks with a higher throughput. The proposed MAC-ASA (medium access control with anticipated scheduling and agreement) protocol uses a modified version of the 802.11 CSMA/CA contention handling procedure integrated with a dynamic (time division multiple access) TDMA-like protocol structure. It combines distributed link scheduling algorithm with power control support for router -router communications with a self agreement protocol for the client -router communications. In addition, the proposed algorithm solves the "exposed node" problem by applying multiple frequencies and time saving policies. These features result in a significant improvement of the throughput in many scenarios. Performance results from an OPNET model are presented in this paper.

The static nature of mesh nodes imposes requirements for designing routing metrics that support high throughput and low packet delay. This paper considers the problem of interference-load aware routing in multi channel wireless mesh networks. We propose a new Interference-Load Aware routing metric, ILA, that finds paths with reduced inter-flow and intra-flow interference. The aim of this metric is to route the traffic through congestion free areas and balance the load amongst the network nodes. We incorporate this new metric in the well known AODV routing protocol and study the performance of ILA through simulations. We show that the proposed metric is able to adapt to changes in interfering traffic better than existing link metrics such as ETT and MIC. We also demonstrate that our metric delivers high throughput in multi channel networks.

This paper proposes the ASIMcast (any-source implicit multicast) protocol which builds a bidirectional tree for routing of multicast traffic. ASIMcast includes features addressing issues which have been slowing down the deployment of multicast until now. ASIMcast does not use class D IP addresses to forward multicast data but normal unicast addresses instead. This prevents the collision of different multicast sessions, but mainly, it eases the deployment of multicast by having non-multicast routers (or domains) process multicast traffic as if it were unicast. For the same reason, multicast interdomain routing stops being an issue. ASIMcast also reduces routers memory usage by having routing states stored only at branching routers; non-branching routers are only involved when the tree is being optimized. Finally, ASIMcast is an efficient approach to provide several channels per multicast session with the possibility for the end-user to specify which channel it wants to receive. Simulation and implementation have proved the feasibility and the scalability of ASIMcast.

The combined use of the differentiated services (DiffServ) and multiprotocol label switching (MPLS) technologies is envisioned to provide guaranteed quality of service (QoS) for multimedia traffic in IP networks, while effectively using network resources. These networks need to be managed adaptively to cope with the changing network conditions and provide satisfactory QoS. An efficient strategy is to map the traffic from different DiffServ classes of service on separate label switched paths (LSPs), which leads to distinct layers of MPLS networks corresponding to each DiffServ class. In this paper, three aspects of the management of such a layered MPLS network are discussed. In particular, an optimal technique for the setup of LSPs, capacity allocation of the LSPs and LSP routing are presented. The presented techniques are based on measurement of the network state to adapt the network configuration to changing traffic conditions.

Emerging applications demand strict quality of service from the network. To meet these demands, a suitable path with enough resources needs to be selected. The paper focuses on the path computation in an MPLS network for a traffic flow, based on distance, bandwidth and delay constraints. The goal of the paper is to find a feasible path that minimizes the cost incurred. The cost is attributed to bandwidth carriage, and switching and signaling efforts in the network for the requested connection.

In this paper, a new policy is introduced to determine and adapt the generalized multiprotocol label switching (GMPLS) network topology based on the current traffic load. The objective of the new policy is to minimize the costs involving bandwidth, switching and signaling. The new policy is based on a threshold criterion. The policy is split into two levels, the first deals with the MPLS network and the second with the lightpath level. The two thresholds depends on the cost coefficients and the number of the intermediate hops. Our policy also performs a filtering control to avoid oscillations which occur due to highly variable traffic. The proposed policy has been evaluated by simulation and numerical results, which show its effectiveness and the achieved performance improvement.

In this paper, a new optimal policy is introduced to determine and adapt the generalized multiprotocol label switching (GMPLS) network topology based on the current traffic load. The integrated traffic engineering paradigm provides mechanisms for dynamic addition of physical capacity to optical networks. In the absence of such mechanisms, the rejection of incoming requests will be higher. The objective of the proposed policy is to minimize the costs involving bandwidth, switching and signaling. The policy is derived by utilizing the Markov decision process theory. The new policy is split into two levels: the MPLS network level and the optical network level. In addition to the optimal policy, a sub-optimal policy and a threshold-based policy are also proposed which are less computationally intensive but have comparable performance to the optimal policy. The proposed policies have been evaluated by simulation and compared to some heuristics. Numerical results, which show their effectiveness and the achieved performance improvement, are presented.

We present a method for an on-line traffic optimal estimation on a communication link. The proposed filtering procedure is based on a traffic model consisting of a birth-and-death process, elaborates the current noisy measurements from the link and minimizes the estimation error conditional variance. Performance of the method is tested by considering both simulated and real data. This result is of interest with reference to a possible procedure for bandwidth allocation in the framework of bandwidth brokers. The bandwidth allocation is necessary to provide quality of service guarantees to users and requires, as a preliminary step, on-line traffic estimation.

In this paper, a method for enhancing current QoS routing methods by means of QoS protection is presented. In an MPLS network, the segments (links) to be protected are predefined and an LSP request involves, apart from establishing a working path, creating a specific type of backup path (local, reverse or global). Different QoS parameters, such as network load balancing, resource optimization and minimization of LSP request rejection should be considered. QoS protection is defined as a function of QoS parameters, such as packet loss, restoration time, and resource optimization. A framework to add QoS protection to many of the current QoS routing algorithms is introduced. A backup decision module to select the most suitable protection method is formulated and different case studies are analyzed.

The explosive growth of the Internet has induced a need for developing tools to understand the composition and dynamics of the Internet traffic. Measurements of the various characteristics of a network provide insight into the state and performance of the network whether it is behaving as expected and whether changes in the network have improved or degraded its performance. Available bandwidth on the links of a network is an important metric which can predict the performance of the network. In this paper, an estimation algorithm for the available bandwidth on a link is presented. The algorithm estimates the available bandwidth and tells the duration for which the estimate is valid with a high degree of confidence. The algorithm dynamically changes the number of past samples that an used for prediction and also the duration for which the prediction holds.