Krishna Moorthy Sivalingam

Recently, there has been a tremendous growth in mobile network traffic. Network providers are looking for techniques that selectively offload the mobile data traffic onto WiFi (IEEE 802.11) networks to balance the load and improve network performance. Several architectures based on Proxy Mobile IPv6 (PMIPv6) have been proposed to support seamless data offloading. The demerits of PMIPv6 include lack of flow mobility and single point of failure. There exist architectures that extend PMIPv6 to support flow mobility, but still face the problem of overhead at the gateway and single point of failure. In this paper, we propose Seamless Internetwork Flow Mobility (SIFM), a new architecture that overcomes these drawbacks and provides seamless data offload supporting flow mobility. Both the PMIPv6 and the SIFM architectures have been implemented and evaluated incorporating salient LTE and WiFi network features in the ns-3 simulator. The performance studies validate that seamless mobility can be achieved for clients in both of these architectures. The results show that for the best possible (scenario dependent) offload value, the SIFM architecture shows an improvement of 13.86%, 29.05% and 11.33% whereas the PMIPv6 architecture shows an improvement of 7.96%, 19.52% and 7.83% in terms of delay, packet loss and throughput respectively compared to no offload scenario in each architecture. Further, we also show that the support for flow mobility in the SIFM architecture provides the flexibility to move selective flows to another network. This helps in achieving better performance gain compared to moving all the flows of the user as done in the PMIPv6 architecture.

Various Centrality measures such as Degree, Closeness, and Betweenness were introduced in order to analyze networks and understand both the global dynamics of the networks and the roles played by individual nodes. It will be worthwhile to rank the centrality measures of each node and an index of the distribution of centrality measures in the entire network. In this paper, we define the notion of entropy of centrality measures, which extends the concept of centrality to the whole network. We show that this measure has wide range of applications, in network design, from designing maximally efficient networks to identifying dominance of one node or link in the context of entire network. In particular, we present an application to tactical wireless networks. Copyright © 2013 by the IEEE.

Tracking mobile targets is an important wireless sensor network application in both military and civilian fields. Often, it may be necessary for sending additional resources to the vicinity of the mobile target. In such a scenario, it is pertinent to provide continuous guidance to the friendly resource moving towards the mobile target. This paper presents a mechanism for the guidance of a friendly object towards the mobile target, and associated performance analysis in terms of the time taken to reach the target. © 2011 IEEE.

3GPP has developed the Discontinuous Reception (DRX) power saving mechanism, which periodically turns off the radio interface to reduce power consumption. However, packets cannot be received during the on period, as a result that the Quality of Services (QoS) may be violated. In addition, channel condition may be unstable during the transmission, so the optimal DRX parameters should also be dynamically adjusted. In this paper, we propose the Dynamic Scheduling with Extensible Allocation and Dispersed Offsets (DXD) scheme, which is composed of two algorithms, DRX parameter decision algorithm, to determine the DRX period by considering channel condition and QoS constraints, and DRX-aware scheduling algorithm, to determine whether to extend the on duration so that QoS would not be affected by DRX. Simulation results demonstrate that our DXD approach can reduce power consumption up to 96.9% compared to no DRX scheme and guarantee QoS as good as no DRX scheme. © 2014 IEEE.

In current generation LTE networks, user mobility leads to high levels of signaling traffic from the eNodeB (Evolved Node B) to the Evolved Packet Core (EPC) for maintaining the GPRS Tunneling Protocol (GTP) and Proxy Mobile IPv6 (PMIPv6) tunnel. Further, the presence of Packet Gateway (PGW) at the network edge introduces additional delay for every signaling procedure. In this paper, we propose an improved EPC architecture based on Software Defined Networking (SDN) concepts. This architecture (logically) centralizes the control plane functionality of EPC thereby eliminating the use of mobility management protocols and reducing mobility related signaling costs. The architecture utilizes the global network view feature of SDN for mobility management. The proposed architecture has been implemented in the ns-3 simulator framework. The results quantify the performance of the proposed architecture in terms of signaling cost, tunneling cost, handover latency and scalability.

Transport technologies such as Optical Transport Network and Synchronous Digital Hierarchy are widely used in access and core networks to carry different types of traffic. These technologies define a hierarchy for multiplexing lower rate traffic containers onto higher rate traffic containers. Provisioning refers to the process of allocation of resources to meet a given traffic demand. Due to the continued expansion of transport networks, the power consumption increases, becoming a bottleneck for further expansion. Power-aware allocation of resources to traffic demands will enable power-efficient operation and help in minimizing the capital and operational costs of the network. In this paper, the power consumed by a switch matrix having the capability to switch different traffic containers at different amounts is considered. The objective is to minimize the number of network elements deployed in the network by allocating resources to traffic demands in power-efficient ways. A formulation based on Integer Linear Programming is first presented; later, four different heuristic approaches, based on how higher order trails are used and the use of grooming, are proposed. It is found that the grooming-based heuristics perform better in terms of the total power consumption relative to the weighted number of requests accepted. In the grooming heuristics, threshold on link utilization is set to determine when grooming is to be done, and for the same performance evaluation, it is found that the threshold of 80% gives better results.

This paper deals with the efficient design of network switch/routers for an optical data center network. Each switch has multiple components such as ingress/egress interfaces, optical and/or electronic buffers, interconnection switching fabric and so on. There are several possible choices available for each of these components. This paper presents a systematic approach to designing the switch architecture using a combination of these component choices, while meeting specified design criteria. It requires formally defining the structure of a switch and enforcing semantics across components. This is formulated as a constraint optimization problem with formal language grammar guiding its search process. This problem formulation is used to identify the best-possible architecture for a hierarchical DCN. Two of the three solutions identified were new and were not reported in literature. These solutions were also validated experimentally.

3GPP has developed the Discontinuous Reception (DRX) power saving mechanism, which periodically turns off the radio interface to reduce the power consumption. However, packets cannot be received during the turn-off duration, as a result that the Quality of Services (QoS) may be violated. Therefore, optimal DRX parameters should be configured to satisfy QoS and minimize power consumption. In addition, channel condition may be unstable during the transmission, so the DRX parameters should also be dynamically adjusted. In this paper, we propose the Dynamic Scheduling with Extensible Allocation and Dispersed Offsets (DXD) scheme, which is composed of two algorithms, DRX parameters decision, to determine DRX period by considering channel condition and QoS constraints, and DRX-aware scheduling, to determine whether to extend the on duration so that QoS would not be affected by DRX. Simulation results demonstrate that the proposed DXD approach can reduce power consumption up to 96.7% compared to No-DRX scheme and guarantee QoS as good as No-DRX scheme. In addition, the power consumption can be reduced by 70.1% and 45.7% compared to the Fixed-DRX (100 ms), start-offset scheme and TS scheme in good channel condition. Our approach effectively reduces power consumption in varied channel conditions and high loading system and still achieves better delay satisfaction ratio than others.

Target tracking is one of the major applications of Wireless Sensor Networks (WSN). In traditional target tracking with directional sensors, the target can be detected only when it is in the field of view (FoV) of a sensor. The target's track is obtained with the help of filtering algorithms/techniques at the base station (BS). These techniques sometimes lead to incorrect location estimation of the target due to measurement errors and noise. It is ideally required that the main sensing lobe/FoV of the sensor follow the target, whenever the target is in the FoV of the sensor. Based on the above considerations, this paper proposes an efficient solution to target tracking with the help of beam steering enabled directional sensors mounted on the nodes for tracking the targets. At every step of beam steering, the sensor node updates the location of the target to the nearest cluster head or base station. Each sensor will continuously monitor the target till it crosses the FoV or sensing range of the sensor. The proposed method has been implemented in OMNeT++ and the performance of the algorithm has been evaluated with directional active and passive sensors. Different target mobilities and different sensor FoV angles have been considered. The results show that the proposed method successfully tracked the target and located the target at every instant of time. Directional active sensors yield more accurate results when compared to passive sensors. It was also seen that the location accuracy of the target was mainly dependent on the FoV angle and FoV/sensing radius of the sensor. © 2012 IEEE.