Showing papers by "Shivkumar Kalyanaraman published in 2011"

Virtual base station pool: towards a wireless network cloud for radio access networks

Abstract: The mobile Internet has seen tremendous progress due to the standardization efforts around WiMAX, LTE and beyond. There are also early trends towards adoption of software radio and a growing presence of general purpose platforms in wireless networking. Such platforms are programmer-friendly and with recent advances on multi-core and hybrid architectures, allow signal processing, network processor class packet processing, wire-speed computation and server-class virtualization capabilities for software radio realizations of 3G and 4G wireless stacks. Software radio over IT platforms will enable the virtualization of base stations and consolidation of virtual base stations into central pools (a local "cloud site") with fiber connectivity to towers, which we call a Wireless Network Cloud (WNC). A Virtual base station (BS) pool supporting multiple BS software instances over a general OS and IT platform is an important step towards the realization of the larger WNC concept. This paper introduces the first TDD WiMAX SDR BS implemented on a commodity server, in conjunction with a novel design of a remote radio head (RRH). We also present the first working prototype of a virtual BS (VBS) pool, exploring the systems challenges in supporting a VBS pool on multi-core IT platforms. The results from our VBS pool prototype for WiMAX verify that these solutions can meet system requirements including synchronization, latency and jitter.

VMFlow: leveraging VM mobility to reduce network power costs in data centers

Abstract: Networking costs play an important role in the overall costs of a modern data center. Network power, for example, has been estimated at 10-20% of the overall data center power consumption. Traditional power saving techniques in data centers focus on server power reduction through Virtual Machine (VM) migration and server consolidation, without taking into account the network topology and the current network traffic. On the other hand, recent techniques to save network power have not yet utilized the various degrees of freedom that current and future data centers will soon provide. These include VM migration capabilities across the entire data center network, on demand routing through programmable control planes, and high bisection bandwidth networks. This paper presents VMFlow: a framework for placement and migration of VMs that takes into account both the network topology as well as network traffic demands, to meet the objective of network power reduction while satisfying as many network demands as possible. We present network power aware VM placement and demand routing as an optimization problem. We show that the problem is NP-complete, and present a fast heuristic for the same. Next, we present the design of a simulator that implements this heuristic and simulates its executions over a data center network with a CLOS topology. Our simulation results using real data center traces demonstrate that, by applying an intelligent VM placement heuristic, VMFlow can achieve 15-20% additional savings in network power while satisfying 5-6 times more network demands as compared to recently proposed techniques for saving network power.

Phase identification in smart grids

Abstract: Electricity is distributed throughout the electrical power network in 3-phase voltage. This power reaches households as a single-phase voltage, generally 115vac or 240vac. This is achieved by allocating households with either phases A, B, or C of the final 3-phase power distributed to the street through a low voltage transformer. A present problem confronting the electrical power industry is identification of which particular phase a household is connected to. This information is often not tracked and the mechanisms for identifying phase require either manual intervention or costly signal injection technologies. Phase information is important as it is a foundation for the larger problem of balancing phase loads. Unbalanced phases lead to significant energy losses and sharply reduced asset lifetimes. In this paper we propose a new approach to compute household phase. Our techniques are novel as they are purely based upon a time series of electrical power measurements taken at the household and at the distributing transformer. Our methods involve the use of integer programming and solutions can be retrieved using branch and bound search algorithms implemented by MIP solvers such as CPLEX. Furthermore, as the number of measurements increase, continuous relaxations of integer programs may also be used to retrieve household phase efficiently. Simulation results using a combination of synthetic and real smart meter datasets demonstrate the performance of our techniques and the number of measurements needed to uniquely identify household phase.

Systems and methods for phase identification

Abstract: Described herein are methods, systems, apparatuses and products for phase determination in an electricity grid. An aspect provides for determining phase for at least one electric grid device via receiving power consumption measurements derived from electricity grid devices connected in the electricity grid, comparing, over a series of time intervals, a total power consumed; and determining a phase for at least one electricity grid device.

CPS-Net: In-network aggregation for synchrophasor applications

Abstract: Synchrophasors are sensors that sample power grids and publish these measurements over a network to a number of grid applications such as voltage monitoring, state estimation, visualization, etc. The sampled data is QoS sensitive and must be delivered reliably with minimal delays to the target applications. However, during network overloads or grid emergencies when the volume of data transmitted is high, it is important to gracefully degrade performance and data stream delivery in an application-specific manner.

Video object placement for cooperative caching

Abstract: A method, an apparatus and an article of manufacture for placing at least one object at at least one cache of a set of cooperating caching nodes with limited inter-node communication bandwidth. The method includes transmitting information from the set of cooperating caching nodes regarding object accesses to a placement computation component, determining object popularity distribution based on the object access information, and instructing the set of cooperating caching nodes of at least one object to cache, the at least one node at which each object is to be cached, and a manner in which the at least one cached object is to be shared among the at least one caching node based on the object popularity distribution and cache and object sizes such that a cumulative hit rate at the at least one cache is increased while a constraint on inter-node communication bandwidth is not violated.

Systems and methods for road acoustics and road video-feed based traffic estimation and prediction

Abstract: Methods and arrangements for employing roadside acoustics sensing in ascertaining traffic density states. Traffic monitoring input is received from a road segment, the traffic monitoring input including traffic audio input. The traffic monitoring input is processed and the processed traffic monitoring input is classified with a predetermined traffic density state. The classified traffic monitoring input is combined with other classified traffic monitoring input.

DTN routing using explicit and probabilistic routing table states

Abstract: Routing in communication networks involves the indirection from a persistent name (ID) to a locator. The locator specifies how packets are delivered to a destination with a particular ID. Such a mapping is provided by a routing table entry, i.e. state. In a DTN, it is hard to maintain routing state because intermittent connectivity prevents protocols from refreshing states when they become inaccurate. In prior work, per-destination state mostly corresponds to utilities, where a high utility value about a destination implies that the probability to encounter the destination for the node maintaining the state is high. This approach depends on a particular mobility pattern in which nodes that met frequently in the past are likely to encounter in the future. In this paper, we use the concept of weak state that does not rely on external messages to remain valid (Acer et al. in MobiCom '07: proceedings of the 13th annual ACM international conference on mobile computing and networking, pp 290---301, 2007). Our weak state realization provides probabilistic yet explicit information about where the destination is located. We build Weak State Routing protocol for Delay Tolerant Networks (WSR-D) that exploits the direction of node mobility in forwarding. It provides an osmosis mechanism to disseminate the state information to the network. With osmosis, a node has consistent information about a portion of the nodes that are located in regions relevant to its direction of mobility. Through simulations, we show that WSR-D achieves a higher delivery ratio with smaller average delay, and reduces the number of message transfers in comparison to Spray & Wait (Spyropoulos et al. in Proceedings of ACM SIGCOMM 2005 workshops: conference on computer communications, pp 252---259, 2005) and Spray & Focus (Spyropoulos et al. in IEEE/ACM Trans Netw, 16(1):77---90, 2008), a stateless and a utility based protocol, respectively.

Multi-tiered, burstiness-aware bandwidth estimation and scheduling for VBR video flows

Abstract: The increasing demand for high-quality streaming video delivered to mobile clients necessitates efficient bandwidth utilization and allocation at not only the wireless channel but also the wired backhaul of broadband wireless networks. In this context, we propose techniques for increasing the link utilization and enhancing the quality-of-experience (QoE) for end users while multiplexing video streams over a wired link. For increasing the link utilization, we present a generic multi-tiered bandwidth estimation and scheduling scheme that can guarantee lower bounds on loss for flows at lower tiers. This scheme can be used for supporting heterogeneous loss classes, differentiated losses for different layers of video streams, or per-flow guarantees using lower aggregate bandwidth than schemes proposed in the literature. For enhancing the end-user QoE, we present a scheme for minimizing correlated losses and improving the smoothness of video quality by minimizing the maximum loss suffered by any logical unit of a stream and also the variability in loss across the length of the stream. In simulations performed using MPEG-4 sources, our loss-minimization approach could lower the maximum loss by a factor of five and the loss variance by more than an order of magnitude. Our multi-tiered scheme could lower the estimated bandwidth and improve statistical multiplexing gains by 10-20% with three classes, 5--20% with two classes, and over 30% in the context of providing deterministic per-flow guarantees.

Caching large objects with multiple, unknown, and varying anchor points at an intermediary proxy device

Abstract: Methods and arrangements for caching video object portions. A request for stand-alone content in a video object is received, the content neither being cached nor being adjacent to a cached video object portion, and a first portion of the video object is cached. A value is assigned to the first video object portion. A subsequent request for content in the video object is received, the subsequent request corresponding to access to the first video object portion and a second, uncached portion of the video object. The value of the first video object portion is updated. For the second video object portion, an amount to cache and a value are determined.

Systems and methods for managed video services at edge-of-the-network

Abstract: Systems and methods for managing video delivery to mobile device clients. Videos are assimilated for transmission to clients, a playout lead is estimated for each video and the videos are transmitted to the clients.

Monitoring mobile user quality-of-experience on a wireless network

Abstract: Embodiments of the invention provide monitoring of the Quality-of-Experience (QoE) of a mobile user of a wireless network without introducing any additional packets or requiring user feedback. Furthermore, embodiments of the invention provide QoE information based on certain control messages that may be utilized for reporting, research, or monitoring purposes. As such, a service provider could utilize the QoE information provided by embodiments of the invention to, among other possibilities, manage, upgrade, or enhance their wireless network to ensure a quality network experience for end users.

An advanced model for the short-term forecast of wind energy

Abstract: A novel short-term wind energy forecasting method, which is being developed under the University of Brunei Darussalam - International Business Machines (UBD-IBM) renewable energy modeling initiative, is described in this paper. The paper starts with a brief review on the existing forecasting methods. Prediction models based on the physical (derived from Numerical Weather Prediction models) and Time Series approaches are discussed. The prediction errors under these methods are described and the need for a reliable forecasting system is emphasized. This is followed by a detailed discussion on the UBD-IBM approach. The baseline of the proposed forecasting system is the IBM Deep Thunder. Deep thunder is a highly modified version of the Regional Atmospheric Modeling System (RAMS). This high resolution Weather forecasting system can predict the local Weather variations on a 'day ahead' basis, at high accuracy levels. For a given wind farm site, specific Deep Thunder models could be developed and calibrated using the surface measured wind data. This enables the Deep Thunder to predict the wind profile at the wind farm locations over shorter time scales. Once the wind spectra at the reference height are obtained from the Deep Thunder, terrain characteristics of the wind farm site are introduced to the model using the geotropic drag law. This will further be extended to the specific turbine location by considering local variations in surface roughness, orographic effects etc. The wind farm wake effect is introduced to the model at this stage. Velocity deficit experienced by the downstream turbines due to the presence of the upstream ones would be modeled. A semi empirical approach, based on the conservation of momentum, would be adopted. With these procedures, the wind velocity, 'actually felt' by individual turbines in the farm could be predicted. From this predicted wind velocity at the hub height, the expected energy yield from individual turbines over a given time period is estimated. For this, the probability density of these wind speeds within the 'look-ahead period' and the power curve of the turbines are combined and integrated over the functional velocity range of the wind generator. The total energy expected from the wind farm can be computed by adding the energy yields from individual turbines.

Towards a Sustainable Services Ecosystem for Traffic Management

Abstract: Traffic management has been a major concern for cities around the world. However, despite traffic problems having a widespread impact in any city, alleviating it has primarily remained the city administrations concern. We argue that sustainable traffic management requires the creation of a services-based ecosystem mediated by city administration but open to businesses and citizens to contribute and benefit from. We illustrate such an eco-system using the case-study of acquiring traffic data by mining mobile phone usage of citizens, and discuss the business and technical considerations to implement it based on our experience in a city of developing country that has heterogeneous vehicles following chaotic patterns.

Managed service delivery in 4g wireless networks

Abstract: Systems and methods for managed service delivery at the edge in 4G wireless networks for: dynamic QoS (Quality of Service) provisioning and prioritization of sessions based on the task (current, future) of the workflow instance; predicting the current and future network requirements based on the current and future tasks of all business process sessions and prepare session QoS accordingly; providing an audit trail of business process execution; and reporting on business process execution.

Object placement for cooperative caches with bandwidth constraints

Abstract: The projected growth in video traffic delivered to mobile devices is expected to stress the backhaul and core of a broadband wireless network. Caches deployed at the edge elements, such as base stations, are one of alleviating this stress. Limits on the sizes of the base station caches and restrictions on frequent upgrades to the hardware necessitate that techniques that can increase the hit rates with the growing traffic, given the constraints, be explored. In this paper, we consider using cooperative caching schemes for the purpose. The edge elements are connected via bandwidth-constrained links, and hence, the assumption made in most prior work that the cooperating nodes are located on a high-speed network do not apply here. We show that the problem of placing objects to maximize hit rate in such a bandwidth-constrained caching system is NP-hard in the strong sense. We develop an efficient placement algorithm when the caches have identical characteristics and show that its performance is within a constant factor of the optimal under practical conditions. We also discuss how to extend the algorithm for the non-identical case. Our simulation experiments show that in practice, the performance of our algorithm is very close to the optimal and a few tens of cooperating nodes are sufficient to significantly increase the hit rate even with a 1% base cache size.