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Jayakrishnan Nair

Publications and source records attributed to Jayakrishnan Nair.

42 records · Page 3Linked to original sources
arXiv2019

Sponsored data with ISP competition

We analyze the effect of sponsored data platforms when Internet service providers (ISPs) compete for subscribers and content providers (CPs) compete for a share of the bandwidth usage by the customers. Our analytical model is of a full information, leader-follower game. ISPs lead and set prices for sponsorship. CPs then make the binary decision of sponsoring or not sponsoring their content on the ISPs. Lastly, based on both of these, users make a two-part decision of choosing the ISP to which they subscribe, and the amount of data to consume from each of the CPs through the chosen ISP. User consumption is determined by a utility maximization framework, the sponsorship decision is determined by a non-cooperative game between the CPs, and the ISPs set their prices to maximize their profit in response to the prices set by the competing ISP. We analyze the pricing dynamics of the prices set by the ISPs, the sponsorship decisions that the CPs make and the market structure therein, and the surpluses of the ISPs, CPs, and users. This is the first analysis of the effect sponsored data platforms in the presence of ISP competition. We show that inter-ISP competition does not inhibit ISPs from extracting a significant fraction of the CP surplus. Moreover, the ISPs often have an incentive to significantly skew the CP marketplace in favor of the most profitable CP.

cs.NI↗
arXiv2019

Temperature Overloads in Power Grids Under Uncertainty: a Large Deviations Approach

The advent of renewable energy has huge implications for the design and control of power grids. Due to increasing supply-side uncertainty, traditional reliability constraints such as strict bounds on current, voltage and temperature in a transmission line have to be replaced by computationally demanding chance constraints. In this paper we use large deviations techniques to study the probability of current and temperature overloads in power grids with stochastic power injections, and develop corresponding safe capacity regions. In particular, we characterize the set of admissible power injections such that the probability of overloading of any line over a given time interval stays below a fixed target. We show how enforcing (stochastic) constraints on temperature, rather than on current, results in a less conservative approach and can thus lead to capacity gains.

math.OC↗
arXiv2019

Sizing Storage for Reliable Renewable Integration: A Large Deviations Approach

The inherent intermittency of wind and solar generation presents a significant challenge as we seek to increase the penetration of renewable generation in the power grid. Increasingly, energy storage is being deployed alongside renewable generation to counter this intermittency. However, a formal characterization of the reliability of renewable generators bundled with storage is lacking in the literature. The present paper seeks to fill this gap. We use a Markov modulated fluid queue to model the loss of load probability (LOLP) associated with a renewable generator bundled with a battery, serving an uncertain demand process. Further, we characterize the asymptotic behavior of the LOLP as the battery size scales to infinity. Our results shed light on the fundamental limits of reliability achievable, and also guide the sizing of the storage required in order to meet a given reliability target. Finally, we present a case study using real-world wind power data to demonstrate the applicability of our results in practice.

eess.SY↗
arXiv2018

Sharing within limits: Partial resource pooling in loss systems

Fragmentation of expensive resources, e.g., spectrum for wireless services, between providers can introduce inefficiencies in resource utilisation and worsen overall system performance. In such cases, resource pooling between independent service providers can be used to improve performance. However, for providers to agree to pool their resources, the arrangement has to be mutually beneficial. The traditional notion of resource pooling, which implies complete sharing, need not have this property. For example, under full pooling, one of the providers may be worse off and hence have no incentive to participate. In this paper, we propose partial resource sharing models as a generalization of full pooling, which can be configured to be beneficial to all participants. We formally define and analyze two partial sharing models between two service providers, each of which is an Erlang-B loss system with the blocking probabilities as the performance measure. We show that there always exist partial sharing configurations that are beneficial to both providers, irrespective of the load and the number of circuits of each of the providers. A key result is that the Pareto frontier has at least one of the providers sharing all its resources with the other. Furthermore, full pooling may not lie inside this Pareto set. The choice of the sharing configurations within the Pareto set is formalized based on bargaining theory. Finally, large system approximations of the blocking probabilities in the quality-efficiency-driven regime are presented.

cs.NI↗
arXiv2018

On QoS-Compliant Telehaptic Communication over Shared Networks

The development of communication protocols for teleoperation with force feedback (generally known as telehaptics) has gained widespread interest over the past decade. Several protocols have been proposed for performing telehaptic interaction over shared networks. However, a comprehensive analysis of the impact of network cross-traffic on telehaptic streams, and the feasibility of Quality of Service (QoS) compliance is lacking in the literature. In this paper, we seek to fill this gap. Specifically, we explore the QoS experienced by two classes of telehaptic protocols on shared networks - Constant Bitrate (CBR) protocols and adaptive sampling based protocols, accounting for CBR as well as TCP cross-traffic. Our treatment of CBR-based telehaptic protocols is based on a micro-analysis of the interplay between TCP and CBR flows on a shared bottleneck link, which is broadly applicable for performance evaluation of CBR-based media streaming applications. Based on our analytical characterization of telehaptic QoS, and via extensive simulations and real network experiments, we formulate a set of sufficient conditions for telehaptic QoS-compliance. These conditions provide guidelines for designers of telehaptic protocols, and for network administrators to configure their networks for guaranteeing QoS-compliant telehaptic communication.

cs.NI↗
arXiv2017

Congestion Control for Network-Aware Telehaptic Communication

Telehaptic applications involve delay-sensitive multimedia communication between remote locations with distinct Quality of Service (QoS) requirements for different media components. These QoS constraints pose a variety of challenges, especially when the communication occurs over a shared network, with unknown and time-varying cross-traffic. In this work, we propose a transport layer congestion control protocol for telehaptic applications operating over shared networks, termed as dynamic packetization module (DPM). DPM is a lossless, network-aware protocol which tunes the telehaptic packetization rate based on the level of congestion in the network. To monitor the network congestion, we devise a novel network feedback module, which communicates the end-to-end delays encountered by the telehaptic packets to the respective transmitters with negligible overhead. Via extensive simulations, we show that DPM meets the QoS requirements of telehaptic applications over a wide range of network cross-traffic conditions. We also report qualitative results of a real-time telepottery experiment with several human subjects, which reveal that DPM preserves the quality of telehaptic activity even under heavily congested network scenarios. Finally, we compare the performance of DPM with several previously proposed telehaptic communication protocols and demonstrate that DPM outperforms these protocols.

cs.NI↗