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We consider a network coding problem with a single source and multiple sinks. A common set of messages is demanded by all sinks. In addition, each sink demands a private set of messages, which is disjoint from the private set of all other sinks. This pattern of demands is called simultaneous multicast and unicast. This is a specific case of the general connections problem, for which determining the...
Present day smartphones like iPhone and Andriod based phones have lead to explosive growth in traffic over cellular networks. The growth has occurred both in volume and diversity in terms of traffic characteristics. Among the different types of traffic, there is prominent increase in background type of data due to popularity of applications like Facebook, Skype, Email clients etc which keeps exchanging...
Battery powered transmitters face energy constraint, replenishing their energy by a renewable energy source (like solar or wind power) can lead to longer lifetime. We consider here the problem of finding the optimal power allocation under random channel conditions for a wireless transmitter, such that rate of information transfer is maximized. Here a rechargeable battery, which is periodically charged...
Dirty paper coding (DPC) is known to achieve the capacity region of a Gaussian Multiple Input Multiple Output-Broadcast channel (MIMO-BC). Practical DPC schemes using finite length codes are still being actively studied. In this paper, we design a zero-forcing DPC (ZF-DPC) scheme using trellis shaping and Low Density Parity Check (LDPC) codes for a MIMO-BC with two transmit antennas and two users...
Communication through fading channels with conventional signal constellation has a limitation that the nearby points may lead to wrong symbol detection even if any one dimension fades. This limitation can be overcome by phase rotation of symbols where each symbol is rotated by a rotation matrix. In the new constellation, each symbol attains unique real and imaginary components which imply higher diversity...
During peak hours, the focus of an Internet service provider (ISP) is on meeting user demand and maintaining the quality of service of a network. However this leads to under-utilization of network devices/components in different parts of the network. Since the power consumption of network devices are constant and independent of their actual workloads, the under-utilized network devices/components...
An anomaly is an activity that deviates from the wellknown behaviour of the system. Anomaly detection in networks is of interest from two perspectives: an organization's perspective and an Internet Service Provider's (ISP) perspective. Protection of its computer network infrastructure is an important task for all organizations. Organizations desire that their networks are robust and resilient to any...
In this paper, we study an amplify-and-forward (AF) based multiple-input multiple-output (MIMO) cooperative relay network in which beamforming is done by using estimated channels in a Rayleigh fading environment. A protocol for training of the source, relay and destination is described and methods of channel estimation are proposed. Simulation results show that the trained MIMO relay system based...
Segmentation is typically the most computationally expensive step involved in majority of speaker diarization systems. Bayesian Information Criterion (BIC) is a very widely adopted method for segmentation of audio data. While BIC returns fairly good results in terms of segmentation performance, it suffers from the problem of enormous complexity. Moreover, BIC based diarization systems encounter the...
We study the diversity order vs rate of an additive white Gaussian noise (AWGN) channel in the whole capacity region. We show that for discrete input as well as for continuous input, Gallager's upper bounds on error probability have exponential diversity in low and high rate region but only subexponential in the mid-rate region. For the best available lower bounds and for the practical codes one observes...
This paper discusses the condition under which the jitter buffer at the receiver is to be operated for minimum output variance in a TDMoIP framework. The above study would be useful in the design of synchronization algorithms at the receiver of a TDMoIP network. This work uses the results derived in [1] to the above problem. We model the receiver jitter buffer as a M/G/1 queueing system with EARMA...
Several researchers have established the superior performance of spatial audio over monaural audio in multi-talker environments. The advantage provided by spatial audio can be incorporated in an audio teleconferencing system for an enhanced user experience. In our earlier work, a novel scheme for the spatial rendition of audio in an audio teleconferencing situation was proposed based on the concept...
Commercial routers available in market are costly and rely on proprietary software and tools for their operations. Routers based on open source platform can be implemented offering scope for customization. We have implemented a resource constrained router which can perform almost as well as full-blown routers. We report the performance of an implemented two router testbed which provides almost equivalent...
Third Generation Partnership Project (3GPP) Long Term Evolution-Advanced (LTE-A) has considered the deployment of Relay Nodes (RNs) for cost-effective throughput enhancement and coverage extension. The coverage extension (increase in cell radius) depends on the radial position of RNs in the cell. This is because the location of a RN affects the Signal-to-Interference-plus-Noise Ratio (SINR) of the...
Multiple-Input Multiple-Output (MIMO) technology has great potential for improving the throughput of Wireless mesh networks (WMNs). In this paper, we investigate joint rate allocation, routing, and stream control scheduling problem in MIMO-based WMNs, where multiple antennas are exploited to increase the capacity via interference suppression (IS) and/or spatial multiplexing (SM). The notion of transmission...
Grid computing has recently gained tremendous momentum but still is in its infancy. It has the potential for significant cost reduction and the increased operating efficiencies in computing. Although security issues are delaying its fast adoption, grid computing is an unstoppable force and we need to provide security mechanisms to ensure its secure adoption. In this paper, we propose a comprehensive...
We investigate the queue stability in Energy Harvesting Sensor (EHS) nodes under indoor conditions wherein solar energy equipped EHS nodes are deployed for intrusion detection. We implement two policies, namely Throughput Optimal and Greedy and test the conditions under which they ensure queue stability. Energy and Data are injected following a distribution. An important observation is the use of...
In this paper, we consider a two-tier communication scenario in an underwater sensor network. The field nodes form single-hop clusters around the gateway nodes and communicate with them via acoustic wireless links, while the gateway nodes communicate directly via radio frequency (RF) wireless links to the sink node. Thus, the field data is collected at the sink node via two-hop communication links...
Reduction of packet loss in communication network by modifying the transmit queue length is an important research topic. A cross layer aware transmission queue adaptation system of a fixed computing system having multiple physical interfaces is presented here. The proposed system determines the condition of communication channel/network associated with the multiple physical interfaces while transmitting...
The quality of the synthesized speech of text-to-speech (TTS) synthesis systems can be improved by controlling the intensities of speech segments in addition to other prosodic features such as intonation and duration. In this paper we proposed Classification and Regression Tree (CART) to model the intensities of syllables. Positional, contextual and phonological features associated to syllables are...
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