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65
Implementing Interference Cancellation to Increase the EVDO Rev A Reverse Link Capacity
 IEEE Comm. Magazine
, 2006
"... The EVDO Revision A system [1] was designed to support applications ranging from wireless internet connectivity to VoIP, video telephony, and broadcast services over a wide area cellular ..."
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Cited by 14 (3 self)
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The EVDO Revision A system [1] was designed to support applications ranging from wireless internet connectivity to VoIP, video telephony, and broadcast services over a wide area cellular
Joint transmission scheduling and congestion control for adaptive streaming in wireless devicetodevice networks,” journal in preparation
"... Abstract—We consider the jointly optimal design of a transmission scheduling and admission control policy for adaptive streaming over wireless devicetodevice networks. We formulate the problem as a dynamic network utility maximization and observe that it naturally decomposes into two subproblems: ..."
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Cited by 11 (3 self)
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Abstract—We consider the jointly optimal design of a transmission scheduling and admission control policy for adaptive streaming over wireless devicetodevice networks. We formulate the problem as a dynamic network utility maximization and observe that it naturally decomposes into two subproblems: admission control and transmission scheduling. The resulting algorithms are simple and suitable for distributed implementation. The admission control decisions involve each user choosing the quality of the video chunk asked for download, based on the network congestion in its neighborhood. This form of admission control is compatible with the current video streaming technology based on the DASH protocol over TCP connections. We also consider a mechanism for dropping bits from the transmission queues in order to obtain deterministic bounds on the queueing delays, which determine the number of video chunks that should be prefetched in order to guarantee smooth playback without interruptions. I.
Accurate Localization of RFID Tags Using Phase Difference
"... Abstract—Due to their light weight, low power, and practically unlimited identification capacity, radio frequency identification (RFID) tags and associated devices offer distinctive advantages and are widely recognized for their promising potential in contextaware computing; by tagging objects with ..."
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Cited by 9 (0 self)
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Abstract—Due to their light weight, low power, and practically unlimited identification capacity, radio frequency identification (RFID) tags and associated devices offer distinctive advantages and are widely recognized for their promising potential in contextaware computing; by tagging objects with RFID tags, the environment can be sensed in a cost and energyefficient means. However, a prerequisite to fully realizing the potential is accurate localization of RFID tags, which will enable and enhance a wide range of applications. In this paper we show how to exploit the phase difference between two or more receiving antennas to compute accurate localization. Phase difference based localization has better accuracy, robustness and sensitivity when integrated with other measurements compared to the currently popular technique of localization using received signal strength. Using a softwaredefined radio setup, we show experimental results that support accurate localization of RFID tags and activity recognition based on phase difference. Index Terms—RFID localization, phase difference, maximum likelihood estimation, softwaredefined radio. I.
Interference Mitigation via Joint Detection
"... This paper addresses the design of optimal and nearoptimal detectors in an interference channel with fading and with additive white Gaussian noise (AWGN), where the transmitters employ discrete modulation schemes as in practical communication scenarios. The conventional detectors typically either i ..."
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Cited by 9 (2 self)
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This paper addresses the design of optimal and nearoptimal detectors in an interference channel with fading and with additive white Gaussian noise (AWGN), where the transmitters employ discrete modulation schemes as in practical communication scenarios. The conventional detectors typically either ignore the interference or successively detect and then cancel the interference, assuming that the desired signal and/or the interference are Gaussian. This paper quantifies the significant performance gain that can be obtained if the detectors explicitly take into account the modulation formats of the desired and the interference signals. This paper first describes the optimal maximumlikelihood (ML) detector that minimizes the probability of detection error for a given modulation scheme, and the joint minimumdistance (MD) detector, which is a lowercomplexity approximation of the ML detector. It is then demonstrated by analysis and by simulation that in an AWGN channel, while interferenceignorant and successive interference cancellation detectors are both prone to error floors, the optimal ML and joint MD detectors are not. This paper further analyzes the performance of joint detection in a Rayleigh fading environment. It is demonstrated that the joint detector can achieve symbol error rates that have the same dependence on the received signaltonoise ratio (SNR) as if the channel were interference free. Thus, the performance of joint detection is fundamentally limited by the SNR rather than the signaltointerference ratio (SIR). Moreover, the joint detector enables the use of transmit diversity schemes to achieve the same diversity order as in the absence of interference. These results show that the use of interferenceaware detectors can significantly alleviate the effect of interference thereby improving the achievable rates and the reliability of future wireless systems.
Cooperative beamforming for wireless ad hoc networks
, 2007
"... Abstract—Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a MACPHY crosslayer s ..."
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Abstract—Via collaborative beamforming, nodes in a wireless network are able to transmit a common message over long distances in an energy efficient fashion. However, the process of making available the same message to all collaborating nodes introduces delays. In this paper, a MACPHY crosslayer scheme is proposed that enables collaborative beamforming at significantly reduced collaboration overhead. It consists of two phases. In the first phase, nodes transmit locally in a random access timeslotted fashion. Simultaneous transmissions from multiple source nodes are viewed as linear mixtures of all transmitted packets. In the second phase, a set of collaborating nodes, acting as a distributed antenna system, beamform the received analog waveform to one or more faraway destinations. This step requires multiplication of the received analog waveform by a complex weight, which is independently computed by each cooperating node, and which allows packets bound to the same destination to add coherently at the destination node. Assuming that each node has access to location information, the proposed scheme can achieve high throughput, which in certain cases exceeds one. An analysis of the symbol error probability corresponding to the proposed scheme is provided. I.
Stbcschemes with nonvanishing determinant for certain number of transmit antennas
 IEEE Transactions on Information Theory
, 2005
"... Abstract — This paper presents a systematic technique for constructing STBCschemes (SpaceTime Block Code schemes) with nonvanishing determinant, based on cyclic division algebras. Prior constructions of STBCschemes with nonvanishing determinant are available only for 2, 3, 4 and 6 transmit ante ..."
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Abstract — This paper presents a systematic technique for constructing STBCschemes (SpaceTime Block Code schemes) with nonvanishing determinant, based on cyclic division algebras. Prior constructions of STBCschemes with nonvanishing determinant are available only for 2, 3, 4 and 6 transmit antennas. In this paper, by using an appropriate representation of a cyclic division algebra over a maximal subfield, we construct STBCschemes with nonvanishing determinant for the number of transmit antennas of the form 2 k or 3 · 2 k or 2 · 3 k or q k (q − 1)/2, where q is a prime of the form 4s +3 and s is any arbitrary integer. In a recent work, Elia et.al. have proved that nonvanishing determinant is a sufficient condition for STBCschemes from cyclic division algebra to achieve the optimal DiversityMultiplexing Gain (DMG) tradeoff; thus proving that the STBCschemes constructed in this paper achieve the optimal DMG tradeoff.
Improving Small Cell Capacity with CommonCarrier Full Duplex Radios
"... Abstract — Recent progress in establishing the capability of radios to operate in full duplex mode on a single channel has been attracting growing attention from many researchers. We extend this work by considering the application to small cells, in particular resourcemanaged cellular systems simil ..."
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Abstract — Recent progress in establishing the capability of radios to operate in full duplex mode on a single channel has been attracting growing attention from many researchers. We extend this work by considering the application to small cells, in particular resourcemanaged cellular systems similar to the TDD variant of LTE. We derive conditions where full duplex operation provides improved throughput compared to half duplex for a single cell scenario. We present a hybrid scheduler that defaults to half duplex operation but can assign full duplex timeslots when it is advantageous to do so. We compare the performance of such a scheduler with a traditional half duplex scheduler in terms of throughput and energy efficiency. Our simulation results show that we achieve as much as 81 % of the capacity doubling promised by full duplex, with limitations deriving from interference effects specific to full duplex operation. I.
1 Preamble Sampling MAC Protocols with Persistent Receivers in Wireless Sensor Networks
"... Abstract — We provide an analytical framework for preamble sampling techniques for MAC protocols in wireless sensor networks, from which we derive closedform formulas for lifetime and reliability calculations. In addition to take into account transmitter behavior that controls the form and the cont ..."
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Abstract — We provide an analytical framework for preamble sampling techniques for MAC protocols in wireless sensor networks, from which we derive closedform formulas for lifetime and reliability calculations. In addition to take into account transmitter behavior that controls the form and the content of the transmitted preamble, our model also considers receiver behavior that controls the duration of preamble reception in case of successful and failed reception. Along with both transmitter and receiver behavior, our model considers a nonperfect channel and thus takes into account the impacts of transmission errors and retransmissions on lifetime and reliability of preamble sampling protocols. Numerical results show that no protocol is universally optimal; that is, each protocol has its own optimal operation point that depends on the given channel and load conditions. I.
Reciprocity in Linear Deterministic Networks under Linear Coding
, 907
"... Abstract—The linear deterministic model has been used recently to get a first order understanding of many wireless communication network problems [1][3][4][8]. In many of these cases, it has been pointed out that the capacity regions of the network and its reciprocal (where the communication links a ..."
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Abstract—The linear deterministic model has been used recently to get a first order understanding of many wireless communication network problems [1][3][4][8]. In many of these cases, it has been pointed out that the capacity regions of the network and its reciprocal (where the communication links are reversed and the roles of the sources and the destinations are swapped) are the same. In this paper, we consider a linear deterministic communication network with multiple unicast information flows. For this model and under the restriction to the class of linear coding, we show that the rate regions for a network and its reciprocal are the same. This can be viewed as a generalization of the linear reversibility of wireline networks, already known in the network coding literature [10]. I.
Cognitive radios in the TV whitespaces: challenges and opportunities,” Master’s thesis
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