113 research outputs found
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Analysis and design of energy harvesting wireless communication systems
Wireless-powered communication is an emerging technology for powering the
large number of miniature devices of the future. In a wireless-powered communication system, low-power sensors extract energy from the incident wireless signals to
power their operations such as information transmission, sensing or reception. Due to sporadic energy availability, however, such a system is fundamentally different from
a traditionally-powered communication system. This dissertation investigates three distinct aspects of wireless-powered communications to get insights on the system operation. First, leveraging concepts from finite-length information theory, an analytical framework is developed for examining wireless-powered communications with short packets, i.e., in the finite blocklength regime. This is relevant as remotely-powered communications may entail short packets due to small payloads, low-latency requirements, or limited energy to support a longer transmission. Second, using a stochastic geometry framework, an analytical model is developed for characterizing the performance of wireless-powered communications in the millimeter wave (mmWave) band. The proposed model incorporates the key features of mmWave systems such as directional beamforming and sensitivity to building blockages. Finally, the power transfer efficiency and the energy efficiency of a wireless-powered communication system aided by massive MIMO is characterized. The broad goal of this dissertation is to better understand wireless-powered communications in the context of the emerging technologies for 5G.Electrical and Computer Engineerin
On Energy Allocation and Data Scheduling in Backscatter Networks with Multi-antenna Readers
In this paper, we study the throughput utility functions in buffer-equipped
monostatic backscatter communication networks with multi-antenna Readers. In
the considered model, the backscatter nodes (BNs) store the data in their
buffers before transmission to the Reader. We investigate three utility
functions, namely, the sum, the proportional and the common throughput. We
design online admission policies, corresponding to each utility function, to
determine how much data can be admitted in the buffers. Moreover, we propose an
online data link control policy for jointly controlling the transmit and
receive beamforming vectors as well as the reflection coefficients of the BNs.
The proposed policies for data admission and data link control jointly optimize
the throughput utility, while stabilizing the buffers. We adopt the
min-drift-plus-penalty (MDPP) method in designing the control policies.
Following the MDPP method, we cast the optimal data link control and the data
admission policies as solutions of two independent optimization problems which
should be solved in each time slot. The optimization problem corresponding to
the data link control is non-convex and does not have a trivial solution. Using
Lagrangian dual and quadratic transforms, we find a closed-form iterative
solution. Finally, we use the results on the achievable rates of finite
blocklength codes to study the system performance in the cases with short
packets. As demonstrated, the proposed policies achieve optimal utility and
stabilize the data buffers in the BNs
Finite Blocklength Rates over a Fading Channel with CSIT and CSIR
In this work, we obtain lower and upper bounds on the maximal transmission
rate at a given codeword length , average probability of error
and power constraint , over a finite valued, block fading additive
white Gaussian noise (AWGN) channel with channel state information (CSI) at the
transmitter and the receiver. These bounds characterize deviation of the finite
blocklength coding rates from the channel capacity which is in turn achieved by
the water filling power allocation across time. The bounds obtained also
characterize the rate enhancement possible due to the CSI at the transmitter in
the finite blocklength regime. The results are further elucidated via numerical
examples.Comment: 10 pages, 2 figures, results for finite valued fading states, typos
corrected, proofs elaborated, lower bound under short term power constraint
improve
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