Department Publications

Multiple antenna techniques that allow energy beamforming have been looked upon as a possible candidate for increasing the transfer efficiency between the energy transmitter (ET) and the energy receiver in wireless power transfer. This paper introduces a novel scheme that facilitates energy beamforming by utilizing received signal strength indicator (RSSI) values to estimate the channel. First, in the training stage, the ET will transmit using each beamforming vector in a codebook, which is predefined using a Cramer-Rao lower bound analysis. RSSI value corresponding to each beamforming vector is fed back to the ET, and these values are used to estimate the channel through a maximum likelihood analysis. The results that are obtained are remarkably simple, requires minimal processing, and can be easily implemented. The paper also validates the analytical results numerically, as well as experimentally, and …

A throughput analysis is conducted for a large scale peer-to-peer wireless network whose devices are capable of operating in both full- and half-duplex modes, using the tools of stochastic geometry. Each device selects its operating duplex mode based on the distance to its partner node. In both duplex modes, the energy consumption and the hardware configurations of the nodes are made equivalent for fair comparisons between full-duplex and half-duplex operations. Using the results of the analysis, an approach is proposed to determine a distance threshold value for duplex mode selection, and the proposed distance threshold can be computed offline. It is found that the throughput performance of the hybrid full-/half-duplex network generated with the proposed distance threshold based duplex mode selection technique outperforms both the pure half-duplex and pure full-duplex network settings for most …

We present a simulation study of a cooperate car following application implemented by the Wireless Access for Vehicular Environments (WAVE) protocol stack, which uses the MAC and Physical layers defined by the IEEE 802.11p protocol. This is a simple Intelligent Transportation Systems (ITS) application which forms the foundation for autonomous driving. As with many safety-critical ITS applications, cooperate car following uses beaconing as the primary means of communication. The beacon frequency and the transmit power of the mobile nodes are considered as the key communication parameters, while the vehicle density is considered as the key traffic parameter. The two main factors affecting the performance, the end-to-end delay and the packet loss, are studied for different scenarios defined by the above parameters. Results indicate how the application performance may be improved by adapting the …

We consider a single-input-single-output (SISO) system with quadrature phase shift keying (QPSK) modulation and derive an easy-to-evaluate expression for the symbol error probability (SEP) when a general n-bit phase quantization is used at the receiver. We further evaluate the expressions asymptotically to characterize the diversity order and the quantization penalty at high signal-to-noise ratios (SNRs). We observe that the system with n-bit phase quantization achieves full diversity order of one when n > 2. Numerical examples are used to verify the analysis.

This paper presents a comprehensive framework to analyze the impact of aggregate interference from an underlay clustered Device-to-Device (D2D) network on the performance of its primary cellular network, when different power control schemes are used at the D2D network. A single base station, located at the center, operates with a cellular network and a D2D network, modeled using a homogeneous spatial Poisson Point Process and a Poisson Cluster Process, respectively. Using this system, the cellular network performance is examined under three power control schemes used by the D2D network namely, no power control, path loss inversion and channel inversion. For each scheme, the coverage probability of the cellular network is analyzed. Numerical results indicate that the cellular network performance is greatly dependent on the D2D system parameters such as density, size of a cell, number of …

Power control schemes are proposed for a full-duplex (FD) device-to-device (D2D) network operating as an underlay of a primary FD network. As networks with different quality of service (QoS) requirements may coexist in future heterogeneous networks, it is assumed that the underlay D2D network is operating with best effort QoS provisioning, while the primary FD network requires guaranteed QoS. A centralized power control (CPC) solution is proposed by casting the power control problem as a convex optimization problem. Furthermore, a heuristic distributed power control (DPC) solution is proposed to reduce information feedback overhead. It is found that the heuristic DPC achieves D2D user data rate that is within 87% and 80% of that provided by the CPC scheme in 3-node and 2-node FD primary network, respectively.