Goran Dimic

PHY-MAC Cross-Layer Approach to Energy-Efficiency and Packet-Loss Trade-off in Low-Power, Low-Rate Wireless Communications

In this paper we analyze energy-efficiency and packet-loss trade-off at physical and medium access control layers. The trade-off can be tuned by proper setting of packet length, transmission power and maximal number of allowed transmissions per packet. Our approach is multi-objective without decision making preferences. We show how energy-efficiency vs. packet-loss Pareto Frontier can be determined. We present numerical results for the case when CC1000 transceiver is used. Contrary to intuition, we find that Pareto Frontier is not a continual locus, meaning that energy-efficiency and packet-loss can not be traded continually in Pareto Optimality sense.

Channel Loss Based Energy Consumption Model for Low-Power Wireless Communications

Transmission power control can significantly improve energy-efficiency of wireless sensor network communications. Power consumption models are typically based on dependence of channel attenuation on distance. However, in practice, information on distance is usually not available and the dependence of channel attenuation on distance is not sufficiently accurate. Therefore, we propose more accurate power consumption model that uses information on total channel-loss, available on the most current low-power transceivers. We formulate the problems of selecting single-hop vs. multi-hop communication, and minimal energy route optimization, based on the proposed power consumption model.

PHY-MAC cross-layer approach to energy-efficiency improvement in low-power communications

This paper presents the improvement of energy-efficiency in low-power communications by joint usage of transmission power control, packet length optimization and packet aggregation techniques. We find that there are optimal transmission power and packet length for each channel condition (within operating range) and control data overhead that minimize energy per transmitted bit of data. Since optimal packet length strongly depends on control data overhead, we employ packet aggregation technique to reduce control data and additionally improve the efficiency. This approach shows more than 60% of energy savings, compared to transmissions of short packets with maximal available transmission power

Distributed RSS-Based Localization in Wireless Sensor Networks with Node Selection Mechanism

In this work, we address the target localization problem in large-scale cooperative wireless sensor networks (WSNs). Using the noisy range measurements, extracted from the received signal strength (RSS) information, we formulate the localization problem based on the maximum likelihood (ML) criterion. ML-based solutions are particularly important due to their asymptotically optimal performance, but the localization problem is highly non-convex. To overcome this difficulty, we propose a convex relaxation leading to second-order cone programming (SOCP), which can be efficiently solved by interior-point algorithms. Furthermore, we investigate the case where target nodes limit the number of cooperating nodes by selecting only those neighbors with the highest RSS measurements. This simple procedure may decrease the energy consumption of an algorithm in both communication and computation phase. Our simulation results show that the proposed approach outperforms the existing ones in terms of the estimation accuracy. Moreover, they show that the new approach does not suffer significant degradation in its performance when the number of cooperating nodes is reduced.

Packet length and transmission power adaptation for energy-efficiency in low-power wireless communications

We analyze how packet length and transmission power influence energy per transmitted bit of data in low-power communication between two neighbouring wireless sensor network nodes. We find that optimal transmission power level and packet length exist for every channel condition and control data overhead that minimize energy per transmitted bit of data. Compared to transmissions of short packets with maximal available transmission power level our approach shows more than 60 % of energy savings, when CC1000 transceiver is used.

A “raised-fractional-power” wireless transmitter power consumption model

Wireless communications afford mobility and flexible network topologies of computer networks. However, their energy efficiency must keep improving. Since the major power consumer in a wireless transmitter is the power amplifier, energy efficiency can be improved by reducing transmit power depending on the channel conditions and performance metrics. We propose a novel transceiver power consumption model for Class A, AB and B power amplifiers. It is a better fit than the existing affine model of the total transmitter power consumption, as a function of the transmit power. In the model, we explicitly upper- and lower-bound transmit power.

HbbTV application for DVB-T2

The purpose of this paper is to present an approach to enable the overview of Internet content via digital terrestrial TV. The chosen content will be transmitted over a DVBT/ DVB-T2 broadcast network to the receiver (Set-top-box) and it will be displayed on TV screens. Simple TV application is developed for emulation of Internet content on TV screen, based on HbbTV standard, but in absence of broadband (or any other) Internet connection and without return channel from TV receiver to the repeater.

Supportive relay with heterogeneous transceivers: Quantification of energy efficiency improvement

Energy consumption of two-hop transmission via supportive relay is derived and compared with energy consumption of the direct link between the same source and destination. First, a model of total transceiver power consumption as a function of transmit power is reviewed. Assuming adaptive transmission power control with perfect knowledge of channel loss, the total transceiver power consumption becomes a function of the channel loss. We derive the ratio between two-hop and single-hop energy consumption as a function of channel loss along each of the three links. The equipotential planes of this ratio are compared with the operating region of the transceivers, in the space of channel losses. We show how the transceiver parameters influence energy efficiency of two-hop supportive relay, relative to the direct link, and apply the analysis to the cellular scenario with one relay between the base station and a user terminal.

A geodesic descent technique for PAPR reduction in MIMO-OFDM

In this paper, we present a geodesic descent technique for reducing the peak-to-average power ratio (PAPR) reduction of multi-input, multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems where each OFDM block is decomposition sets of subcarriers, each one weighted by a different complex factor. We present a new iterative sphere-geodesic descent method for obtaining these weighting factors so as to minimize the PAPR of the transmitted signals. This method, makes an efficient use of the Riemannian structure of the power constraint. Our performance results show that our technique allows good trade-off between the PAPR reduction and the bit error rate (BER) performance.

Industrial Single Board Computer based on OMAP5 processor

This paper presents a detailed hardware architecture of an industrial embedded computer based on the newest OMAP5 processor from Texas Instruments (TI). This processor has specialized hardware blocks for digital signal processing, video acceleration, 3D graphics and others. Device supports rich set of interfaces, covering wide range of required protocols in industrial applications. Wireless support is enabled via special module, which can be inserted in an on-board connector.