Nikola Zogovic

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

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.

State-of-the-art low-power transceivers for the next generation of wireless sensor networks motes

In this paper we evaluate capabilities of the last generation commercial off-the-shelf low-power wireless communication transceivers for energy/spectrum-efficient transmission while satisfying quality of service requirements. We set ten appropriate criteria and select six transceivers to evaluate. We find that provided decision space regarding energy-efficiency at PHY/MAC layers is improved, compared to the previous generation of the transceivers, but an ample space for spectrum-efficiency improvement still exists.

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.

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 controller for transmission parameters adaptation to wireless channel with energy-efficiency goal

In this paper we present a controller for transmission power and packet length adaption to wireless channel attenuation change with an energy-efficiency goal. Due to convexity of energy function the controller can be based on Hill Climbing method. The proposed method achieves minimum energy point even in 12 steps, reducing complexity up to 10000 times compared to classical numerical evaluation, making it run-time compatible.

Energy efficiency utilizing lookup table in wireless sensor networks

In this paper we present a method for calculation of minimal energy parameters in packet transmission using lookup table. The parameters are transmission power and packet length. The proposed solution depends on careful selection of transmission energy points to be pre-calculated to achieve accuracy greater than 99.9%. This way, energy minimum can be found almost instantaneous with as little as 7700B of memory space usage. From the perspective of wireless sensor network nodes, methods utilizing lookup tables can reduce time needed for obtaining solution considerably, compared to numerical methods, since it is faster to locate data in table than to calculate it, especially when complex calculations are required.

Optimal Pulse-Doppler Waveform Design for VHF Solid-State Air Surveillance Radar

VHF radars are suitable in some air surveillance applications, due to their cost-effectiveness and the fact that radar cross section of an aircraft is larger at VHF band than at higher frequencies, making detection easier. To ensure coverage of all ranges and velocities of interest, contemporary VHF radars utilize a complex waveform. We formulate the design of this waveform as a multiobjective optimization problem, with signal-to-noise ratio (SNR), Doppler visibility and Doppler resolution as objectives, which should be maximized. We show that the objectives are in conflict and use a particular example to explore the Pareto frontier (PF) for the problem. We find that reasonable tradeoff can be made between SNR and Doppler visibility, leading to an idea of multiple modes of operation, selectable at run time. We conclude that this subject is worth of further investigation, and that finding an efficient method for determining the PF would facilitate further research.