Marcos Tomio Kakitani

Energy Efficiency Analysis of Some Cooperative and Non-Cooperative Transmission Schemes in Wireless Sensor Networks

We compare the energy efficiency of some transmission schemes in wireless sensor networks. By constraining the system to end-to-end throughput requirements, we assume that the nodes in multi-hop and cooperative schemes operate at a spectral efficiency which is twice that of the single-hop transmission. By taking into account the energy consumption of the RF circuitry, we show that cooperation may be considerably more energy efficient than non-cooperative schemes even in small transmission ranges, specially if a feedback channel is available.

Energy Efficiency of Transmit Diversity Systems Under a Realistic Power Consumption Model

We compare the downlink energy efficiency of spatial diversity multiple transmit antenna schemes. We determine the minimum required transmit power for a given outage probability. Our analysis shows that antenna selection is in general the most energy efficient option as it requires a single radio-frequency chain. We also investigate the limiting distances up to which the antenna selection technique outperforms the transmit beamforming scheme for different numbers of transmit antennas.

Comparing the energy efficiency of single-hop, multi-hop and incremental decode-and-forward in multi-relay wireless sensor networks

In this paper we analyze the energy efficiency of single-hop, multi-hop and incremental decode-and-forward in wireless sensor networks composed of multiple nodes. The energy efficiency analysis is constrained by a target outage probability and an end-to-end throughput, while the Nakagami-m distribution is used to model the small scale fading. Our results show that in most scenarios the cooperative incremental decode-and-forward scheme is more energy efficient than the other methods.

Energy efficiency contours for amplify-and-forward and decode-and-forward cooperative protocols

In this paper we compare the energy efficiency of different cooperative schemes by means of energy efficiency contours. We consider a three-nodes cooperative scenario, employing either the amplify-and-forward (AF) or the decode-and-forward (DF) protocol. In the case of the DF protocol we analyse the performance of both repetition coding (RC) and parallel coding (PC). Our analysis shows that the maximum energy efficiency operating point is usually related to the allocation of different transmission rates to each user, while enforcing rate fairness leads the system to a sub-optimum operating point in terms of energy efficiency. Depending on the particular topology, the most energy efficient scheme may be AF or DF, with a clear advantage of DF when the two users are close. Moreover, we demonstrate that the exploitation of a return channel may have a large impact in the energy efficiency, being able to almost double it.

On the energy efficiency of some cooperative and non-cooperative transmission schemes in WSNs

In this paper we compare the energy efficiency of single-hop, multi-hop, selective decode-and-forward and incremental decode-and-forward in wireless sensor networks. The system is constrained by maximum packet loss and end-to-end throughput requirements. For meeting the end-to-end throughput requirement, we assume that the nodes in multi-hop and cooperative transmission schemes operate at a spectral efficiency which is twice that of the single-hop transmission. Our analysis includes the energy consumption of the RF circuitry and contradicts some previous results in the literature, showing that the cooperative transmission may be considerably more energy efficient than the non-cooperative transmission even in small transmission ranges, specially if a feedback channel is available.

Energy efficiency of some non-cooperative, cooperative and hybrid communication schemes in multi-relay WSNs

In this paper we analyze the energy efficiency of single-hop, multi-hop, cooperative selective decode-and-forward, cooperative incremental decode-and-forward, and even the combination of cooperative and non-cooperative schemes, in wireless sensor networks composed of several nodes. We assume that, as the sensor nodes can experience either non line-of-sight or some line-of-sight conditions, the Nakagami-m fading distribution is used to model the wireless environment. The energy efficiency analysis is constrained by a target outage probability and an end-to-end throughput. Our results show that in most scenarios cooperative incremental schemes are more energy efficient than the other methods.

Energy efficiency of amplify-and-forward, repetition coding and parallel coding in short range communications

In this paper we exploit cooperative relaying for energy savings in narrowband short range communication scenarios. The nodes can operate under cooperative decode-and-forward with repetition coding (RC) or with parallel coding (PC), and cooperative amplify-and-forward (AF) protocols. The system is constrained by maximum packet loss and end-to-end throughput requirements. Our results show that, when the relay is closer to the source, AF and RC present similar performance in terms of energy consumption, while PC significantly outperforms the other schemes. On the other hand, when the relay is near the destination, AF offers the best efficiency.

Energy Efficiency vs. Economic Cost of Cellular Networks under Co-channel Interference

In this paper we analyze the efficiency of cellular network designs, by taking into account the co-channel interference among cells, different amounts of available bandwidths, and frequency reuse. A realistic power consumption model is considered for the energy efficiency analysis, and for the economic analysis it is employed a model in which the total cost is composed by three factors: spectrum license, energy and infrastructure costs. Our results show that different conclusions can be obtained according to the focus of the network design: energy efficiency or total costs. Assuming an economic point of view, the most cost efficient solutions can be obtained when the number of base stations and the available bandwidth are the factors to be balanced, as the infrastructure cost and the spectrum license costs correspond to the most relevant fraction of the total costs. However, considering the energy efficiency anlysis, it can be more beneficial to employ a higher system bandwidth and balance the number of base stations and the reuse of frequencies in order to minimize the required transmit power.

Downlink Energy Efficiency Analysis of Some Multiple Antenna Systems

In this paper we compare the energy efficiency of different multiple antenna transmission schemes for long-range wireless networks, assuming a realistic power consumption model. We consider the downlink, between a base station and a mobile station, in which the Alamouti scheme, transmit beamforming, receive diversity, spatial multiplexing, and transmit antenna selection are compared. Our analysis shows that, for different types of base stations, outage probability requirements and spectral efficiencies, the transmit antenna selection scheme is in general the most energy efficient option. Although antenna selection is not the best in terms of outage probability, it becomes the most efficient in terms of overall power consumption as it requires a single radio-frequency chain to obtain spatial diversity.