Energy Efficient Route Construction Scheme with Continuous and Discrete Power Control in Ad Hoc Sensor Networks

Distributed power control is an important issue in wireless networks. Recently, due to the bursty nature of data communication, packet switching is used in cellular systems. In addition, majority of previous power control algorithm assume that the transmitter power level can take values in a continuous domain. However, recent trends such as the GSM standard and QUALCOMM's proposal to the IS-95 standard use a finite number of discretized power levels. These motivate the need to investigate solutions for distributed discrete power control for bursty transmission. Therefore, we propose a probabilistic power adaptation algorithm and analyze its theoretical properties along with the numerical behavior for bursty transmission. We approximate the discrete power control iterations by an equivalent ordinary differential equation (ODE) to prove that the proposed stochastic learning power control algorithm converges to a stable Nash equilibrium. Conditions when more than one stable Nash equilibrium may exist are also studied. Experimental results are presented for several cases and the impact of data burstiness on the proposed algorithm is also concerned.

Wireless sensor networks (WSNs) are one of the very active research area. They have many applications like military, health care, environmental monitoring and industrial monitoring. The sensor nodes have limited energy source. Since in many cases the nodes are deployed in unreachable areas, hence recharging or replacing the battery of the sensor nodes is not an option. Therefore, one must employ techniques to conserve the energy by reducing the energy consumption by the nodes. In this paper, we discuss about the different energy saving schemes investigated by different research community in WSNs to reduce the energy consumption of the nodes and thereby improving the lifetime of the overall network. Energy saving protocols such as duty cycle, energy efficient routing, energy efficient medium access control (MAC), data aggregation, cross layer design and error control code (ECC) are discussed. Sleep/wake up method is adopted by the duty cycle approach to reduce the active time of the nodes and conserve their energy. The routing and MAC protocols use suitable energy efficient algorithms for saving energy. The data aggregation aims to save energy by reducing the number of transmissions. On the other side, cross layer approach looks for a cross layer optimization solution to improve the energy efficiency of the network. ECC reduces energy consumption by virtue of coding gain it offers which allows lower signal-to-noise ratio (SNR) to achieve the same bit error rate (BER) as an uncoded system. Some techniques such as use of directional antennas, topology control and transmission power control which have been widely investigated for other ad-hoc networks for energy conservation are also discussed in brief in this paper.

A power control framework for selfish users in a wireless DS-CDMA uplink with imperfect successive interference cancellation is offered. After presenting a feasibility constraint and a centralized power control solution, the system is analyzed and simulated as a noncooperative game for both continuous and discrete power control cases. Assuming a fixed a priori cancellation order, a unique Nash equilibrium corresponding to a centralized solution is shown to exist in the continuous case. It is shown that the realizable gains of the SIC receiver in a game-theoretic context, although strongly dependent on spreading gain and residual cancellation error, nevertheless are significant when compared to traditional matched filter detection, as expected. If the action space is discrete and sufficiently coarse, empirical results indicate a high probability of Nash equilibrium existence.

Medium access control (MAC) protocols simultaneously integrating transmission power (TP) control with directional antennas have the potential to enhance both energy savings and capacity throughput in wireless multihop Mobile Ad hoc NETworks (MANETs). In this paper, we present a model to calculate future interference in networks with directional antennas, and based on this model, we derive some relations that should exist between the required TP of RTS, CTS, DATA, and ACK frames for successful data packet delivery in MANETs based on the directional version of the IEEE 802.11 distributed coordination function. From these relations, we propose a distributed power control scheme. Furthermore, we show, via simulations, that the true potentials from the proposed control scheme cannot be shown due to the imperfection of the derived model. Based on these observations, we introduce another class of power control algorithm that instead deploys a prediction filter (Kalman or extended Kalman) to estimate future interference. Simulation experiments for different topologies are used to verify the significant throughput and energy gains that can be obtained by the proposed power control schemes.

Throughput and lifetime are usually conflicting objectives in designing wireless sensor networks; hence, the right balance needs to be found. With this aim in view, we address in this paper the problem of minimizing the frame length defined within a time division multiple access scheme and the problem of maximizing network lifetime subject to a maximum frame length. The pursued solution in either case leverages a wide range of parameters related to coverage, routing, transmission power, and data rate. Furthermore, it is consistent with the physical interference model. To this end, we rely on column generation technique to derive near‐optimal solutions even when the integrality constraints on coverage and flow variables are enforced. Moreover, we propose a polynomial‐time heuristic algorithm to solve efficiently the underlying NP‐hard problem of concurrent link selection with discrete power control and rate adaptation. Simulation results show that our heuristic algorithm leads to solutions within 3% of optimality while saving around 99% of computation time. Besides, the results illustrate the significant impact of power control and rate adaptation on throughput and lifetime improvement. Interestingly, we found that network lifetime can be significantly prolonged when traffic demands are sufficiently low at the affordable cost of small decrease in throughput. Copyright © 2015 John Wiley & Sons, Ltd.

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There are many voltage‐dependent loads (VDLs) in power systems. When the unit reserve supply is low, the transmission network adjusts the voltage of grid‐connected nodes to provide additional resources. Many reactive power devices with different regulatory performance levels and timescales must be coordinated to employ flexible VDLs to the maximum extent, and consequently, a transient stability‐constrained optimal power flow (TSCOPF) problem with mixed integers and multiperiod coupling must be solved. A multitimescale scheduling ‘day‐ahead‐intraday‐real‐time’ framework is designed for the optimal economic scheduling of VDLs. In the day‐ahead stage, the optimal scheduling period of the discrete reactive power control devices is determined. In the intraday stage, a rolling optimization model based on model predictive control is established, and the specific action times of the discrete reactive power devices are determined. In the real‐time stage, the optimal regulation strategy of the continuous reactive power control device is optimized by rolling. Then, to consider the speed and accuracy of the solution at the same time, a continuous sensitivity correction method is adopted to simplify and solve the original model. Finally, with a modified IEEE‐39 system and a modified IEEE‐118 system as examples, it is verified that the multitimescale scheduling framework maximizes the exploitation of the flexible resources of VDLs to ensure voltage security and stability and improve the economy of system operation under different scenarios.

Communication is usually the most energy-consuming event on mobile ad hoc networks. Hence, medium access control (MAC) protocols use techniques tomitigate energy consumption on the transmission of data. This chapter presents one such technique, which consists of adjusting the transmission power of the packets. We discuss the fundamentals of transmission power control (TPC), showing their effects in wireless communication and the requirements of TPC solutions. Next, we examine the issues associated with their implementation and show the difficulties of implementing those techniques on real hardware, based on our experience with TPC-aware MAC protocols for wireless sensor networks. We close this chapter with a glimpse of future challenges of TPC-aware MAC protocols on MANETs and WSNs.

A novel transmit power control (TPC) bit estimation technique for FDD-UMTS downlink is proposed. Conventional FDD-UMTS downlink TPC bit estimation algorithm is based on coherent detection, which utilizes pilot bits for channel estimation and uses this estimate to remove the wireless channel effect on TPC bits. However, joint utilization of pilot and TPC bits can improve the detection performance as well as minimize the inherent overhead caused by excessive pilot bits usage in the transmission. In the proposed algorithm, pilot and TPC bits are used collectively for non-coherent detection of the power control command. Power increase and decrease orders are represented by two orthogonal vectors which are made up of pilot and TPC bits. TPC bit error rate (BER) performance comparisons of conventional and proposed algorithms are presented for various multi-path channels and slot formats. It is shown that in all the slot formats and different channel conditions, the proposed algorithm provides superior performances in terms of TPC bit error rate. This performance gain can go up to 15 dB at practical TPC BER (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ) with certain channel conditions and slot formats.

In this paper, we propose a novel transmission power control scheme to improve energy efficiency in high density clustered wireless sensor networks(WSNs). Our scheme is based on cross-layer strategy that combines both medium access control (MAC) layer and physical (PHY) layer. The algorithm consists of an efficient time slot allocation and opportunistic transmission power control to support energy-efficient intracluster communication. Performance evaluation results reveal that our approach is more energy efficient and can maximize the network lifetime in high density clustered WSNs. Our approach can achieve a network lifetime of up to 2 times longer than that generated by the current schemes. Furthermore, our approach outperforms traditional layered protocols.

Transmitter power control has proven to be an efficient method to control cochannel interference in cellular PCS, and to increase bandwidth utilization. Power control can also improve channel quality, lower the power consumption, and facilitate network management functions such as mobile removals, hand-off and admission control. Most of the previous studies have assumed that the transmitter power level is controlled in a continuous domain, whereas in digitally power controlled systems, power levels are discrete. In this paper we study the transmitter power control problem using only a finite set of discrete power levels. The optimal discrete power vector is characterized, and a Distributed Discrete Power Control (DDPC) algorithm which converges to it, is presented. The impact of the power level grid on the outage probability is also investigated. A microcellular case study is used to evaluate the outage probabilities of the algorithms.

In this paper, we propose a cooperative routing in mobile ad-hoc wireless sensor networks with Rayleigh fading environments. The main features and contributions of the proposed cooperative routing are as follows. First, the construction of stable routing route by using entropy concepts in the view points of mobility of nodes. Second, the cooperative-aided transmission using the stable relay which can be selected by using entropy concepts. Third, we present a theoretical analysis model for the proposed cooperative routing with the outage probability of the end-to-end performance. Fourth, we consider a realistic approach based on mobile nodes as well as fixed nodes in the points of view of the mobile ad-hoc wireless sensor networks. The performance evaluation of our protocol is implemented via simulation and analysis.

Joint power control and spectrum allocation for cognitive radio networks via pricing

Towards fast rerouting-based energy efficient routing

Transmission power control (TPC) is essential in third generation systems for several reasons. Fast power control (or closed-loop power control) is intended to track fast channel fading. We investigate fast power control for FDD-UMTS with the help of Markov chain models in order to obtain analytical results of the performance. The effect of TPC errors and SIR estimation errors is explained. The Markov chain models are derived for small velocities, but can be considered as bounds for moderate speeds as well. We also explain how SIR estimation errors can be modelled as TPC errors.