Decentralized Simultaneous Energy and Information Transmission in Multiple Access Channels

In this report, the fundamental limits of decentralized simultaneous information and energy transmission in the two-user Gaussian multiple access channel (G-MAC) are fully characterized for the case in which a minimum energy transmission rate b is required for successful decoding. All the achievable and stable information-energy transmission rate tuples (R_1, R_2, B) are identified. R_1 and R_2 are in bits per channel use measured at the receiver and B is in energy units per channel use measured at an energy-harvester (EH). Stability is considered in the sense of an η-Nash equilibrium (NE), with η >= 0 arbitrarily small. The main result consists of the full characterization of the η-NE information-energy region, i.e., the set of information-energy rate triplets (R_1,R_2,B) that are achievable and stable in the G-MAC when: (a) both transmitters autonomously and independently tune their own transmit configurations seeking to maximize their own information transmission rates, R_1 and R_2 respectively; (b) both transmitters jointly guarantee an energy transmission rate B at the EH, such that B >= b.Therefore, any rate triplet outside the η-NE region is not stable as there always exists one transmitter able to increase by at least η bits per channel use its own information transmission rate by updating its own transmit configuration.Dans le présent-rapport, les limites fondamentales de la transmission décentralisée et simultanée de l'information et de l'énergie dans les canaux Gaussiens à accès multiple à deux utilisateurs (G-MAC) sont déterminées dans le cas où un débit minimal b de transmission d'énergie est requis pour un décodage réussi. Tous les triplets de débits atteignables et stables de transmission d'énergie et d'information (R_1,R_2,B) sont identifiés. Les débits d'information R_1 et R_2 en bits par utilisation canal sont mesurés au niveau du récepteur et le débit d'énergie B en unités d'énergie par utilisation canal est mesuré au niveau d'un collecteur d'énergie.La stabilité est considérée au sens d'un η-équilibre de Nash ( η-NE), avec η >= 0 arbitrairement petit. Le résultat principal est la caractérisation complète de la région η-NE d'information-énergie, i.e., l'ensemble des triplets d'information-énergie (R_1,R_2,B) qui sont atteignables et stable dans le G-MAC quand: (a) les deux transmetteurs règlent leurs configurations d'émission d'une manière autonome et indépendante dans le but de maximiser leurs débits individuels de transmission d'information R_1 et R_2, respectivement; (b) les deux transmetteurs garantissent conjointement un débit de transmission d'énergie B au niveau du collecteur d'énergie tel que B >= b. Par conséquent, tout triplet en dehors de la région η-NE n'est pas stable car il doit toujours y avoir un transmetteur qui soit capable d'augmenter son débit d'information par au moins η bits par utilisation canal en ajustant sa propre configuration d'émission

Decentralized Simultaneous Energy and Information Transmission in Multiple Access Channels

International audienceIn this paper, the fundamental limits of decentralized simultaneous information and energy transmission in the two-user Gaussian multiple access channel (G-MAC) are fully characterized for the case in which a minimum energy transmission rate b is required for successful decoding. All the achievable and stable information-energy transmission rate tuples (R1, R2, B) are identified. R1 and R2 are in bits per channel use measured at the receiver and B is in energy units per channel use measured at an energy-harvester (EH). Stability is considered in the sense of an η-Nash equilibrium (NE), with η>=0 arbitrarily small. The main result consists of the full characterization of the η-NE information-energy region, i.e., the set of information-energy rate triplets (R1, R2, B) that are achievable and stable in the G-MAC when: (a) both transmitters autonomously and independently tune their own transmit configurations seeking to maximize their own information transmission rates, R1 and R2 respectively; (b) both transmitters jointly guarantee an energy transmission rate B at the EH, such that B>=b. Therefore, any rate triplet outside the η-NE region is not stable as there always exists one transmitter able to increase by at least η bits per channel use its own information transmission rate by updating its own transmit configuration

Wireless Power Transfer and Data Collection in Wireless Sensor Networks

In a rechargeable wireless sensor network, the data packets are generated by sensor nodes at a specific data rate, and transmitted to a base station. Moreover, the base station transfers power to the nodes by using Wireless Power Transfer (WPT) to extend their battery life. However, inadequately scheduling WPT and data collection causes some of the nodes to drain their battery and have their data buffer overflow, while the other nodes waste their harvested energy, which is more than they need to transmit their packets. In this paper, we investigate a novel optimal scheduling strategy, called EHMDP, aiming to minimize data packet loss from a network of sensor nodes in terms of the nodes' energy consumption and data queue state information. The scheduling problem is first formulated by a centralized MDP model, assuming that the complete states of each node are well known by the base station. This presents the upper bound of the data that can be collected in a rechargeable wireless sensor network. Next, we relax the assumption of the availability of full state information so that the data transmission and WPT can be semi-decentralized. The simulation results show that, in terms of network throughput and packet loss rate, the proposed algorithm significantly improves the network performance.Comment: 30 pages, 8 figures, accepted to IEEE Transactions on Vehicular Technolog

On the Two-user Multi-carrier Joint Channel Selection and Power Control Game

In this paper, we propose a hierarchical game approach to model the energy efficiency maximization problem where transmitters individually choose their channel assignment and power control. We conduct a thorough analysis of the existence, uniqueness and characterization of the Stackelberg equilibrium. Interestingly, we formally show that a spectrum orthogonalization naturally occurs when users decide sequentially about their transmitting carriers and powers, delivering a binary channel assignment. Both analytical and simulation results are provided for assessing and improving the performances in terms of energy efficiency and spectrum utilization between the simultaneous-move game (with synchronous decision makers), the social welfare (in a centralized manner) and the proposed Stackelberg (hierarchical) game. For the first time, we provide tight closed-form bounds on the spectral efficiency of such a model, including correlation across carriers and users. We show that the spectrum orthogonalization capability induced by the proposed hierarchical game model enables the wireless network to achieve the spectral efficiency improvement while still enjoying a high energy efficiency.Comment: 31 pages, 13 figures, accepted in IEEE Transactions on Communication