Throughput Maximization for Full Duplex Wireless Powered Communication Networks

In cooperative cognitive radio networks (CCRN), secondary users (SUs) relay data for primary users (PUs) for the redounding spectrum opportunity from PUs. Furthermore, financial and environmental considerations make the green communication as a new trend in the optimization of CCRN. In this paper, a new power and time allocation scheme is proposed for green CCRN. The problem of minimizing the overall energy consumption under service quality constraints is modeled. And a joint power and time allocation strategy is proposed for the problem. Extensive simulation results demonstrate that the proposed scheme significantly outperforms the existing single-SU cooperative scheme on energy saving.

In this paper, we investigate the optimal power and time allocation for a wireless relay network, called BCFR (Broadcasting Channel with Fixed Relay), where the relay node is limited by the half-duplex operation. Introducing a relay in two-node broadcasting channel for a node which has a link of bad quality or requires higher transmission rate enlarges the rate region with well-designed power and time allocation. Also, BCFR is a common component of many relay networks, in which either orthogonal or non-orthogonal transmission can be adopted at the information source node. In particular, for the non-orthogonal transmission, the layered transmission with superposition coding is applied at the source node. By deriving the optimal power and time-fraction allocation at each node of BCFR, we show that the non-orthogonal structure enhances the capacity region and achieves higher log-sum capacity than the orthogonal transmission.

In this letter, we investigate the joint optimization of sensing time and power allocation for amplify-and-forward cognitive relay networks. By jointly considering the sensing slot and the data transmission slot, the optimization problems are respectively formulated to maximize the average network throughput and minimize the approximate outage probability of secondary transmission under the average transmit power constraint of secondary users and the average interference power constraint of primary user. The optimal algorithms are developed to acquire the optimal sensing time and power allocation. Simulation results demonstrate that significant improvements in the average throughput and outage behavior are achieved through the joint optimization.

Wireless energy transfer (WET) is a promising technique to prolong the lifetime of an energy-constrained wireless network. In this paper, we consider a two-hop communication system with multiple relay nodes powered by WET. To minimize the transmission time, we propose an optimal transmission scheme, in which the relay nodes adopt a “harvest-then-decode and forward” policy. The optimal transmission time allocation of the source and each relay node is calculated by a linear program under causality constraints on both data and energy arrivals. The analytical and simulation results reveal the relationship between the optimal time allocation and system parameters.

In this paper, we propose an optimal time and power allocation scheme in a wireless power supply full-duplex (FD) relay system, where we consider the number of relay antennas in the energy harvesting stage. At the same time, the energy efficiency optimization problem of the system is structured, where optimization issues related to time allocation factors and power allocation are established. For the FD dual-antenna and the FD single-antenna energy harvesting system, energy efficiency function is proven to be a concave function over the time-switch factor, and the optimal time-switching factor is theoretically obtained using the Lambert function. Then, according to the given value range of the optimal time switching factor, the optimal power distribution scheme is obtained by analyzing the derivative function of the system energy efficiency and using the properties of the Lambert function. The time-switching factor and transmission power are optimally selected at the wireless power supply FD relay. Results reveal that the performance of energy efficiency of the dual-antenna energy harvesting at the FD relay outperforms that of the single-antenna. Moreover, our results demonstrate that FD relay systems always substantially boost the energy efficiency compared with half-duplex (HD) relay systems.

In this paper, time-switching based wireless powered relay systems, where the source and destination jointly transfer energy to the relay, is studied. Given a certain transmission duration, there is a time trade-off between wireless energy transfer and information cooperative transmission. Although more time for energy harvesting causes more available power at the relay, it shrinks the duration of information transmission and may incur less system throughput. To obtain the optimal time allocation, we derive the information outage probability of the relay system. And then we solve the optimization problem of time allocation to achieve the maximum system throughput. Finally, simulation results verify our derived theoretical results. And it is also shown that the proposed time allocation scheme indeed achieves maximum average throughput.

Optimal Time Allocation for Process Improvement and Growth for Entrepreneurs

In this contribution, we address the resource allocation problem in cognitive radio (CR) broadcast channels (BC) when the radio resources are shared between the primary user of the spectrum band and the CR-BC secondary network. Specifically, we propose utilizing spectrum sensing information about the primary's activity at the secondary base station for an efficient allocation of the resources, namely, transmission time and power, to the secondary users. For this purpose, we assume that the spectrum sensing information, obtained using spectrum-aware sensors deployed in the secondary transmission range, and secondary channel side information, are available at the CR-BC secondary transmitter and receivers. Based on this information, we obtain an optimal time and power allocation policy to maximize the achievable capacity of fading cognitive radio broadcast channels, where the spectrum-sharing requirements are specified by appropriate constraints on the average received-interference at the primary receiver and on the peak transmit-power of the secondary base station. Finally, we sustain our theoretical results by numerical and simulation analysis.

This paper studies a cooperative cognitive radio network (CRN), where the primary system leases the licensed band to the secondary system for a fraction of time in exchange for the secondary user (SU) acting as a decode-and-forward relay. Our aim is to determine the cooperative resource allocation strategy among the primary user (PU) and SU so as to minimize both the total power consumption and the leased time. Considering the delay-sensitive applications in CRN, the proposed policy ensures delay-related quality-of-service (QoS) requirements of both PU and SU. To this end, a multi-objective optimization problem of power and time allocation is formulated based on the effective capacity. Via employing weighting method the optimization problem is transformed to a convex one and solved based on the lagrangian dual method. The proposed policy has been shown to be deterministic functions of delay QoS exponent and channel fading states. In particular, the power allocation is achieved by multi-level QoS based water-filling policy. Moreover, numerical results are provided to demonstrate the performance of the proposed resource allocation policy.

Generation and characterization of entanglement are crucial tasks in quantum information processing. A hypothesis testing scheme for entanglement has been formulated. Three designs were proposed to test the entangled photon states created by the spontaneous parametric down conversion. The time allocations between the measurement vectors were designed to consider the anisotropic deviation of the generated photon states from the maximally entangled states. The designs were evaluated in terms of the p-value based on the observed data. It has been experimentally demonstrated that the optimal time allocation between the coincidence and anti-coincidence measurement vectors improves the entanglement test. A further improvement is also experimentally demonstrated by optimizing the time allocation between the anti-coincidence vectors. Analysis on the data obtained in the experiment verified the advantage of the entanglement test designed by the optimal time allocation.

The increasing demand for data services has given rise to efficient utilization of available resources (e.g., energy) in modern wireless communication. In order to address the energy requirements a wireless powered communication network (WPCN) with separate energy source (ES) and access point (AP) is considered in this work. The transmitters here adopt harvest-then-transmit (HTT) protocol for transmission to AP. An optimal dynamic time allocation and scheduling policy is considered which maximizes the throughput of the system. The throughput maximization problem formulated is convex in nature and solved using convex optimization techniques. The fairness of proposed policy is compared with max-min policy which use harvest-or-transmit (HOT) protocol in terms of Jain's fairness index. Simulation results highlights the trade-off between throughput and fairness and show that the proposed policy is more reliable for the overcrowded scenario.

This paper studies the case of an overlay cognitive radio network where the primary user leases spectral resources to the secondary user in exchange for cooperation, considering that both type of users have specific quality of service requirements. We investigate the problem of joint power and time allocation for the secondary access during the cooperative phase, with a view to optimizing the effective capacity of the primary user given an average energy constraint for the secondary user. Afterwards, the optimal power allocation of the secondary user for its own transmission phase is investigated in order to maximize the effective capacity of the secondary link. The proposed joint power and time allocation mechanism is compared with an optimal time/constant power allocation scheme and a less sophisticated baseline allocation scheme, i.e. power allocation under constant time and its superiority is proven for various network parameters. The reference model of one primary---one secondary user is extended to a general multi user cognitive radio network through the proposed pairing mechanism based on matching theory. Particularly, considering the remarks of the reference scenario, we propose two different matching schemes (with/without consideration of primary users' quality of service requirements) and we confirm their superiority compared to other matching mechanisms.

For non-orthogonal multiple access (NOMA) assisted mobile edge computing (MEC) system, intelligent reflecting surface(IRS) is added to the system model, where power, phase shift and time allocation are jointly optimized to decrease the energy consumption of computational offloading. Closed-form expression of the optimal power and time allocation solution is obtained, and optimal phase shift is obtained. Then we can use it to determine whether orthogonal multiple access (OMA), pure NOMA or hybrid NOMA should be used conditions for MEC uninstallation. The simulation results show that the proposed optimization scheme can save the energy consumption of MEC offloading. Compared with the OMA effect, the performance is also improved.

Energy consumption is one of the concerned focuses in current wireless communication network, so more and more network designs take green communication into consideration. This paper presents an optimal energy efficient strategy for the cooperative spectrum sharing networks. In the proposed network, secondary users cooperate to improve primary user's transmission efficiency, in exchange for the use of the channel licensed by the primary user. We propose the system model of cooperative spectrum sharing network, and the optimal power and time allocation of multiple cooperative users is given, based on the criterion of minimal energy consumption. Karush-Kuhn-Tucker (KKT) conditions are utilized to solve the optimal problems. The simulation results show that, system throughput grows as the number of cooperative users increases, while the system energy efficiency doesn't go the same way. As for energy efficiency, our results show that selecting appropriate number of cooperative users can make the system optimally energy efficient.

A Dynamic decode-and-forward (DDF) relaying protocol with partial Channel state information at the transmitter (CSIT) for a three-node half-duplex single-antenna network, which consists of a single source destination pair and a relay, is proposed. A Diversity multiplexing trade off (DMT) analysis is presented, in which the DMT of the proposed protocol is derived in a closed form and an adaptive time allocation strategy is also developed to achieve the optimal performance. It is shown that time allocation with partial CSIT significantly improves the achievable DMT for DDF relaying. Moreover, unlike the existing DDF protocol with CSIT, which is performed with the assumption of long-term power constraint, the proposed protocol can be generalized to the practical scenarios where a strict short-term power constraint is often imposed on, due to the environmental safety and interference prevention.