Tradeoff Analysis and Joint Optimization of Link-Layer Energy Efficiency and Effective Capacity Toward Green Communications

A joint optimization problem of link-layer energy efficiency (EE) and effective capacity (EC) in a Nakagami-m fading channel under a delay-outage probability constraint and an average transmit power constraint is considered and investigated in this paper. First, a normalized multi-objective optimization problem (MOP) is formulated and transformed into a single-objective optimization problem (SOP), by applying the weighted sum method. The formulated SOP is then proved to be continuously differentiable and strictly quasiconvex in the optimum average input power, which turns out to be a cup shape curve. Furthermore, the weighted quasiconvex tradeoff problem is solved by first using Charnes-Cooper transformation and then applying Karush-Kuhn-Tucker (KKT) conditions. The proposed optimal power allocation, which includes the optimal strategy for the link-layer EE-maximization problem and the EC-maximization problem as extreme cases, is proved to be sufficient for the Pareto optimal set of the original EE-EC MOP. Moreover, we prove that the optimum average power level monotonically decreases with the importance weight, but strictly increases with the normalization factor, the circuit power and the power amplifier efficiency. Simulation results confirm the analytical derivations and further show the effects of fading severeness and transmission power limit on the tradeoff performance

Multi-carrier link-layer energy efficiency and effective capacity tradeoff

A joint energy and spectral efficient power allocation strategy for a point-to-point multi-carrier link, subject to a delay-outage probability constraint, is proposed in this paper. Since the two objectives, namely, link-layer energy efficiency (EE) and effective capacity (EC), conflict with each other, the tradeoff problem falls into the scope of multi-objective optimization problems (MOP). With the ε-constraint approach, the MOP is converted into a single-objective optimization problem (SOP) by maximizing the multi-carrier EC, subject to an EE constraint. Then, by introducing an adjustable performance indicator, EE-loss-rate (αEE), into the EE constraint limit, the tradeoff level is flexibly controlled. Finally, we prove that the proposed tradeoff formulation is a concave maximization problem and the optimum power allocation strategy can be derived using Lagrangian method. Analytical results indicate that the proposed power allocation has a similar structure to the one for EE-maximization problem over a frequency-selective fading channel, but with a different cut-off threshold

Weighted tradeoff between effective capacity and energy efficiency

This paper proposes a new power allocation technique to jointly optimize link-layer energy efficiency (EE) and effective capacity (EC) of a Rayleigh flat-fading channel with delay-outage probability constraints. Specifically, EE is formulated as the ratio of EC to the sum of transmission power and rate-independent circuit power consumption. A multi-objective optimization problem (MOP) to jointly maximize EE and EC is then formulated. By introducing importance weight into the MOP, we can flexibly change the priority level of EE and EC, and convert the MOP into a single-objective optimization problem (SOP) which can be solved using fractional programming. At first, for a given importance weight and a target delay-outage probability, the optimum average transmission power level to maximize the SOP is found. Then, the optimal power allocation strategy is derived based on the obtained average input power level. Simulation results confirm the analytical derivations and further show the effects of circuit power, importance weight, and transmission power constraint limit on the achievable tradeoff performance

Link-Layer Capacity of NOMA Under Statistical Delay QoS Guarantees

In this paper, we study the achievable link-layer rate, namely, effective capacity (EC), under the per-user statistical delay quality-of-service (QoS) requirements, for a downlink nonorthogonal multiple access (NOMA) network with M users. Specifically, the M users are assumed to be divided into multiple NOMA pairs. Conventional orthogonal multiple access (OMA) then is applied for inter-NOMA-pairs multiple access. Focusing on the total link-layer rate for a downlink M-user network, we prove that OMA outperforms NOMA when the transmit signalto- noise ratio (SNR) is small. On the contrary, simulation results show that NOMA prevails over OMA at high values of SNR. Aware of the importance of a two-user NOMA network, we also theoretically investigate the impact of the transmit SNR and the delay QoS requirement on the individual EC performance and the total link-layer rate for a two-user network. Specifically, for delay-constrained and delay-unconstrained users, we prove that for the user with the stronger channel condition in a twouser network, NOMA prevails over OMA when the transmit SNR is large. On the other hand, for the user with the weaker channel condition in a two-user network, it is proved that NOMA outperforms OMA when the transmit SNR is small. Furthermore, for the user with the weaker channel condition, the individual EC in NOMA is limited to a maximum value, even if the transmit SNR goes to infinity. To confirm these insightful conclusions, the closed-form expressions for the individual EC in a two-user network, by applying NOMA or OMA, are derived for both users and then confirmed using Monte Carlo simulations

Adaptive networking control method and application of 5G vehicle networking node

at present, with the development of information technology, 5G network has been born, which also makes the Internet of things and the Internet based on the network develop rapidly. In this context, vehicular ad hoc network technology has attracted much attention. This technology has promoted the development of intelligent transportation from the research, birth and application in practice, so that intelligent transportation has been supported at the technical level, and its intelligent system has been optimized. In addition, vehicular ad hoc network technology plays a key role and value in road rescue, driverless and remote dispatching management. Therefore, this paper not only strengthens the greedy traffi c aware routing, but also optimizes the problems existing in its operation, and puts forward improved methods for the reference of the industry

Statistical delay QoS driven resource allocation and performance analysis for wireless communication networks

Delay quality-of-service (QoS) guarantees play a critical role in enabling delay-sensitive wireless applications. By applying the theory of effective capacity (EC), the maximum arrival rate with a guaranteed delay-outage probability constraint, is analyzed and investigated in terms of delayconstrained resource allocation and link-layer throughput analysis. Firstly, a joint optimization problem of link-layer energy efficiency (EE) and EC in a single-user single-carrier communication system, is proposed and investigated, under a delay violation probability requirement and an average transmit power constraint. Formulated as a normalized multiobjective optimization problem (MOP), the problem is transformed into a weighted single-objective optimization problem (SOP), and then solved. The proposed optimal power value is proved to be sufficient for the Pareto optimal set of the original EE-EC MOP. Secondly, a total EC maximization problem subject to the individual linklayer EE requirement as well as the per-user average transmit power limit, in a multi-user multi-carrier orthogonal frequency-division multiple access (OFDMA) system, is proposed and analyzed. Formulated as a combinatorial integer programming problem, the problem is decoupled into a frequency provisioning problem and an independent per-user multi-carrier EE-EC tradeoff problem. A low-complexity heuristic algorithm is proposed to obtain the subcarrier assignment solution coupled with a per-user optimal power allocation strategy, across frequency and time domains. Finally, the achievable link-layer rate under the per-user delay QoS requirements is studied for a downlink M-user non-orthogonal multiple access (NOMA) network. The impact of the transmit signal-to-noise ratio (SNR) and the delay QoS requirement on the per-user achievable EC and the total link-layer rate is investigated and compared between NOMA and orthogonal multiple access (OMA) networks. All theoretical conclusions and closed-form expressions are confirmed with Monte Carlo results

Example Based Caricature Synthesis

The likeness of a caricature to the original face image is an essential and often overlooked part of caricature production. In this paper we present an example based caricature synthesis technique, consisting of shape exaggeration, relationship exaggeration, and optimization for likeness. Rather than relying on a large training set of caricature face pairs, our shape exaggeration step is based on only one or a small number of examples of facial features. The relationship exaggeration step introduces two definitions which facilitate global facial feature synthesis. The first is the T-Shape rule, which describes the relative relationship between the facial elements in an intuitive manner. The second is the so called proportions, which characterizes the facial features in a proportion form. Finally we introduce a similarity metric as the likeness metric based on the Modified Hausdorff Distance (MHD) which allows us to optimize the configuration of facial elements, maximizing likeness while satisfying a number of constraints. The effectiveness of our algorithm is demonstrated with experimental results

Structure and electronic transport in graphene wrinkles

Wrinkling is a ubiquitous phenomenon in two-dimensional membranes. In particular, in the large-scale growth of graphene on metallic substrates, high densities of wrinkles are commonly observed. Despite their prevalence and potential impact on large-scale graphene electronics, relatively little is known about their structural morphology and electronic properties. Surveying the graphene landscape using atomic force microscopy, we found that wrinkles reach a certain maximum height before folding over. Calculations of the energetics explain the morphological transition, and indicate that the tall ripples are collapsed into narrow standing wrinkles by van der Waals forces, analogous to large-diameter nanotubes. Quantum transport calculations show that conductance through these collapsed wrinkle structures is limited mainly by a density-of-states bottleneck and by interlayer tunneling across the collapsed bilayer region. Also through systematic measurements across large numbers of devices with wide folded wrinkles, we find a distinct anisotropy in their electrical resistivity, consistent with our transport simulations. These results highlight the coupling between morphology and electronic properties, which has important practical implications for large-scale high-speed graphene electronics.Comment: 5 figures supplemental information in separated fil

Skew-Morphisms of Elementary Abelian p-Groups

A skew-morphism of a finite group $G$ is a permutation $\sigma$ on $G$ fixing the identity element, and for which there exists an integer function $\pi$ on $G$ such that $\sigma(xy)=\sigma(x)\sigma^{\pi(x)}(y)$ for all $x,y\in G$. It has been known that given a skew-morphism $\sigma$ of $G$, the product of $\langle \sigma \rangle$ with the left regular representation of $G$ forms a permutation group on $G$, called the skew-product group of $\sigma$. In this paper, the skew-product groups of skew-morphisms of finite elementary abelian $p$-groups are investigated. Some properties, characterizations and constructions about that are obtained

Energy efficiency in energy harvesting cooperative networks with self-energy recycling

Cooperative communication has been identified as an important component in the 5G system. This paper considers a decode-and-forward (DF) relaying wireless cooperative network, in which the self-energy recycling relay is powered by radio-frequency (RF) signal from the source and its transmitted power from the loop-back channel. The harvested energy is used to support the relay transmissions. Based on a self-energy recycling relaying protocol, we study the optimization of energy efficiency in wireless cooperative networks. Although the formulated optimization problem is not convex, it can be re-constructed to a parametric problem in the convex form by using the non-linear fractional programming, to which closed form solutions can be found by using the Lagrange multiplier method. The simulation results are presented to verify the effectiveness of this solution proposed in this paper