Distribution system provides a link between the high voltage transmission system and low voltage consumers thus I2R loss in a distributed system is high because of low voltage and high current. Distribution companies (DISCOs) have an economic enticement to reduce losses in their networks. Usually, this enticement is the cost difference between real and standard losses. Therefore, if real losses are higher than the standard ones, the DISCOs are economically penalized or if the opposite happens, they obtain a profit. Thus loss minimization problem is a well researched topic and all previous approaches vary from each other by selection of tool for loss minimization and thereafter either in their problem formulation or problem solution methods employed. Many methods of loss reduction exist like feeder reconfiguration, capacitor placement, high voltage distribution system, conductor grading, Distributed Generator (DG) Allocation etc. This paper gives a bibliographical survey, general background and comparative analysis of three most commonly used techniques (i) Capacitor Placement, (ii) Feeder Reconfiguration, (iii) and DG Allocation for loss minimization in distribution network based on over 147 published articles, so that new researchers can easily find literature particularly in this area.

Loss minimization techniques used in distribution network: bibliographical survey

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits.

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A Survey on the Path Computation Element (PCE) Architecture

With the rapid increase in demand for mobile data, mobile network operators are trying to expand wireless network capacity by deploying wireless local area network (LAN) hotspots on to which they can offload their mobile traffic. However, these network-centric methods usually do not fulfill the interests of mobile users (MUs). Taking into consideration many issues such as different applications' deadlines, monetary cost and energy consumption, how the MU decides whether to offload their traffic to a complementary wireless LAN is an important issue. Previous studies assume the MU's mobility pattern is known in advance, which is not always true. In this paper, we study the MU's policy to minimize his monetary cost and energy consumption without known MU mobility pattern. We propose to use a kind of reinforcement learning technique called deep Q-network (DQN) for MU to learn the optimal offloading policy from past experiences. In the proposed DQN based offloading algorithm, MU's mobility pattern is no longer needed. Furthermore, MU's state of remaining data is directly fed into the convolution neural network in DQN without discretization. Therefore, not only does the discretization error present in previous work disappear, but also it makes the proposed algorithm has the ability to generalize the past experiences, which is especially effective when the number of states is large. Extensive simulations are conducted to validate our proposed offloading algorithms.

A deep reinforcement learning based approach for cost- and energy-aware multi-flow mobile data offloading

Use of disaggregated equipment in optical transport networks is emerging as an attractive solution to bring flexibility and break vendor lock-in dependencies. The disaggregation process requires standard protocols and interfaces between the control plane and network equipment. NETCONF has been selected as the standard protocol, and multiple initiatives are currently working on the definition of standard models for each type of data plane device. Different levels of disaggregation of the data plane are under evaluation, and it is still not clear up to which level it will be useful to disaggregate the data plane. The disaggregation of optical networks yielded the development of several controllers based on software-defined networking concepts, providing an environment for creating and deploying networking application on optical networks. Among them, the Open Network Operating System (ONOS) controller features the most active community with the recent establishment of the Open and Disaggregated Transport Network (ODTN) working group, specifically focused on the introduction of required functionality to control and monitor disaggregated transport networks. This paper reports on the state-of-the-art, potentials, and limitations of the ONOS controller applied to disaggregated optical networks with specific focus on the ongoing activities within the ODTN working group. Then, the paper describes a set of experiments performed on a setup including both emulated and real optical devices controlled with ONOS. The performed experiments consider both the establishment of a connectivity service and the recovery of the connectivity in case of failure on the data plane.

Control of open and disaggregated transport networks using the Open Network Operating System (ONOS) [Invited]

With offloading the tasks that mobile users (MUs) running in their mobile devices (MDs) to the data centers of remote public clouds, mobile cloud computing (MCC) can greatly improve the computing capacity and prolong the battery life of MDs. However, the data centers of remote public cloud are generally far from the MUs, thus long delay will be caused due to the transmission from the base station to the public clouds over the Internet. Mobile edge computing (MEC) is recognized as a promising technique to augment the computation capabilities of MDs and shorten the transmission delay. Nevertheless, compared with the traditional MCC and MEC generally has a limited number of cloud resources. Therefore, making a choice on offloading task to the MCC or MEC is a challenging issue for each MU. In this paper, we investigate service selection in a mobile cloud architecture, in which MUs select cloud services from two cloud service providers (CSPs), i.e., public cloud service provider (PSP) and an edge cloud service provider (ESP). We use M/M/$\infty $ queue and M/M/1 queue to model PSP and ESP, respectively. We analyze the interaction of the two CSPs and MUs by adopting Stackelberg game, in which PSP and ESP set the prices first, and then the MUs decide to select cloud services based on performances and prices. In particular, we study the relationship between PSP and ESP in the simultaneous-play game (SPG) scenario, in which they compete to set prices of their cloud services simultaneously. Our numerical results show that MUs prefer to select service from the edge cloud if the number of tasks they run is small. In another hand, more tasks will be offloaded to the remote public cloud if the number of tasks they run becomes large.

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Optimal Pricing and Service Selection in the Mobile Cloud Architectures

We demonstrate a field-trial experiment of a low-speed/latency/loss tolerable SDN control/management-plane which can take advantage of the widely available IoT resources and easy-to-create wireless mesh for the timely recovery of the C/M-plane after disaster.

Field-Trial of the Recovery of Fiber Networks C/M-Plane via an IoT-based Narrow-band and Lossy Links System (FRENLL)

WDM optical networks represent the direction to the future high capacity wide-area network applications. By creating the optical paths between several nodes in the core networks, logical topology can be created over the physical topology. The network can dynamically change its logical topology corresponding to the changing traffic conditions. We consider the method of logical topology reconfiguration in wavelength routed optical networks. The exact formulation of the logical topology problem is usually given as a mixed integer linear programming, but it grows intractable with increasing size of network. Heuristic approaches have been proposed, here we also proposed a different heuristic approach to determine the logical topology reconfiguration.

A heuristic method of logical topology reconfiguration in IP/WDM optical networks

In this paper, we propose multistage wavelength conversion by sharing limited range wavelength converters in wavelength division multiplexed (WDM) all-optical packet switching networks. By using multistage wavelength conversion and converter sharing technology expensive resources can be maximally utilized. Our interest is to investigate how converters of lower capability in terms of conversion limit can be effectively utilized for performance improvement rather than using converters of full conversion capability. We summarize the benefits of multistage wavelength conversion and wavelength converter sharing using limited range wavelength converters and demonstrate some outlines for the choice of conversion limit, number of converters, and the number of stages of conversion by simulation. Simulation results dictate that, with wavelength converters fewer than the number of wavelength channels to or from the optical cross-connect, significant improvement in performance in terms of packet loss probability before saturation can be achieved with multistage conversion at some lower limits of conversion.

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Limited range wavelength converter sharing in WDM networks

We experimentally demonstrate 1-to-9 optical wavelength multicasting, based on dualpump four-wave mixing in highly-nonlinear fiber. A 100-km field trial experiment is also conducted to demonstrate the feasibility of optical wavelength multicasting.

Nine-way optical wavelength multicasting and field trail transmission over optical network test-bed (JGN2Plus)

The exponential traffic growth and the increasing complexity of WDM networks demand a more sophisticated control protocol that will provide a more efficient use of optical network capacity. Many researchers propose to extend GMPLS protocol suite to activate WDM networks, such as by enhancing OSPF-TE, RSVP-TE, etc., the decentralization of control functions is also an inevitable trend of developing WDM networks, when the network continues to scale up. However, the control difficulty is raised by the lack of accurate network state information in this distributed system. Therefore, an effective measure is required to tolerate a certain inaccuracy of such information without significantly increasing the overhead of the control system, such as the traffic volume of the control packets, connection set-up delay, etc. In this paper, a dynamic routing and wavelength assignment with multi-wavelength probing is conceived, which extends our previous case-study toward translucent wavelength convertible WDM networks. For the simulation purpose, we assume that wavelength converters have been sparsely placed in the network, and inside these nodes, the optoelectronic 3R regeneration is potentially obtainable too. The path computation element is served as the calculation unit for the control tasks. In experiment, not only the blocking performance of the proposal is investigated by comparing with traditional single or full probing methods and with centralized control case, but also the control overhead is measured, e.g., update traffic volume, set-up delay. The results reveal that the multi-wavelength probing approach trades off the above two aspects, and is proved to be well-suited for distributed WDM networks.

Sugang Xu

Papers

Field-Trial of the Recovery of Fiber Networks C/M-Plane via an IoT-based Narrow-band and Lossy Links System (FRENLL)

A heuristic method of logical topology reconfiguration in IP/WDM optical networks

Limited range wavelength converter sharing in WDM networks

Nine-way optical wavelength multicasting and field trail transmission over optical network test-bed (JGN2Plus)

Distributed GMPLS optical control in translucent wavelength convertible WDM networks