Energy-Efficient Long-Reach Passive Optical Network: A Network Planning Approach Based on User Behaviors

The extended network span of next-generation long-reach passive optical networks (LR-PONs) results in extremely long propagation delays that severely degrade the performance of centralized bandwidth allocation algorithms. This is because these algorithms are based on bandwidth negotiation messages frequently exchanged between the optical line terminal (OLT) in the central office and optical network units (ONUs) near the users, which become seriously delayed when the network is extended. To address this problem, we propose a decentralized media access scheme for emerging LR-PONs to make the performance independent of the physical length between the OLT and ONUs. We also maintain centralized control over the network, usually missed in conventional decentralized schemes, to support and manage quality of service according to user service level agreements. The scheme thus combines decentralized media access with centralized control to meet the special requirements of emerging LR-PONs. We investigate the performance of the proposed scheme in contrast with centralized schemes under worst case conditions. We also explore various approaches to further enhance the performance of our scheme. Simulation results show that the average upstream packet delay can be decreased by 60% while also maintaining a high throughput.

The long reach passive optical network (LR-PON) is a promising scheme for access networks that cover large areas. For designing an access network, an exact solution of the network performance (e.g., mean packet delay) is useful. Since long propagation delay causes unused time slots (idle time), and its effect on performance degradation is difficult to analyze, existing analysis of the LR-PON is done only for the no-idle time situation with modified optical line terminal (OLT) and each optical network unit (ONU). In this paper, we propose an exact solution of the mean packet delay for LR-PON with idle time. Our analytical solution is derived by a non-trivial extension of the existing work for the short range PON. We confirm a good match between the mean packet delay derived by the simulation and our analytical solution.

With the advances in optical technology, the span of a broadband access network using passive optical network (PON) technology can be increased from today's standard of 20 km to 100 km or higher, and thereby serve a lot more users. Such an extended-reach PON is known as SuperPON in the literature, and we call it a long-reach PON (LR-PON). A major challenge in LR-PON is that the propagation delay (for data as well as signals) between the telecom central office (CO) and the end user is increased by a very significant amount. Now, traditional PON algorithms for scheduling the upstream transmission, such as dynamic bandwidth allocation (DBA) algorithms, may not be sufficient; actually, they may lead to degraded performance because of the long delay of the CO-to- Users control loop. This challenge motivates us to propose and study a multi-thread polling algorithm to effectively and fairly distribute the upstream bandwidth dynamically. This algorithm exploits the benefits of having multiple polling processes running simultaneously and enabling users to send bandwidth requests before receiving acknowledgement from the CO. We compare the proposed algorithm with traditional DBA, and show its advantage on average packet delay. We then analyze and optimize key parameters of the algorithm, such as initiating and tuning multiple threads, inter-thread scheduling, and fairness among users. Numerical results demonstrate the algorithm's advantage to decrease the average packet delay and improve network throughput under varying offered loads.

OTACT: ONU Turning with Adaptive Cycle Times in Long-Reach PONs

One of the major challenges in long reach passive optical network (LR-PON) is the longer end-to-end traffic delay between the central office (CO) and the end user. This longer delay significantly hampers the quality of services (QoSs) of the optical access networks. The QoSs of the LR-PON are easily affected by delaying or dropping packets as a consequence of parameters such as latency, jitter, bandwidth utilization and packet loss. Most of the studies have only focused on capacity allocation amongst the multiple optical network units (ONUs) of the network by the optical line terminal. Some research also proposed to schedule the packets in multiple threads based on the priority. However, due to the lacking of intra thread scheduling scheme the high priority (HP) data packet still suffering from more delay. In this paper, we propose a decentralized intrathread scheduling scheme that provides lower queuing delay as well as end-to-end packet delay of the HP traffic. The performance measurements involve several scenarios which combine different traffic types, intra ONU scheduling and queuing policies. The goal of this research is to identify the most suitable scenario to provide qualitative services and efficient resource utilization among different traffic types. The performances of the proposed scheme have been analyzed and compared with the existing scheme by numerical simulations. The numerical results proves the advantages of the proposed scheme over the existing one in terms of lower average packet delay of high priority data packets and higher network throughput under varying offered loads.

We present for the first time remote powering of a 3-D MEMS for optical switching using light over fibre. The low power switch with integrated optical splitters is suitable at non-powered remote PON distribution sites. Introduction The rapid deployment of fibre-to-the-home (FTTH) poses a number of new operational challenges in managing fibre due to the growing outside fibre plant infrastructure and the inherent churn in access networks [1]. Automating fibre management using remotely controlled optical switches has been proposed to efficiently manage subscriber connectivity and fault localization without human intervention, and to reduce the number of network and test equipment [2]. Early field trials have confirmed the benefits to operate and maintain fibrebased networks [3]. The deployment of switches in Central Offices (CO) for FTTH point-to-point networks is relatively simple. The insertion of optical switches, however, in Passive Optical Networks (PON) at Fibre Distribution Hub (FDH) sites in the field is much more difficult because those sites are usually not powered. We demonstrate in this paper a remotely powered fibre management solution using a low-power 3DMEMS optical switch and a light-over-fibre powering technique. We also report improved environmental performance for field switch operation. Integrated PON 3-D MEMS Switch Fig.1 shows a typical FDH layout in a PON: a first bay with optical splitters is connected to the Optical Line Terminal (OLT) at the CO; a second bay with fibre terminations is connected to residential homes. Optical splitters Patch-cords OLT ONU CO Homes Outside Plant Truck-rolls for patching Field OTDR measurements ONU FDH Fig. 1. PON FDH with discrete splitters and manual fibre management requiring technician dispatch to connect subscriber to OLT or test fibres with OTDR. Each time a subscriber is added, a technician must be dispatched at the FDH site to connect it to an unused OLT port. If subscribers are connected up-front, additional OLTs are required due to limited market penetration, thus increasing greatly the initial investment cost per paying subscribe. Technicians also go in the field to perform OTDR measurements to certify fibre installation or to trouble-shoot faults. All those costly and error-prone human interventions can be alleviated by the insertion of an optical switch at the FDH sites (Fig.2). The software-controlled switch connects a subscriber to the desired splitter port, packing subscribers onto the minimum number of OLTs in real time. All the home run fibres can be checked using a test fibre connected to an OTDR at the CO that can be shared among multiple FDH sites. Optical switch with splitters OLT ONU CO Outside Plant

Nowadays the safety of computer networks becomes more important than other characteristics. The services which are used by a huge number of users entice hacker. Especially, online payment services are often the main target of malicious software. In the article, the computer virus SpyEye spread via Internet resources is considered. The Petri-object model of propagation process is created with the use of Petri-object simulation software written in Java. The model reproduces the events of damaging website, infecting user’s resource, sending information about vulnerabilities and sending personal data. It was suggested that users are connected when they use the same website. The investigation of the spreading time for different kinds of users’ connections topology is presented. It was considered not only well-known star and chain topologies but also their combinations and the topology with random connections. Simulation results confirm the virus spreading time dependence on user’s connections topology.

To date, the mainstream ethernet passive optical network (EPON) bandwidth allocation schemes as well as the new IEEE 802.3ah Ethernet in the first mile Task Force specifications have been centralized, relying on a component in the central office [optical line termination (OLT)] to provision upstream traffic. Hence, the OLT is the only device that can arbitrate time-division access to the shared channel. Since the OLT has global knowledge of the state of the entire network, this is a centralized control plane in which the OLT has centralized intelligence. This paper proposes novel distributed EPON architectures, and in the process proves that these distributed networking architectures and the associated bandwidth allocation algorithms and protocols have characteristics that make them far better suited for provisioning quality of service (QoS) schemes necessary for properly handling data, voice, video, and other real-time streaming advanced multimedia services over a single line. Specifically, this paper proposes a novel ethernet over star coupler-based PON architecture that uses a fully distributed time-division multiple-access (TDMA) arbitration scheme. Supported by the decentralized scheme, this paper proposes several QoS-based dynamic bandwidth allocation (DBA) algorithms in which the OLT is excluded from the implementation of the time slot assignment. In contrast with the mainstream centralized EPON architectures that combine priority queuing [intra-optical network unit (ONU) scheduling] with DBA schemes (inter-ONU scheduling), the proposed distributed EPON architecture supports differentiated services through the integration of both scheduling mechanisms at the ONU (intra-ONU scheduling). The introduction of this integration feature that can only be supported by a decentralized architecture provides better QoS guarantees. Furthermore, in addition to the added flexibility and reliability, the overall performance of the proposed decentralized EPON architecture and the associated bandwidth allocation algorithms are shown to be at least as efficient as their centralized counterparts.

Content in collaborative systems, such as Online Social Networks, is often co-owned by multiple users with different privacy expectations, leading to possible multiuser privacy conflicts. In order to address these conflicts, we argue that users should be supported by trustworthy agents that adhere to the following criteria: (i) concealment of privacy preferences, such that only necessary information is shared with others; (ii) equity of treatment, such that different kinds of users are supported equally; (iii) collaboration of users, such that a group of users can support each other in agreement and (iv) explainability of actions, such that users know why certain information about them was shared to reach a decision.

The following paper describes the implementation of three different controllers for a wheelchair. It was built for improving people's life that could have disabilities associated with functions regarding muscle strength, power of muscle of all limbs, tone of muscle of all limbs and endurance of all muscles of the body. Using three programmed methods that allow the user to have full control over the wheelchair. By acquiring voltage signals generated in eye's movements and using Neuro-Fuzzy Networks for differentiating each one, the wheelchair is able of being controlled by eye's movements. Figuring out about different kinds of user's needs and environments, the wheelchair includes voice control in spaces where noise levels are less than 40dB. The voice commands are detected using the Speech Recognition software which is a default program installed on Microsoft Windows operative system. The eye and voice controls were designed using LabVIEW and the intelligent control toolkit (ICTL). There were developed virtual simulators on C# code that enable the patient to have a previous training for having a better wheelchair control and performance. The system was tested on a person with cerebral palsy.

The nature of explanation dialogues is examined and an expert system that provides acceptable and appropriate answers and explanations to the questions posed by different kinds of users is designed. An empirical study and analysis of natural dialogues between experts, novices and partial experts is described. From this analysis a theory of explanation dialogues (extended schema-based theory, or EST) is developed. In EST questions are interpreted by combining information from different, semantically related question types that together best capture the essence and meaning of the question. This theory is applied to the design of an architecture and computational model for interpreting questions and generating explanations. The expert system, EXPLAIN, understands the nature of the question and is able to take account of the previous dialogue. The system can tailor its responses to an individual user's characteristics, including level of expertise and depth of knowledge in the domain. >

The long-tail phenomenon tells us that there are many items in the tail. However, not all tail items are the same. Each item acquires different kinds of users. Some items are loved by the general public, while some items are consumed by eccentric fans. In this paper, we propose a novel metric, item eccentricity, to incorporate this difference between consumers of the items. Eccentric items are defined as items that are consumed by eccentric users. We used this metric to analyze two real-world datasets of music and movies and observed the characteristics of items in terms of eccentricity. The results showed that our defined eccentricity of an item does not change much over time, and classified eccentric and noneccentric items present significantly distinct characteristics. The proposed metric effectively separates the eccentric and noneccentric items mixed in the tail, which could not be done with the previous measures, which only consider the popularity of items.

Today it is not easy to imagine what would be the future of user experience (UX) design in the world of Artificial Intelligence (AI). Referring to the sector of autonomous vehicles the paper aims to explore the changes that will be brought by artificial intelligence to the innovative sector of the self-driving car. According to these transformation car interiors and passengers experiences will become very different from the actual one. The aim of the research is, starting from different kind of passengers needs (Human Centered Design approach) individuating essential factors to design autonomous cars interiors and in particular to design innovative interfaces for a better communication with the passengers and a high level of living experience for different kind of users.

Different categories of drinking houses, it is claimed, are historically related to different kinds of users and usages. Industrialism, however, entrenched the ubiquitous pub amidst the song, sin and insobriety of the poor and the new working-class urban proletariat. The public house thus became a focus of social freedoms and sexual licence, as well as a locus of more formal elements of rational recreation. Yet the public house was subject to social controls of a ferocious kind and not simply licensing constraints, and some discussion is developed in examining the class basis of recreation and leisure controls. Attention finally turns to viewing the public house as an intermediate context in a relational sense, in an historical sense and in a time sense, and one deserving further sociological attention. Historically, different types of public drinking houses have generally developed out of distinct categories of social usage. The inn developed from the coaching tradition of providing refreshment and lodgings for travellers. Such houses tended over time to foster recreation and itinerant entertainers and to be a focus of not just wealthy travellers but plyers of wares and trades-but always perhaps within the context of a dominant use by the relatively wealthy. Such drinking houses catered for catholic drinking tastes-spirits, wines and beers. The taverns were originally concerned with selling wine, the availability of wine itself being boosted by the cultivation of vines in the medieval monasteries. Such taverns, by the late eighteenth century, were virtually indistinguishable from inns and met the needs of the casual drinker, catering for a wide range of users. The alehouse was the traditional village drinking house; it had none of the accommodation or the formal entertainment patterns of the inn. It was effectively the local community drinking and meeting place and was

Machine learning algorithms are widely employed in plenty of classification or regression problems. While in real business world, it is confronted with huge and disorder data pattern. To recognize different kinds of users on the internet accurately and fast becomes a challenge. In a Wechat online bargain activity, the staff found that some strange users are highly like robots or malicious users. Thus we tried a two-level stacking model to detect them. This design got a good result of 0.98 accuracy after the training phase and an accuracy of 0.90 in a new term of the testing set. Moreover, this model is adaptable to linear and nonlinear datasets because of its diverse stacking of first-level classifiers. Therefore, this paper indicates a potential of the stacking classification model in big data times.