Limei Peng

Novel Node-Arc Model and Multiiteration Heuristics for Static Routing and Spectrum Assignment in Elastic Optical Networks

We consider an elastic optical network and study the static routing and spectrum assignment (RSA) problem aiming to minimize the maximum number of frequency slots required to accommodate all lightpath demands. We introduce a novel node-arc integer linear programming (ILP) model, which jointly decides optimal routes and assigned spectra for lightpaths between all source-destination pairs. To reduce the total number of variables, and therefore lower the computational complexity, our new node-arc model extends previous work by representing the spectrum assigned to each lightpath by two variables (i.e., the starting and ending boundary frequency slot indexes). To achieve scalability, we also develop an efficient spectrum-window-based greedy heuristic algorithm, and further propose three multiiteration-based algorithms that consider the effect of demand-serving sequences. Analytical and numerical results show that comparing with an existing approach, our solution to the RSA problem based on the new node-arc ILP model achieves a significant computational complexity improvement. Further numerical results demonstrate that the proposed multiiteration algorithms obtain solutions closer to optima than existing algorithms.

CADRE: Cloud-Assisted Drug REcommendation Service for Online Pharmacies

With the development of e-commerce, a growing number of people prefer to purchase medicine online for the sake of convenience. However, it is a serious issue to purchase medicine blindly without necessary medication guidance. In this paper, we propose a novel cloud-assisted drug recommendation (CADRE), which can recommend users with top-N related medicines according to symptoms. In CADRE, we first cluster the drugs into several groups according to the functional description information, and design a basic personalized drug recommendation based on user collaborative filtering. Then, considering the shortcomings of collaborative filtering algorithm, such as computing expensive, cold start, and data sparsity, we propose a cloud-assisted approach for enriching end-user Quality of Experience (QoE) of drug recommendation, by modeling and representing the relationship of the user, symptom and medicine via tensor decomposition. Finally, the proposed approach is evaluated with experimental study based on a real dataset crawled from Internet.

A Novel Approach to Optical Switching for Intradatacenter Networking

In this paper, we propose to apply a novel paradigm called labeled optical burst switching with home circuit (LOBS-HC) for intradatacenter networking to provide a high bisection bandwidth and significantly reduce the cost and energy consumption associated with electronic packet switching. The unique features of LOBS-HC that make it more suitable than either optical circuit switching (OCS) or optical packet/burst switching are exploited to enable all-to-all communications with a guaranteed lossless transmission bandwidth between any given pair of pods, while also supporting bursty transmissions through wavelength-sharing among home circuits (HCs) and statistical multiplexing. As a case study, hypercube-like topologies are considered for the interconnection among the pods within a datacenter. In particular, we first propose a simple but efficient HC assignment scheme called complementary HC for 2-D cube or ring, and then extend our works to n-cube and generalized hypercube by applying the concept of spanning balanced tree (SBT) for their HC assignment. Our analysis results show that with such datacenters, the minimum number of wavelengths needed in each case is significantly reduced from that needed with OCS and also, the network cost in terms of wires and transceivers needed is considerably reduced from that incurs with datacenters using electronic packet switching. We then evaluate the traffic performance of such hypercube-based datacenters using LOBS-HC through simulation experiments via the OPNET simulator. The performance results obtained for a variety of communication patterns and traffic models within a datacenter demonstrate the feasibility of the proposed approach.

Green data center with IoT sensing and cloud-assisted smart temperature control system

With the growing shortage of energy around the world, energy efficiency is one of the most important considerations for a data center. In this paper, we propose a green data center air conditioning system assisted by cloud techniques, which consists of two subsystems: a data center air conditioning system and a cloud management platform. The data center air conditioning system includes environment monitoring, air conditioning, ventilation and temperature control, whereas the cloud platform provides data storage and analysis to support upper-layer applications. Moreover, the detailed design and implementation are presented, including the dispatch algorithm for the temperature control, topological structure of the sensor network, and framework for the environment monitoring node. A feasibility evaluation is used to verify that the proposed system can significantly reduce the data center energy consumption without degradation in the cooling performance.

A Node-Grade Based AODV Routing Protocol for Wireless Sensor Network

This paper proposes an improved Ad-hoc On-Demand Distance Vector (AODV) routing protocol based on node-grade to reduce the energy consumption of nodes in wireless sensor networks. The improved AODV called Grade-AODV (G-AODV) assigns a grade to each node according to the hop distance of the node to the sink node. The lower grade a node has, the closer it is to the sink. Each node is restricted to receive the route request (RREQ) packet from the nodes which have larger grade than itself. Therefore, the proposed G-AODV can reduce the energy consumption of nodes from two aspects: 1) the useless broadcast of RREQ can be avoided; 2) each packet uses less network resources because the route paths with less hop distance are set up. The performance of G-AODV is evaluated by simulation through OPNET modeler. The simulation results show that the G-AODV has better performance than AODV in view of the utilization and lifetime of network.

Hybrid Protection Architecture against Multipoint Failure in WDM-PON

In this paper, we propose hybrid protection architecture, to protect against multipoint failure in WDM-PON which component failure can potentially lead to an enormous loss of traffic. The proposed architecture is fully configured and the protection fiber can be used to transmit extra traffic under normal states, to increase the survivability and efficiency of the network. If failure is detected, normal traffic is switched to the protection path and extra traffic is preempted. Wavelength assignment and protection methods are also proposed for our protection architecture. The performance of proposed architecture is evaluated in terms of cost, channel utilization and queuing delay.

A novel kind of programmable 3(n) feed-forward optical fiber true delay line based on SOA.

A new kind of 3(n) feed-forward programmable optical fiber true delay line was proposed. Theoretical analysis was presented on its delay performance and expandability. Experimental demonstration was given to show the implementation of such delay lines using SOAs and Farady rotation mirrors. Delay step as small as 0.5 ps with precision of about 0.03 ps was achieved. Measurement was performed to verify the feasibility and results are given.

Investigation of the Design of MAC Protocols for TT-TR-Based WDM Burst-Switched Ring Networks

Multiple-token-based media access control (MAC) protocols are investigated for an efficient optical-burst-switching (OBS) ring network with nodes using a tunable transmitter, tunable receiver (TT-TR), since it suffers from resource contention due to the limited network resources. As tokens manipulate the wavelength accessibility and destination queues decide the burst scheduling, token-releasing discipline (TRD) and queue-scheduling discipline (QSD) are crucial. Two TRD schemes that were proposed to avoid source and wavelength contention are reviewed. Three QSD schemes differing in how to group round-robin queues are proposed to avoid or reduce the receiver contention. The performance for different TRD and QSD protocols are simulated and evaluated.

Theoretical Analyses of Lightpath Blocking Performance in CO-OFDM Optical Networks with/without Spectrum Conversion

This paper provides the first analysis of the impact of spectrum conversion on the lightpath blocking performance in the CO-OFDM optical networks. Two analytical models for the cases of using and not using spectrum convertors are developed for an H-hop end-to-end lightpath and a network, respectively. Numerical results show that the use of spectrum convertors can significantly improve the lightpath blocking performance.

Design and performance comparison of multiple-token based MAC protocols for optical burst switched ring networks

Optical burst switching (OBS) has been proposed as a new optical switching paradigm for the next generation Internet due to its flexibility and feasibility compared to OCS and OPS. Moreover, serving as a backbone that interconnects a number of access networks, OBS ring topologies have been a good choice for solving the current metro gap problem between core network and access network owning to its simplicity and scalability. In this paper, we provide an insight into the OBS ring network that consists of nodes using TT–TR (Tunable Transmitter–Tunable Receiver). The node architectures with TT–TR may make efficient use of network resources even though traffic pattern, such as IP traffic with self-similarity dynamically change, and can support good expandability. However, all nodes share the limited network resources. This may result in contention such as wavelength contention and transceiver contention leading to burst loss. In order to use the shared network resources fairly and efficiently as well as reducing the resource contention, we focus on the design of medium access control (MAC) protocols based on multiple tokens. Each token is allocated to one wavelength to denote the accessibility of that wavelength, i.e., once the token is captured, the corresponding wavelength can be used to transmit a burst. As tokens hold the key for using wavelengths to transmit bursts, token management including the token release time is crucial in the proposed MAC protocols. Thus, two kinds of multiple-token based MAC protocols with different token release times are proposed: token release after transmitting burst (TRTB) and token release after transmitting control header (TRTC). Each of them is classified into two schemes called TRTB/TRR and TRTB/RCA and correspondingly TRTC/TRR and TRTC/ RCA. RCA stands for receive collision avoidance. The target is to increase the performance while reducing the processing overhead at each node. The performance of the TRTB and TRTC protocols are evaluated and compared in terms of queuing delay, burst loss rate, and channel utilization by OPNET simulation. The effects of various design parameters are also investigated through simulation in order to evaluate their scalability. In all the proposed schemes, tokens are just used to denote the accessibility of each wavelength. Finally, as an alternative, we also propose a new scheme based on the TRTC protocol called TRTC/CAT (collision avoidance by tokens) to avoid contention by using tokens.