Changcheng Huang

Efficient resource allocation for device-to-device communication underlaying LTE network

Device-to-device (D2D) communication as an underlaying cellular network empowers user-driven rich multimedia applications and also has proven to be network efficient offloading eNodeB traffic. However, D2D transmitters may cause significant amount of interference to the primary cellular network when radio resources are shared between them. During the downlink (DL) phase, primary cell UE (user equipment) may suffer from interference by the D2D transmitter. On the other hand, the immobile eNodeB is the victim of interference by the D2D transmitter during the uplink (UL) phase when radio resources are allocated randomly. Such interference can be avoided otherwise diminish if radio resource allocated intelligently with the coordination from the eNodeB. In this paper, we formulate the problem of radio resource allocation to the D2D communications as a mixed integer nonlinear programming (MINLP). Such an optimization problem is notoriously hard to solve within fast scheduling period of the Long Term Evolution (LTE) network. We therefore propose an alternative greedy heuristic algorithm that can lessen interference to the primary cellular network utilizing channel gain information. We also perform extensive simulation to prove the efficacy of the proposed algorithm.

Modeling and simulation of self-similar variable bit rate compressed video: a unified approach

Variable bit rate (VBR) compressed video is expected to become one of the major loading factors in high-speed packet networks such as ATM-based B-ISDN. However, recent measurements based on long empirical traces (complete movies) revealed that VBR video traffic possesses self-similar (or fractal) characteristics, meaning that the dependence in the traffic stream lasts much longer than traditional models can capture.In this paper, we present a unified approach which, in addition to accurately modeling the marginal distribution of empirical video records, also models directly both the short and the long-term empirical autocorrelation structures. We also present simulation results using synthetic data and compare with results based on empirical video traces.Furthermore, we extend the application of efficient estimation techniques based on importance sampling that we had used before only for simple fractal processes. We use importance sampling techniques to efficiently estimate low probabilities of packet losses that occur when a multiplexer is fed with synthetic traffic from our self-similar VBR video model.

Building reliable MPLS networks using a path protection mechanism

It is expected that multiprotocol label switching (MPLS) based recovery could become a viable option for obtaining faster restoration than layer 3 rerouting. To deliver reliable service, however, MPLS requires a set of procedures to provide protection for the traffic carried on the label switched paths. We propose a path protection mechanism that is simple, scalable, fast, and efficient. We describe in detail our design considerations, the communication of fault information to appropriate switching elements, and the fault detection protocol. In particular, we propose a reverse notification tree structure for efficient and fast distribution of fault notification messages.

A Novel Fault Detection and Localization Scheme for Mesh All-optical Networks Based on Monitoring-cycles

We previously showed the feasibility of a fault detection scheme for all-optical networks (AONs) based on their decomposition into monitoring-cycles (m-cycles). In this paper, an m-cycle construction for fault detection is formulated as a cycle cover problem with certain constraints. A heuristic spanning-tree based cycle construction algorithm is proposed and applied to four typical networks: NSFNET, ARPA2, SmallNet, and Bellcore. Three metrics: grade of fault localization, wavelength overhead, and the number of cycles in a cover are introduced to evaluate the performance of the algorithm. The results show that it achieves nearly optimal performance.

MPEG4 traffic modeling using the transform expand sample methodology

The transfer of digital video will be a crucial component of the design of future home networking applications. This transfer was made feasible by the advancement of digital video encoding techniques that reduced the bandwidth required for this transfer to a practical level. MPEG4 is an encoding technique that is suitable for home networking applications with its low bit rate. It also has the advantage that allows viewers to interact with encoded objects. In this paper, we present our work that enables the study of MPEG4 properties and performance on the Internet using simulation. We propose a traffic generator that is able to generate traffic that has almost the same first and second order statistics as an original trace of MPEG4 frames that is generated using an MPEG4 encoder. We model and generate this traffic based on the transform expand sample (TES) methodology using TEStool. We present the model and show the performance of the generator in terms of good matching of the characteristics of the modeled trace.

Fault detection and path performance monitoring in meshed all-optical networks

Fault detection is critical for all-optical networks (AON). This paper introduces the concept of monitoring cycles and proposes a mechanism for fault detection and path performance monitoring based on decomposing AON into monitoring cycles. Two monitoring cycle finding algorithms are developed: heuristic depth first searching (HDFS) and shortest path Eulerian matching (SPEM). The two algorithms are compared in terms of wavelength overhead in nodes and links. The comparison results are obtained for four typical networks, including NSFNET, ARPA2, SmallNet and Bellcore. It is shown that the proposed fault detection mechanism based on monitoring cycles is effective and cost efficient.

The Design and Evaluation of a Wireless Sensor Network for Mine Safety Monitoring

This paper describes a wireless sensor network for mine safety monitoring. Based on the characteristics of underground mine gallery and the requirements for mine safety monitoring, we proposed a distributed heterogeneous hierarchical mine safety monitoring prototype system, namely HHMSM This system is capable of monitoring methane concentration, and locating miner. We proposed a novel overhearing-based adaptive data collecting scheme which exploits the redundancy and correlation of the sampling readings in both time and space to reduce traffic and control overhead with a well-bounded offset error for large-scale sensor networks. This mechanism is easy to implement and low-cost compared to other more theoretically based mechanisms such as Kalman filter. Experimental results show that HHMSM achieves better performance on flexibility, correctness, coverage, and lifetime compared with other existing wireless mine safety monitoring systems.

Fast simulation for self-similar traffic in ATM networks

Self-similar (or fractal) stochastic processes were proposed as more accurate models of certain categories of traffic (e.g., Ethernet traffic, variable-bit-rate video) which will be transported in ATM networks. Existing analytical results for the tail distribution of the waiting time in a single server queue based on fractional Gaussian noise and large deviation theory, are valid under a steady-state regime and for an asymptotically large buffer size. However, the predicted performance based on steady-state regimes may be overly pessimistic for practical applications. Theoretical approaches used to obtain the transient queueing behavior and queueing distributions for a small buffer size become quickly intractable. The approach we followed was based on fast simulation techniques for the study of certain rare events such as cell losses with very small probability of occurrence. Our simulation experiments provide an insight on the transient behavior that is not possible to predict using current analytical results. Finally they show good agreement with existing results when approaching steady-state.

Hybrid Cluster Routing: An Efficient Routing Protocol for Mobile Ad Hoc Networks

Routing is one of the fundamental but challenging issues in mobile ad hoc networks. During the past several years, a large number of routing protocols have been proposed, which can basically be categorized into three different groups including proactive/table-driven, reactive/on-demand, and hybrid. In this paper, we propose a novel hybrid routing protocol for large scale mobile ad hoc networks, namely HCR (Hybrid Cluster Routing). Here nodes are organized into a hierarchical structure of multi-hop clusters using a stable distributed clustering algorithm. Each cluster is composed of a clusterhead, several gateway nodes, and other ordinary nodes. The clusterhead is responsible for maintaining local membership and global topology information. In HCR, the acquisition of intra-cluster routing information operates in an on-demand fashion and the maintenance of inter-cluster routing information acts in a proactive way. Simulation results show that HCR conduces better scalability, robustness and adaptability to large scale mobile ad hoc networks compared with some well-known routing protocols, e.g. AODV, DSR, and CBRP.

End-to-end signaling and routing for optical IP networks

This paper outlines an approach, called the optical border gateway protocol (OBGP) of extending the BGP routing protocol to support light path setup and management across an optical network. OBGP is a distributed approach, which gives more control to the edge customer and allows customers to better manage their optical wavelengths. It provides an interdomain routing/signaling solution that integrates heterogeneous domains into an end-to-end optical network and can coexist with most of the existing intradomain solutions. OBGP has the capability of setting up light paths in both networks with wavelength converters as well as in networks without wavelength converters. By combining routing with signaling in OBGP, signaling functions can leverage some features of existing routing functions and thus provide a lightweight solution. The development of OBGP has been discussed by reviewing current BGP behavior and design requirements for OBGP. An implementation of OBGP using simulation tools has been presented, along with initial test results, which have shown that a seamless migration from BGP to OBGP is possible.