Showing papers by "Pin-Han Ho published in 2015"

A Cross-Layer Secure Communication Model Based on Discrete Fractional Fourier Fransform (DFRFT)

Abstract: Discrete fractional Fourier transform (DFRFT) is a generalization of discrete Fourier transform. There are a number of DFRFT proposals, which are useful for various signal processing applications. This paper investigates practical solutions toward the construction of unconditionally secure communication systems based on DFRFT via cross-layer approach. By introducing a distort signal parameter, the sender randomly flip-flops between the distort signal parameter and the general signal parameter to confuse the attacker. The advantages of the legitimate partners are guaranteed. We extend the advantages between legitimate partners via developing novel security codes on top of the proposed cross-layer DFRFT security communication model, aiming to achieve an error-free legitimate channel while preventing the eavesdropper from any useful information. Thus, a cross-layer strong mobile communication secure model is built.

Neighborhood failure localization in all-optical networks via monitoring trails

Abstract: Shared protection, such as failure-dependent protection (FDP), is well recognized for its outstanding capacity efficiency in all-optical mesh networks, at the expense of lengthy restoration time due to multihop signaling mechanisms for failure localization, notification, and device configuration. This paper investigates a novel monitoring trail (m-trail) scenario, called Global Neighborhood Failure Localization (G-NFL), that aims to enable any shared protection scheme, including FDP, for achieving all-optical and ultra-fast failure restoration. We first define the neighborhood of a node, which is a set of links whose failure states should be known to the node in restoration of the corresponding working lightpaths (W-LPs). By assuming every node can obtain the on--off status of traversing m-trails and W-LPs via lambda monitoring, the proposed G-NFL problem routes a set of m-trails such that each node can localize any failure in its neighborhood. Bound analysis is performed on the minimum bandwidth required for m-trails under the proposed G-NFL problem. Then, a simple yet efficient heuristic approach is presented. Extensive simulation is conducted to verify the proposed G-NFL scenario under a number of different definitions of nodal neighborhood that concern the extent of dependency between the monitoring plane and data plane. The effect of reusing the spare capacity by FDP for supporting m-trails is examined. We conclude that the proposed G-NFL scenario enables a general shared protection scheme, toward signaling-free and ultra-fast failure restoration like p-Cycle, while achieving optimal capacity efficiency as FDP.

SRLG failure localization using nested m-trails and their application to adaptive probing

Abstract: This article explores a recently introduced novel technique called the nested monitoring trail m-trail method in all-optical mesh networks for failure localization of any shared risk link group SRLG with up to d undirected links. The nested m-trail method decomposes each network topology that is at least d-connected into virtual cycles and trails, in which sets of m-trails that traverse through a common monitoring node MN can be obtained. The nested m-trails are used in the monitoring burst m-burst framework, in which the MN can localize any SRLG failure by inspecting the optical bursts traversing through it. An integer linear program ILP and a heuristic are proposed for the network decomposition, which are further verified by numerical experiments. We show that the proposed method significantly reduces the required fault localization latency compared with the existing methods. Finally, we demonstrate that nested m-trails can also be used in adaptive probing to find SRLG faults in all-optical networks. The nested m-trail based probing method needs a significantly reduced number of sequential probes. Thus, the method overcomes one of the important hurdles to deploy adaptive probing in all-optical networks: the large number of sequential probes needed to localize SRLG faults. © 2015 Wiley Periodicals, Inc. NETWORKS, Vol. 664, 347-363 2015

Low Complexity BICM MIMO OFDM Demodulator

Abstract: In this paper, we consider low-complexity detection of coded spatial data streams with uniform power and non-uniform rate distribution in a single-user MIMO system. The receiver decodes these different streams as if facing a multiple access channel (MAC). Conventional receiver solutions for such schemes are based on successive interference cancellation (SIC) by employing a linear minimum mean square error (MMSE) successive stripping detector, where the optimality is nonetheless constrained to Gaussian codebooks. As a remedy, this paper introduces a novel near-optimal low-complexity max-log-MAP demodulator for a $2\times n_{r}$ system ( $n_{r}$ is the number of receive antennas) which reduces the complexity of detection from ${\cal O}(\vert\chi\vert^{2})$ to ${\cal O}(\vert\chi\vert^{1})$ , where $\vert\chi\vert$ indicates the size of the signal set. In the sequel, we extend the proposed low-complexity demodulation scheme to higher-dimensional MIMO systems via a hybrid detector, where significant complexity saving is realized at the expense of slight performance degradation.

Failure Restoration Approaches

Abstract: This chapter is on enumerating dynamic survivable routing schemes in mesh optical networks. By taking dynamic connection requests that arrive one after the other without any knowledge of future arrivals, the survivable routing schemes are required to allocate a disjoint working and protection path-pair for each connection request according to the current link-state. Without loss of generality, a working or a protection path is taken as a lightpath, either with a single wavelength if it is in a WDM network, or with some bandwidth allocated if it is in a spectrum-sliced elastic optical network supported by the optical orthogonal frequency division multiplexed technology.

Failure Localization Via a Central Controller

Abstract: To achieve fast Unambiguous Failure Localization, an essential problem for the network operators is to determine how to efficiently probe the network elements such that the number of probes is the minimum. By launching a set of m-trails, the transmitter of each m-trail constantly probes the health of the links along the m-trail, and the monitor at the receiver issues an alarm once detecting any irregularity. A failure may interrupt multiple m-trails which incurs a set of alarms. The m-trails should be allocated such that the network controller can uniquely and precisely localize the failure state according to the issued alarms. The chapter is on the m-trail allocation problem by introducing algorithms and approaches in presence of single and multiple link failures, respectively. With single-link failures, an essentially optimal construction for m-trail allocation is provided for lattice topologies. For general topologies, a suite of heuristics are presented, including Random Code Swapping (RCA–RCS) for single-link failures, Adjacent Link Failure Localization and Link Code Construction for adjacent link failures, and Greedy Code Swapping (CGT-GCS) for dense-shared risk link group failures based on combinatorial group testing.

Joint Power Minimization Over Multi-Carrier Two-Way Relay Networks

Abstract: The study considers a three-node, two-way relaying network (TWRN) over a multi-carrier system, aiming to minimize the total power consumption of all the transmit and receiver activities. By employing digital network coding (DNC) and physical-layer network coding (PNC), respectively, as well as a novel hybrid PNC/DNC switching scheme, the total transmission power of the considered multi-carrier TWRN system is firstly analyzed; and the derived analytical expressions are then used to formulate a set of nonconvex optimization problems. We will show how those nonconvex functions are convexified for better computational tracbility. It is observed in the numerical results that, the PNC scheme generally consumes less power than DNC but becomes worse in the very low SNR regime. The proposed hybrid PNC/DNC switching scheme that takes advantage of both, is shown to outperform in all SNR regimes.

Global Neighborhood Failure Localization

Abstract: The distributed m-trail framework (i.e., NL-UFL) introduced in the previous chapter enables every node to be able to instantly localize a failed SRLG such that the failure restoration can be performed automatically in the optical domain. This is obviously not necessary since a node may not need to respond to a failure event if the node is not traversed by any P-LP whose W-LP is subject to the failure. In response to such an observation, this chapter defines and investigates an interesting m-trail scenario, called Global Neighborhood Failure Localization (G-NFL). As a one step advance of NL-UFL, G-NFL defines the neighborhood of a node, which is a set of links whose failure states should be known to the node in restoration of the corresponding W-LPs, and the G-NFL problem routes a set of m-trails such that each node can localize any failure in its neighborhood. To gain insight into the G-NFL problem, the chapter provides bound analysis on the minimum bandwidth required for m-trails, along with a simple yet effective heuristics.

Distributed Failure Localization

Abstract: The chapter continues the topic of bm-trail allocation as in Chap 3, by assuming a distributed control environment where a remote network controller for collecting the alarms is absent Instead, the scenario that a node can individually perform UFL without relying on any failure notification mechanism is targeted Accordingly, a constraint is imposed on the previously formulated bm-trail allocation problem where the alarms locally available to a node should form a complete alarm code table (ACT) for making the failure localization decision This is also referred to as local unambiguous failure localization (L-UFL) at the node A step further to L-UFL is that all the nodes are required to be L-UFL capable, which leads to the scenario referred to as Network wide L-UFL (NL-UFL) The chapter presents solutions to the bm-trail allocation problems for L-UFL and NL-UFL, respectively, via both bound analysis and heuristics under various network failure scenarios

Introduction to Optical Fault Management

Abstract: In this chapter we introduce the survivable network design framework and identify the design goals of survivable network planning (ie, resource efficiency and fault management complexity), and the trade-off between these objectives is discussed in protection and restoration approaches A short summary on network faults and the shared risk link group model is presented, followed by a discussion of the phases of GMPLS-based fault recovery, and at the end of the chapter a brief summary is given

Dynamic Survivable Routing with M-Trails

Abstract: We have seen in the previous chapters that m-trails can be incorporated with a survivable routing scheme in the optical network backbones such that the desired ultra-fast and all-optical restoration can be achieved with little additional cost. The chapter turns to the issues of dynamic survivable routing in mesh optical networks where connection requests for lightpaths arrive in the network one after the other with little knowledge of future arrivals. Firstly, we will review the spare capacity allocation problem under dedicated or shared protection schemes. A dynamic routing scheme, called Dynamic Joint Design Heuristic (DJH) , is introduced with its goal to allocate each request based on the failure dependent protection principle while reconfiguring the m-trails for achieving the desired ultra-fast and signaling-free failure restoration. DJH is featured as an FDP scheme that can jointly allocate a W-LP and its P-LPs to satisfy an arriving connection request, as well as the m-trails that should be newly added to the network, such that the W-LP can be restored in an all-optical fashion as in Chap. 6. By launching the m-trails possibly by reusing the spare capacity for P-LPs, the amount of WLs (wavelength channels) dedicated to the m-trails can be significantly reduced.