Daryoush Habibi

Loss performance analysis for heterogeneous ON-OFF sources with application to connection admission control

The bufferless fluid flow model (bffm) is often used in the literature for loss performance analysis. In this paper, we propose an efficient and effective means of investigating cell loss using the bffm. We define the cell loss rate function (clrf) and use it to characterize the loss performance of traffic sources in the bffm. Stochastic ordering theory is used to study the clrf. The introduction of the stochastic ordering theory not only simplifies the theoretical analysis but also makes it possible to extend the scope of applications and theoretical analysis presented in this paper. A cell loss upper bound for heterogeneous ON-OFF sources is proposed. The proposed cell loss upper bound is tighter than those previously proposed in the literature. A connection admission control (CAC) scheme using online measurements is designed based on the cell loss upper bound. Extensive simulation is carried out to study the performance of the CAC scheme. Particular attention is paid to the impact of inaccuracies in user-declared traffic parameters on the performance of the CAC scheme. Simulation results indicate that the proposed CAC scheme can ensure QoS guarantee, is robust to inaccuracies in declared traffic parameters, and is capable of achieving high link utilization.

Performance evaluation of IEEE 802.15.4 for mobile sensor networks

The IEEE 802.15.4 standard medium access control (MAC) protocol for low rate wireless personal area networks (LRWPAN) is design mainly for static sensor networks and its capability to support mobile sensor networks has not yet been established. To the best knowledge of authors, this is the first paper that evaluates the suitability of IEEE 802.15.4 MAC in mobile sensor networks environment. We evaluate the performance based on nodes speed and beacon order, and observe the effect on energy usage, packet delivery ratio and time required to associate with its coordinator. From the experiment we observe that the moving nodes experienced serious problems in association and synchronization and show results on energy usage, throughput , association and reassociation rate with different speeds of moving node. We also identify some key research problems that need to be addressed for successful implementations of IEEE 802.15..4 in mobile sensor networks environment.

Classification of digital modulation schemes using neural networks

Modulation recognition systems have to be able to correctly classify the incoming signals modulation scheme in the presence of noise. This paper addresses the problem of automatic modulation recognition of digital communication signals using neural networks. Seven digital modulation schemes have been considered and seven features have been used as inputs to the neural network (NN) to perform the classification. Several NN structures have been tested that perform at over 99% accuracy at signal-to-noise ratios (SNR) of 10 dB. Design considerations for the NN classifier are discussed and the implementation of these has been shown to produce significant reduction in network size. The performance of the NN-based classifier has also been compared with that of a decision-theoretic classifier; it was found that the NN slightly outperforms the decision-theoretic classifier.

A novel mobile WiMAX solution for higher throughput

The IEEE 802.16 standard, also known as WiMAX, has emerged as an exciting technology for broadband wireless communications with potentials to offer high throughput and support high bandwidth demanding applications. WiMAX, however, has yet to prove its effectiveness when the end terminals are not fixed and have the capacity to move from one place to another at different speeds. Recent studies suggest that while WiMAX (802.16e) has the potential to deliver a data rate up to 75 Mb/s for fixed wireless communications, it fails drastically for mobile wireless communications, often providing a data rate less than 1 Mb/s when the mobile nodes travel at high speeds, which offers a huge challenge for QoS management. Multipath fading that causes high bit error rate at the receiver end is a key reason for low throughput at high speed. Bit error rate and maximum packet size determine the packet error rate, and error recovery for higher number of corrupted packets is not always an attractive option for many real-time applications with delay and jitter constraints. In this paper, we propose a mathematical model to estimate the bit error probability when the mobile station travels at different speeds. The estimated value of bit error probability is then taken into account to proactively compute the appropriate maximum packet size that offers the best chance to achieve improved throughput at different operating conditions. We simulated the proposed scheme for a centralized video surveillance system in a public train where the train is the mobile node and sends real-time video data to the base stations. The results show that the proposed scheme achieves significantly higher throughput and lower jitter compared to other standard schemes.

QRP02-5: Joint Optimization in Capacity Design of Networks with p-Cycle Using the Fundamental Cycle Set

We propose a joint optimization model for capacity design of networks with p-cycles. The model is based on a modified definition of network fundamental cycles and the available straddling links. Concepts about visible and hidden straddling links, which are essential components of our model are also introduced. This is the first ILP model for joint optimization of p-cycle network that can be solved without enumerating p-cycle candidates, and has the ability to achieve optimum solutions. In addition, the complexity of our proposed model is much smaller than any conventional models, particularly when applying to a planar network. This model is suitable large size networks and for shared risk link group networks or backbone networks protected by p-cycle schemes.

Transmission improvement of UMTS and Wi-Fi signals through energy saving glass using FSS

This paper presents a dual-bandpass (DBP) frequency selective surface (FSS) based on hard-coating energy saving glass (ESG). The objective of this study is to generate a novel design of FSS on ESG, which is to be used for future energy smart buildings at Edith Cowan University (ECU). The ESG is made of a transparent coating of conducting layer on glass substrate, which attenuates infrared (IR) radiations for energy saving purpose. However the coating also attenuates useful UMTS and Wi-Fi signals which are necessary for the communication systems within the University. FSS technique is used to improve transmission of RF/MW signals through ESG by generating an array of patterns in the hard coating layer. The design of the DBP-FSS presented here has achieved transmission requirements for two specific frequency bands, with stable frequency response for both transverse electric (TE) and transverse magnetic (TM) polarization at normal and oblique incidence angles up to 60°. The double square loop (DSL)-FSS sustains 92.7% efficiency of ESG by attenuating IR radiations. This design methodology can be adapted as a general reference, which is suitable for applications under similar circumstances. Optimized design and theoretical results are presented.

Service Class Resource Management for Green Wireless-Optical Broadband Access Networks (WOBAN)

Exponential growth in the volume of wireless data, boosted by the growing popularity of mobile devices, such as smartphone and tablets, has forced the telecommunication industries to rethink the way networks are currently designed, and to focus on the development of high-capacity mobile broadband networks. In response to this challenge, researchers have been working toward the development of an integrated wireless optical broadband access network. Two major candidate technologies, which are currently known for their high capacity as well as quality of service (QoS) for multimedia traffic, are passive optical networks (PON), and fourth generation (4G) wireless networks. PON is a wired access technology, well known for its cost efficiency and high capacity; whereas 4G is a wireless broadband access technology, which has achieved broad market acceptance because of its ease of deployment, ability to offer mobility, and its cost efficiency. Integration of PON and 4G technologies in the form of wireless-optical broadband access networks, offers advantages, such as extension of networks in rural areas, support for mobile broadband services, and quick deployment of broadband networks. These two technologies however, have different design architectures for handling broadband services that require quality of service. For example, 4G networks use traffic classification for supporting different QoS demands, whereas the PON architecture has no such mechanism to differentiate between types of traffic. These two technologies also differ in their power saving mechanisms. In this paper, we propose a service class mapping for the integrated PON-4G network, which is based on the M/G/1 queuing model. We also propose a class-based power saving mechanism which significantly improves the sleep period for the integrated optical wireless unit, without compromising support for QoS. Results indicate that our proposed class-based power saving scheme reduces power consumption by up to 80%, and maintains the QoS within the requirements of the service level agreement.

Transmission power control in multihop wireless sensor networks

One of the major challenges in wireless sensor networks (WSNs) deployment is to decrease sensor nodes energy consumption to prolong the lifetime of the finite-capacity batteries. Using multihop has been viewed as one of the main techniques to prolong operational lifetime in wireless sensor networks. In this paper we offer a study on transmission power control (TPC) in multihop WSNs using typical Telosb platform parameters, which is IEEE 802.15.4 standard compliant. We offer a new approach to test TPC in multihop networks at the physical layer and provide energy consumption performance results via simulation and numerical model in multihop WSNs. Our simulation and numerical model results illustrate that energy spent to send packets using short-range multihop path instead of single hop does not necessarily save energy as suggested by some of the earlier research.

An optimal current control strategy for a three-phase grid-connected photovoltaic system using Particle Swarm Optimization

A robust current control strategy for PV (photovoltaic) grid-connected systems is required for reliable use of solar energy as an abundant and clean renewable energy. This paper presents real time optimization parameters of the current control strategy for a 3-phase photovoltaic grid-connected Voltage Source Inverter (VSI) system. The proposed controller scheme is implemented based on a synchronous reference frame; the Phase-Locked Loop (PLL) is used as grid phase detector. Particle Swarm Optimization (PSO) algorithm is an intelligent searching algorithm that is used to implement the real time self-tuning method for the current control parameters. Two conventional PI controllers are used and feed-forward compensation is applied with the inner inverter current control loop to achieve fast dynamic response. The main aim of this work is to achieve high dynamic response for the inverter output current with acceptable harmonics level in steady-state condition all of which is required for power quality improvement. The results show that the proposed strategy provides an excellent dynamic response within real time optimization.

High Utility Video Surveillance System on Public Transport Using WiMAX Technology

Video surveillance on public transport is a useful tool to fight against anti-social behaviour like vandalism, harassment, graffiti and terrorism. Real-time video surveillance on moving public transport faces serious technological challenges mainly due to limited throughput offered by existing communication technologies at high vehicular speeds. Success of real-time video surveillance on public transport heavily depends on future communication technologies like WiMAX. WiMAX has emerged as an exciting technology with promises to offer high throughput and improved quality of services (QoS), key requirements for video surveillance on public transport. WiMAX however, offers limited throughput at high vehicular speeds mainly because of multipath fading that causes high bit error rate at the receiver at vehicular speeds. In our previous works, we showed that it is possible to estimate the bit error rate at the receiver end at various vehicular speeds in WiMAX and accordingly, some proactive measures can be adopted to improve the throughput to some extents. Overall throughput however, may still be insufficient to support the streaming video data from all the cameras mounted on a public transport at high vehicular speeds. In this paper, we propose a new scheme that estimates utility for different cameras and puts some low utility cameras offline and thereby maintains high utility of the video surveillance system when the throughput at high vehicular speeds become insufficient. Simulation results confirm the effectiveness of the proposed scheme.