1. Research and Software Development of TETRA & TETRAPOL Networks Models Using OPNET

Investigator(s): Asst. Prof. Chong Han Joo Peter, Qiu Liwei, Chen Li, Wang Yubo

TETRA Direct Mode Operation (DMO) represents direct communication between  two or more TETRA Direct Mode (DM) terminals or Mobile Stations (MS)  without the use of trunking network infrastructure. It operates in a simplex and no duplex spacing mode whereby only one party is able to speak at a time with both receive and transmit frequencies being identical.

The main advantage of using TETRA DMO is to provide an undemanding but robust system that allows communication using parameters as similar to the TETRA Trunk Mode Operation (TMO) system as possible, in areas where there is no TMO coverage.

However due to its limitation in the capability and resource efficiency, it is restricted from being able to replace the TMO system. There are four DMO reference models namely DMO Terminal to DMO Terminal, DMO Repeater TETRA V+D to DMO Dual Watch and DMO Gateway. In this project, we are only exploring into the DMO Terminal to DMO Terminal models.

DMO terminal to DMO terminal operation applies to a simple point-to-point or point to multi-point communication between DM-MSs using Direct Mode Air Interface, Ud. The DM-MS providing the synchronization reference is defined as the “Master” whereas the rest of the DM-MSs which synchronize on this “Master” are termed as “Slaves”.

We will be using OPNET Modeler to simulate the group Direct Mode Operation and investigate the effect of different parameters and conditions on the connectivity, blocking probability and dropping probability of each talkgroup. The parameters we are simulating are: Average number of  calls per hour (call/hr), Average call length (mins), Transmission range (m), Coverage area (km), Number of talkgroups and Number of mobile stations.

In conclusion, we will study the results obtained from the simulations to determine the most appropriate parameters to achieve the optimum reliability and discuss the findings if the results are not as expected.

This project is a continuation of a previous project to develop TETRA TMO in a wireless environment.

Publications

• Y Wang, P H J Chong, L Qiu, L Chen, E Lee, L C Seck, and D Cheung, “Research and Software Development of TETRA & TETRAPOL Networks Models for IP-Based Data Services Using OPNET,” Proc-OPNET2006, Washington D.C. Aug. 28-Sept. 1, 2006.

• A TETRA TMO model has been contributed to OPNET in 2006.

2. QoS Service over Wireless LAN

Investigator(s): Assoc. Prof. Ma Maode, Frankie Chan Kok Liang

This project is to work on the proposal for IEEE 802.11e standard to support QoS service in Wireless LAN. Based on the current IEEE 802.11e standard which introduces Hybrid Coordination Function (HCF), two new access mechanisms known as i) Enhanced Distributed Channel Access (EDCA) and  ii) HCF Controlled Channel Access (HCCA) will be studied. Simulation models will be built using OPNET Modeler to study the performance of these two models compare to the original 802.11 standard which does not support QoS. Besides the original models of 802.11e, work will also be done on enhancement of the current models such as to design a new queuing and scheduling algorithm on the Wireless MAC layer in order to provide improvement on the QoS.

The latest version of OPNET Modeler, v11.5 includes the 802.11e EDCA model which is useful to this project where some design work and simulation can be done based on that available model to get performance results and analyze the difference in performance (delay and throughput) between different types of services (background, best effort, video and voice). Preliminary result in simulation shows that EDCA model provides good support (shorter delay) for services like voice and video due to the priority given to these two services. Furthermore, more effort will be spent on designing the HCCA model which is concentrated on the scheduling mechanism and admission control of the wireless MAC layer on OPNET Modeler environment. The HCCA model is still not available in the latest version of OPNET Modeler. To come out with the new scheduling algorithm, the node model and process model need to be designed and programmed in OPNET where C++ programming will be used in order to come out with our new QoS support model.

Publications

• F. K. L. Chen and Maode Ma, ”Supporting Quality of Services in Wireless LANs by EDCA Access Scheme,” Proc-MMU International Symposium on Information and Communications Technologies (M2USIC 2006), Malaysia, November 2006.

3. QoS Service Provisioning in WiMax Networks

Investigator(s): Asst. Prof. Ma Maode, Li Dongwei

The objective of this project is to work on the proposals for the IEEE 802.16e standard to support QoS service in WiMax system. Simulation model which support QoS service will be built using OPNET Modeler. The new model is designed and programmed in OPNET using C language. The performance of the IEEE 802.1 1e standard simulated using OPNET Modeler will be studied. I will also need to propose a solution to improve the state-of-the-art solutions.

Publications

Work in progress

4. Design and Performance Analysis of Medium Access Control protocol for Qos service in Wireless Access Networks (Wimax) Report

Investigator(s): Assoc. Prof. Ma Maode, Lu Jinchang

Recent development on the wireless communication technology has brought much innovation’s to make wireless access networks to be able to replace the wired access networks with much more bandwidth.

The objective of this project is to provide novel solutions for Qos service in the Wimax networks, which are also useful for military C2 systems. I will propose novel scheduling algorithms for Qos service and evaluate the performance of them. The impact on Qos service of mobile base station and end user nodes will also be studied.

OPNet simulation system will be used to simulate the 4 type of services, namely, UGS, rtPS, nrtPs and BE, which provide the optimum services in different environment or situation.

A modification will be made in the scheduling and queuing system. The performance of scheduling and queuing system after modification will be evaluated by using OPNET simulator.

After the novel Medium Access Control protocol is designed, the performance of the proposed protocol will be evaluated by modeling in OPNET simulator.

Publications

Work in progress

5. Performance Study of QoS Serives in WiMax Networks

Investigator(s): Asst. Prof. Ma Maode, Yan Rongfeng

WiMAX is defined as Worldwide Interoperability for Microwave Access. It is not a technology, but rather a certification mark, or 'stamp of approval' given to equipment that meets certain conformity and interoperability tests for the IEEE 802.16 family of standards. To support QoS service in WiMax system is an important topic in current research of wireless access networks. IEEE 802.16e standard, which published in February of 2006, has specified a framework for the wireless access network ---WiMax.

In this project, I will work on the proposals for the IEEE 802.16e standard to support QoS service in WiMax system. I will set up a simulation model to study the performance of the IEEE 802.11e standard and propose a solution to improve the state-of-the-art solutions.

So I want to use the OPNET software to simulate the Wireless MAN model.

Publications

Work in progress

6. Multi Access Scheme for Ethernet Passive Optical Network (EPON)

Investigator(s): Asst. Prof. Ma Maode, Zhu Yongqing

The object of our project is to propose a MAC protocol used in the upstream channel sharing in EPON network. The proposed BGP scheme incorporates the SLA into MAC protocol design. It can achieve bandwidth guarantee for high-demand customers, while provide best-effort service to low-demand customers. We also combine a CAC mechanism to BGP to enrich the scheme. In order to support differentiated services and provide different QoS in EPON, the strict priority queues and other scheduling methods are deployed in the intra-ONU scheduling and BGP as the inter-ONU scheduling scheme.

OPNET’s character of explicit layer configuration is very helpful to simulate the network environment of EPON. We have completed the basic design for BGP scheme, CAC mechanism, combined schemes of inter-ONU and intra-ONU scheduling schemes. Simulations have been done using OPNET to evaluate the performance of average waiting delay, throughput, queue size and loss rate. The simulation results show that our BGP scheme is powerful and efficient combined with CAC mechanism to meet the demand of service provider and customers. And the solutions of inter- and intra-ONU schemes are effective to provide the differentiated services in the EPON environment.

Publications

• Y. Zhu, Maode Ma, and T. H. Cheng, “IPACT with Grant Estimation for EPON,” Proc-IEEE Tenth International Conference on Communication Systems (ICCS’06), Singapore, November, 2006

7. Blocking Performance of Hose Model and Pipe Model for VPN Service Provisioning over WDM Optical Networks

Investigator(s): Assoc. Prof. Poo Gee-Swee, Wang Haibo

For the past months, my research work concentrated on the blocking performance of pipe model and hose model for OVPN provisioning. Pipe model and hose model are two resource management models for VPN. They play a key role in providing QoS guaranteed service.

Previous studies on pipe model and hose model largely focus on the resource efficiency aspects: devise algorithms to compute optimal resource reservations in the network, and compare the resource requirements for these two models. But the performance issues are barely considered.

In our work we set out to study the blocking performance of pipe model and hose model in a multi-rate network. We use both discrete event simulations and queuing model analysis in the study, with the simulation carried out using OPNET. The results from both methods show a close match. OPNET is a great help in this study. In the coming months, OPNET will continue to be a great help to my research work.

Publications

Work in progress

8. Optical Resilient Packet Ring based on all optical buffering techniques

Investigator(s): Assoc. Prof. Zhang Liren, Tang Wenli

The objective of this project is to identify and resolve some critical issues about Optical Resilient Packet Ring (O-RPR) network, such as fairness algorithm, intelligent protection switching and fair access to the ring. We would conduct some research on the fairness control mechanism and protective algorithm of RPR network with our novel optical buffer.

In the first place, a novel fairness control algorithm is going to be proposed. Then OPNET is used to evaluate the network performance with this algorithm by analyzing the obtained results like a node’s throughput, access delay and system utilization. Furthermore, the simulations with the existing modes of operations for the fairness algorithm both proposed by the IEEE 802.17 Working Group and other papers are compared with ours.

Next, different switch models involved in optical packet switched networks are going to be investigated. Most of them use wavelength-division multiplexing on each input fiber, so wavelength conversion controls the switch path (analogue to space switch). We are going to propose a novel switch model which can also provide the functions similar to the time switch. Therefore, the resulting switching node is able to perform switching in both time and space domains. Moreover, the optical packet switched network can achieve high utilization because of the wavelength-division multiplexing. However, the real network is infeasible to be constructed and experimented due to its complexities and limitations. With the help of OPNET, the single switch node can be designed and implemented, so that the whole network performance analysis is facilitated.

Publications

Work in progress

9. Detection and Mitigation of Co-operative Attacks in Wireless Mobile Ad Hoc Networks (MANET)

Investigator(s): Assoc. Prof. Zhang Liren, Ng Siew Ying, Ng Tiah Khoon

The existing works on MANET security typically addresses specific attacks and then strengthen the existing protocols or propose a new protocol to defend against specific attacks.  However, these solutions are designed with specific attacks in mind and they usually work well in defending against anticipated attacks but may fail under unanticipated attacks.

To arrive at a good solution, one need to

1. Analyze and quantify the effects of cooperative attacks on mobile ad hoc networks

2. Develop and evaluate approaches to detecting and preventing cooperative attacks.

This project objective:

1. Create a Simulation of Wireless Mobile Ad Hoc Networks (MANET) using OPNET.

2. Identifying the problem of cooperative attacks by multiple malicious nodes acting as a group. 

3. Developing and testing a feasible solution for identifying multiple black hole nodes cooperating as a group. 

Publications

Work in progress