ABSTRACT The necessity of having a high demand for real-time applications has brought about the demand for good quality multimedia applications such as voice, video and online gaming. All three multimedia applications have similar characteristics in terms of satisfying consumers. This project researches into the foundation principles of WiMAX as it metamorphoses into the latest technology for mobile users willing to use real-time applications on their mobile devices. Also, it will simulate real life scenarios of user in a WiMAX networked environment using the IEEE 802. 1 j standard. The results of the simulated scenarios are explained as well as the effect of each mode -transparent and the non-transparent modes, the advantages of using each node, the scenarios where each mode are quite useful.
Finally, this project being based on OPNET 16 modeler in the university had some challenges due to memory capacity of the virtual machines used for the simulation. However, this did not hinder the expected results as it was as expected and also confirmed the industry standards. THESIS AUTHOR CONSENT FORM AUTHOR’S NAME: TITLE OF THESIS: PERFORMANCE EVALUATION OF REAL TIME APPLICATIONS IN WIMAX RELAY NETWORK DEGREE: MSC COMPUTER NETWORKING Please read carefully and sign the following as appropriate. I HAVE READ AND UNDERSTOOD THE UNIVERSITY’S REGULATIONS AND PROCEDURES CONCERNING THE SUBMISSION OF MY THESIS.
I UNDERSTAND THAT I HAVE ALREADY SIGNED A DECLARATION AGREEING TO MY DISSERTATIONS BEING KEPT IN THE LEARNING RESOURCES CENTRE (LRC) WHEN I ENROLLED. WE WOULD LIKE NOW, TO EXTEND THIS AGREEMENT BY MAKING THE THESIS AVAILABLE ONLINE. FURTHER TO THIS, I AGREE AS FOLLOWS: – THAT I AM THE AUTHOR OF THE WORK. – THAT I HAVE EXERCISED REASONABLE CARE TO ENSURE THAT THE WORK IS ORIGINAL, AND DOES NOT TO THE BEST OF MY KNOWLEDGE BREAK ANY UK LAW OR INFRINGE ANY THIRD PARTY’S COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. – THE LRC AND BREO ADMINISTRATORS DO NOT HOLD ANY OBLIGATION TO TAKE LEGAL ACTION ON BEHALF OF THE DEPOSITOR (YOU), OR OTHER RIGHTS HOLDERS, IN THE EVENT OF BREACH OF INTELLECTUAL PROPERTY RIGHTS, OR ANY OTHER RIGHT, IN THE MATERIAL DEPOSITED. DELETE ONE OF THE FOLLOWING OPTIONS AS APPROPRIATE: 1.
... made me realize how hard it really is in the real world. I now work that much harder in school to ... that I only enjoy working on cars in my free time, not when it was a requirement everyday. The pay also ... did after graduation was to go out and find a real job. I was sick of school and I just wanted ... senior year. The day when high school is over and "real life" begins. I felt this day was the day I ...
I HEREBY EXTEND MY CONSENT TO THIS THESIS BEING INCLUDED IN THE LRC AS WELL AS ON BREO VIA ONLINE ACCESS. AUTHOR’S PERSONAL SIGNATURE: AUTHOR’S STUDENT NUMBER: Table of Contents 2010/11 1 ABSTRACT 2 ACKNOWLEDGEMENTS 3 THESIS AUTHOR CONSENT FORM 4 1. 0 INTRODUCTION 9 1. 1 OVERVIEW 9 1. 2 MOTIVATION 10 1.
3 AIM AND OBJECTIVES 10 1. 4 PROBLEM DEFINITION 11 1. 5 METHODOLOGY 12 1. 6 SCOPE AND LIMITATIONS 12 1. 7 THESIS ORGANISATION 13 2. 0 LITERATURE REVIEW 13 2.
1 IEEE STANDARDS 16 2. 1. 1 IEEE 802. 16 18 2. 1.
2 IEEE 802. 16 a 18 2. 1. 3 IEEE 802. 16 c 19 2. 1.
4 IEEE 802. 16 d 19 2. 1. 5 IEEE 802. 16 e 19 2. 1.
6 IEEE 802. 16 f 19 2. 1. 7 IEEE 802. 16 g / h /i / j /k / m /Rev 20 2. 2.
0 IEEE 802. 16 PHYSICAL (PHY) LAYER 22 2. 2. 1 Orthogonal Frequency Division Multiplexing (OFDM) 23 2. 2. 2 OFDM Parameters in WiMAX 24 2.
2. 2. a Fixed WiMAX OFDM Physical Layer 25 2. 2.
2. b Mobile WiMAX OFDMA Pysical Layer 25 2. 2. 3 MERITS AND DEMERITS OF OFDM 26 2. 2. 4 Orthogonal Frequency Division Multiplexing Access (OFDMA) 27 2.
2. 3. a MERITS AND DEMERITS OF OFDMA 28 2. 2. 4 PHY LAYER FEATURES 29 2.
3 QUALITY OF SERVICE OF WiMAX 30 2. 4 RECENT TRENDS IN WIMAX 33 2. 5 RELAY BASED NETWORKS (IEEE 802. 16 j) 37 2. 5. 1 TYPES OF IEEE 802.
16 j RELAY NETWORK 39 2. 5. 1. a TRANSPARENT relay station (T-RS) 39 2. 5. 1.
... development and manufacture of the industry's most advanced information technologies, including computer systems, software, storage systems and microelectronics. ... of marketplace and influence of market opportunity research and analysis for different firms. It seems that market opportunity ... The answer is unknown, because the market opportunity analysis for every product is playing an important role in ...
b NON-TRANSPARENT RELAY STATION (NT-RS) 39 2. 6 RELATED WORK ON IEEE 802. 16 j 40 3. 0 MARKET SURVEY 42 3. 1 OBJECTIVES 42 3. 2 USABILITY EVALUATION 42 3.
3 PARTICIPANTS 42 3. 4 RETURNS 43 3. 4. 1 How familiar are you with WiMAX technology? 43 3. 4. 2 What application will you be using mainly? 44 3.
4. 3 Will you prefer to combine all three services together? 44 3. 4. 4 What are your expected drawbacks about WiMAX? 45 3. 4.
5 Which will you prefer? 45 3. 5 Discussion 46 4. 0 FRAMEWORK OF THE SYSTEM 46 4. 1 SYSTEM DESIGN 46 4. 2 CHOICE OF SIMULATION TOOL 46 4. 2.
1 OPNET 46 4. 3 REQUIREMENT ANALYSIS 48 5. 0 IMPLEMENTATION 48 5. 1 DESIGN CONFIGURATION 49 5. 1.
1 WiMAX Attributes Configuration 50 5. 1. 2 Applications Parameters Configuration 51 5. 1. 3 Profiles Parameter Configuration 52 5.
1. 4 Server Configuration 53 5. 1. 5 Configuration of the base station 53 5. 2 CONCLUSION 54 6.
0 EVALUATION & ANALYSIS OF RESULTS 54 6. 1 I INTRODUCTION 54 6. 2 DELAY RESULTS 54 6. 2. 1 Analysis of WiMAX delay results 55 6. 2.
2 Analysis of voice packet delay variation 55 6. 3 VOICE TRAFFIC 56 6. 3. 1 Analysis of voice traffic received 56 6. 3. 2 Analysis of voice traffic sent 57 6.
4 WiMAX JITTER 57 6. 5 WiMAX THROUGHPUT 58 7. 0 CONCLUSION 58 REFERENCES 59 APPENDICES 61 QUESTIONNAIRE 61 POSTER 63 GANTT CHART 64 1. 0 INTRODUCTION 1. 1 OVERVIEW The importance of having internet access in developing economies as well as disaster affected areas has brought about the need to use a technology that is easy to deploy and has wider area coverage than Wi-Fi. This brings about the use of WiMAX as a technology to resolve this problem.
“WiMAX is an acronym that stands for Worldwide Interoperability for Microwave Access and is a standards-based wireless technology that provides high-throughput broadband connections over long distances”  WiMAX will facilitate further efficiency in terms of communications which can be demonstrated by a seamless voice and video support experience which will be valuable in terms of accommodating more mobile users whilst taking advantage of increased bandwidths to offer an exceptional blend of performance and throughput. By being built upon an IP infrastructure, mobile WiMAX is scalable thus will enable a continuous increase in bit throughput with a decrease in cost. The working definition used for WiMAX systems is part of a larger group of IEEE 802. 16 industry standards that are used for mobile broadband wireless access. The WiMAX technology supports wireless communication systems that allow computers and other computer-based applications to use high-speed information networks like the Internet, by using radio wave transmission rates that can exceed 120 Mbps for each of the channels used. It has replaced numerous conventional telecommunication technologies with a transfer rate of about 70 Mbps, providing last-mile modes of connection with advanced speed at longer distances, from 30 to 50 miles.
... (1994) described the major phases of data analysis: data reduction, data display, and conclusion drawing and verification. Data Entry and Storage Qualitative researchers usually transcribe ... the diagrams used in causal modeling is called a network diagram. – A network diagram is a diagram showing the direct links ...
According to  “A WiMAX network is made up of a Base Station (BS) and subscriber units like in cellular networks. For Fixed WiMAX network (802. 16 d), subscriber units are called Customer Premises Units (CPE) while in Mobile WiMAX (802. 16 e) they are called mobile units, which can be a computer / laptop or a cell phone.” 1.
2 MOTIVATION Just as DSL/cable technologies need lines to be over long distances to provide customers with internet access. In third world countries, the prospects for broadband access is enormously high, considering the trend of Internet requests. Though, the infiltration of DSL/cable is not so much, mainly owing to a lack of dependable infrastructure, cables or backbone switching equipment. Based on the fac t that WiMAX is an emerging technology with multiple advantages, it is viewed that a real implementation will alleviate the problems of internet users in rural areas as well as third world countries where there is limited access to the internet as WiMAX can bring about data rates of 75 Mbps within a 30 mile reach, though, in distinctive operational situations, data rates go down with rising reach.
1. 3 AIM AND OBJECTIVES The aim of this thesis is to design, implement and analyse the performance of real-time voice traffic in converged networks using mobile WiMAX as well as evaluating the effects of voice calls concurrently with data traffic in the simulated environment. The objectives are outlined below: o Design of a WiMAX converged network on Microsoft Visio office program o Implementation, configuration, and simulation of the designed network in OPNET 16. 0 modeler o Performance analysis of real-time protocols, evaluation frameworks through literature review as well as targeting the key evaluation metrics o To simulate a WiMAX network with and without relay stations connected to the main station for real time and data traffic o To provide a critical analysis and performance evaluation of the results and provide suggestions for future work o Analysis and evaluation of the experimental results showing how beneficial the experiments will be to companies willing to provide voice and data services in developing countries o Controlling the progress of this project through the use of PRINCE 2 project management tools.
... the Internet Protocol Security (IPSec) standard. Equally important is traffic control to eliminate bottlenecks at network access points and guarantee swift delivery of ... and its branch offices, the primary technology requirements are strong data encryption to protect sensitive information; reliability to ensure the prioritization ...
1. 4 PROBLEM DEFINITION Having worked in the network department of a telecommunications firm and being responsible for part deployments of network, I discovered the company had issues connecting remote sites with internet access especially when a fast set-up is required to permit residents convey electronic data – coupled with the conveyed data, small businesses in the areas also require voice traffic between themselves and their respective regional / head -offices outside the region. The thought arose from the fact that WiMAX network can support voice with little modifications and additional inexpensive voice equipment / software on WiMAX networks, hence the need to perform a performance analysis of real time traffic simultaneously with data traffic on the network to analyse the effect of voice calls across the network and how it is going to affect the transfer of data on the network and vice versa. Just as Voice over Internet Protocol (VoIP) makes it feasible to make voice calls over converged networks without using landlines and with the notion that 3 G networks are basically for making calls and WiMAX for data, this project will be looking at a scenario whereby 3 G networks cannot function, but WiMAX can, thus passing voice and other real time traffic over the data network. This could further reduce the cost of making calls in such environment.
However, this is expected to face some challenges which are stated below: o Features to consider when designing a WiMAX IEEE 802. 16 converged network? o How to determine suitable designs that can carry real time traffic over WiMAX network o What type of protocol / design mode will provide QoS sensitive and best effort traffic as compared in transparent and non-transparent mode? o What simulation software will be perfect for the configuration and implementation of the designed network? o Effect of real time applications / traffic on the network? o Performance evaluation and effectiveness of the WiMAX relay network in supporting real time traffic in IEEE 802. 16 j 1. 5 METHODOLOGY I will be making use of two research strategies in actualizing this project namely background and secondary research. Background knowledge of this project was initially gotten from my experience where I last worked before coming for my MSc, peer reviewed journals, books and conferences on WiMAX, coupled with reasons why voice is required in terrestrial difficult areas where WiMAX can be utilized for data services with different locations needing to make voice calls within the community to save cost and benefit from other call technology integration opportunities such as voicemail. This gives birth to the idea of measuring key evaluation metrics and evaluating the performance of voice traffic in WiMAX converged networks, especially focusing on simulation of a voice traffic and its effects on the evaluation metrics (such as packet loss, jitter, delay and bandwidth utilization).
... The ambition was to make ITTP a standard for value added services in mobile networks. During 1996 and 1997 Unwired Planet, Nokia ... concepts in the area of value added services on mobile networks.Unwired Planet presented Handheld Device Markup Language (HDML) ... or rather a concept, for value added services on mobile networks. The protocol was named Intelligent Terminal Transfer Protocol (ITTP), ...
1. 6 SCOPE AND LIMITATIONS The scope of this project will cover the design of a converged network using WiMAX with a design which includes relay (transparent and non-transparent) for redundancy, QoS and best effort traffic optimisation. For the simulation, two WiMAX base stations will be used with two relay stations each. The Base Stations will be connected to the internet and this will present a real-life converged network scenario using WiMAX to connect to mobile and fixed users, particularly targeting users on the move within the WiMAX coverage This project will be limited to configuration of different applications available on OPNET as well as statistical data as can be generated on OPNET. 1. 7 THESIS ORGANISATION Below is the outline of the chapters: Chapter 2 (Literature Review) Chapter 3 (Market Survey) Chapter 4 (Design and Methodology) Chapter 5 (System Implementation) Chapter 6 (Analysis and Evaluation of Experiments) Chapter 7 (Conclusions) 2.
... standards of transmitting information. D. Industry/Telecom Aspect ... .Strategic alliances between Korean and foreign mobile companies d. Economic development: started up with NMT standard mobile business now has approximately 5 major ...
0 LITERATURE REVIEW WiMAX, an acronym that stands for ‘Worldwide Interoperability for Microwave Access’ is an IP based broadband wireless access that maintains fixed and mobile internet access. WiMAX is one of the emerging wireless technologies that provide high speed mobile data and telecommunication services. This technology is based on IEEE standard 802. 16 with a maximum data rate of 75 Mbps under the best possible situations. Its coverage range extends 30-50 km as a result it can be used for providing wireless broadband across city and country-wide.
It is also used as a substitute last mile to cable and Digital Subscriber Line (DSL) . To realise the dream of achieving broadband internet access “in almost any location – anytime and anywhere”, the IEEE created working group called IEEE 802. 16 to formulate standards for wireless broadband internet access in Metropolitan Area Network (MAN).
This working group initiated a set of standards for fixed and mobile broadband internet access known as “WiMAX.” The name- WiMAX was given by the WiMAX Forum (an industry alliance responsible for certifying WiMAX products based on IEEE standards).
WiMAX utilizes scalable orthogonal frequency-division multiple access (SOFDMA) with 256 sub-carriers. It also supports multiple antennas for better coverage and better power consumption.
The Medium Access Control (MAC) layer of WiMAX uses a scheduling algorithm for the preliminary access of the Subscriber Stations (SS) into the network. This is followed by the Base Station (BS) assigning an access slot to SS and other subscribers cannot use that slot at the same time. The scheduling algorithm is also used for controlling the bandwidth efficiency and quality of service (QoS) parameters by adjusting the time slot duration based on the subscriber station’s application needs. WiMAX operates in 2.
3 GHz, 2. 5 GHz and 3. 5 GHz licensed bands. WiMAX was included in the IMT-2000 standards in 2007 .
IMT-2000 standards are defined by the radio communication sector of the International Telecommunication Union (ITU-R) thus making it possible for any country that recognizes IMT- 2000 standards to be able to use to use WiMAX equipments. Rising from the fact that MAN technologies have generally not been commercially successful, WiMAX stands out as having real prospects for success. This technology being standardized by IEEE standard 802. 16 means World-wide Interoperability for Microwave Access. WiMAX commonly refers to Fixed and Mobile WiMAX.
Fixed WiMAX refers to IEEE 802. 16-2004 or 802. 16 d standard; it denotes that the technology does not provide for handoff among access points . This, it is designed to provide connections between a service provider and a fixed location.
For example: a residence or an office, thus not supporting mobile devices. An illustration of fixed WiMAX is shown below. Source: WiMAX Technology from PCTECHGUIDE  Mobile WiMAX refers to IEEE 802. 16 e-2005 or 802. 16 e.
This technology offers handoff between access points thus can be used for mobile devices like laptops, mobile phones and I PADs. An illustration of mobile WiMAX is shown below. Source: Arab Crunch. com – Samsung WiMAX solutions  The idea of mobile WiMAX leads to an amendment of the current models to IEEE 802. 16 j – the Multihop Relay Specification for 802. 16 in WiMAX.
Due to the fact that a lot of devices support IEEE 802. 16 e, IEEE 802. 16 j is designed to support this specification This chapter further discusses IEEE 802. 16 standards and some important features of WiMAX as will be required for this dissertation. 2. 1 IEEE STANDARDS The Institute for Electrical and Electronics Engineers (IEEE) Standards are documents developed by working group members within the IEEE Societies and the Standards Coordinating Committees of the IEEE Standards Association (IEEE-SA) Standard board.
The IEEE develops its standard through an agreed development process, approved by the American National Standards Institute, which gather Engineers and researcher together with different innovations, discoveries, viewpoints and interests to achieve the final and accepted Standard. The figure below shows the IEEE standard working group and their different wireless applications in telecommunication. Figure 1. 0 IEEE Standard Working Group The IEEE 802. 16 Standards as a solution to the Broadband Wireless Access (BWA) widely deployed and applied in WiMAX provides high bandwidth over long range transmission.
According to Syed and Zaki r, the diagram below shows the evolution and timeline of WiMAX IEEE 802. 16 Standards approved by IEEE working group . Figure 2. 0 WiMAX IEEE Standards Evolution and Timeline The wireless internet architecture of IEEE 802 standards with their network application is shown in the diagram below. The IEEE 802. 16 is a wireless network standard applicable for highly speed connectivity within a large area (about 100 km square) .
Figure 3. 0 IEEE 802 Wireless Internet Architecture 2. 1. 1 IEEE 802. 16 The IEEE 802. 16 was developed and approved in December 2001.
It operates on Frequency Spectrum range of 10-66 GHz with Line of Sight (LOS) towers to fixed locations in order to provide fixed broadband wireless connectivity. It makes use of single modulation carriers’ techniques such as 16 Quadrature Amplitude Modulation (QAM), 64 Quadrature Amplitude Modulation (QAM) and Quadrature Phase Shift Keying (QPSK) in Physical Layer and Time Division Multiplexed (TDM) techniques in MAC layer. 2. 1.
2 IEEE 802. 16 a The standard was developed in January 2003 and has the following features and advantages over the IEEE 802. 16: o Operates on lower Frequency range of 2-11 GHz which includes both licensed and licensed free frequency bands applicable in both fixed and mobile communication. o Requires no LOS for transmission. o Deploys on Orthogonal Frequency Division Multiplexing (OFDM) on PHY layer and also employs Orthogonal Frequency Division Multiple Access (OFDMA) on the MAC layer. o Claims data transfer rate of about 75 Mbps.
o Provides selectable channel bandwidths from 1. 25 MHz to 20 MHz up to 16 logical sub-channels. 2. 1.
3 IEEE 802. 16 c The Standard evolved in December 2002 and has similarity with the IEEE 802. 16. 2. 1. 4 IEEE 802.
16 d The IEEE 802. 16 d was developed in June 2004 as a replacement and amendment for IEEE 802. 16, IEEE 802. 16 c and IEEE 802. 16 a Standards.
It was formerly named IEEE 802. 16 REVd but due to its acceptability and credibility of many amendments in September 2004 was renamed IEEE 802. 16 d. 2. 1. 5 IEEE 802.
16 e The standard was developed and approved in December 2005 with the following advantages and features: o Enhances system performance as a result of support of Adaptive Antenna Systems (AAS) and Multiple-in Multiple-out (MIMO).
o Supports mobility up to 65 mph (105 Km / hr ).
o Introduces mobile WiMAX to provide wireless services for mobile, nomadic, fixed and portable users. o Supports regional roaming for mobile WiMAX with a typical data transfer of 15 Mbps with a cell radius of 1-3 miles o Updates security features included in privacy sub-layer. The IEEE 802.
16 e replaced the IEEE 802. 16 d but did not provide backward compatibility. 2. 1. 6 IEEE 802. 16 f The IEEE 802.
16 f standard was developed in December 2005 and has the following qualities and features: o Management Information Base (MIB) for the PHY and MAC layers o Provides service flow database which enhances service flow and Quality of Service (QoS) for mobile users. o Enhances the application of meshed and multi-hop networking. 2. 1. 7 IEEE 802. 16 g / h /i / j /k / m /Rev The IEEE 802.
16 g / h /i / j /k / m /Rev were all published and developed in 2007. The standards are characterising by the following features and advantages: o The IEEE 802. 16 g provides amendments for Management Plane procedures and services. o The IEEE 802. 16 h deploys amendments for improved coexistence mechanism for license-exempt operations. o The IEEE 802.
16 i provides changes for mobile Management Information Bases (MIBs).
o The IEEE 802. 16 k caters for changes in bridging The IEEE 802. 16 d. o The IEEE 802. 16 k provides amendments for mobile multi-hop relays o The standards provide high connection speed of about 100 Mbps for mobile and 1 Gbps for fixed users.
The table below shows the general overview of the WiMAX’s IEEE 802. 16 standards : FEATURES 802. 16/c 802. 16 a 802. 16 d 802. 16 e / f 802.
16 g / h /i / j /k / m Year Published 2001 (802. 16) 2002 (802. 16 c) 2003 2004 2005 2007 Assigned Spectrum 10-66 GHz 2-11 GHz 2-11 GHz 2- 6 GHz Mobile, 2-11 GHz Fixed 2- 6 GHz Mobile 2-11 GHz Fixed Applications Backhaul Wireless, DSL & Backhaul VOIP Mobile VOIP Mobile VOIP Channels conditions LOS NLOS NLOS NLOS NLOS Gross data rate 32 – 134. 4 Mbps 1 Mbps – 75 Mbps 1 Mbps – 75 Mbps 1 Mbps – 75 Mbps 1 Mbps – 75 Mbps Modulation techniques QPSK, 16 QAM & 64 QAM QPSK, 16 QAM & 64 QAM QPSK, 16 QAM, 64 QAM & OFDM Scalable OFDMA (SOFDMA) Scalable OFDMA (SOFDMA) Mobility Fixed Fixed Fixed Pedestrian Mobility & Regional Roaming Pedestrian Mobility & Regional Roaming Multiplexing Burst TDM/TDMA Burst TDM/TDMA Burst TDM/TDMA/OFDMA Burst TDM/TDMA/OFDMA/ SOFDMA Burst TDM/TDMA/OFDMA/ SOFDMA Duplexing TDD & FDD TDD & FDD TDD & FDD TDD & FDD TDD & FDD Channel Bandwidth 20 MHz, 25 Hz & 28 MHz 20 MHz, 25 Hz & 28 MHz 1. 25 MHz, 1.
75 MHz, 3. 5 MHz, 5 MHz, 7 MHz, 8. 75 MHz, 10 MHz, 14 MHz, 15 MHz 1. 25 MHz, 1. 75 MHz, 3.
5 MHz, 5 MHz, 7 MHz, 8. 75 MHz, 10 MHz, 14 MHz, 15 MHz 1. 25 MHz, 1. 75 MHz, 3. 5 MHz, 5 MHz, 7 MHz, 8. 75 MHz, 10 MHz, 14 MHz, 15 MHz QoS Yes Yes Yes Yes Yes Table 1.
0 General Overview of IEEE 802. 16 Standards 2. 2. 0 IEEE 802.
16 PHYSICAL (PHY) LAYER The physical (PHY) layer of WiMAX depends on the IEEE 802. 16 standards. The PHY layer is based on the following principles: o Orthogonal Frequency Division Multiplexing (OFDM) o Orthogonal Frequency Division Multiplexing Access (OFDMA) The IEEE 802. 16 d-2004 and IEEE 8024-2005 standards defines five PHY layers which can be applied with media access control (MAC) layer to produce a broadband wireless communication systems.
The PHY layer interface includes : o WirelessMAN -SC: The WirelessMAN -SC PHY layer uses single-carrier modulation techniques whose frequency ranges between 10-66 GHz for LOS transmission. o WirelessMAN -SCa: The WirelessMAN -SCa PHY layer employs single-carrier modulation techniques with frequency range of 2-11 GHz for point-point operation in NLOS transmission. o WirelessMAN -OFDM: The WirelessMAN-OFDM uses a 256-point FFT-based OFDM PHY layer for point-to-multipoint operations with frequency range of 2-11 GHz in non-LOS transmission. This PHY layer interface is widely useful in fixed WiMAX application. o WirelessMAN -OFDMA: It uses a 2048-point FFT-based OFDMA PHY layer for point-to-multipoint operations with frequency band 2-11 GHz in NLOS transmission. The PHY layer has been upgraded to Scalable OFDMA (SOFDMA) in IEEE 802.
16 e-2005 and the FFT size varies with the following values; 128, 512, 1024, and 2048. The variable FFT size makes the PHY layer operation optimal over a wide range of channel bandwidths. It is widely deployed and useful in mobile WiMAX. o WirelessMAN-HUMAN: It uses TDD duplexing techniques with frequency range of 2-11 GHz.
It is based on single-carrier, OFDM, and OFDMA modulation techniques for non-LOS. The table below shows the features of the IEEE 802. 16 PHY layer interfaces: PHY LAYER INTERFACE MODULATION DUPLEXING PROPAGATION MODES FREQUENCY RANGE WirelessMAN -SC Single-carrier FDD and TDD LOS 10-66 GHz WirelessMAN -SCa Single-carrier FDD and TDD Non-LOS 2-11 GHz WirelessMAN -OFDM OFDM FDD and TDD NLOS 2-11 GHz WirelessMAN -OFDMA OFDMA, SOFDMA FDD and TDD NLOS 2-11 GHz WirelessMAN -HUMAN SC, OFDM, OFDMA TDD NLOS Below 11 GHz Table 2. 0 IEEE 802. 16 PHY Layer Interfaces 2. 2.
1 Orthogonal Frequency Division Multiplexing (OFDM) The OFDM also known as Multicarrier modulation (MCM) employs multiple carrier signals at different frequencies. It was developed in the 1970 by Bell Labs. OFDM is derived from the traditional Frequency Division Multiplexing (FDM).
OFDM as a transmission scheme provides high-speed data, multimedia and video communications in broadband systems such as DSL, Wi-Fi, WiMAX, Media FLO, and Digital Video Broadcast-Handled (DVB-H) . OFDM depends on the transmission schemes called Multicarrier Modulation (MCM) techniques, which is based on the theory of dividing incoming high-bit-rate data streams into several parallel data streams of lower bit rates and modulating each streams on separate carriers (subcarriers).
The MCM techniques in FDM require guard band to reduce or eliminate intersymbol interference (ISI) between different frequencies which causes bandwidth wastage, decreases spectrum-efficient and increases the cost of the solution.
But OFDM is cost-effective and highly spectrum-efficient because it eliminates all the guard bands and makes the modulated signals orthogonal to reduce the Intersymbol interference (ISI) level as shown in the diagram below Figure 4. 0 Bandwidth Utilization in FDM and OFDM 2. 2. 2 OFDM Parameters in WiMAX The OFDM physical layer parameters in WiMAX are implemented in the following applications: o Fixed WiMAX o Mobile WiMAX 2. 2. 2.
a Fixed WiMAX OFDM Physical Layer Fixed WiMAX OFDM PH layer is based on IEEE 802. 16 d-2004 standard. It uses 256 fixed sizes FET, 192 subcarriers out of the 256 FET carry data, 8 serve as pilot subscribers for channel estimation and synchronization, and the remaining 56 subcarriers are used as guard band. As a result of fixed size of FET, subcarrier spacing increases as the bandwidth increases while the symbol time decreases. The reduction in symbol time causes the delay spread to increase. The delay spread can be reduced by allocating a larger fraction of symbol time as guard band.
2. 2. 2. b Mobile WiMAX OFDMA Pysical Layer The FET size is scalable and ranges from 128 to 2048 in Mobile WiMAX. As the bandwidth increases, the FET size also increases such that the subcarrier spacing is constant at 10. 94 kHz.
The subcarrier spacing of 10. 94 kHz maintains a good balance between Doppler spread and delay spread requirements for operating in both fixed and mobile environments. The subcarriers spacing of 10. 94 kHz means that 128, 512, 1024, and 2048 FET sizes are deployed when the channel bandwidth is 1.
25 MHz, 5 MHz, 10 MHZ, and 20 MHz respectively. A scalable design of the FET size in mobile WiMAX makes it more cost-effective and efficient. The WiMAX OFDM parameters for fixed OFDM PHY layers and mobile OFDMA PHY layers are show in respectively in the table below . PARAMETER FIXED WiMAX OFDM- PHY MOBILE WiMAX SCALABLE OFDMA-PHY FET SIZE 256 128 512 1024 2048 Number of Used data subscriber 192 72 360 720 1440 Number of pilot subscriber 8 12 60 120 240 Number of guard band subscriber 56 44 92 184 368 Cyclic prefix/ guard time (Tg/ Tb) 1/32 1/32 1/16 1/8 1/4 Channel bandwidth (MHz) 3. 5 1.
25 5 10 20 Subscriber Frequency spacing 15. 625 10. 94 10. 94 10. 94 10.
94 Useful symbol time (us) 64 91. 4 91. 4 91. 4 91.
4 Guard time assuming 12. 5 % (us) 8 11. 4 11. 4 11. 4 11.
4 OFDM symbol duration (us) 72 102. 9 102. 9 102. 9 102. 9 Number of OFDM symbols in 5 ms frame 69 48. 0 48.
0 48. 0 48. 0 Table 3. 0 Fixed and Mobile WiMAX OFDM PARAMETERS 2. 2. 3 MERITS AND DEMERITS OF OFDM The advantages of OFDM surpass its demerit and make it a better choice in high-speed transmission solutions.
Advantages of OFDM o Multi-access Scheme: OFDM can be employed as multi-access scheme different subscribers are divided among multiple users. This scheme provides fine granularity in channel allocation and enhance subscriber capacity o Coherent demodulation: OFDM is useful for coherent demodulation because of the relatively easy pilot-based channel estimation and synchronization in the system. o Narrowband interference: OFDM is robust against narrowband interference because intersymbol interference (ISI) influences only a fraction of the subscribers. o Reduced computational complexity: It’s very easy to implement OFDM with the aid of FFT/FFT and the application requirements grow moderately faster than linearly with data rate. The computational complexity of OFDM is given by: O (Blog BTm) B = Bandwidth Tm = Delay spread o Frequency diversity exploitation: OFDM boosts coding and interleaving across tones in the frequency domain, which ease robustness against burst errors caused by part of the transmitted frequency undergoing deep fades.
o Performance degradation under excess delay: OFDM is best useful for adaptive modulation and coding, which helps the system to make the best of the available channel conditions. This balances the abrupt degradation caused by error propagation that single-carrier system experience as the delay spread surpasses the value for the design system. Disadvantages of OFDM o OFDM cannot guaranteed accurate frequency synchronization o It causes power inefficiencies o It is prone to phase noise and frequency dispersion o It has high Peak-to-Average-Power ratio (PAPER) that create nonlinearities and clipping distortion 2. 2. 4 Orthogonal Frequency Division Multiplexing Access (OFDMA) OFDMA is a multiple-user version and upgrade of OFDM. Unlike OFDM where each user is assigned to all sub-carriers and causes limited resource management time slots allocated to each user, In OFDMA, the total carrier is divided into N groups and each of them includes M carriers as shown in the diagram 2.
5. All the carriers are then divided into M sub-channels, each with one carrier per group. The modulation, amplitude and signal coding in OFDMA are assigned separately to each sub-channels based on channel conditions which made easier optimization and utilization of network resources possible. The sub-channelization in OFDMA permits different sub-channels to be allocated to different subscribers according to their requirement and channel conditions. Scalable OFDMA (SOFDMA) is introduced to efficiently increase the flexibility of the system resources. It enables smaller FFT sizes to increase the system performance and make the bandwidth channels cost-effective.
Figure 5. 0 Uplink Access in OFDM and OFDMA 2. 2. 3. a MERITS AND DEMERITS OF OFDMA ADVANTAGES OF OFDMA o OFDMA has the ability to reduce or eliminate peak-to-average-power ratio. o It permits the same data rate to be transmitted over a longer period of time using the same total power.
o The lower data rates and bursty data experienced in OFDM are efficiently suppressed in OFDMA. o It provides highly efficient network resource management than OFDM. o It is applied to solve the problem of minimum throughput and delay requirements of different flows to optimise the overall system throughput. DISADVANTAGES OF OFDMA o OFDMA requires pilot signals for synchronizations o It involves dynamic channel allocation with advanced coordination among the adjacent base stations. o Tight synchronization between users are needed for receiver in FET. 2.
2. 4 PHY LAYER FEATURES The other features of IEEE 802. 16 PHY layers standards that allow the performance of the technology for provision of rugged network performance over a wide range of frequencies, different channels condition and environments include the followings: o Elastic Channel Bandwidth: This feature allows the IEEE 802. 16 standards for compatibility of the elastic channel bandwidth with wireless technologies. The PHY layer uses bandwidth range 1.
25 MHz – 20 MHz o Adaptive Modulation: The 802. 16 standards deploy different combinations of modulation techniques such as QPSK, QPSK, 16 QAM, 64 QAM, and 256 QAM in the down and uplink link communications. WiMAX employs the adaptive modulation scheme to change the burst by burst basis per link with reference to channel conditions. o Adaptive Antenna System (AAS): The AAS deploys the multiple antennas at both the receiver and the transmitter ends (MIMO system) to increase channel capacity by moving the antenna beams towards multiple users to gain in-cell frequency reuse. AAS is also useful for reduction of required of power due to utilizing beams formed by adaptive antennas. o Error Correction Mechanism: Forward Error Correction (FEC) control mechanism is used to provide robust error correction.
The FEC is deployed in two stages. Firstly, it applies Reed Solomon Encoder to corrects burst error at byte level and improve the efficiency of the link in multipath propagation. Secondly, FEC employs convolution coder for correcting independent bit errors. o Space Time Coding: This feature is the down link communications for supporting space transmit diversity.
It presumes that the base station uses two transmit antennas and the subscriber station employs one transmit antenna. 2. 3 QUALITY OF SERVICE OF WiMAX Quality of Service (QoS) is the measure of the service-level performance of different types of traffic from source to the destination. The WiMAX MAC layer forms an integral part of support for QoS. It is very important when multiple data streams are competing for limited physical capacity of media or network transmission devices. The vital elements needed to implement QoS on a network are as follows : o QoS Performance Metrics: The performance metrics such as jitter, delay, throughput, and packet loss are used to monitor the network performance defined by metrics associated with data stream.
o Traffic Shaping: The network devices of an incoming packet determine how to classify the packet and whether the packet can be sent. The packet could be lost, if the packet delivery is not satisfied and the network is congested. o Request and Grant: Request and grant is also known as admission control. In WiMAX, the BS is the central control point while the SS requests a connection with certain QoS parameters.
The request will be rejected, if the network did not have the resources and granted if it has sufficient resources. The BS checks if the SS is allowed to use the resources and after authorization, the BS will guarantee the service throughout the connection. o Scheduling Policy: The scheduling policy is useful for determination and when to process packets in the priority queues. Round-robin can be used as a scheduling policy to process packets in each priority queue and assign more resources for high-priority queues.
In WiMAX, the IEEE 802. I 6 standards support five QoS scheduling services. The scheduling services and their fundamental characteristics are as follows: o Unsolicited grant services (UGS): This service is for transmitting fixed-size data packets at a constant bit rate (CBR).
Services such as T 1/E 1 emulation, DS 0, and VOIP without silence suppression.
The service requires a fixed amount of data at a fixed time interval and guarantee maximum traffic rate, tolerated jitter, maximum latency, transmission policy, delay and throughput. o Real-time polling services (rtPS): This service supports the transmission of compressed multimedia (e. g video streaming) and other real-time services such as MPEG video that produce variable-size data packets on a periodic period. The BS implements a polling mechanism to the SSs at a fixed interval. The SS specify the bandwidth requirement for each time interval as provided by each poll.
o Non-real-time polling services (nrtPS): This service supports non-real time applications, delay-tolerant data streams such as an FTP, which requires variable-size data grants at a minimum guaranteed rate. It requires the BS to poll the SSs at a fixed time interval, but not at a rigid time interval like rtPS. The BS puts the SS in a waiting group, if the SS fails to respond to the poll after n times in a row. When the waiting is polled, all SSs in the group will be contending for network access. This scheduling service prevents stations with little traffic to waste valuable polls.
o Best effort (BE) service: This scheduling service supports data streams such as Web browsing that does not require a minimum service-level guarantee. It requires no poll. An SS must contend with other SSs for bandwidth and network service access. The bandwidth requests are in the time slots marked in the UL-MAP as available for contention. The back-off algorithm employed in Ethernet is also used when request collision occurs.
o Extended real- time variable rate (ERT-VR): This scheduling service support real-time traffics, such as VOIP with silence suppression that have variable data rates but data rate and delay must be guaranteed. It is also known as extended real-time polling service (Rtps) and its available in IEEE 802. 16 e standard The table below shows the summary of the various WiMAX QoS scheduling services: Qos Scheduling Services Meaning Description Qos Parameters Application (UGS) Unsolicited grant services Supports real-time constant bit rate (CBR) applications Maximum sustained rate, maximum latency tolerance and jitter tolerance VOIP without silence suppression (rtPS) Real-time polling services Supports real-time variable bit rate (VBR) applications Maximum reserved rate, maximum sustained rate, maximum latency tolerance and traffic priority Streaming audio and video, MPEG nrtPS Non-real-time polling services Ensures a default CBR bandwidth and dynamically provides additional resources Maximum reserved rate, maximum sustained rate, and traffic priority File Transfer Protocol (FTP) BE Best effort service Supports non- real-time variable bit rate (VBR) applications Maximum sustained rate, and traffic priority Web browsing and data transfer ERT-VR Extended real- time variable rate Maximum reserved rate, maximum sustained rate, maximum latency tolerance, jitter tolerance and traffic priority VOIP with silence suppression Table 4. 0 WiMAX QoS Scheduling Services 2. 4 RECENT TRENDS IN WIMAX WiMAX as a new evolution and one of the emerging technologies will create many new business opportunity in the telecommunication industries. It will reposition and revolutionize the way businesses are been done in the wireless network.
According to Deepak the diagram below shows the important factors that will promote the acceptance of a new wireless technology service in the telecommunication industries and the end users . Figure 6. 0 Wireless Connectivity Evolutions Wimax is generally accepted because it’s efficient, faster, reliable, flexible, cost-effective and useful for both real-time and non-real-time traffic. The products and services renders by WiMAX is summarized below. Figure 7.
0 WiMAX Services According to Radha and Radha mani, there are over 400 member companies that have deployed WiMAX for both fixed and mobile services across the globe. The major service providers of WiMAX approved by the WiMAX Forum are shown in diagram below : Figure 8. 0 WiMAX Vendors & Service Providers The Wimax Forum is a non-profitable, industry-led body that aid the promotion, certification and complaint of broadband wireless products within the IEEE 802. 16 and ETSI Hiper MAN standards. The Forum collaborate with members industries to develop WiMAX products with the following frequency bands; 2. 3 GHz, 2.
5 GHz, 3. 5 GHz and 5. 8 GHz The market forecast and revenue generated [12[ by WiMAX service providers worldwide from 2005 is shown below Figure 9. 0 WiMAX Market WiMAX is widely deployed in the mobile industries. The application of WiMAX for mobile services ranges from cellular mobile, VOIP, multimedia and broadband data over IP network.
The global mobile subscriber’s trend for WiMAX services from 2003 to 2008 is shown in the diagram below: Figure 10. 0 Global Mobile WiMAX Users 2. 5 RELAY BASED NETWORKS (IEEE 802. 16 j) The relay based network was developed in 2006 by the IEEE 802. 16 Working Group (WG) and focused on the Relay Task Group (TG) . The WiMAX relay station system can be delivered with the application of the IEEE 802.
16 j standard. The IEEE 802. 16 j relay based network has three main important purposes: o It will increase and enhance the system capacity o It will increase the network coverage and make it more efficient o Its deployment is cost-effective The IEEE 802. 16 j standard is also useful in Mobile Multi-hop Relay (MMR) based WiMAX. The MMR WiMAX network based consists of a Base Station (MR- BS) and many Relay Stations (RSs) and Mobile Stations (MSs) connected to the MR-BS through single or multiple hops. WiMAX relay based network architecture is like a tree unlike a multi-hop mesh network.
Figure 11. 0 Typical WiMAX Relay Based Network According to Steve and Roberts, the Task Group developed the IEEE 802. 16 J relay networks using the following scenario : o Fixed Infrastructure: The Base Stations (BSs) as a fixed infrastructure relays were deployed by the service providers in stationary environment to serve general traffic. This increases the coverage area and throughput of the network because they are likely to be installed above roof tops to allow an LOS with the BS. o Temporary Coverage: The Multi-hop capability of the IEEE 802.
16 j allowed some of the traffic generated by densely populated station to be routed to BSs in the adjacent or closer cells. Temporary relays can be deployed where BSs might have been damaged. o Coverage on a Mobile Vehicle: A highly complex mobile relay can be deployed on a vehicle to provide efficient, reliable and better coverage to users. This reduces the challenges encountered by Network Engineers to deployed wireless network on a mobile vehicle such as bus or train. o In-Building Coverage: Some mobile phones perform very poorly inside buildings, subways or near tunnels, so relays will be placed both by the service providers and the end users near or inside the building to fill the “coverage hole” in the building.
These relays can be nomadic, operate with NLOS channel can be powered by battery. 2. 5. 1 TYPES OF IEEE 802. 16 j RELAY NETWORK The IEEE 802. 16 j relay network is divided into two, namely: o Transparent Relay Station (T-RS) o Non- Transparent Relay Station (NT-RS) 2.
5. 1. a TRANSPARENT RELAY STATION (T-RS) In T-RS, the uplink sub frame is divided into access zone and relay zone. The access zone is employed by the MSs to transmit access link to both the MR-BS and RSs while the relay zone is employed by the relay stations to transmit to their superordinate RSs or MR-BS.
The MR-BS is used to allocate resources and T-RS must operate in the centralized scheduling mode. 2. 5. 1. b NON-TRANSPARENT RELAY STATION (NT-RS) The NT-RS is deployed where the MTs are beyond the BS coverage area and the network depends on the RS for both the downlink and uplink signals and data transfer rate.
In IEEE 802. 16 j relay network under NT-RS, two types of frame structure can be used. Firstly, frame structure (single frame) is when the BS and its NT-RS are scheduled in the duration of one point to multipoint (PMP) frame duration. The second frame structure is called the multi-frame structure, where the NT-RS can be deployed in a periodic way over the duration of multiple PMP frames. The table below shows the comparison between the T-RS and NT-RS based on different PHY layer processing and network factors : PHY processing T-RS NT-RS Scheduling mode Centralized Centralized Distributed Security mode Centralized Centralized Centralized Distributed Throughput? ? ? ? Coverage area? ? ? Latency? ? Bandwidth utilization? Table 5. 0 Comparison between T-RS and NT-RS 2.
6 RELATED WORK ON IEEE 802. 16 j The IEEE 802. 16 j covers areas such as backwards compatibility, multi-hop capability and relay station implementation options. According to , relay technologies improve effectively service coverage and system throughput when multiple relay stations are deployed. They also discovered that the complexity and added delay makes it possible for the DCF scheme to perform better than AF and DMF relay schemes.
Furthermore, they proposed that in order to have more user equipment function effectively on the network in a multiple relay station cum user equipment scenario, they proposed centralized and distributed pairing schemes which supports multiple user equipment with a higher cell throughput performance. In the performance of IEEE 802. 16 with relay stations,  analysed the scenario with the introduction of relay stations by investigating two types of relay stations; centrally and de-centrally controlled. By their analysis, it can be deduced that MAC overhead with relay station is higher in comparison with IEEE 802. 16 standard thus concluding that with a wide channel size, the general system performance is noticeable. However, they faced some challenges such as requirements in the standardization and implementation of relay stations into WiMAX systems which include Quality of Service (which will be discussed in detail in this project due to its need in real time applications, radio resource management, frequency usage and the use of advanced antenna technologies.
IEEE 802. 16 j has two forms of relaying; transparent and non-transparent.  Transparent refers to when the base stations and relay stations are immobile whilst non-transparent refers to the mobile user support WiMAX networks. Also, Wireless relay has been proposed as a solution to extend the coverage of a single base station.  Analyzed the reduction of user access capacity due to multi-hop relay when it is used for coverage extension in a WiMAX system.
He discovered when the hop number was increased, the practicable user admittance capacity declined severely. Also, using higher-level modulation scheme or higher turbo-coding rate can appreciably augment the possible access capability. Effectively, for the viable application of a multi-hop WiMAX relay system, he recommended that: ” (i) radio processing of relay station should be enhanced to support 64 QAM-3/4 in the radio relay link; (ii) hop number should not be larger than 3 in order that there’s enough capacity left for local user access.” 3. 0 MARKET SURVEY The researched topic in WiMAX will require a market survey / research to gather information and get users perspective out of it. These perspectives will be used to derive a methodology that will shape the design and implementation of the proposed simulation. 3.
1 OBJECTIVES o To determine the potential of the market o Resource evaluation planning based on customer requirement o Customer expectations and familiarity with the WiMAX relay networks 3. 2 USABILITY EVALUATION This market survey is designed to further validate the implementations of WiMAX in transparent and non-transparent relay modes particularly targeting experienced IT professional who are familiar with WiMAX. The participants respond to the following questions as stated in the questionnaire: 1. How familiar are you with WiMAX technology? 2. What applications will you be using mainly? 3.
Will you prefer to combine all three services (data, real-time applications and cable TV) together 4. What are your expected drawbacks about WiMAX? 5. Identify your preference in terms of: o A WiMAX network with wider coverage and less efficiency o A WiMAX network with less coverage but greater efficiency 3. 3 PARTICIPANTS Sixty questionnaires were distributed to sixty participants and forty-three responded. Of the forty-three, there were thirty-five males and eight females – all within the age bracket of 20-30. All the participants are students in the Department of Computing, University of Bedfordshire and they have knowledge of WiMAX networks and have had to use them at home before or at work.
This eliminates the risk of not having results from users who have an idea about the technology. Also, the questionnaire was designed in simple and not technical terms for easy understanding. 3. 4 RETURNS The results of the pre-designed questionnaire are presented and analysed below based on responses from participants. Of the sixty questionnaires sent out, forty-three responded representing seventy-two percent – a value quite high based on the fact that the questionnaires were administered within a two-week window period in the course of this project. 3.
4. 1 How familiar are you with WiMAX technology? As seen from the above figure, it can be deduced that twenty-three of the forty-three participants are strongly familiar with the full operations of WiMAX technology, fifteen are familiar and five are ordinary users. No participant is unfamiliar. These values represent a total of eighty-eight percent of participants who are familiar with the technology and the remaining twelve percent are ordinary users of WiMAX. This symbolizes the fact that a high percentage of the participants are able to answer the remaining survey questions successfully thus satisfying one of the objectives of the survey – familiarity with WiMAX relay networks. 3.
4. 2 What application will you be using mainly? The essence of the second question in this survey is to identify which applications users will like to use mainly. From the above figure, it can be deduced that most participants use real-time applications i. e. twenty-six participants representing sixty percent and eleven participants representing twenty-six percent are traditional data users whilst the remaining six participants (fourteen percent) use it for cable TV. This indicates one of the objectives – customer expectations which imply that in the design and implementation, emphasis will be laid on WiMAX relay networks that will support mainly real-time applications as highlighted by participants.
3. 4. 3 Will you prefer to combine all three services together? On a scale of 1-5 with forty-three participants, fifteen (the highest value achieved) preferred combining the three services (data, real-time and cable TV) together – an indication of customer expectations. The implications of this is whilst focusing on real-time applications, a design which will be suitable for user expectations whereby all three services will be combined will also be factored in implementation. 3. 4.
4 What are your expected drawbacks about WiMAX? From the above chart, customers expected drawbacks ranged in descending order of cost, technology stability, efficiency, before speed. Customers are willing to enjoy the benefits of WiMAX technology but their greatest concern is cost which is a factor of business case followed by technology stability – this can be attributed to limited deployments of WiMAX around the globe whilst efficiency and speed is due to the fact that participants will want to compare it to technologies such as fibre and gigabit Ethernet which ordinarily provide higher speed than WiMAX. 3. 4. 5 Which will you prefer? o A WiMAX network with wider coverage and less efficiency Responses – (22) o A WiMAX network with less coverage but greater efficiency Responses – (21) From the above, it is too close to call which of the options participants prefer. This leads us to creating two models of WiMAX relay networks (transparent and non-transparent modes) which satisfies both sets of participants as this will also determine the potential of the market after the trial period.
3. 5 Discussion A summary of the analyses above as gathered from the survey indicates participants views vary but are generally willing to enjoy the best service at an affordable rate. 4. 0 FRAMEWORK OF THE SYSTEM 4.
1 SYSTEM DESIGN Designing an 802. 16 j WiMAX network emphasizes the importance of mobility in WiMAX networks. However complex this network is as it can be further sub-divided into transparent and non-transparent network. Just as this chapter outlines the process and choices involved in actualizing the proposed design and the result of the market survey as presented in the chapters’ preceding this.
In this dissertation, two scenarios were created as follows: Scenario 1: Transparent Network – This involved having a WiMAX IEEE 802. 16 j base station serving users communicating with each other. In this simulation, a call was placed from a user to another user on the same network and the effect of such calls on the network was evaluated. Scenario 2: Non-transparent Network – this comprises of a Base station and 2 relay stations. The relay stations serve the users and are connected to the base station. Same procedure ws repeated by placing calls on the network.
The diagram below demonstrates the WiMAX relay network designs. 4. 2 CHOICE OF SIMULATION TOOL There are a lot of simulation tools available such as OPNET, Packet tracer and NS-2. The choice of simulation tool depends on the technology to be simulated and the intended objectives of the network design. In this scenario, the most suitable is OPNET and it will be discussed in brief below. 4.
2. 1 OPNET OPNET is a network simulation tool used in application development, research and development as well as network performance management. This dissertation is dealing with network performance management in WiMAX networks using relay networks. Since OPNET supports the detailed model of communication networks analyzing the performance networks through simulation.
OPNET supports Graphical User Interface (GUI) for the developed network model There are three hierarchical layer [24, 25, 26] in OPNET which are: (i) the network layer, (ii) the node layer, and (iii) the process layer which uses C or C++ as its source code and describes the different protocols and algorithm occurring in the system. According to : The OPNET Modeler (R) Wireless Suite provides high fidelity modeling, simulation, and analysis of a broad range of wireless networks. Technology developers leverage advanced simulation capabilities and rich protocol model suites to design and optimize proprietary wireless protocols, such as access control and scheduling algorithms. (OPNET, 2011) 4.
3 REQUIREMENT ANALYSIS Every network has a set of different hardware devices and components that are connected together in order to perform a particular set of functions. Several different fundamental hardware and software components are required, or at least simulated, in the network design within this project. These are requirement listed in the following table: Required items Type of items 1) OPNET simulator software OPNET 16. 0 modeler (available in the CST lab) 2) 2 Servers WiMAX network Servers for convergence applications 3) 28 caller systems Systems used to demonstrate calls between a caller and a callee (for real time applications) 4) 2 IP Clouds For internet conn ection 5) 2 Base Stations Transparent Network Non-transparent Network 6) Internet Connecting to an ISP 7) 2 Relay Stations Serving as a connection between the base station and the users 5. 0 IMPLEMENTATION This chapter discusses the process of setting up the devices on OPNET 16. 0 modeler.
It involves configuring the application, profile and WiMAX settings as will be displayed below. For the transparent mode, there is a base station connected to the IP cloud and server. This serves the users within a 30 kilometre range. Transparent mode And the non-transparent mode is represented by having two relay stations and one base station connected to the IP cloud and server. Non-transparent relay network 5.
1 DESIGN CONFIGURATION The implementation of the design is done in two stages. The first stage involves placing all required equipment on the workspace, whilst the second stage involves configuring the application, profile and WiMAX settings as well as the Base Stations, relay stations and call systems. 5. 1. 1 WiMAX Attributes Configuration The above figure shows WiMAX attributes configuration with the details of the type of services configured as designed and implemented on OPNET. Below is the detailed process of how this was achieved.
WiMAX > Edit Attributes > MAC Service class Definitions attribute and set rows to 7 > Rows 0-6 i. Row 0 > Expand the Description hierarchy > Assign 10 Mbps to Maximum Sustained Traffic rate to 10 Mbps, Minimum Reserved Traffic rate to 5 M pbs, Maximum latency to 10 ms with UGS scheduling type and no traffic priority ii. Repeat these steps for rows 1-6. The settings above details the explanation for WiMAX attributes.
5. 1. 2 Applications Parameters Configuration The above figure shows the Applications Parameters attributes configuration with the details of the type of service used in testing for real-time traffic in this case (VOICE IP TELEPHONY) as configured, designed and implemented on OPNET. Below is the detailed process of how this was achieved. APPLICATIONS > Edit Attributes > Set Number of Rows to ‘1’ and name it VOICEIPTELEPHONY. Then set the voice description to ON 5.
1. 3 Profiles Parameter Configuration The profile setting is configured by right-clicking on: Profiles > Edit Attributes > Profile Configuration and set rows to 1> then name it VOICE Then select VOICEIPTELEPHONY. The settings are default and maintained on an as-is basis. 5. 1.
4 Server Configuration The server setting is configured by: Server > Edit Attributes > Application: Supported Profile and set rows to 1> then select VOICE 5. 1. 5 Configuration of the Base Station The Base Station attributes are set by editing the following: BS > Edit Attributes > WiMAX Parameters and set Antenna gain to 15 dBi > then Maximum Transmission Power in Watts to 0. 5, PHY Profile to Wireless OFDMA 20 MHz for 802. 16 j for relay networks. Same settings are made on the relay stations, caller and callee systems for uniformity.
5. 2 CONCLUSION This chapter displays graphically how the settings for devices configured on OPNET were able to set up the process for the simulation to take place. The results of the simulated scenarios will be discussed in the next chapter 6. 0 EVALUATION & ANALYSIS OF RESULTS 6. 1 I INTRODUCTION This chapter presents the detailed analysis and evaluation of the simulated results. The evaluation metrics were varied on both scenarios: 1.
Transparent Network Scenario 2. Non-transparent Network Scenario A summary of the effects of the calls connected between the caller and the callee will be assessed based on delay, voice traffic, load, jitter and throughput. At the end of this chapter, a conclusion will be made based on the effects of these results in general application and this will be compared with expected results. It is expected there maybe little variation based on the system CPU and memory drawbacks as it affects the virtual machines during simulation. 6. 2 DELAY RESULTS For WiMAX simulation in OPNET, there are three parameters for measurement and each one is analysed using the two scenarios as discussed earlier in the previous chapter i.
e. transparent mode and non-transparent mode. 6. 2. 1 Analysis of WiMAX delay results As can be seen from the graph above, in the transparent mode, there was virtually no WiMAX delay partly due to the fact that there was no intermediate station and all devices connected directly with the base station unlike the non-transparent mode where the devices connected via relay stations to the base station.
6. 2. 2 Analysis of voice packet delay variation The voice packet delay variation for the transparent mode was approximately zero whilst that of the non-transparent mode was on an average of 15. This indicates that with the multiple relay stations, there is greater delay. 6. 3 VOICE TRAFFIC 6.
3. 1 Analysis of voice traffic received As seen from the above graph, it can be deduced that the transparent mode receives more traffic (about 60% higher) than the non-transparent mode. This is because the transparent mode has less loss due to a single base station relay system unlike the non-transparent mode which has multiple relay stations with multiple user equipment. 6. 3. 2 Analysis of voice traffic sent The difference in voice traffic is seen in traffic received.
From this graph, we can see that almost the same amount of traffic is sent because this Is the calling process. What differentiates both scenarios is in terms of receiving. The transparent mode has limited loss compared to the non-transparent mode due to distance issues and additional device (relay station) in between the caller and the calle. 6.
4 WiMAX JITTER Jitter – a variation in delay is greatly affected by the relay station added onto the system. The more relay stations, the greater the jitter. This makes the non-transparent mode have a higher jitter of about 4. 5 msec whilst the transparent network mode has no variation in delay.
6. 5 WiMAX THROUGHPUT As can be seen from the graph above, there is a higher throughput in the transparent network – with an increase of about 50% from the non-transparent network. This shows that the transparent network is more reliable for real-time applications. 7.
0 CONCLUSION This dissertation analysed the effect of real-time traffic using voice as a typical example whilst simulating in transparent mode and non-transparent mode relay WiMAX networks. The effects vary according to performance and what is need ed by the engineer, Critically discussing, where a larger coverage is required – non transparent network performs better but with greater delay whereas where perfection or less loss is required, transparent mode acts better and is more accurate due to its nature of having less losses, higher throughput and higher traffic received. REFERENCES  Dingwall, C. 2006 “Municipal Broadband: Challenges and Perspectives.” Federal Communications Law Journal, 59 (1): 67-68.  Mlo zi, S. & Jing, F.
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