ONG JAW FEE1. This report is submitted in partial fulfillment of the requirements for the Bachelor of Computer Science (Computer Networking)

Transcription

1 PERFORMANCE OF VOICE OVER INTERNET PROTOCOL (VOIP) IN WIRELESS LOCAL AREA NETWORK (WLAN) ONG JAW FEE1 This report is submitted in partial fulfillment of the requirements for the Bachelor of Computer Science (Computer Networking) FACULTY OF lnformation AND COMMUNICATION TECHNOLOGY UNIVERSITI TEKNIKAL MALAYSIA MELAKA

2 ABSTRACT In this project, the suitability of b networks to carry real time voice traffic communication will be assessed using the Internet Protocol, where in the network the voice session have to share the link with data, video and voice. Measurements of the quality of voice are performed in the wireless networks compared to the wired kind of network. Measurements are focused on the three major Voice over Internet Protocol (VoIP) parameters: loss, delay and jitter. The environment factors such as the distance between nodes, network traffic and other obstacles are also being considered when carrying out this research. Due to the unpredictable nature of the wireless environment, providing Quality of Service (QoS) service is a challenging task. Voice Mic is more susceptible to the three major performance QoS parameters: delay, jitter and packet loss in the wireless domain than data traffic. In order to ensure the QoS of VoIP in wireless LAN, some experimental investigations have been carried out to test on the performance limitations in establishing VoIP in wireless LAN. All these experimental testing have been done under three varying scenarios network which are working under an ideal and real condition. The analysis is based upon the software that are being used in this project, Clearsight analyzer and Ethereal, from packet loss, jitter and delay measurements. According to the results, measures and graphs of packet delay, packet jitter and lost packet rate show the performance limitations when VoIP runs in wireless LAN. VoIP is a multimedia application that requires timely servicing of the voice traffic even when using QoS enforcement. As a result, a dedicated bandwidth with several time constraints is the main conditions for VoTP in wireless LAN environment to avoid the degradation of performance of VoIP service in the received signal.

3 ABSTRAK Dalam projek ini, kesesuaian rangkaian b akan dikaji untuk menghantar komunikasi trafik suara masa nyata dengan menggunakan Internet Protocol, dimana rangkaian pembawa voice session, mesti dikongsi untuk membawa data, video dan suara. Suatu teknik sukatan kualiti suara digunakan dalarn rangkaian tanpa wayar berbanding dengan rangkaian wayar. Sukatan berkenaan terturnpu kepada tiga parameter VoIP yang utama: loss, delay dan jitter. Faktor persekitaran seperti jarak antara dua titik, trafik rangkaian dan halangan-halangan lain juga merupakan faktor yang perlu diambil kira semasa menjalankan kajian ini. Oleh sebab sifat yang tidak stabil persekitaran rangkaian tanpa wayar, untuk memenuhi permintaan kualiti perkhidmatan (00s) VoIP-WLAN merupakan suatu tugas y-g agak mencabar. Prestasi trafik suara boleh dipengaruhi oleh tiga pweter QoS yang utama seperti delay, jitter dan packet loss terutarnanya dalam r~gkaian tanpa wayar berbanding dengan rangkaian yang menghantar data sahaja. Untuk mengenal pasti kualiti perkhidmatan VoIP dalam LAN tanpa wayar, eksperimen telah dijalankan untuk menguji had-had kepada prestasi penggunaan YoIP. Uji kaji telah dilakukan dengan tiga senario yang berbeza dalarn keadaan ideal dan nyata. Analisa dilakukan berdasar kepada perisian yang digunakan dalam projek, iaitu Clearsight analyzer dan Ethereal untuk mengukur delay, packet loss dan jitter. Merujuk keputusan yang didapati, ukuran dan graf-graf packet delay, packet jitter dan lost packet dilakar menunjukkan prestasi VoIP yang terhad pada LAN tanpa wayar. VoIP ialah sejenis aplikasi multimedia yang memerlukan ketepatan masa dalam penghantaran trafik suara walaupun menggunakan penguatkuasaan QoS. Sebagai keputusan, lebar jalur dedikasi dengan kekangan masa merupakan keadaan utama bagi VoIP dalam persekitaran LAN tanpa wayar bagi mengelakkan prestasi perkidmatan VoIP menurun pada isyarat yang diterima.

4 CHAPTER I INTRODUCTION 1.1 Project Background The world is becoming increasingly Internet Protocol (IP) oriented, with a large number of devices getting networked every day. At the same time, individuals are starting to favor smaller and lighter devices such as laptops since they are portable and not too bulky compared to the normal desktop computers. As their modalities and patterns of use get shaped, there is a trend of doing some researches of the performance of the Voice over IP (VoIP) service whenever the distance of the wireless laptops are getting bigger to a certain distance with coverage of wireless that can provide the good quality of VoIP service. Thus communicating through VoIP can be more reachable between these devices in the same Local Area Network (LAN) environment. VoIP is one of the fastest growing Internet applications today. It has two fundamental benefits compared with voice over traditional telephone networks. First, by exploiting advanced voice compression techniques and bandwidth sharing in packet-switched networks, VoIP can dramatically improve bandwidth efficiency. Second, it facilitates the creation of new services that combine voice communication with other media and data applications like video, white boarding and file sharing. At the same time, driven by huge demands for portable access, the Wireless LAN (WLAN) market is taking off quickly. Due to its convenience, mobility and high speed access, WLAN represents an important future trend for the Internet access.

5 As a result of the convergence of these two trends, we believe VoIP over WLAN is poised to become an important Internet application. Before that can happen, however, two technical problems need to be solved. The first is that the system capacity for voice can be quite low in WLAN. The second is that VoIP traffic and data traffic from traditional applications such as Web and can interfere with each other and bring down VoIP performance. As we know, when deploying VoIP in this environment, one of the challenges is meeting the performance requirements to provide the best condition which meet with the Quality of Service (QoS) in VoIP. When roaming around in a wireless network environment, at some point the mobile device will have to switch access point that is being associated with due to the media in wireless network is not constant. These media may be very different and each of it will face an additional problem such as the delay, jitter and losses as a network problem that can affect the voice quality of the VoIP service that is being used at that time. Voice quality is an end-to-end matter with various network equipment, ptotocols and policies. The performance of voice service is sensitive to delay, and the voice quality can tolerate some dropped packets within a certain limit of packet loss rdte. It is supposed that delays are made small enough to make two ways cdfiversation possible. Beside that, it is important to know how long it takes for a packet to travel through a network. The quality of a voice call is not only depends on network conditions, but also on the perceptual characteristic of the end users and how these network impairments affect the user's perception. Other factors are the user's expectation, since the mood and human memory can increase or decrease the perceived quality.

6 1.2 Problem Statements The coverage of the wireless LAN is limited. As a result, we need to do a research on the quality of the VoIP service as the distance of the device (laptops) are getting bigger. To maintain the quality of service (QoS) in VoP, we need to find out which length of distance is the most suitable distance to get the best service of Vow. Besides, the performance of the VoIP service must be monitored to ensure that every packets that being sent by the sender can be received by the receiver without any loss of information. There may be a problem if the distance between two devices getting bigger, the quality of the VoIP can be degraded to a certain extend based on the wireless LAN environment. This research aimed to come out with a graph to observe every packets of information that is sent by VoIP service whenever there are any changes of distance between these two laptops in a Wireless LAN (WLAN) environment. 1.3 Objectives We conduct measurements of critical parameters that affect the quality of voice over wireless networks, namely loss, delay and jitter. Delay has the important ch&acteristics that once introduced it cannot be hidden or minimized, hence it is important to know where exactly it is introduced into the system. Loss on the other hand can be compensated for typically by adding redundancy to the transmitted signal allowing some of the received signal to be reconstructed at the receiver. This research explores the causes of the degradation of those parameters, and finds an optimal condition of the environment for software, hardware to be deployed in order to improve voice performance of VoIP over Wireless LAN (WLAN). Therefore, this research will be done due to the purpose:

7 i. To maintain the coverage of wireless network in order to provide a good quality of VoIP service in a LAN. The coverage of the wireless network is limited and not too constant, so we need to set up a good wireless LAN environment to ensure the quality of service in VoIP is up to standard. ii. To analyze the quality of VoIP when the distance between the devices are getting bigger as the delay, jitter and packet loss will cause the performance of VoIP degrades. When we located two devices (laptops) in a certain distance, a testing will be made to check if the quality of the VoIP is satisfied. The length of distance can be varied in order to get the best quality of service for VoIP service. iii. To map the coverage of the wireless network for a VoIP service to communicate between devices. We can get a brief coverage of the Wireless LAN (WLAN) to enable the two laptops to communicate in a wireless efivironment although there may be a loss of data when transmitted through VoIP service whenever the distance has being changed. 1.4 Scopes The scopes of this research topic are included the following: i. The performance of VoIP - This performance of VoIP will be measured in the term of loss rate, delay of data and jitter using the specialized quality of service (QoS) Measurement Tools.

8 ii. The distance of the laptops - The length of distance between the two laptops will be changed from time to time to test on the quality of the VoIP service in a Wireless LAN (MAN) environment. iii. The coverage of wireless - The coverage distance of the wireless network may be different due to some factors such as walls, windows and interference sources and with typical open-air operating distances of 100 to 500 meter or 300 to 1500 feet (Trulove, 2002). iv. The brand of the laptops - In this research, the laptops that is being used has been specified to ensure that the communication in VoIP service between these two devices is constant and not affected by any hardware or software issue due to the differences for the brand of laptops. 1.5 Project Significance This research will be used as a guideline for those users who wish to use VoIP service in a Wireless LAN (MAN) environment to enable the quality of the VoIP service is always being fulfilled within the coverage of distance. In addition, for those Network Expert, this research can be studied more in depth to solve the problem that deal with the quality of service (QoS) in VoIP service as the length of distance between these two wireless devices are getting bigger and the ways to improve it without any loss of data or delay during the transmission of voice packets.

9 1.6 Expected Output In this research, we need to find out that the reason of degradation of those parameters during the conversation in VoIP service such as the traffic and distance of each node to access point. In the normal condition, we can expect that the closer the devices to the access point the stronger the signal will be received. When the distance of the devices are getting bigger, the quality of the VoIP service will be degraded in the term of loss packet, delay of voice packets and jitter. 1.7 Conclusion As the Internet growing fast recently, VoIP just like PCs, web access, will grow out of the enterprise market and get into the residential market. It is because this technology can be considered as a cheaper, simpler, and more cohvenient to use and it is expected to replace the legacy network idiastructure. However the appeal of the efficiencies of VoIP and Wireless Network (802.11) cannot be ignored and the end result may be very well being a mix of technology. The following chapter is the Literature Review and Methodology in order in completing this research. This chapter can be viewed as an important element in the development process as it can used as a guideline to the researcher. The method that is being used to do this research will include the facts that we have found in any journals or articles in researching in this topic and the requirements in doing this research will be stated out as well.

10 CHAPTER I1 LITERATURE REVIEW AND PROJECT METHODOLOGY 2.1 Introduction In this chapter, we will discuss and study about the quality of service (QoS) of the Voice over IP (VoIP) service, the distance of coverage in Wireless Local Area Network (WLAN) and the method we used in executing this research. To complete a full thesis topic, we need to do more research and study more on that topics or terms in order to understand the research topic more clearly. Those researches that we have gathered such as journals or articles can be used as a guideline to ensure that the research can be executed successfully. We need to study more in depth in the area of scope for this research topic, its main objective, find out the system requirement of this research topic and a comparison can be made if there is any similar research topic which has been done before this. To fulfill the requirements in executing this research, there are a few tasks which need to be done in order to complete this chapter. Firstly, we need to search for particular information through Internet, reference books and journals that published through article in Internet. Besides this, this research also can be done by comparing with other existing research so that we can do some enhancements on it to make it better and valuable for future market research. All these information can be used as a source and guideline in completing this research.

11 The techniques which are being used in executing this research play an important role as it can be used as a research element whether the techniques are something that have never been learned before or those that are currently used in the market. For the methodology part, every step that is being used in executing this project will be stated out clearly from the beginning of planning until producing the end product and getting the desired result. The method that used may be varied from other research thesis but with the same purpose or vice versa. The project requirements are those equipments or tools that needed in executing this research such as the hardware, sohare and network requirements. These requirements enable a project can be planned properly before carrying out and developing it. There is a session named project schedule and milestone which allow students to plan their project according to the time frame and organize their time table wisely so that they managed to complete the project in the duration of time given. As a result, each student must plan their project according to the schedule and follow it in order to complete the project. As a conclusion, this chapter allows students to search for the particular information about the existing research and try to figure out its weaknesses or enhance it to a more valuable research in the market. Therefore, this chapter can be used as a reference to study the current research and then come out with our own new idea that is unique and totally different from those that are currently can be found easily in our life or environment.

12 2.2 Facts and Findings In this section, some researches will be studied for its clarity and reliability before they are being used in the thesis paper. All the facts that have been found must be based on the research that has been done for which the students is enrolled in. Each statement that has written in the thesis papers must be based on the facts no matter it is based on any reading materials either in the journals, articles, reference books or through Internet. Some of the research that has been done based on the topic, Performance of Voice over Internet Protocol (VoTP) in Wireless Local Area Network (WLAN), is being shown as below: Domain In this section, we will be identified a few keywords which are related with the research topic. The main terms that we are going to stress out in this research paper are shown as below: Voice over Internet Protocol (VoIP) in Wireless Local Area Network (WLAN) VoIP in WLAN refers to the provisioning of voice services across wireless LANs, usually ]-based (also knows as voice over Wi-Fi). A VoIP in WLAN system works by translating a Private Branch exchange (PBX) telephone call to IP packets and sends these IP packets over an WLAN. The phones with or softphones will reassemble those pack& and output the audio to the user. The reverse path is similar, but without the synchronous timing of a telephone network.

13 In computing, a softphone is a software for making telephone calls over the Internet using a general purpose computer, rather than using dedicated hardware. A softphone is often designed to behave like a traditional telephone which sometimes may be appeared as an image of a phone or with a display panel and buttons with which the user can interact. A softphone is usually used with a headset connected to the sound card of the Personal Computer (PC) (Wikipedia, 2007). This new technology can bring a lot of benefits to people. It has all the advantages of VoIP systems but with a greater mobility. Mobility usually means increased productivity since it also reduces the cost for deployment of wired phones. When the world is introducing voice to IP networks, VoIP in WLAN has the same problems as VoIP regarding of the deployment method. Some characteristics of wireless networks can cause some additional difficulties. As a result, there are several major issues that needed to be solved before this technology can be fully accepted. i. Latency can induce VoIP performance degradation as users roam. This latency is usually caused by the reauthentication that required when associating with a new access point. International Telecommunication Union (ITU) recommends that the total latency in a voice call should not exceed 150 milliseconds. In VoIP in WLAN practice, the delay of roaming and authentication should be kept under 50 milliseconds (Khan and Lang, 2004). ii. Lack of Quality of Service (QoS) mechanisms. In order to keep the real time features of voice traffic, voice packets should be assigned higher priority then normal data packets to maintain the quality of voice. In this sense, QoS is needed. Currently, there is no standard way of doing this. However, Institute of Electrical and Electronics Engineers (IEEE) is developing a QoS standard called e and it is expected to be a new technology that can carry the voice packets without any

14 QoS problem. In le, two different types of QoS are provided. One is prioritized QoS, which uses priority tagging to place different types of traffic in different queues. Although voice gets priority treatment, it cannot get a reserved bandwidth as it is not guaranteed that low priority frames will always wait until all higher priority frames are transmitted, so in order to provide better service to streams with higher priority, a reserved bandwidth may be helpful solution. The other one is called parameterized QoS, which effectively reserves a certain amount of bandwidth for a certain stream (Khan and Lang, 2004). iii. Limited number of voice calls. Due to the capability of access points for handling calls simultaneously, the number of calls is limited. Currently, when the number of calls reach around thirty, an access point becomes overloaded, thus the quality degrades. With a, g and h standards coming into the picture, this problem will be solved to a certain extent. Although VoIP in WLAN has a few problems especially in performance, it still has a bright future and would appear to have a broad market sooner or later. With the decreasing of cost for deployment and the introduction of new products and services, VoIP in WLAN will surely be accepted more widely Voice over Internet Protocol (VoIP) Voice over Internet Protocol, also called VoIP, IP Telephony, Internet Telephony, Broadband Telephony, Broadband Phone and Voice over Broadband, is the routing of voice conversations over the Internet or through any other IP-based network.

15 There are two types of Public Switched Telephone Network (PSTN) to VoIP services: Direct Inward Dialing (DID) and Access Numbers. DID will connect the caller directly to the VoIP user while Access Numbers require the caller to input the extension number of the VoIP user. Access Numbers are usually charged as a local call to the caller and free to the VoIP user while DID usually has a monthly fee. There are also DIDs that are free to the VoIP user but chargeable to the caller (Wikipedia, 2007). VoIP can facilitate tasks that may be more dificult to achieve using traditional networks: Ability to transmit more than one telephone call down the same broadbandconnected telephone line. This can make VoIP a simple way to add an extra telephone line to a home or ofice. b Incoming phone calls can be automatically routed to user's VoIP phone, regardless of where the users are connected to the network. Call center agents using VoIP phones can work from anywhere with a suficiently fast and stable Internet connection. VoIP is location independent, only an Intemet connection is needed to get a connection to a VoIP provider. VoIP phones can integrate with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books and passing information whether other (e.g. friends or colleagues) are available online to interested parties.

16 Since the User Datagram Protocol (UDP) does not provide a mechanism to ensure that data packets are delivered in sequential order or provide QoS guarantees, VoIP implementations face problems dealing with latency and jitter. This can be proved especially when the satellite circuits are involved due to long round trip propagation delay (400 milliseconds to 600 milliseconds for geostationary satellite). The receiving node must restructure IP packets that may be out of order, delayed or missing while ensuring that the audio stream maintains a proper time consistency. This hnctionality is usually accomplished by means of a jitter buffer (Wikipedia, 2007). Another challenge is routing VoIP traffic through firewalls and address translators. Private Session Border Controllers are used along with firewalls to enable VoIP calls to and from a protected enterprise network. As an example, Skype uses a proprietary protocol to route calls through other Skype peers on the network, allowing it to traverse symmetric Network Address Translators (NATs) and firewalls. Other methods to traverse firewalls involve using protocols such as Simple Traversal of UDP Through NATs (STUN) which is a network protocol that allowing a client behind a NAT (or multiple NATs) to find out its public address. This information is used to set up UDP communication between two hosts that are both behind NAT routers (Wikipedia, 2007). On the other hand, there are some challenges that are faced by VoIP services nowadays such as the available of bandwidth, delay or network latency, packet loss, jitter, echo, security and reliability. All these challenges must be overcome in order to provide a good quality of service in VoIP. Fixed delays cannot be controlled but some delays can be minimized by marking voice packets as being delay-sensitive. The principal cause of packet loss is congestion which can be controlled by congestion management and avoidance. Besides this, a jitter

17 can be defined as variation in delay. The effects of jitter can be mitigated by storing voice packets in a buffer (called a play-out buffer) upon arrival, before playing them out. This avoids a condition known as buffer underrun, in which the playout process runs out of voice data to play because the next voice packet has not yet arrived, but increases delay by the length of the buffer. Common causes of echo include impedance mismatches in analog circuitry and acoustic coupling of the transmit and receive signal at the receiving end (Wikipedia, 2007) Wireless Local Area Network (WLAN) A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum or Orthogonal Frequency Division Multiplexing (OFDM) (802.1 la) modulation technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still can be connected to the network (Wikipedia, 2007). For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. Public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service. Large wireless network projects are being put up in many major cities. The popularity of WLANs is a testament primarily to their convenience, cost efficiency, and ease of integration with other networks and network components. The majority of computers sold to consumers today come pre-equipped with all necessary wireless LAN technology.

18 There are many benefits of using or applying wireless LANs in the office, campus or housing areas which include: i. Convenience: The wireless nature of such networks allows users to access network resources from nearly any convenient location within their primary networking environment (home or office). With the increasing saturation of laptop-style computers, this is particularly relevant. ii. Mobility: With the emergence of public wireless networks, users can access the internet even outside their normal work environment. Most chain coffee shops, for example, offer their customers a wireless connection to the internet at little or no cost. iii. Productivity: Users connected to a wireless network can maintain a nearly constant affiliation with their desired network as they move from place to place. For a business, this implies that an employee can potentially be more productive as his w her work can be accomplished from any convenient location. iv. Deployment: Initial setup of an infrastructure-based wireless network requires little more than a single access point. Wired networks, on the other hand, have the additional cost and complexity of actual physical cables being run to numerous locations (which can even be impossible for hard-to-reach locations within a building). v. Expandability: Wireless networks can serve a suddenly-increased number of clients with the existing equipment. In a wired network, additional clients would require additional wiring.

19 vi. Cost: Wireless networking hardware is at worst a modest increase from wired counterparts. This potentially increased cost is almost always more than outweighed by the savings in cost and labor associated to running physical cables. WLAN technology, while replete with the conveniences and advantages described above, has its share of downfalls. For a given networking situation, wireless LANs may not be desirable for a number of reasons. Most of these have to do with the inherent limitations of the technology which include: i. Security: Wireless LAN transceivers are designed to serve computers throughout a structure with uninterrupted service using radio frequencies. Because of space and cost, the antennas typically present on wireless networking cards in the end computers are generally relatively poor. In order to properly receive signals using such limited antennas throughout even a modest area, the wireless LAN transceiver utilizes a fairly considerable amount of power. This means that not only can the wireless packets be intercepted by a nearby adversary's poorlyequipped computer, but more importantly, a user willing to spend a small amount of money on a good quality antenna can pick up packets at a remarkable distance; perhaps hundreds of times the radius as the typical user. In fact, there are even computer users dedicated to locating and sometimes even hacking into wireless networks, known as wardrivers. On a wired network, any adversary would first have to overcome the physical limitation of tapping into the actual wires, but this is not an issue with wireless packets. To combat this consideration, wireless networks users usually choose to utilize various encryption technologies available such as Wi-Fi Protected Access (WPA). Some of the older encryption methods, such as Wired Equivalent Privacy (WEP) are known to have weaknesses that a dedicated adversary can compromise.

20 ii. Range: The typical range of a common g network with standard equipment is on the order of tens of meters (Smyth, 2004). While sufficient for a typical home, it will be insufficient in a larger structure. To obtain additional range, repeaters or additional access points will have to be purchased. Costs for these items can add up quickly. iii. Reliability: Like any radio frequency transmission, wireless networking signals are subject to a wide variety of interference, as well as complex propagation effects that are beyond the control of the network administrator. In the case of typical networks, modulation is achieved by complicated forms of phase-shift keying (PSK) or quadrature amplitude modulation (QAM), making interference and propagation effects all the more disturbing. As a result, important network resources such as servers are rarely connected wirelessly. iv. Speed: The speed on most wireless networks (typically Mbit/s) is reasonably slow compared to the slowest common wired networks (100 Mbit/s up to several Gbit/s). There are also performance issues caused by Transmission Control Protocol (TCP) and its built-in congestion avoidance. For most users, however, this observation is irrelevant since the speed bottleneck is not in the wireless routing but rather in the outside network connectivity itself. For example, the maximum Asymmetric Digital Subscriber Line (ADSL) throughput (usually 8 Mbitls or less) offered by telecommunications companies to general-purpose customers is already far slower than the slowest wireless network to which it is typically connected. That is to say, in most environments, a wireless network running at its slowest speed is still faster than the internet connection serving it in the first place. However, in specialized environments, the throughput of a wired network might be necessary. Newer standards such ai In are addressing

21 this limitation and will support peak throughputs in the range of Mbitls (Wikipedia, 2007) Existing System These days a massive deployment of VoIP is taking place over data networks. Most of these networks are Ethernet based and running IP protocol. Many network managers are finding it very attractive and cost effective to merge and unify voice and data networks into one. It is easier to run, manage and maintain. However, one has to keep in mind that IP networks are best-effort networks that were designed for non-real time applications. On the other hand, VoIP requires timely packet delivery with low latency, jitter, packet loss and sufficient bandwidth. To achieve this goal, an efficient deployment of VoIP must ensure these real-time traffic requirements can be guaranteed over new or existing IP networks. When deploying a new network service such as VoIP over existing network, many network architects, managers, planners, designers and engineers faced with common strategic and sometimes challenging questions. Due to these challenging questions, they have led to the development of some commercial tools for testing the performance of multimedia applications in data networks. A list of the available commercial tools that support VoIP with the two most common approaches in assessing the deployment of VoIP into the existing network. One approach is based on first performing network measurements and then predicting the network readiness for supporting VoIP. The prediction of the network readiness is based on assessing the health of network elements. The second approach is based on injecting real VoIP traffic into existing network and measuring the resulting delay, jitter, and loss.

22 Other than the cost associated with the commercial tools, none of the commercial tools offer a comprehensive approach for successful VoIP deployment. In particular, none gives any prediction for the total number of calls that can be supported by the network taking into account important design and engineering factors. These factors include VoIP flow and call distribution, future growth capacity, performance thresholds, impact of VoIP on existing network services and applications, and impact background traffic on VoIP. The research paper attempts to address those important factors and layout a comprehensive methodology for a successfbl deployment of any multimedia application such as VoIP and videoconferencing. However, the research paper focuses on VoIP as the new service of interest to be deployed in a new environment, WLAN (Salah, 2005) Technique To analyze the suitability of IEEE b networks to carry out voice traffic, a series of experiments will be performed that covering a range of factors which affecting the voice quality, including both networks and link quality aspects. To compute the endto-end delay, loss and jitter at the end point, a few tools such as QoS Measurement Tools that can be used to achieve those goals. QoS Measurement Tools is a central component for testing the quality voice data in a wireless VoIP Communication network. ClearSight Analyzer is a network analyzer software that completely overlooked on everyday traffic and issues in the network. It is designed purposely for packet decoding and network diagnosis, monitors the network traffic transmitted over a local host and a local network with the ability of real time packet capture and the network troubles. ClearSight Analyzer was installed in the receiver or sender nodes through a hub to be connected to the network to capture all the IP packets and Media Access control (MAC) frames. The other measurement tool is Ethereal which allows user to monitor both MAC layer frames

23 and IP layers traffic and that it is available under an open sources license. This is due to the fact that Ethereal has a large community supporting to its development. Ethereal was used in the receiver and sender nodes to capture all the IP packets and MAC frames.

24 2.3 Project Methodology The Waterfall Model derives its name due to the cascading effect from one phase to another (Sommerville, 2004). In this model, each phase is well defined from the starting point until the ending point with identifiable deliveries to the next phase. Sometimes this model also can be referred as the linear sequential model or the software life cycle as shown in the Figure 2.1. Analysis Designand Planning i I I I Testing j, Figure 2.1: Waterfall model

25 Requirement Analysis - All parts of analysis element will be conducted such as requirement analysis and planning analysis. Besides that, understanding of objectives, functions, requirements and planning of this research topic are very important in order to produce a good quality of research paper. Specifications - Research specification is produced from the detailed definition of the requirement analysis. As a result, the objectives of the research should be studied first and try to figure out the main purpose of doing this research and explain it briefly so that other people can understand the research topic as well. Design and Planning - In this stage, the hardware requirements can be determined along with a brief idea of the architecture of the research. The hardware and software should be linked together to execute the project. The network design will be an overview of the project which will be used for the whole research and it can be used as a guideline to overcome some network problems. Implementation - In this phase, the network diagram that has design earlier will be implemented into a real environment with the hardware and software required. This phase is important since wrongly implemented may affect the end result of the research. This phase can be changed according to the hardware or software provided.

26 Testing - For testing phase, the VoIP in WLAN system will be tested from time to time in order to get the best result out of it. At the mean time, the skill of trial and error may be helpful in executing this research as this research is an assumption for future research enhancement. This phase is critical since the result may be depending on the implementation stage and each time implementation has changed, so is the result of testing stage. Documentation - After every testing session, the result of the experiments can be recorded and a conclusion will be made at the final of this research to determine the level of QoS for VoIP functions well in WLAN. The documentations will be based on a series of experiment that are carried out during the research. 2.4 Project Requirements Project requirements are the sofhvares, tools or equipments that are needed to carry out the research in order to achieve the goal of the objectives proposed at the early stage of this research. The requirements for this research are shown as following:

27 2.4.1 Software Requirements a) Equipments or Development Tools - Skype (VoIP function) - Clearsight Analyzer - Ethereal - Microsoft Project Microsoft Visio 2003 b) Operating System or Sewer - Windows XP Hardware Requirements - Wireless Switch (Access Point) - Laptops with Wireless - Personal Computers (Pcs) - Wireless USB adapter (for Client PC) - Category 5 (CATS) Unshielded Twisted Pair (UTP) Cable - Switch - Router