Analysis Of Voice Over Wireless LAN Computer Science Essay

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Based on the project scope author have already finished the background literature reading, site survey and design. Based on IEEE 802.11 Architecture this IEEE 802.11 supports three basic topologies for WLANs the IBSS, BSS and ESS. All three configurations are supported MAC layer implementation. The 802.11 standard defines two modes ad hoc and infrastructure mode. Logically an ad hoc configuration is analogous to a peer to peer office network in which no single node is required to function as a server. Directly with one another on an ad hoc, peer to peer office network in which no single node is required to function as a server. IBSS WLAN is include a number of nodes or wireless stations that communicate directly with one another on an ad hoc, peer to peer basics building a full mesh or partial mesh topology. Generally ad hoc implementations cover a limited area and are not connected to a larger network.

Using infrastructure mode, the wireless network consists of at least one AP connected to the wired network infrastructure and a set of wireless end stations. This configuration known as basic service set. Most corporate WLANs require access to the wired LAN for services they will operate in infrastructure mode and rely on an AP that acts as the logical server for a single WLAN cell or channel.

A process for Implementation of VoWLAN design and deployment firstly define what voice applications and clients will be deployed and who the stakeholders are, coverage areas and project phases, Planning, RF audit and site survey, pre research and development test and Network Simulation and retest, Deploy infrastructure, RF Test, Final adjustments and retuning and finally ongoing operation support.

Author analysed site survey, analyse and design scenarios by using OPNET simulation tool, Wi-Spy ,Xirrus Inspector tool, wire shark and channelizer.

Problem Areas

During the simulation period author expected unacceptable delay and some licence issues, anyway when increase the O drive Quota this issue shorted out. For triplicate scenario SOHO VoWLAN design. Author couldn't associate with the Access point with handheld VoWLAN device, because ACL restricted in Green Net Infrastructure to associate VoWLAN device, so author choose to Soft phone to replicate this scenario. When deploying SOHO WLAN infrastructure in KW lab , author used to Netgear wireless Router. When login to Comms domain in KW lab terminals restricted to access to Internet there's no connectivity with Internet to access my SIP gateway , so Author chose green Net infrastructure connection through laptop and VoWLAN soft phone used to generate and test voice calls in WLAN.

Key works during Next Periods

Author is going to restructure the report as professional standard, Analysis the OPNET results, evaluate the project scope in details.

Part B- Draft Project report to date

Abstract

I intend to provide in this literature my study on the Wireless Network and Voice technologies aligned with Quality of Service and how to overcome the impediments in improving the same. This research may not completely cover all the areas of this technology but to constructively provide strength to further studies based on the evidences that I provide case by case basis.

In 21 CN major telecom operators and multiple service providers are focus the wireless technologies and VoIP applications to enhance their business applications and deliver latest technologies to the market. Growing of WLAN in domestic and business worldwide consequently. Voice over IP (VoIP) is playing major role in voice business globally, most enterprises considering low cost international calling, mobility and coverage to their business suite. Through this project study I can analyse how to improve quality of WLAN, VoWLAN designs, VoWLAN deployment requirements in QoS. Study in wireless mobility and QoS are useful to design 802.11 networks with the voice traffic implementation. existing issues in voice traffic in 802.11 related wireless networks are quality ,handoff when roaming to one cell to another cell this mean between the access point unable to send and receive data from AP s to client or vice versa.VoWLAN known as ability to send voice traffic over 802.11 networks this VoWLAN concept develop by combining VoIP and WLAN. VoIP solutions are rapidly increasing and the acquire traditional circuit switched networks to packet switched networks. Wireless 802.11 networks have rapidly growth in recent years .everywhere in the world easily can find the wireless networks. So this cause to develop requirement in VoWLAN. These days most of the business and domestic segments playing the use of VoWLAN applications , so mobile phone manufactures are manufacture the 802.11 compatible mobiles to the market, so certain factors should be consider the manufactures t deliver good handset to the market by considering QoS and coverage factors.

This project is about improving the performance and quality of WLAN, VoWLAN designs and QoS issues. These issues will be considered various point of views to analyse investigate different WLAN coverage, mobility, capacity planning, protocols and QoS. Voice over Wireless LAN deployment in WLAN environment QoS should be well designed and organized , in real wireless networks voice traffic should given high preference than data, and QoS parameters should be defined accordingly in networks.

Preface

It is the prerequisite of achievement in the entire process of this study to provide the complete literature of this thesis as of the requirement pertaining to the completion of the Master's Project. This text covers the entire work done during past 18 weeks of research and study. The study is done with reference to many previous literatures, text, case studies and Text books; I have tried my best to include the reference to these as much as possible. The title for this research is chosen by me by own interest. My MSc program is Computer Systems and Networking which is all about networking issues where I studied about mobile Technologies, Network Management, Network Security and Advance Network Technologies, Demand in VoWLAN market and I have experience in Telecommunication industry more than three years.

Rapid increase in the wireless technologies in the global market had tempting affect in immergence of countless number of SME/SOHO enterprises in to the world arena. As the IP voice technologies improves a striking balance in the strength of individuals to compete with the large scale enterprises had provided extra boost. VOIP now plays a major part in the business globally in cost effective communication among organizations internally and externally.

Through this project study I have analysed the various aspects of improving quality of WLAN, VoWLAN designs, VoWLAN deployment requirements in QoS. I have provided further evidence on the importance of the understanding in wireless mobility and QoS to design 802.11 networks with the voice traffic implementation. Some of the existing implementation issues in voice traffic in 802.11 related wireless networks are quality handoff in switching between cells in the roaming scenario. Hence the lack of communication between accesses points due to compatibility and other issues had cause a major drawback in the improvement of this technology. I will suggest and provide my case in improving the quality factors in the real world.

Acknowledgements

It would be impossible to acknowledge in this space all of the people who helped me in the success of this project. First and foremost, I'd like to give my heartiest thanks to Mr. Brian Brass, without him this task would be impossible. I enjoyed very much working with him and I submit my gratitude for his constant support in the success of this project and the entire cause of this degree. And also I would like to thank Digital Air Wireless Managing Director Mark A. Julier , who gave me great support and consultation to do SME and Enterprise WLAN designs and deployment.

Secondly, I would like to thank all the CMS school members, technical staffs, supervisors and all the other members of this school who helped me in several means and guided me on the right direction during this program. Their words of wisdom and the support help me develop myself as a new person with courage, strength and knowledge.

Finally, I must thank all of my family members and friends who are extra strength for my attitude towards success.

Sanjeev Krishnarajah

January 2010

Contents

ANALYSIS OF VOICE OVER WIRELESS LAN (VoWLAN) DESIGN AND DEPLOYMENT 1

Interim Report 1

Abstract 4

Preface 5

Acknowledgements 6

1.Introduction 8

1.1.Motivation 8

1.2.Objectives 9

1.3.Project Deliverables 10

1.4.Overview of next chapters 10

2.Background and Literature review 11

2.1 IEEE 802.11 Standards 11

2.2 Voice Over 802.11 11

2.3 Voice over Internet Protocol 11

2.4 Switching TDM and VoIP Networks 16

2.5 Voice Quality Engineering in Wireless Networks 17

Quality Service tools 19

2.6 Scalability in Wireless VoIP Networks 19

3.Defining Project Scope 21

3.1 Site Survey 22

3.2 Analysis of the Wireless Voice Design and Deployment Hardware and Software Requirements. 24

3.3 Methodologies 25

3.4 Summery 25

4.Network Simulations Results and Analysis 25

Introduction

Motivation

Wireless technology has become day today household word among the people around the world. Wireless LAN in particular had taken resident in many household these days than few years before. Despite many technology drawbacks Small, Medium, Home based enterprises increasingly use this technology due to the ease of acquisition and the cost effectiveness. Amongst many aspects the Voice over IP technology has taken a leap in to the household and medium scaled enterprises.

I intend to provide a comprehensive analysis and study on the role of Wireless LAN with VoIP technology toward improving the quality aspects and eliminations of impediments currently prevalent in this particular area.

It is wiser to admit that roaming obstacle with the current Voice over wireless LAN in terms of inter communication between access points due to many reasons and how RTS/CTS frames will help us overcome the hidden node problem and hence increase the quality of service. As I go further in to the details of this literature I will present the result of my simulation case by case basis.

WLAN technology itself had long suffered in indoors due to propagation complexities. Shortest path between Transmission and Receiving locations is affected due to physical impediments such as thick walls, ceilings and other objects. These objects can drastically degrade the radio signals strength that is vital in quality of service.

Objectives

Throughout this project I intend to analyse and investigate different elements of Wireless LAN, Voice over Wireless LAN (VoWLAN) performance characteristics when combining with multiple traffic loads & variable set of WLAN implementations. Further, I had focussed on requirement capturing for VoWLAN implementation and related QoS and security issues in WLAN to suit Voice implementation and thus I suggest improvements that can be made affective in order to improve the quality factors in the real world wireless networks that is intending to use Voice technologies.

Project Deliverables

Analysis of WLAN/VoWLAN design consideration

Voice traffic Analysis

Voice with WFQ with same TOS

Voice with WFQ different TOS

Speech Activity Detection Enabled

Speech Activity Detection Disabled

SIP

H323

Voice Call Capacity planning in IEEE 802.11a/b/g/n

Hidden node Considerations when wireless stations are set to roaming

Suggestions for QoS and Security improvements

Hidden node situation and RTS/CTS frame

WLAN security best practices

Overview of next chapters

Next chapters in this project will expand and elaborate with detailed analysis of information that I have introduced in my introduction (Chapter 1). In Chapter 2, I will put forward my summary of the analysis and reference to the text, case studies and Books relating to this study. Chapter 3, I will be handling the above scenario case by case basis and provide detailed description for each scenario. Last Chapter (Chapter 4), I will present my view on the entire subject and present the suggestion in terms of Quality and Security.

Background and Literature review

2.1 IEEE 802.11 Standards

The Institute of Electrical and Electronic Engineers INC. deliver IEEE standards on wireless Local Area Networks.

They have specified recommended practices and ways to use wireless LAN in the frequency of 2.4, 3.6, 5 GHz.There are amendments of this original standard which are 802.11a, 802.11b, 802.11g, 802.11-2007 and 802.11n.802.11n the new amendment of IEEE 802.11 published in October 2009, which can handle multi input and multi output(MIMO) and leads to higher throughput improvement.

2.2 Voice Over 802.11

The IEEE have deliver standard protocols for voice conversations through wireless LAN.There are several challenges to overcome on transmitting voice over a wireless locl area net work than a physical transmitting medium such as quality of voice, limited band width on air.

2.3 Voice over Internet Protocol

The Voice over Wireless Local area network is implemented by Internet protocol where it uses internet or other packet switched networks. VoIP is a session controlled protocol where it has set up, tear down and audio codecs where it encodes the voice which has been transmitted. Transmitting voice with lower cost through long distance, less bandwidth for more calls, efficient way of using network resources and distributed network are important benefits of VoIP. Transmitting the voice over IP happens in several ordered steps as follows;

In Voice over Internet protocol it first process the speaker's voice to digital signals.

Then suppression of unwanted signals happens and compresses the voice signal.

Here it discards unwanted packets which does not contain any voice

Complex algorithms are added to reduce the amount of information sent to other party

The voice is then packetized and VoIP protocols added.

Store some amount of data to be transmitted until it collect the voice data.

Packets are addresses with its destination, sequence number added for proper ordering, and additional details added for error checking.

Packets sent through the network towards the destination.

When the packets arrive the destination the sequence of the packets checked and ordered.

Decomposition algorithms used to restore the data to original source data.

Clock synchronization and delay handling methods used to ensure the proper spacing of message.

Packet loss can happen with VoIP while it been travels through network because of network delays or congestion. And also packets can be discarded due to errors while transmitting. These issues will result insufficient quality of voice. VoIP cannot handle error by just retransmitting the data since this voice data is time sensitive. In order to overcome this problem a sound is created using complex algorithm to approximate the missing data and filling that in the missed gaps.

Signaling establishes the virtual circuit over the network for media stream where the packetized voice conversation flows. There are two popular type of signaling; H.323 and SIP

H.323

International Telecommunication Union recommends H.323 for packet based multimedia communication.H.323 widely used by companies who wanted to connect remote locations through IP using wireless connections.

SIP

Session Initiation Protocol (SIP) is also used to control multimedia communication sessions such as voice, video. SIP uses text based syntax and SIP uniform resource locators take the form of web addresses. SIP falls in to a client server architecture where it originated at the client side and terminated at the server side. There are four types of SIP severs;

User Agent Server

A SIP device can act as a user agent server as well as a client, since it can initiate a SIP request as a client and receive and respond to SIP request as a server.

A SIP transaction means, the User Agent client sends request and a User agent Server responds to that request.

Invites

180 Ringing

200 OK

200 OK

Media Session

BYE

ACK

Calling Party

Called Party

Figure 2.1 SIP User agent server to UA server call.

Figure 2.1 illustrates the SIP User agent server call.

INVITES: this is the first message sent by the client calling party to invite the user to participate in the session. It contain several information such as

Calling party

Call - ID

Called party

Call and sequence number

TRYING: 180 ringing send response for the Invite signal.

OK: 200 is a response message sent when the called party answers the call.

ACK: When the calling party receives the response for the INVITE call there will be an acknowledgement sent to call party side. This is a three way hand shake.

BYE: This is used to terminate the session. BYE from one party enough to terminate the session in a two party conversation.

Redirect Server

This server accepts the requests and maps the destinations address to zero or more new addresses and replies the translated address to the originator of the request. There after request originator will send requests to the replied addresses. So a redirect server never originates requests by itself. This server simply enables the client to follow its path and no longer involved in the conversation.

Proxy Servers

A SIP client will send a request to a proxy server whether it can handle by it self or send to another sever. So the secondary server in the middle sees as the request coming from the client not by a proxy server. A proxy sever act as a client and as a server for sending and receiving responses where it asks the client to follow it.

Register

A register server accepts REGISTER requests means that user tells the server he or she is available on that address. More than one user agents can register with the server, when a request is received to that SIP address it will be forwarded to all registered addresses.

2.4 Switching TDM and VoIP Networks

Time division multiplexing is a way of transmitting multiple signals in a single path. The earliest way of multiplexing is FDM - Frequency division Multiplexing. Since FDM had many issues TDM was developed.

TDM divides the time rather than the frequency. This is a digital transmission scheme that uses a small number of discrete signal states. Digital carrier systems have only three valid signal values:

one positive

one negative

zero

A regenerator, can receive a weak and noisy digital signal, remove the noise, reconstruct original signal, and amplify it before transmitting the signal to the next transmission. The advantages of digitization are better maintenance, troubleshooting capability, better reliability and allow improved configuration flexibility.

The process of converting of an analog signal into a digital signal is called pulse code modulation (PCM). This is a four-step process consisting of,

Pulse amplitude modulation (PAM) sampling

Companding

Quantization

Encoding.

PAM Sampling

The analog signal is sampled at a rate that is equal to twice the bandwidth of the channel over which the signal is to be transmitted. As each analog voice channel is allocated 4 kHz of bandwidth, each voice signal is sampled at twice that rate, or 50 Voice over 802.11 8,000 samples per second. If the sampling rate is too high, too much information is transmitted and bandwidth is wasted. If the sampling rate is too low, aliasing may result. Aliasing is the interpretation of the sample points as a false waveform due to the lack of samples.

Companding

Companding is the process of compressing the values of the PAM samples to fit the nonlinear quantizing scale that results in bandwidth savings of more than 30%.

Quantization

The values are assigned to each sample within a constrained range. Using a limited number of bits to represent each sample, the signal is quantized. The difference between the actual level of the input analog signal and the digitized representation is known as quantization noise.

Encoding

Encoding is performed by a codec. There are three types of codecs:

waveform codecs

Source codecs

Hybrid codecs.

Waveform codecs sample and code incoming analog signals without regard to how the signals were generated. Quantized values of the samples are then transmitted to the destination where the original signal is reconstructed at least to a certain approximation of the original. Waveform codecs are known for simplicity with high-quality output. The disadvantage is that they consume considerably more bandwidth than the other codecs.

Source codecs, also known as vocoders, match an incoming signal to a mathematical model of how speech is produced. Vocoders are most widely used in private and military applications.

Hybrid codecs, perform some degree of waveform matching while mimicking the architecture of human speech. Hybrid codecs provide better voice quality at low bandwidth than waveform codecs.

2.5 Voice Quality Engineering in Wireless Networks

Quality of voice in wireless networks is an important concern in the world market. Current market has two way of testing the voice quality.

MOS: mean opinion score, holdover from circuit-switched voice industry.

PSQM: perceptual speech quality measurement, come forwarded with popularity of VoIP.

MOS

ITU-T P.800 defines the techniques of measuring the mean opinion score. This method is based on testing the volunteers who listen to voice samples and rate the quality of the conversation. The factors that would decrease the quality are loss, circuit noise, side tone, talker echo, distortion, delay, and other transmission problems. The rates 1 to 5 given for the samples, where 5 means excellent and 1 being bad. MOS 4 is considered as toll quality where it can be considered as public switched telephone network (PSTN).

PSQM

This is based on ITU-T RecommendationP.861, defines a model to map actual audio signals to their representations inside the head of a human. Voice quality contains a mix of objective and subjective parts and varies widely among the different coding schemes and the types of network topologies used for transport.

Measurements of processed signals derived from a speech sample are collected and an objective analysis is performed comparing the original and the processed version of the speech sample. Perceptual speech quality measurement scores result in an absolute number, not a relative comparison between the two signals.

QoS

Quality of service is one of the primary concerns about wireless data delivery.

Quality of service can be reduced by loss of packets, atmospheric interference

, delay, jitter and echo.

Delay: this is the time different between end to end voice transmissions. Packet delay can occur to the buffering, queuing, and switching or routing delay of the IP routers. This is determined by the packet length, link layer operating parameters, and transmission speed. Delay can be minimized by shorting the packets.

Jitter: This occurs because packets have varying transmission times. This is caused by different queuing times in the routers and possibly by different routing paths. So there is unequal time spacing between the arriving packets will occur so a jitter buffer is there to ensure smooth, continuous playback of the voice stream.

Packet Loss: The packets that never arrives the destination during the transmission called loss packets. This can occur to hardware and network issues.

Bandwidth: Greater bandwidth delivers better voice quality in VoIP.

To achieve the good Quality of Service over the wireless Network and reduce the error , consider over scheduling techniques / algorithms ,throughput.

Quality Service tools

Delay depends on two components, which are fixed delay and queuing delay. Fixed delay is due to the processing within the individual nodes and is only depend on the path taken. Queuing delay is the delay within the various nodes. Queuing is an IP-based quality of service mechanism that is available in traditional packet-forwarding systems and can differentiate and appropriately handle uniform traffic to deliver optimal QoS on Vo802.11 networks. There are few methods identified for queuing.

Queuing / scheduling methods

1.FIFO

2.Round robin queue

3. Weighted fair Queue

FIFO: First-in, first-out (FIFO) simply forward packets in the order of their arrival.

Round Robin Queue: This assigns time slices to each process in equal portions and in circular order, handling all processes without priority.

Weighted fair Queue: schedules interactive traffic to the front of the queue to reduce response time, then fairly shares the remaining bandwidth among high-bandwidth flows.

2.6 Scalability in Wireless VoIP Networks

Bandwidth is determinant of the maximum number of simultaneous conversations. Trees, buildings, and weather can mortify the access capabilities of 802.11 through space.

When distance from the access point increases, greater the degradation in bandwidth occurs, which limits the total number of simultaneous calls per access point.

Free space path loss can be calculated by this for 2.4GHz

Free-space path loss 20 log(d [m]) 40 dB

As long as one can see along the level of service from the receiver and the transmitter and have a sufficient amount of area around that path. This is called the Fresnel zone.

For indoors, this formula will be more complicated and depends on factors such as building materials, furniture, and occupants.

Indoor path loss (2.4 GHz) = 55 dB + 0.3 dB/d [m]

Adding gain to an antenna is balanced gain because it adds gain for both transmitting as well as receiving.

802.11b is the most widely used standard protocol and it requires direct-sequence spread spectrum (DSSS) technology, specifying a maximum over-the-air data rate of 11 Mbps and a scheme to reduce the data rate when higher data rates cannot be sustained.

802.11b protocol supports 5.5-, 2-, and 1-Mbps over-the-air data rates and 11 Mbps using direct-sequence spread spectrum and Complementary Code Keying.

This wireless transmission of nearly 11 Mbps of raw data at indoor distances to about 300 feet and outdoor distances of perhaps 20 miles in a point-to-point use of the 2.4-GHz band. The distance of transmission depends on impediments, materials, and LOS.

The 802.11a standard specifies Orthogonal frequency-division multiplexing (OFDM ) using 52 subcarriers for interference and multipath avoidance, supports a maximum data rate of 54 Mbps using 64QAM,and mandates support of 6-, 12-, and 24-Mbps data rates.

802.11g is an extension to 802.11b and operates in the 2.4-GHz band. This increases 802.11b's data rates to 54 Mbps using the same orthogonal frequency-division multiplexing technology that is used in 802.11a. This is the protocol best for range and bandwidth combination and it is upwardly compatible with 802.11b equipments as well.

802.11n wireless networks let you create a quality working environment by combining the mobility of wireless with the performance of wired networks.

Defining Project Scope

This project scope chapter details the methodologies and sequential approach used in this research project.

Methodologies and experiments were performed during the project period.

Radio Frequency Spectrum Site Survey.

Analysis of VoWLAN hardware and software requirements.

OPNET Modeller design and simulation.

Re-Design and test.

VoWLAN deployment.

By using Wireshark Network protocol Analyse and SIP call trace and investigation

Observation and calculation.

Conclusion.

Measurement and Approach

3.1 Site Survey

Site survey is vital to understand the RF behavior within the infrastructure; it will give the information regarding existing coverage area of the transmission, current infrastructure status about interference, drawbacks in the coverage areas. Author examined Wireless site survey by using Wi-Spy dongle, Channelizer lie, Netstumbler and XIRRUS Wi-Fi Inspector. According to this site survey all access points and signal strengths RSSSI measured.

Following steps should be carryout during the Site Survey.

Infrastructure facility diagram

Pre Inspection the facility

Study the potential user areas

Identify the APs locations

Locate the points of deployment interests areas and client receive position

During planning cycle in Voice over Wireless LAN infrastructure first analyze the performance affecting factors and how to performance enhanced to considering those performance affecting factors.

VoWLAN performance affecting factors

Distance between Access Point and Voice Client

When voice client moves further away from AP voice client will lose signal strength. Theoretically signal strength is inverse cube relationship with distance from access point.

Objects that absorb radio Frequency signals, Physical Obstacles.

WLAN is operating low frequency bands like 2.4GHz, 5GHZ. So it won't penetrate long distance through free space, even if consider indoor infrastructure we cannot get good enough signal at all times in all indoor areas because of internal infrastructure partitioning by cells so radio frequency suffer obstacles to reach the destination.

Interference

Non-Wireless LAN interference - this effect will add the noice to existing WLAN. This cause sources from 2.4 GHz or 5GHz devices such as cordless phones, microwave ovens and automation equipment .etc.

Adjacent Wireless LAN interference - WLAN becomes popular this deploys all over the places so if use same frequency or same channel there may be interference

Network Load

Shared medium

Incorrectly oriented antennas

Limited Spectrum

Multi path fading

VoWLAN overheads

Performance Enhancement of VoWLAN

As mentioned above performance affecting factors should be consider when enhancement of VoWLAN.

VoWLAN Deployment challenges

Bandwidth Management

Packet Loss

Latency

Jitter

Security

Location Tracking

Battery Life

Coverage

Reoaming

3.2 Analysis of the Wireless Voice Design and Deployment Hardware and Software Requirements.

3.2.1 Choice of IEEE 802.11 a/b/g/n Technology.

In this research the author used IEEE 802.11g WLAN technology because existing University Wireless infrastructure deployed by using G WLAN technology with TKIP encryption it provides data rate 54 Mbps with 2.412 ~2.472 GHz ISM band. it uses OFDM for Modulation ,high resiliency to RF interference and low multi path distortion.

3.2.2 Hardware Requirements

Controller based WLAN

WLAN Controller

Light Weight access points

Wi-Fi supported handheld phones

SIP proxy / IP based telephony system

Autonomous WLAN AP can deploy without the WLAN controller architecture. Author preferred to deploy the autonomous WLAN. But there is no facility to deploy the controller based WLAN architecture in KW lab.

NETGEAR Wireless Firewall Router Model -WGT 624

IEEE Standard Used - IEEE 802.11g

Network Speed - 108 Mbps

Frequency - 2.412~2.472 GHz (Europe ETSI)

Security Features - Double Firewall (NAT + SPI

ZyXEL Prestige 2000W-V2 VoIP Wi-Fi Phone

Wi-Spy Dongle Spectrum Analyzer

3.2.3 Software Requirements

Network Stumbler

Channelizer lite

XiRRUS Wi-FI inspector

OPNET Modeler 15.0

Wireshark

X-lite 3.0 Soft Phone

3.3 Methodologies

3.4 Summery

This chapter describes various kind of technologies and deployment scenarios made by author, here analyze various kind of Hardware and software tools used to analyze VoWLAN technology.

4.Network Simulations Results and Analysis

The Author chooses these projects model and investigates some of the features and algorithms of the Wireless LAN technology which is directly depends to the Voice over Wireless LAN Design and deployment. IEEE standards like 802.11a/b/g/n and 802.11e, by using OPNET WLAN models author is going to analyse access point functionality and BSS and EBSS functionalities , coexistence of IEEE 802.11 e capable and IEEE 802.11e not capable devices in the same BSS and IEEE 802.11e standards specifications in network performance.

IEEE 802.11e Study Scenario

In this scenario IEEE 802.11e supports at WLAN layer and analysis the collision of WLAN layer QoS deployment on network performance.

Objective

Wireless stations generating application traffic for all Quality of Service are present, how the 802.11e capable Access Point (QAP)

WLAN Data dropped buffer overflow bits/sec

The figure shows The total size of higher data packets dropped by the all the WLAN MAC s in the network due to the Full higher level layer data buffer or the size of higher layer packet which is which is greater than the maximum allowed data size defined in the IEEE 802.11 standard.

Total higher layer data traffic in bits/sec dropped by the all the WLAn MACs in the network as a result of consistently failing retransmissions. This statistic reports the number of higher layer packets that are dropped because the MAC couldn't receive any ACKs for the (re) transmissions of those packets or their fragments, and the packets short or long retry counts reached the MACs short retry limit or long retry limit respectively. If the network contains QSTAs 802.11e capable WLAN MACs that use Block ACK mechanism as originator for some or all of their communications with other QSTAs, then this statistic will also include any higher layer data traffic of those MACs transmitted and retransmitted within blocks. Not acknowledged in following block ACks and dropped due to reaching the transmit lifetime limit.

Delay

This graphs represents that end to end delay all of the packets received by the Wireless LAN MACs of all WLAN nodes in the network an forwarded to the higher layer. this delay includes medium access delay at the source MAC, reception of all the fragments individually and transfer of the frames via AP, if access point functionality is enabled

Load

This Load graph represents Total load in bits/sec submitted to Wireless LAN layer by all higher layers in all WLAN nodes of the network.

Network Load Bits/sec in BSS1,BSS2 & BSS3

Throughput

Voice Analysis

Voice with WFQ with same TOS

Results

Voice with WFQ with different TOS

Appendix

Signals Captured during the project site survey

3-D view smoothing

Density View

Wi-Fi Rader View for KW lab

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