OFDM modulation technology


A WLAN is a wireless local area network using to connect 2 and more than 2 computers & devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area. This gives users the mobility and foredoom to move around within a broad coverage area and still be connected to the network.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 (Johns Hopkins, 2007).

Wireless local area network can be step by step more familiar mainly on Further Education College as well as common campus on behalf of example modern survey of academic institutions originate with the intention of near every one plan towards install a wireless network regarding already contain a limited functions as well as only some have a complete utilize. Even though equipments of IEEE 802.11b are largely deploy also handling is growing radically modest is recognized about how the networks are use. A comprehensible considerate of treatment patterns into real WLANs is important in order used for persons who build up install & control. WLAN equipments used for those who build up system with application software for wireless networks. This type of research papers shows the outcome result commencing from the major and most widespread sketch of network activity into a huge assembling wireless LAN. Dartmouth College had 12 Mbps 802.11 actions in favor of almost each building on college grounds. As well as every managerial educational and housing buildings. The majority healthy facilities (Nieh, 2003).

Wireless networkings know how to prove the extremely useful in public places libraries offices hotels institution cafeteria along with universities are all type of places wherever individual might discover wireless access towards internet. Inside with the finical point of view this is helpful for mutually the supplier as well as client. The supplier would propose the service used for a charge exactly doubtfully lying on a pay for every exercise system client would be there able toward get benefit of this service within an appropriate position missing from office & home. A disadvantage of wireless internet is about QoS (Quality of Service) is not definite as well as if there is some obstruction by the relation after that the connection might be unable to find (Tabona, 2004).

Rising reputation of wireless networks furthermore need toward conquer more rapidly data rates contain formed extensive attention in study associated towards multi channel multi Radio wireless networks. Multi channels are hopeful clarification. The majority of these types of networks are configured by the Non overlap channels do not deduction through each other. Within IEEE 802.11a/b/g channels 1 6 as well as 11 are measured to exist none overlapping with consequently the premise that these channel be able to use such that various networks can work into close immediacy lacking snooping among all others (Sharma and Raghavendra, 2006).

At this time there is a rising body of study going on the area under discussion other than extremely a small amount of but any of the analysis provides a fair analysis of the skill, which illustrate its procedure & circumstances implication used for business. In this type of attempt toward seriously examine the Bluetooth technology commencing from different perspective. This begins through an explanation of the tools in conditions of its hardware software & about other network communications. After that it addresses the related issues of interference, security, and reliability. This microanalysis is followed by superior macro logical outlooks which include the reward of this knowledge. Its responsibility within universal third generation (3G) wireless method physical condition security issue with big business implication. It concludes by the applications of Bluetooth with its future prospective (Erasala, 2002).

The integration of WLANs with the high speed WAN with constantly on broadband access with the intention of might provide an well-organized with cost efficient put in the ground WLAN mobility organization require the present WLAN internet functioning protocol improved. The Inter Access Point Protocol describes means used for access point synchronization above a sharing method to support WLAN inter functioning without some of central aptitude to support mobility. The performance of mobility managing among a few external central controls within an allocation system together with broadband such the same as DSL is not precise into several WLAN. Include 802.11a/b/g. Implementation of a distribution system among broadband DSL access central system manage designed for IEEE 802.11a/b/g WLAN mobility. After that the alteration to the IAPP protocol messaging required for the broadband supported mobility management for WLAN is accessible, initial replication results representing the efficiency of the planned allocation as well as its signals can also be provide. (Rahman and Harmantzis, 2004).

Wireless Networks Types

The types of wireless networks are given as under:

  • WPANs
  • WLANs
  • WMANs
  • WWANs

Upcoming of construct Wireless networks with the aim of container coverage the globe the arrangement is toward make use of software separate access points to model the Radio Frequency environs with multicast it toward previous associated access points who promote it forward toward the wireless node. As a result of testing this fundamental thought inside a model with categorize its events. This unique assembly lump is able to result in a lot of attractive architectures along with protocol plan attempts (Singh, 2008).

There are numerous types of wireless networks. A familiar method of categorize wireless networks is toward consider the relative variety with difficulty of every category of network. In favor of this journal the main category of wireless networking structural design are as follows:

(WPAN) Wireless personal area network

The small size wireless networks with the intention of require minor or else no communications with operate inside a short range. The WPAN is naturally used with only some devices in single area as a substitute of connecting the devices among cables. For illustration WPANs can be able to present print services & facilitate a wireless keyboard and mouse to correspond through a personal computer.

(WLAN)Wireless local area networks

Wireless networks unconventional to a computer LAN that uses two-way radio instead of wires to broadcast data back and forth among computers in a small region such like a home office and school. Wi-Fi is universally used wireless networks in computer systems in the direction of allow connection to the internet & different devices that contain Wi-Fi functionalities.

(WMAN)Wireless metropolitan area networks

Wireless network that connects several Wireless LANS surrounded with a few miles of each other. A lot of WMAN implementations make available for wireless access to clients in metropolitan areas networks.

(WWMAN)Wireless wide area networks

A Wireless Wide Area Network WWAN is wireless connectivity towards the Internet achieve throughout with cellular tower equipments WWAN connectivity allow a client through a laptop and WWAN card to surf the Internet check email & connect to a Virtual Private Network (VPN) commencing from wherever surrounded by the local limitations of cellular service. Because there are lot of types of wireless networks it is not sufficient for this journal to cover every type of wireless networking technology. In this journal a sophisticated overview of some used form of wireless networking technologies. The other journals provide comprehensive information going on single of IEEE 802.11 a/b/g and single form of WPAN. Other forms are not cover deepness in this research.


There are no of wireless components and devices available on markets; a core set of wireless devices comprises most wireless networks. An overview of each of core components is included in the section. Client devices in wireless networks also known as (STA), serve as wireless endpoint devices. Client devices enable end users to gain access and utilize recourses provided by wireless networks. Common examples of client devices are laptops computers, personal digital assistants (PDA), cell phones, and other consumer electronic devices with wireless capabilities. (http://en.wikipedia.org/wiki/Wireless_network)

Access Points(AP)

The wireless access point can be an apparatus that will allow wireless communication devices to join a wireless network with Wi Fi. Bluetooth with associated standards. WAP typically connects with wired networks can communicate data between the wireless devices like computers and printer. Wired devices lying on the network. An AP consists of a wired network port (eg.RJ-45 port) and at least one radio to provide wireless connectivity. Inside organize toward plan a WLAN it can be frequently essential in the direction to achieve an amount promotion to make sure that the WLAN provide the desired exposure & capability like throughput used for the future user. Inside the adding together we examine the collision of interferences lying on the worth of video while stream over WLAN (Boulmalf et al, 2008).

IEEE 802.11 based APs contain exposure area up to 300 feet and 100 meter. Access point provide freedom to connect without wires in home, office or limited areas through their laptops, PDAs and Wi-Fi enabled cell phones. APs can link mutually toward provide user to wander between APs inside a structure or university grounds operations on APs (en.wikipedia.org/wiki/Access_point).

Wireless Bridges

Is a hardware element use to connect 2 and more then 2 network segment? This can be actually or sensibly estranged. This can do not essentially for all time require towards the hardware device because a number of OS (operating systems) like Window Linux Mac OS X & FreeBSD make available software toward bridge different types of protocols. That is seeing usually in protocol above wireless to cable. Consequently in wisdom the computer acts like a bridge by means of using bridging OS software's. Various wireless routers & wireless APs present moreover a bridge type and a repeater mode. Mutually they perform a comparable ordinary function. There are differences individual the bridge mode connects toward dissimilar protocol types & a repeater mode relay the similar protocol types. Wireless routers access points & bridges can be obtainable to be acquiescent by means of the IEEE802.11a/b/g or n standard. The regularity band intended for these wireless standards is able to used license free in most countries (http://en.wikipedia.org/wiki/Wireless Bridges).

Base Stations

A base station or radio transceiver is similar to an AP, but covers a WMAN.A base station typically a two-way radio installed at a fixed location to provide wireless access. A base station covers much larger physical area then an IEEE 802.11 AP and serves significantly more clients. The specific range and client support vary by base station vendor and technology.

Wireless Modes

WLANs can function in 2 main types of modes:

  1. Infrastructure (BSS)
  2. Ad Hoc (IBSS)

This is additional conventional of these are the infrastructure modes. Infrastructure modes uses by wireless users to converse to LAN and the Internet throughout an access point. Yet as soon as the users can communicate through every one all other traffic go throughout the APs. The infrastructure mode wireless networking bridges can joins a wireless network toward a wired Ethernet network. In infrastructure mode wireless as well supports central association points designed for WLAN users. The wirelesses AP are necessary used for infrastructure mode wireless networking. Toward join WLANs the access point or every wireless client has to be configured to use the similar SSID (Anderson and Youell, 2002).

To compare the unconventional adhoc wireless network infrastructure mode networks present the benefit of centralized scalability and safety administration to enhanced accomplishment. Drawback for the transportation wireless networks is just the supplementary cost toward pay for access point hardware.


When analyzing or troubleshooting the operation of a wireless LAN, you'll likely be using an 802.11 packet analyzer to monitor the communications between radio network interface cards (NICs) and access points. After capturing the packets, you need to understand the different 802.11 frame types as a basis for deciphering what the network is or isn't doing. In this tutorial, I'll give you an overview of the more common 802.11 frames to help you become more adept at comprehending the operation of a wireless LAN and solving network problems (Geier, 2002).

The 802.11 standard defines various frame types that stations (NICs and access points) use for communications, as well as managing and controlling the wireless link. Every frame has a control field that depicts the 802.11 protocol version, frame type, and various indicators, such as whether WEP is on, power management is active, and so on. In addition all frames contain MAC addresses of the source and destination station (and access point), a frame sequence number, frame body and frame check sequence (for error detection).

The IEEE 802.11a/b/g data frames transmit protocols or data commencing on upper layers contained by the frame organization. The data frame in favor of example might be transportation the HTML code beginning from Web page absolute with TCP/IP headers to facilitate the user is presentation. Additional frame that the station utilize in favor of organization as well as manage transmit exact information concerning with the wireless connection in the structure body. In favor of a beacon's frame example body contain the service set identifier timestamp or additional relevant information concerning about the APs. 1.4.1 Management Frames:

The IEEE 802.11a/b/g management frames allow station in the direction of set up or continue infrastructure associations. Then the subsequent can be general IEEE 802.11 management frame types.

Authentication frames:

The authentication can be a procedure wherever the APs also accept and reject the individuality of a radio NIC. Then radios NIC begin the procedure through transfer an authentication frames contain its individuality toward the APs. By way of open system, authentications the radio NIC send simply the single confirmation frame or the APs. Respond through a confirmation frame seeing that a reply representative acceptance & rejection. By means of the elective common key authentication then radio NIC sends an preliminary authentication frame and then the APs respond among an authentication frame contain confront transcript. Then radios NIC have to send an encrypted report of the confront text by means of its WEP key in an authentication frame back to the APs. The APs ensure with the intention of the radio NIC has the exact WEP key which can be the foundation used for authentication. By considering whether the confront text recovered subsequent to decryption is the similar that can be sent before. On the behalf of pending results of this assessment APs reply to the radio NIC through an authentication frame suggestive of the effect of authentication.

Deauthentication frames:

The locations send a deauthentication frame in the direction of an additional location if it desires in the direction to cease protected infrastructure communication.

Association request frames:

An organization enables and assures the APs to assign assets for coordinate with a radio NIC. The radio NIC begins the relationship development by transfer an association demand to an AP. This type of frame carries information concerning the NIC and supported data rates or SSID of the networks. It needs to associate with. Subsequent to receiving the relationship demand the AP considers associating with the NIC or memory space establish a relationship ID used for NIC.

Association response frames:

The APs launches a connection response frame contain an approval and refusal notice toward the radio NIC demand relationship. Although the APs accept the radio NIC the frame contain information concerning the relationship like a relationship ID and hold up data rates. Circumstance the outcome of association is constructive the radio NIC can be able to make use of the APs to correspond by means of additional NICs on the network with systems on the allocation side of the APs.

Reassociation request frames:

If there is a radio NIC wander gone from the presently connected APs and discover an additional APs contain a stronger bonfire signal. Radio NIC determination send a reassociation frame toward the new APs. There is new APs then synchronize the advancement of data frames to may at a halt in the buffer of earlier APs for the future for broadcast to the radio NIC

Reassociation response frame

All APs launch the recovery response frame working and enclose to the approval and refusal. Observe in to the radio NIC demand for regarding about the connection. Related toward the involvement of the development then frame contains the information concerning about the relationship such the same as association ID or carry data rates.

Disassociation frames:

A station sends a disassociation frame to another station if it needs toward finish the connection. In the favor of example radio NIC which can be shutdown elegantly be capable of launch a disassociation frame toward alert APs. Now the NIC is without electric power. Then APs can will give up memory allocations or also eliminate the radio NIC commencing from the association chart.

Probe request frames:

The position for the launch probe demand frame. While it desires to get hold of information commencing from an additional positions. A radio NIC can be sending a probe demand for conclude where APs are contained by the range.

Probe response frames:

The probe response frame will act in response by the means of a probe response frame. Having ability to given the information supported data rates while after it obtains the probe request for the frames.

Control Frames

The IEEE 802.11a/b/g control frame help out in the deliverance of data frames connecting between locations then subsequent can be the familiar type of 802.11a/b/g control frames.

Request to Send frames:

The request to send the frames purpose can be the non-compulsory or decrease the frame collisions. There after the concealed stations contain relations with the similar type of APs. The posting launch a request to send frames to a further more locations as the initial phase of two way handshake essential sooner than transfer a data frame.

Clear to Send frames:

When a station takes action on the request to send among the clear to send the frames. Provided that authorization used for the requesting location to send a "data frame". Then "CTS" contain a time of value that can be source of all further "stations" among hidden locations to hold off the communication of "frames" used for a long time period essential for the demanding station to launch its frames. These reduce conflict between the hidden stations that can be result within higher throughput condition you execute it accurately.

Acknowledgement frames:

When data frames are receiving then receiving location will be exploiting an inaccuracy examination processes to identify the occurrence of errors. Then getting location determination launches an acknowledgement frames toward the transfer of data from one place to another place. If there no errors can be originated then the sending locations do not obtain an acknowledgement subsequent to a period of moment then transfer location will be retransmitting the frames.

Wireless local area networks

Wireless local area networks can be the identical as the conventional LAN other than they contain a wireless interface. Among the beginning of small portable devices such the same as "personal digital assistants" then WLAN technology can be attractive very accepted. WLANs make available high speed data communication in small regions such the same as building and office. It also allocates users toward move around in a restricted area. Whereas they can be at a standstill connected to the networks. Wireless Local Area Networks based on IEEE802.11a/b/g standards can be increasing speedily. WLANs can be able to make available the settlement of network connectivity with no of the limitations of being together at a place and limited by wires. In spite of this expediency of mobility the presentation of a WLAN should be able to address suspiciously before it can be able to accepted or organized in any surroundings. Now we can address the collision of a range of key limitations on the genuine performance of IEEE 802.11a/b/g. The series of controlled conduct experiments can be approved out to assess the performance of "IEEE 802.11g" in the occurrence of interferences or also discover the maximum throughput under reasonable circumstances (Boulmalf, 2008).

IEEE 802.11a/b/g

The genuine editions of the IEEE standards are 802.11. This was released during 1997 or can be explained in 1999 although it is today superseded. Its specific 2 net bit rates of 1 and 2 megabits per second "Mbit/s" and also plus forward error adjustment in the code. These precise three options on physical layer technology disseminate infrared operating at 1 "Mbit/s" frequency bounding in spread spectrum functioning on "1 Mbit/s" and "2 Mbit/s" or straight series of spread spectrum operating at 1 "Mbit/s" and 2 "Mbit/s". The later 2 radio technologies using microwave transmission above the "Industrial Scientific Medical frequency band at (2.4 GHz)". A few former WLAN technologies used inferior frequencies such as the U.S. 900 MHz ISM band. IEEE "802.11" is a set of standards delivering away wireless local area network computer communication in the "2.4 or 3.6 or 5 GHz" frequency bands. They can be executing by the IEEE LAN & MAN Standards Committee (IEEE 802).In this there can be a remarkable boost in the learning ro presentation of wireless technologies. They can consideration of wireless networks occurrence throughout the 802.11 standards they speedily develop into the established through the wireless LAN called "Wi-Fi". Then enhancing the habit of "Wi- Fi" make possible laptops PDA's or other devices can clearly sign of "Wi-Fi" ordinary agreement. "Wi Fi" can be a compilation of standards open to the elements of which the three main standards are 802.11a & 802.11b & 802.11g. Then two of the standards 802.11b & 802.11g contain interoperable characteristics even as the other 802.11a work on a fully changed stability or therefore not have such interoperability (Clincy, 2006).

IEEE 802.11 Standards

IEEE 802.11 also known as the Wi-Fi standard denotes a set of standards for wireless LAN. The original IEEE 802.11 standard released in 1997, defines a common media access control (MAC) layer that control the operations on all802.11-based WLANs by performing core functions such as managing communications between radio network card and access points. Subsequent amendments to802.11 defines specific physical (PHY) layers such as 802.11b, 802.11a or 802.11g.The physical layers define the data transmission for the WLAN, using various modulation schemes

Much of the impetus for standardization has come from the Wi-Fi Alliance, an organization of technology and service companies dedicated to the adoption of a single worldwide-accepted Standard for high-speed wireless local area networking. In common usage, the term Wi-Fi comes to embrace the 802.11b, 802.11g and 802.11 a physical layers standards, and the products based on those standards.


IEEE 802.11b-1999 or 802.11b, is an amendment to the IEEE 802.11 specification that extended throughput up to 11 Mbit/s using the same 2.4 GHz band. This specification under the marketing name of Wi-Fi has been implemented all over the world. The amendment has been incorporated into the published IEEE 802.11-2007 standard. 802.11b has a maximum raw data rate of 11 Mbit/s and uses the same CSMA/CA media access method defined in the original standard. Due to the CSMA/CA protocol overhead, in practice the maximum 802.11b throughput that an application can achieve is about 5.9 Mbit/s using TCP and 7.1 Mbit/s using UDP.802.11b products appeared on the market in early 2000, since 802.11b is a direct extension of the DSSS (Direct-sequence spread spectrum) modulation technique defined in the original standard. Technically, the 802.11b standard uses Complementary code keying (CCK) as its modulation technique. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology. (IEEE_802.11b-1999)

802.11 b Channels

The no of channels differs through country according toward confined regulatory limitations. Then FCC describes 11 channels for "USA" 12 channels are used within the majority of Europe or 14 are available used for Japan. Then limited number of existing channels in the "2.4 GHz" band places an inherent constraint on the capacity of an 802.11b network. "802.11b" standard describes a maximum number of "11 Mbps" channels which makes available of sensible throughput of "4-6 mbps" under ordinary circumstances.


The IEEE 802.11a is the modification towards the IEEE 802.11 measurement that added further a privileged throughput of up in the direction of "54 Mbit/s" & uses the "5GHz" band width. Then it can observe extensive worldwide accomplishment mainly surrounded by the community workstation. Then modification can be incorporated keen on the available for "IEEE 802.11-2007" standard. Then "802.11" are a set of IEEE standards through the reason of handle wireless networking communication techniques. The most regularly used nowadays in their "802.11a & 802.11b & 802.11g" editions to make available for wireless connectivity in the home and office or several commercial organizations (IEEE_802.11a_1999).

When network by means of the 5 GHz band provides 802.11a important benefit because the 2.4 GHz band is greatly used toward the position of individuals jam-packed. Dreadful conditions origin through the differences can be the cause of regular dropped connections or dreadful conditions of service. But this is high transporter frequency furthermore carries an insignificant drawback. Then the useful on the whole range of 802.11a is somewhat less than so as to 802.11b/g & 802.11a signals cannot break through since far those used for 802.11b as they are engrossed additional willingly by walls or extra solid substance in their passageway. Lying on the further offer OFDM have essential broadcast advantages as a high multipath surroundings such like as an inside the office or the privileged frequencies allow the building of smaller antennas among advanced radio frequency system increase which frustrate the shortcoming of a higher band of functions. Then amplified the number in working condition channels 4 to 8 times as many in FCC countries or also near the deficiency of additional nosy systems like microwave ovens and cordless phones and also baby monitors provide 802.11a major comprehensive bandwidth and consistency compensation over the IEEE802.11b/g.

There are some regularity issues with 802.11a. Many states contain different authoritarian carries even though a 2003 World Radio telecommunications Conference enhanced international standards synchronization. The 802.11a is currently accepted by the system in the United States & Japan however in further areas such like the European Union and it have to wait for longer endorsement. European standards were allowing for the use of the European "HIPERLAN" standard other than in the mid of 2002 vacant the 802.11a for make use of in Europe. Within U.S in a mid 2003 FCC decision might be open for additional spectrums toward the 802.11a channels.


The wireless networks IEEE 802.11g 2003 and 802.11g is an adjustment toward the "IEEE 802.11" requirement to unlimited the throughput up to the "54 Mbit s" using the equal frequency "2.4 GHz " band the same as "802.11b". These specifications below the promotion given name of Wi Fi have been executing all over the world. Now the 802.11g protocol is on Clause 19 of the available "IEEE 802.11" 2007 standards.

The 802.11g is the third "modulation standard" used for Wireless LAN. It can works in the" 2.4 GHz" band like 802.11b other than the functions on a highest unrefined data rate of 54 "Mbits" and concerning with the "19 Mbits" network throughputs like to 802.11a central part and apart from used for several extra inheritance transparency for toward the back compatibility. The 802.11g hardware is completely backwards well-matched through the "802.11b" hardware. Detail information for making of b & g work glowing mutually engaged a large amount of the remaining technical process. In the 11g networks on the other hands the occurrence of an inheritance 802.11b contributor will be considerably decrease the speed of the in general 802.11g networks. Then modulation system used in "802.11g" is "orthogonal frequency division multiplexing" OFDM derivative commencing after the 802.11a through data rates of "6 9 12 18 24 36 48 54" Mbit with reverts toward CCK similar to the 802.11b standard used for 5.5 and 11 Mbit. However although 802.11g work in the similar frequency band like the "802.11b" now it can be able to accomplish higher data rates for the reason that of its inheritance to 802.11a standard.

Benefits of wireless local area network:

The reputation of wireless LANs is the evidence first and foremost toward their expediency cost or efficiency & ease of combination by means of other networks or network mechanism. Then mainstream of computers advertise to the clients today move toward prepared through all essential wireless LAN technology. Now the payback of wireless LANs includes.

Client Mobility:

Among the appearance of public wireless network client can access the internet yet external their standard work surroundings. The majority sequences of coffee shops used for example present their clients a wireless connection to the internet at little and no charge.


The clients connected with a wireless network can be able to continue a nearly steady association by means of their preferred network because they move from place to place. Intended for a business this means that an employee is able to potentially be more creative as his & her work can be talented from any suitable location. Intended for the example a hospital and store may put into practice. Voice over WLAN applications that enable mobility and cost savings.


In the preliminary setup of an infrastructure supported wireless network wants little more than a single APs wired networks lying on the additional hand over contain the additional cost or complexity of actual physical cables being run to numerous locations which can even be impossible for hard to arrive at locations inside the buildings.


In the wireless networking hardware is on the most horrible and modest amplify commencing from wired matching parts. This potentially enlarged the cost is approximately always more than the offsets by the savings in cost or labor connected to running physical cables.


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.

Problem Statement

In WLan environment having large no of APs configured with same frequency channels and with nonoverlaping.obsctuls may be placed between APs in the environment they can create frequency inference and overall network performance.


To design a method to configure these APs to achieve maximum network performance

  • To find effect of varying obstacles (wood, wall and glass)on throughput and response time.
  • To find effect of varying obstacles (Rain, humidity and sunlight) on throughput and response time.
  • To find the effect of varying power on an environment on consisting of different obstacles on the throughput and response time.
  • To find the effect of packet size on throughput and response time with the same environment.

Proposed Solution

Configure AP by using all the frequency channels and there must a distance of 20 inches between the antennas of AP.



Bing (1999) stated that useful network performance of industrial IEEE 802.11 accommodating WLAN network is measured at the standard access control sub-layer. An amount of test conduct over the WLANs yields vital description like throughput and response time above a variety of network loads. The results expose to the buffering and fragmentation of data frames is capable to acutely weight the routine of an IEEE 802.11 WLAN. even though the length of a data frame as well as the bit rate of the wireless transceiver besides shape the WLAN's communication capability, its performance is commonly impassive by the form of frame addressing and the use of condition frames such the same as request-to-send (RTS) and clear-to-send (CTS). These explanations boast not be report in the analytical, model or extent studies passed out as a result far. Thus, the complete practical results existing in this paper force are helpful for administrators of IEEE 802.11 WLAN systems.

Tang and Baker (2000) defined that in which way users obtain benefit of wireless networks, he examines a sketch of a campus-wide local-area wireless network. He analyze the network for normally user (as soon as and how intensively people employ the network and how a large amount they shift around), generally network traffic and load description (experimental throughput and balance of outside and inside traffic), and traffic features from a user end of view (practical mix of application and number of hosts linked to by users). Surrounded by other results, he fined that users are separated into diverse location-based sub-communities, both with its individual association, activity, and custom features. Generally users develop the network for messenger chat-oriented activities, session-oriented activities and web-browsing. The activities of chat-oriented shows that a lot of users get advantage of the portable network for sack of synchronous communication with others. In adding together to these user-specific results, he also find that height throughput is typically cause by a single client and submission. Also, while external interchange dominate departing traffic overall, the reverse tend to be true through period of peak throughput; imply that major unevenness in network ability could be adverse for his users. While these results are just official for this local-area wireless complex and user society, he believes that parallel environment may reveal parallel manners and trend. He hopes that his notes will supply to a growing insightful of mobile client deeds.

Kotz and Essen (2002) described that wireless local-area networks (WLANs) is vital for individuals who build up, install, and administer WLAN tools, as well as individuals who expand systems and function software for wireless networks. Custom model in wireless local-area network (WLANs) be very important used for persons who build up, organize, and run WLAN technology. Web protocols are the single largest module of traffic volume; network backing and file sharing contribute an amazingly huge amount to the traffic. While there was several roaming inside a network conference, he here amazed with the amount of condition in which cards roam clearly, not capable to clear up on single access point. Cross-subnet roams here an unusual problem, as they broke IP connections, signifying the need for answer that keep away from or provide lodgings such roams.

Gast (2002) stated that wireless networking nowadays creature a typical choice for linking mobile users to business funds, administrators charge with implementing the expertise need capital of their personal. By implementing various he browsing patterns on different scenarios in both infrastructure and ad-hoc modes on wireless 802.11 networks. regularly the details of how wireless means and how to homework and set up wireless networks, so with the aim of the administrator who wants to get a wireless network up and running be able to do so hastily.

Clincy et al (2003) presented that the Wireless networking in universal, be unmoving in it enlargement phase and the standards 802.11a, b, and g have been the canter-of-attraction for wireless connectivity. Many of standards specifications are approximate, mainly the operating frequency and transfer rates. Wireless networks are severely unfair by environmental background at some given point-in-time. Signal and channel intrusion, geographic location is several of the former factors that can shape 802.11x wireless standards.

Yang et al (2003) stated that web applications are suitable more and more fashionable in support of mobile wireless systems. Though, wireless networks be able to high packet failure rates, which preserve disgrace web browsing performance on wireless systems. Alternative move towards is wireless thin-client computing, inside which the web browser runs taking place a out-of-the-way thin server with a more dependable wired link to the Internet. A mobile client after that maintain a association to the thin server to accept display updates above the lousy wireless network. To measure the feasibility of this thin-client come close to, he compare the web browsing presentation of thin clients adjacent to fat clients that scamper the web browser nearby in lousy wireless networks. Results demonstrate that thin clients be able to control quite well over lousy networks. Compare to fat clients operation web browsers close by, his results show amazingly that thin clients can be faster and more flexible on web applications over lousy wireless LANs even with having to dispatch extra information above the network.

Rahman and Harmantzis (2004) defined the addition of wireless local area networks (WLANs) and the soaring haste wide area network (WAN) using forever on broadband admission that could give a well-organized and price useful inter-WLAN mobility running requires the existing WLAN internetworking protocol improved. The lay to rest Access Point Protocol (IAPP) define method used for access point harmonization more than a division system to hold WLAN interworking lacking any mid brains to bear mobility. The performance of mobility administration with one outside inner run in a division system, with broadband such as DSL, is not specific in any WLAN, with 802.11. This document, first, present an operation of a circulation system with broadband DSL access central system manage for IEEE 802.11 inter-WLAN mobility. Then the adaptation to the IAPP procedure messaging compulsory for the broadband support mobility running for inter-WLAN is accessible. Introductory model results representing the use of the proposed distribution and its signal are too providing.

Leitgeb et al (2004) presented a mixture of open gap Optic system among WLAN and Satellite infrastructure to offer Video conferencing and information move for employ in Civil

Military collaboration and tragedy revival application. A modular announcement system industrial at TU Graz is described, which facilitate universal admission to the Internet before

A few other system (depending on the exacting application) by combine Satellite connections, FSO and WLAN networks. Satellite communications supply the needed back for statement among outlying location in the world, free liberty Optics allow quick putting in of broadband permanent wireless friends with no the want of any cable and at last, the WLAN offer connectivity to movable user in the system cell, situated at the goal purpose. The moment piece of the paper present result of a arrangement show at a civil-military employ in spring 2004 in Austria, anywhere mobile Satellite Earth Stations be second-hand in grouping with FSO and WLAN to allow Videoconferencing among military and civil organization.

Yeo et al (2004) stated that dimension and classification of wireless LANs (WLANs) contain be perform of late. Mainly of this capacity contain conduct beginning the wired piece of the network foot on wired monitor (e.g. sniffer at a number of tense direct) or SNMP figures. More just, wireless monitor, the traffic dimension from a wireless van clients against fat clients that run the web browser locally in loss age face, be too broadly adopt in together wireless investigate and industrial WLAN running product progress. Wireless monitoring system can supply exhaustive PHY/MAC in order on wireless middling. For the set-up judgment point (e.g. incongruity finding and refuge monitor) such detailed wireless in sequence is extra of use than the in order provide in SNMP or tense monitoring. In this paper he has explore a variety of issues in implement the wireless monitoring system designed for an IEEE 802.11 base wireless network. He identifies the pitfall that such scheme wants to be conscious of, and then give possible solution to stay away from those pitfalls He gear an real wireless monitoring system and demonstrate its efficacy by characterize classic computer science division WLAN traffic. Our classification reveal rich in succession in relation to the MAC/PHY layers of the protocol such IEEE 802.11 since the typical traffic combine of diverse casing types, their chronological features and association by means of the user deeds. Furthermore, he identifies a variety of anomaly in protocol and defence of the IEEE 802.11 MAC. Concerning the security, he identifies hateful usage of WLAN, such as email larva plus network. Results too show extreme retransmissions of a number of organization casing types dipping the of use throughput of the wireless network.

Nicol and Liu (2005) identified that Simulation provides an appropriate work surface meant for potential and active network services and protocols. Still, some significant issue have to be address suitably for major network imitation to twist into a with no problem adopted instrument for system researchers. The unique and most important subject is to surround the difficulty of the reproduction model. Even although this difficulty is in part solve by as a rule network simulators at present offering software module that put into exercise diverse ordinary network protocols and military, it be yet so a frightening job what time it come to implement new complex etiquette or modify an alive representation.

Kaleshi et al (2005) described that right of entry organize (MAC) protocols contain a large collision on the realizable system presentation for wireless ad hoc networks. Since of the limits of alive analytical model intended for ad hoc networks, a lot of researchers contain opted to learn the crash of MAC protocols using discrete-event simulation. Though, since the network scenario, traffic pattern and techniques may modify appreciably, simulation alone is not proficient to dig up insight keen on the impacts of MAC protocols under system show. In this paper, we analyze the concert of IEEE 802.11 circulated management function (DCF) in multihop network state of dealings. We are predominantly involved in thoughtful how physical layer technique can influence the MAC protocol act. For this purpose, the features of prying variety is calculated and taken into explanation of the logical model.

Harold (2006) stated that WLANs are opening to have fun a good deal larger role in business network environment plus be previously extremely accepted designed for home networking applications. This augment in convenience has shaped big security gap for hackers and robber to violent behaviour, which is ultimately creature address by stronger sanctuary method such as sophisticated encryption algorithms and proficient confirmation process. To constrain this breakdown, he have deployed an transportation of over 140 two-way radio monitors that at once capture all 802.11b and 802.11g motion in a large campus building. He describe the challenge posed by together the scale and uncertainty inherent in such an architecture, and explain the algorithms and supposition techniques he urban to address them.

Cheng et al (2006) stated that recent universities, commercial campuses and administration offices habitually organize score of access points to cover their site through wireless Internet access. Though, as the fine-grained of the 802.11 protocol itself have be torment considered his sympathetic of how big 802.11 network acts in their full experiential difficulty is astoundingly imperfect. In this paper, he in attendance a scheme call Jigsaw to use several monitors to supply a lone combined observation of all physical, link, system and transport-layer motion lying on an 802.11 network. To constrain this scrutiny, he boast deploy an transportation of over 150 walkie-talkie monitors that all together capture all 802.11b and 802.11g movement in a large university campus (1M+ cubic feet). He illustrate the challenge pose beside together the size and vagueness native in such a preparation, and make clear the algorithms and conclusion technique he urbanized to address them. in the end, using a 24-hhis spread hint containing more than 1.5 billion actions, he use Jigsaw's international cross-layer view to cut off routine artifacts, both clear, such as operation inefficiencies, and unspoken, such as co-channel nosiness.

Nicholson et al (2006) presented a regular access point innovation and variety system. Different active systems that choose access points base completely on external signal power, Virgil scans used for all presented APs at a site, rapidly links to all, plus run a series of test to view the value of all AP's relation to the Internet. Virgil too probes intended for blocked-up or redirect port, to lead AP assortment in errand of preserve function military with the intention of are now in utilize. Grades of our appraisal diagonally five neighbourhood in three cities illustrate Virgil find a working link beginning 22% to 100% additional a lot than select base on sign force without help. By caching AP test results, Virgil both improve presentation and sensation rate. Our visual projection is good enough and is exposed to be sooner than physically choose an AP with Windows XP.

Hsieh et al (2006) stated that IEEE 802.11 WLAN technology has developed into the de facto benchmark for wireless Internet contact. The spotted treatment of WLAN access points, though, limits the applicability of numerous real-time services same as VoIP inside the edge of the WLAN overhaul area. Inside this paper, we examine the difficulty of pretty VoIP check for everywhere statement in a WLAN with spotted check region. We believe a campus campus to have a traditional communications for political SIP-based VoIP package through wired or wireless data networks. The university grounds WLAN service does not contain 100% complete coverage, and therefore users cannot make VoIP calls somewhere on campus. The objective of this paper is in the way of conquering the limits of such dead spots for exciting the employ of site IP telephony service. In the direction of proceed, we begin with two approaches called one-hop addition and dual-mode announcement. The first move towards use multi-hop relay to expand the WLAN exposure, whereas the second come awake to leverages the ease of employ of dual-mode handsets intended for ever-present voice communication. We apply the two approaches, and assess their presentation inside the campus tested surroundings. We discover that as the two approaches are able to efficiently let voice communication in WLAN dead spots, they contain one ordinary trouble as the probable need of hold used for voice call permanence so as to can reason squalor of the talking class to a vigorous call. We assume a cross-layer resolution base on signal giving not in algorithms to tackle the crisis, thus achieve not to be fault voice call permanence even as enable ever-present voice communication on top of campus. Test bed appraisal show talented results for outlook study all along the future course.

Kane and Browne (2006) presented a categorization of implementations of right of entry control system base on lattice classification anywhere the axes are property of the functioning. The present taxonomy have six axis signifying: partition of manage more than sharing of right of entry manage diploma, allocation of the condition pertinent to right of entry control decisions, .delity of policy enforcement, the individuality decree machine, local against central decision, plus still or adaptive trust management. The classification reveal that distributed system for some point on the mesh with attractive admission manage species have not so far be implement. The association of this categorization to conservative classifications by type (for example, role-based access control or mandatory access control) and device (for instance, access control list or capabilities) is for a short time discussed. Some implementations of access control are secret by their principles meant for these properties. The role of access control within formulation and process of dispersed systems are discuses.

Zhang et al (2006) presented roughly have be a huge propagation of wireless local area networks (WLANs) base on the IEEE 802.11 WLAN standard. As 802.11 connectivity become extra ever-present, multihop infrastructure resolve survive ever more used for access point choice additional room and coverage improvement. In this paper, we at this juncture a plan for an IEEE 802.11-based control saving access point (PSAP), planned for use in multihop series and solar/battery motorized application. These type of APs boast numerous sensible application with be able to exist deploy extremely speedily and cheaply to give reporting improvement in situation such because campus, building complex, plus quick operation scenario. Different conservative wired access points, within this kind of system; control reduction on the AP itself is a very important object. A input plan restraint is to the future PSAP be to the stern like-minded to a extensive choice of IEEE 802.11 functionality plus alive wired access points. Within this paper, we bring in the protocols necessary in the direction of achieve this compatibility; explain the constraint compulsory by this restraint, and there routine results used for the future system.

Delibasic et al(2006) stated that TCP is the most commonly use transport protocol on top of the Internet tune to act upon well in long-established network finished up of wired associates among low bit error rates. Networks through superior bit error rates, such as persons with wireless links, disobey countless of the assumption finished by TCP, cause dilapidation of end-to-end routine. This paper present simulation-based presentation evaluation of record Westwood+ TCP procedure in wired/wireless surroundings. The ns-2 simulation results explain that in mainly of measured scenario, Log Westwood have the similar before improved goodput, compare to Westwood, except by minor justice file. It is indicating to add upgrading of LogWestwood algorithm in wireless surroundings is essential by important new Wmax and parameter.

Begerano and Bhatia (2006) presented a structure for as long as fair overhaul and following quality of service (QoS) wants in IEEE 802.11 networks through many access points (APs). These issues become significant since IEEE 802.11 wireless LAN are extensively deploy into all over the country networks, connecting tens of thousands of hotspots for provided so as to jointly real-time (voice) plus non real-time (data) services towards a huge population of mobile users. But, both fairness and QoS guarantee cannot be real supported in the current 802.11 paradigm. Termed MiFi, relies lying on central management of the APs. throughout several agreed occasion of the contention-free era merely a pot of non-interfering APs is activate as the others are silence. Furthermore, the quantity of overhaul decided towards an AP is relative towards its cargo with the system's performance be optimized by employ proficient preparation algorithms. We prove with the function of such coordination can be implement lacking require any alteration of the fundamental MAC protocol standard before the performance of the mobile stations. Our plan is balancing to the rising 802.11e standard for QoS and guarantee towards conquer the unseen lump and the overlap stand trouble. Our model set up to the plan ropes sprite and so is able to give QoS promise for real-time traffic, as stay awake a relation elevated throughput.

Ergin et al (2007) presented a methodical new learn of the result of inter-cell meddling on IEEE 802.11 presentation. by means of growing diffusion of Wi-Fi into housing area plus custom in ad hoc conference setting, chaotic accidental deployments are fetching the standard quite than an exemption. These networks regularly function a lot of close access points and station on the identical channel, also unpaid to lack of skill or deficient accessible canal. As an effect, inter-cell meddling is general but not well-understood. According to square insight, the competence of an 802.11 network is strong-minded by the number of lively clients. Shockingly, we discover that with a characteristic TCP-dominant workload, increasing system throughput is categorized by the number of snooping access points quite than the amount of clients. We find that owing to TCP stream control, the amount of back-logged position in such a network generation two times the number of access points. Therefore, an only access point network proves very healthy still by means of in excess of one hundred customers. Numerous snooping access points, though, guide to an add to in collision so as to reduce throughput and affect volume of traffic during the network.

Dekleva et al (2007) identified that mobile services, with commerce, will be significantly subjective by complete and reliable global access to wireless networks at superior bit rates. The present and rising wireless networks, counting 3G, 3.5G, and possibly 4G, are likely to effect in a prevalent use and deployment of mobile services, in particular in the era of digital multimedia broadcasting (DMB). Mobile and wireless networks boast fast evolve all about the world. Japan and South Korea are currently the world leaders, have introduce 3G wirelesses near the beginning since 2000 and 2001, in that order. Because of September 2006, Japan becomes the first country to have more than 50% of its subscribers via 3G applications.

Microsoft (2007) stated that wireless networks provide freedom of movement; they also allow us to speak to protection issue that is not because common on a personal cabling system for a wired LAN expertise such as Ethernet. The main safety issue is the verification of wireless customers and the encryption and data reliability of wireless LAN frames. This paper discuss the safety issue of IEEE 802.11 wireless networks and show how Microsoft Windows operating systems be able to used to make 802.11 wireless networks since safe because the existing set of 802.11-related technologies let. They also describe two operation methods for protected wireless right of entry, one for small office/home office (SOHO) network plus single intended for little association to be domain-based network, build by Windows Server 2003 technologies. This paper contain in sequence you be able to use to decide the favoured means for deploy safe wireless access in active SOHO network or small institute networks. The themes also provide step-by-step commands for location up secure wireless links, after the chosen use method has been single-minded.

Ahmed and Ramani (2007) presented a literature study on the requirements of Quality of Services (QoS) within Mobile Ad-Hoc Networks (MANET'S) which be universally growing area. MANET'S were initially proposed for use in military and battle field, due to the rapid expansion of the Multimedia Technology, Mobile Technology and civilian applications has to strictly adhere to QoS. The paper presents the description about the QoS and the issues of MANETS like Routing, Medium (or Channel) access, Mobility Management, Security and Reliability, and Power Consumption and also the current approaches including models and solution strategies. The focus of our paper is on those approaches that are relevant to our work.

Cheng and Wu (2007) stated that a numerous access control (MAC) protocols participate a main function in wireless LANs. The IEEE 802.11 MAC protocol specifies two management functions with the purpose of Point Coordination Function (PCF) and Distributed Coordination Function (DCF). Although both DCF and PCF are accessible in a wireless cell, we suggest a novel way in method called Adaptive Coordination Function (ACF) to carry different classes of traffic. The ACF super frame comprise two periods, one TDMA period planned for real-time traffic and follow with an adaptive stage which adaptively employ DCF or PCF to carry non-real-time traffic. Inside this paper, we relate the assumption of M/G/1 queues to analyze the presentation of adaptive episode in provisions of, end-to-end delay, queuing delay and saturation throughput. Among our analytic model, DCF or PCF be capable of be invoke properly according in the direction of the amount of station, packet payload size packet arrival rate and effective channel bit rate. Logical results are derived used for an wide throughput and delay presentation estimation of both DCF and PCF.

Chang and Sung (2008) stated that information technology have qualified breakthrough inside current years. Enterprise include begin to bring in command systems near help by income of business operation. Frequently before silent perennially inside employ, high-tech computer equipments are presentation hardware abnormality or malfunction on pinnacle of a normal base. Inside analysis of the problem, this revision use a multifunctional integrative skilled structure en route for help protection staff analyse with eliminate CPU system effort among the awareness firm happening hardware problem deletion. Usual professional systems, but, be beneath progress in addition to addition constraint, such because the detail to its growth be additional time-consuming, towards it cannot exist worn repeatedly along by income of so as to cross-platform claim is difficult. This study so attempts towards use the idea of service-oriented architecture (SOA) and set up two mixed web services mechanism as well as the computer preservation expert system and the preservation organization in sequence system. It also incorporates the use of wireless LAN (WLAN) in one classification inside direct near express the combination and function of the professional system and WLAN in web services surroundings.

Liu et al (2008) presented that an Internet neighbourhood be initiate by National Research and Education Networks (NRENs) to peers with each previous at IP Layer. With way of earnings of the stable enlargement of transfer stress from E-Science application, visual networks have been introduced inside behind 90s for explore senior bandwidth and improved QoS promise. Trouble occurs when integrate the entire novel visual communications through recent IP backbone, with controlling data lane and network administration. In this paper, we hub happening slip supervision issue in mix network contain SDH, DWDM and IP technologies. For instance, when readily existing is a fiber slash in DWDM layer, tens of noise the fear would approach hooked on vision at once courier scheme break inside DWDM, SDH and IP layer alone, which resolve puzzle engineers designed for mistake locate. So, we experiment with some scenario and offer a book association way in the centre of this layer according to association diagram. Our giving would earnings NRENs through hybrid networks used for root-cause sentence among sound the fright cross unlike network layers.

Balasubramanian et al (2008) stated that Mobile Internet users have several options today, including such high-bandwidth cellular information services as 3G, which is the option for a lot of. Though, the ubiquity plus short cost of Wi-Fi suggest an attractive option, that is, opportunistic employ of open Wi-Fi access points (APs) otherwise intended civic mesh networks. Unluckily, for vehicular users, the blinking temperament of Wi-Fi connectivity presents a confront for following trendy interactive applications, such as Web search as well as browsing. Our effort is focused with two questions. a) How can we allow system hold for interactive web applications on the method to stand disruption in connectivity from mobile nodes? b) Can opportunistic mobile-to-mobile (m2m) transfer improve application presentation above only by means of APs.

Anderson et al (2008) stated a parametric form which improved capture the effects of different broadcast environment on directional antenna systems; we too demonstrate that the unoriginal model are receptive to together the course of indication put on top of in addition to the situation in which the receiver is used. Regularly important, we display how researchers are able to use cheap equipment to proof data for their hold environment. Even though we use perceptive vector gesture analyzers in our capacity, we prove that by means of product wireless networking cards produces effectively equivalent models. We believe that a mixture of the exact model we suggest and the course by which we meet data to get that replica willpower authority the false presentation of wireless network protocols to rely on directional antennas, given that a extra sensible evaluation of those protocols. We furthermore tender some general supervision for researchers attempt to use directional antennas towards adapt a wireless network topology or decrease interference.

Boulmalf et al (2008) presented that Wireless Local Area Networks (WLANs) base on top of IEEE 802.11a/b/g principles are increasing fast. WLANs be capable of supply the benefits of network connectivity with no the limits of being tied to a position or limited by wires. Even with this expediency of mobility, the concert of a WLAN must be address watchfully before it can be adopt and deployed in any environment. In this paper, we address the blow of various key parameters on the real performance of IEEE 802.11g. A series of controlled experiments are carried out to measure the performance of IEEE 802.11g in the presence of interferences, and to find the highest throughput below sensible conditions.

Jiang et al (2009) stated that dynamic natural world of mobile ad hoc networks poses fundamental challenges to the design of service composition schemes that can satisfy the end-to-end quality of service requirements and reduce the effect of service disruptions caused by dynamic link and node failures. This paper proposes a new service composition and recovery framework designed to achieve minimum service disruptions for mobile ad hoc networks. The framework consists of two tiers: service routing, which selects the service components that support the service path, and network routing, which finds the optimal network path that connects these service components though existing research on mobile ad hoc networks has focused on improving reliability, little existing work has considered service deliveries spanning multiple mechanism. Furthermore, service composition strategies proposed for wire line networks (such as the Internet) are inadequately suited for highly dynamic wireless ad hoc networks. Our structure is base on the commotion directory, which is a book concept that characterizes different service disruption aspects, such as frequency and duration that are not captured adequately by conventional metrics, such as reliability and availability. Using the definition of disruption index, we formulate the problem of minimum-disruption service composition and recovery (MDSCR) as a dynamic programming problem and analyze the properties of its optimal solution for ad hoc networks with known mobility plan. Based on the derived analytical insights, we present our MDSCR heuristic algorithm for ad hoc networks with uncertain node mobility. We use simulations to evaluate the results of our algorithm in various network environments. The results validate that our algorithm can achieve better performance than conventional methods.



Performance of 802.11 Wirelesses LAN

In this chapter, I first explain the value of presentation estimation or presentation learns of system. Developed like an easy and cost-effective wireless technology used for finest effort services, IEEE 802.11 has gain fame at an unparalleled rate. Though, suitable towards the need of built-in value of service stay up IEEE 802.11 experience serious challenge in conference the weight of multimedia services and application. This expose survey 802.11 QoS schemes, including service separation in the MAC layer, bandwidth condition and admission control in MAC and superior layers, and link variation inside the physical layer, designed to meeting these challenge with only if the required enhancements for the required QoS. Furthermore, the article addresses issues that arise when end-to-end QoS has to be guaranteed in today's pervasive varied wired-cum-wireless networks. between these challenges, protocol interoperability, multichip scheduling, full mobility support, and seamless vertical handoff among multiple mobile/wireless interfaces are specially address (Zhu et al, 2004).

Entry points to content delivery networks (e.g. portals) have to cope with the primary need of distributing multimedia stuffing to 3G mobile procedures. inside this paper he talk about the software planning of a wireless Internet application he have planned and implement to hold up the sharing of Mp3-based songs to 3G UMTS devices. Beside the operational explanation of the planned architecture, efforts have been complete to examine the effects that Internet traffic has on the performance of UMTS networks, due to the sharing of Mp3 files by means of his wireless application (Roccetti et al, 2005).

Performance Evaluation

Select an exact mechanism to calculate a performance of http on WLAN to will give best service to users require positive obverse information and testing. The frequency channel selection means are very important and beneficial for high performance network, except if they are not use properly or chose adequately, they can actually decrees the productivity or presentation of wireless network (Senat, 2006).

IEEE 802.11g model which was ratifying within June 2003 and it extend the data rates of 802.11b beginning 12 to 54Mbps per channel. Just like the 802.11b, it operates within 2.4GHz range. The orthogonal frequency division multiplexing (OFDM) is the modulation plot use with the 8012.11g intended for the data rates of 6, 9, 12, 18,24,36,48 and 54 Mbps and reverts to CCK for 5.5 plus 11 mbps and DSSS for 1 and 2 Mbps. among this standard 802.11b devices resolve effort while coupled to an 802.11g access point, and 802.11g devices will work when connected to an 802.11b access point, in both gear using the minor 802.11b data rate (Stallings, 2004).

IEEE 802.11 standard has been available to set up quality of service (QoS) hold to the conservative IEEE 802.11 wireless local area network (WLAN).so as to be, the time interval as of the finish of the busy channel preserve live secret into different disputation zones based on the different AIFSs use by different sets of stations, and these different sets of stations may have diverse transmission probabilities in the same contention zone. Secondly, he analyzes the possibility that a station's back off procedure may be hanging due to transmission beginning other stations (Xiong and Mao (2007).

Response Time

at what time it comes to wireless LAN ,the response time be the point required for traffic to travel between two points or the time between a user's needs for service and services return of result. This is the best quantify that can help and used to determine the effectiveness of a network. No matter what the reason off slow response, users will always be aggravated as an effect of delayed traffic

During piece of information, when possible, the response time must be measured since it appears to users. A user perceives reply as the time beginning when they press enter or click on a button in anticipation of the screen displays. This elapsed time includes the point necessary for all network devices, the user workplace and the destination server to route the traffic (Janvier, 2006).


Universal process of transport WLANs has made Wi-Fi a basic part of today's Internet access tools. This duality obviates the need for link layer flow control for throughput development but necessitates traffic control for fairness and QoS. next, TCP-over-WLAN achieves high throughput equal through that of cable line TCP under sodden condition, not easy the broadly supposed observation that TCP throughput fare poorly over WLANs when subject to heavy contention.TCP-over-WLAN competency is facilitate by the self-governing behaviour of DCF and TCP congestion control that jointly drive the shared physical channel on an helpful load of 2--3 wireless stations, even when the amount of active stations is very large. These results stress subtle inter-layer dependency counting the explanatory load of TCP-over-WLAN on dynamic rate varying (Choi, 2005).

In a wireless LAN, principally of the time while the users reduce the throughput increase and while the users enlarge the throughput decrease.

Error Rate

This is measure of edge traffic that does not effect in error over network. It knows how to be expressed in conditions of percentage that compare the victory rate to whole package rate in excess of a period of time. To be able to gain the accuracy of a network, it is very vital to compute the fault fee for the quantity of packet coming into the complex, for example if 8 out of every 100 packets effect in fault, the error rate would be 8 %and exactness rate would be 92 %certain aspects that can cause error rate: electrical and frequency prying, faulty software or hardware (Senat, 2006).

Delay-bound conservation

By recording the lost service and compensating flows after an error phase, long-term throughput and long-term equality can be maintain. This paper stress that what is most relevant to current wireless QoS however, is the preservation of delay guarantees for sessions in the face of channel errors. Wireless packet schedulers have concentrated for the most part on preserving fairness in a network surroundings anywhere channels are area under discussion to location-dependent errors. A traffic outline and precedence based wireless fair queuing (TPP-WFQ) scheduling approach is future, which utilize all available remains bandwidth in the system to permit sessions to hold up to their error-free service as fast as possible. In adding up, a bandwidth management stage that adjusts session weights for utilize by the scheduler is existing. Precedence is given to real-time traffic among strict delay bounds for both bandwidth utilization and return. Replicated results exemplify how maintain short-term delay guarantees in this method does not affect extended expression justice and throughput guarantee for other sessions more broad-minded to delay (Walsh, 2006).

Maximizing Wireless LAN performance

When the wireless LANs first became available in the early 1990s, primary applications were wireless bar code solutions for need like inventory control and retail price marketing. Data transfer for these types of applications don't demand very high performance. In fact 1 Mbps data rates are generally sufficient to handle the transfer of relatively small bar codes for a limited number of users.

Today, enterprises are deploying wireless LANs for large no of users with needs for corporate applications that involve e-mail, web browsing, and access to various server-based databases. The needs for higher data rates and techniques to improvement the performance of wireless LANs is becoming crucial to support these types of applications. To get that extra performance, you have lot to consider (Senat, 2006).

Network researchers plus designer rely on network simulation tools towards recital evaluation. Around a number of unlike network simulation tools, each with a set of publicly available models. More popular tools, Opnet and t ns-2 have a bulky records of available models. The existing models can be used to configure simulation experiments in a relatively quick and easy manner. The choice of simulation tool often depends on the availability of models as hell as the user's preference. Most users assume that performance results on different simulators will be comparable, particularly when using models that have been widely used and tested. Using simple simulation experiments, this paper shows that TCP performance results obtained from ns-2 and Opnet can have significant differences. The differences are exposed when TCP is tested with error rates ranging from 1% packet loss to 20% packet loss. A study of the actions taken by TCP as a result of the losses provides insight into the performance differences (Kim and Hood, 2007).

Radio Frequency inference Avoidance

Electromagnetic interference also called radio frequency interference and RFI is the interruption of the signals so that have an effects on an electrical circuit suitable to either electromagnetic transmission & electromagnetic radiation discharge commencing from an outside the source. Then interruption may interrupt the obstruct or else corrupt along with limit the efficient presentation of the circuits. Then starting place could be any entity fake & natural to facilitate takes speedily changing electrical currents then such as an electrical circuit and the Sun of the Northern Lights.

Then EMI can be able to purposely used in the favour of radio jamming and also know as in a number of forms of electronic warfare and contain occurrence accidentally as a result of specious emissions in favour of example from end to end intermediation products they can like. Then it commonly affects the reaction of AM radio within the urban areas. Now it can be able to as well affect cell phones FM radio and television reactions even though to a slighter extent.

Righty use of Access Point Channels

Linksys recommends using the same channel when setting up another access point. Everyone else says to use a different channel. I think you should use a different channel. Roaming should work as well in this situation where you walk with your laptop and it will switch to the stronger signal without losing a connection. When deciding on channel numbers, use non-overlapping channels. Good choices would be 1 and 6, 2 and 7, 3 and 8, and so on. Channels 1 and 11 would work fine too. You want to minimize the interference for access points that are within proximity of each other.

As another example, let's say you had a three access points where the first and third access point are too far apart for their signal to reach each other. In that situation, you could use channels 1, 6, and 11 or you something like 1, 6, and 1. Even though the first and third are the same, they are too far apart for it too matter. Be sure all other settings are identical such as SSID and WEP/WPA/none. The only difference should be IP address and channel number.

Radio Frequency Coverage Destiny

The "GPRS" General Packet Radio Service is the worlds for the most part everywhere wireless data services accessible now among the almost each GSM network. GPRS is a connectivity explanation based on Internet Protocols to supports a wide range of activity and end user applications. Then throughput rates of the up to "40 Kbits" users include a similar access speed to dial-up modems but by the means of the ease of being able to connect from wherever. GPRS clients take pleasure in advanced feature in rich data services such as colour and internet browsing e-mail on the move of powerful optical communications such as the same as video streaming and multimedia messages location based services. intended for operators then adoption of GPRS is a fast and cost effective approach that not only supports the real first wave of mobile Internet services other than also correspond to a big step towards 3GSM and wideband CDMA network services.

Selection of correctly Physical Layer

Physical Layer is first as well as lowest layer in the seven-layer "OSI" model of networking. Then Physical Layer consists of the fundamental hardware broadcast technologies of a network. That is the essential layer underlying the logical data structures for the higher level features in a network. Suitable to the excess of available hardware technologies through extensively changing descriptions this is possibly the most difficult layer in the OSI model. The performance of this layer is frequently termed PHY.

It also defines the means for transmitting raw bit slightly than logical data packets above a physical link connecting network nodes. The bit stream might be grouped keen on code words or the symbols and changed into a physical signal that is transmitted above a hardware transmission medium. The Physical Layer provides a mechanical, electrical, and procedural edge to the broadcast medium. The shapes and properties of the electrical connectors, the frequencies to transmit on modulation method to use related low-level parameters are specific here.

Testing Environment

On testing location was selected for research. Testing environment consisted of one 802.11b and 802.11g APs and 802.11wireless cards, Compaq Presario cq60 and Acer Aspire same windows on both laptops.

Hardware Used

  • Access Points: 802.11 G TP-Link TL-WA-601G
  • Access Points: 802.11b Tp-LinkWR340G
  • Wireless Network Cards: 802.11 G TP-LINK TL-WN 62G
  • Wireless Network Cards: 802.11 G TP-LINK TL-WN 62G
  • Laptops: Compaq Presario CQ60.Dual Core 2.0 GHz,2GB RAM
  • Laptops: Acer Aspire-7720-6155.Dual Core 2.0 GHz,2GB RAM

Software used

The performance of network was tested with two programs which were chosen to meet the following requirements

  • Measure the minimum response time for TCP.
  • Measure the maximum possible throughput for TCP.
  • Determine the effect of transmission power on TCP throughput.

All these points were addressed by the software described below


Ping coded by Mike Muuss in 1983,is a network tool testing the reachable of a certain host within an IP network. Now the ping is the computer networks tool used for the test whether a exacting host can be accessible across an IP networks. It can also make use of self test the network interface card for the computer and as a latency test. It working with transferring the ICMP "echo request" packets to the target host and listening for ICMP "echo response" answering. Ping measures the round trip time and records several packet losses and prints where completed a statistical summary of the "echo" reaction packets arriving with the minimum mean max and in some versions the standard deviation of the "round trip time". The helpfulness of ping in supporting the "diagnosis" of Internet connectivity concern was the damages from late in "2003" as a number of Internet Service Providers start in on filtering out the ICMP Type 8 "echo request" messages at their network limitations.

That can be partially due to the escalating use of ping for target investigation the given example shows the Internet worms such because Welchia the flood of the Internet with ping requests in order to locate new hosts to communicate to disease. They Not only did the accessibility of ping answers leak information to an attacker. It can added to the overall load on networks reasoning problems for routers crossways the Internet (Mike, 2006).


The Iperf is normally used network testing tool to make TCP as well as UDP data streams as well as measure the throughput of the network that can be carrying them. The Iperf is a modern tool for network performance measurement in programming languages.

It can allocate the user to locate the variety of parameters to be used for testing a network and alternately used for optimizing as well as tuning a network. The Iperf contain a client and server functionalities as well as can measure the throughput between the two nodes moreover unidirectional as well as bi-directionally. It is the open source software runs on a variety of platforms including Linux UNIX as well as Windows. It is supported by the "National Laboratory for Applied Network Research".

While used for testing TCP capabilities the Iperf measures the throughput of the payload. The one thing to note in to Iperf uses "1024*1024" for megabytes and "1000*1000" for megabits. In this "Graphical user interface" GUI front end accessible called iperf also a Google Code project for iperf here. Now typical Iperf output have times stamped report of the amount of data transferred and the throughput considered.

Iperf is significant as it is a standardized tool that can be run over any network and output standardized performance measurements. Thus it can be used for comparison of wired and wireless networking equipment and technologies in an unbiased way. As it is open source, the measurement methodology can be scrutinized by users.


SPSS was released in its first version in 1968 after being developed by Norman H. Nie and C. Hadlai Hull. Norman Nie was then a political science postgraduate at Stanford University, and now Research Professor inside the Department of Political Science at Stanford and Professor Emeritus of Political Science at the University of Chicago. SPSS is amid the most widely worn programs for statistical analysis in social science. It is use by market researchers, health researchers, survey companies, government, teaching researchers, advertising organization and others. The original SPSS manual (Nie, Bent & Hull, 1970) has been described as Sociology's largely influential book. In addition to statistical analysis data organization (case selection, file reshaping, creating derived data) and data documentation (a metadata dictionary is stored in the data file) are features of the stand software. Statistics included in the base software:

  • Descriptive statistics:, Frequencies, Cross tabulation Descriptives, Explore, Descriptive Ratio Statistics
  • Bivariate statistics: t-test, ANOVA, Means, Correlation (partial, bivariate, distances) nonparametric tests.
  • Prediction for numerical outcomes: Linear regression

Calculation for identifying groups: Factor analysis, cluster analysis (two-step, K- means, hierarchical), Discriminant

Testing Locations

Wireless links are highly influenced by their surround environment. The testing location was selected an experimental lab was prepared that supported all the parameters and requirements that were needed in experiment.

  • The obstacles (glass, wall and glass) for indoor experiments.
  • The obstacles (Rain, Humidity and Sunlight) for outdoor experiments.

Were arranged to get measurement reading.

During the experiments this was assured that no wireless network in the neighbourhood. This was not possible for me to do experiment in an ideal location. So test were done in the computer lab that was prepared by me in university campus.

Tested Environment

As access point were placed on the table at the height of 4 feet from the ground surface. power supply established using APC UPS 1KVA due to loadsheding and interface 802.11G AP is presented with channel 1 enabled on AP1 the frequency channel of AP2=1,2,3,4,.....11 were changed during experiments. Distance between two APs was 25 inches. Distance between client and laptops were 5 feet.


In this chapter the carried out 802.11g measurement are introduced at first test sequence is defined which was run for the most of the further described tests. then before beginning the actual work, references test were done to verify if the chosen hardware was suitable for measuring. Finally the wireless test scenarios are outlined with their result being disguised in next chapter.

Reference Tests

Prior to actual wireless multichannel tests reference values were measured to get an understanding of the maximum performance of the hardware and the wireless channel.



Multi Access Point Networks

In multi access point network two APs were used for TCP throughput measurement the two access points are plaed in 20 inches distance from each other. A bridge was established between the APs traffic was generated between the laptop by iperf and ping tool.

During the experiment the frequency channel of one AP remain keep 1 and the frequency channel of 2nd AP keep changed from 1,2,3,4....11.

TCP Analysis

Wireless links are highly influenced by their surround environment. The testing location was selected an experimental lab was prepared that supported all the parameters and requirements that were needed in experiment.

  • The obstacles (glass, wall and glass) for indoor experiments.
  • The obstacles (Rain, Humidity and Sunlight) for outdoor experiments.

Were arranged to get measurement reading.

During the experiments this was assured that no wireless network in the neighbourhood. This was not possible for me to do experiment in an ideal location. So test were done in the computer lab that was prepared by me in university campus.

Frequency Channel and Distance

Network researchers and designers rely on network simulation tools to do performance evaluation. There are a number of different network simulation tools, each with a set of publicly available models. Two of the more popular tools, ns-2 and Opnet have a large library of available models. The existing models can be used to configure simulation experiments in a relatively quick and easy manner. The choice of simulation tool often depends on the availability of models as hell as the user's preference. Most users assume that performance.

Tested Environment

Wireless links are highly influenced by their surround environment. The testing location was selected an experimental lab was prepared that supported all the parameters and requirements that were needed in experiment.

  • The obstacles (glass, wall and glass) for indoor experiments.
  • The obstacles (Rain, Humidity and Sunlight) for outdoor experiments.

Were arranged to get measurement reading.

During the experiments this was assured that no wireless network in the neighbourhood. This was not possible for me to do experiment in an ideal location. So test were done in the computer lab that was prepared by me in university campus.

Frequency Channel and Distance

Network researchers and designers rely on network simulation tools to do performance evaluation. There are a number of different network simulation tools, each with a set of publicly available models. Two of the more popular tools, ns-2 and Opnet have a large library of available models. The existing models can be used to configure simulation experiments in a relatively quick and easy manner. The choice of simulation tool often depends on the availability of models as hell as the user's preference. Most users assume that performance.



Overall high throughput was achieved in 802.11g standard by using TCP traffic generated by iperf when the APs were configured with non-overlapping frequency channel schemes.

In research different parameter were used like antenna, transmission power, frequency channel scheme of APs.Obscuteles like Wood, glass and wall for indoor environment and rain, humadity and sunlight for outdoor environment. Different experiments were conducted by different frequency channel schemes of AP with and without obscultels.

But high result achieved by using non-overlapping frewuencychannel schemes' at high transmission power.

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