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Chapter 1: Introduction:
Wireless communication is the major media of communication in the present real time world. Every organization needs its communication standards to be efficient and cost effective. This led a path for the development of the WLANs and research on it standards. The authorization of the 802.11b standards by IEEE in 1999 gave birth to the Wireless communication. This authorization completed the limitations of the wireless communication in the business world and supported as the way to satisfy all purposes of it. Rapid growth of the wireless communications is on various issues like reduced time of installation, scalability, cost effective, efficiency and the main reason is it can be connected to the area where even the wired connections connected be reached. WLANs are built in user convenience from the early stages which satisfy the needs from the minimum network requirements to vast area of applications.
In the past few years WLANs are extensively implemented in many business fields, education, scientific applications, military etc.., The applications of the WLANs have been increased with the increase in the demand for there usage in different areas. Some of the other motivating reasons for the growth of this technology are increase in the production of the economical hardware, the high data rates of transmission (1 Mbps-54 Mbps and even more with different applications) and the demand for the portable devices like laptops, Tablet PCs, PDAs, Gadgets etc.., Every field of business is passing its hands to join in the wireless community for there communication purposes.
The recent survey on the WLANs revealed that the more than 70% of the UK enterprises are using or willing to implement WLANs. The present project work is designing and implementation of the WLAN for one of the Best Hotels "Menzies Hotel (Best Western)". All the real project criteria's are been considered. We design the network model using the hardware which support the "IEEE 802.11g Extended Physical Connection" which is one of the IEEE standards for the WLANs. The present work of design is to be made with careful analysis of the building architecture and considering all the real time limitations of the technology. Every advantage and limitation is clearly explained in this report.
1.1. Project Background and motivation:
WLANs are becoming the motivation for every business organization to expand there hands in this modern communication world. The main advantages of the WLAN like cost effective, providing the coverage for the areas where the wired connections cannot be given, increase in the standards of the WLANs day by day for the betterment of the transmission rates, throughput, etc.., which are very effective issues for the communication are being satisfied. These reasons made WLANs to be adapted by many organizations for their communication purposes.
In this project work we are designing and implementing the WLAN for the Menzies Hotel which is a real time project. The motivation for the project is the suggestion of my Supervisor Wei Heung to do a real time project. With his support i made appointments with some of the organizations (Sainsbury's Harpenden, Menzies Hotel Luton, Iceland Luton) to extend or to design a WLAN for them. With the positive feedback from the Menzies Hotel Luton to design a WLAN for their organization i forwarded the proposal for my project on it. This design is then implemented in OPNET and simulations are been carried out and analyzed to verify the output of the network against the real time performance standards.
1.2. Objectives of the project:
a) To review the Literature: It is to provide review on the technologies used in this project.
b) To Gather and analysis of the Requirements: It is to gather the primary requirement information (Raw requirements) from the management of the Hotel and analyze the requirements to filter the raw requirements and come out with the Specific requirements which can be possible to implement in the real time application.
c) To Design the System: It is to design the network model for the analyzed requirements with proper selection of the hardware type considering performance, cost and proper requirement of the technology.
d) To Implement and Test it in the OPNET: It is to test the designed network model by implementing it in OPNET and gathering the simulation results.
e) To Analyze the Simulation results: It is to analyze the simulated results against the performance standards we considered in before implementing the network in OPNET.
f) To Outcome with final report of the Project.
1.3. Problem definition:
Wireless network have become the major communication medium for most of the business organizations. In this present communication world every organization is trying to expand their communication standards very effectively for which WLAN is been adapted. The present project work is one of the problems of designing and implementing the WLAN network for the Menzies Hotel using IEEE 802.11g. WLANs are being designed as user convenience from the early stages. Major issue while designing the wireless network in the real time application is to consider the performance standards and cost of the network that we are going to build. We maintain these standards till end of the project and deliver the optimized network. In this project work we are designing the network for the Menzies Hotel by considering all the management requirements and performance standards specified by the organization for the network. Then this design is been implemented in the OPNET modeler to get the simulated results and analyze these results against the standards we meant to maintain till the end of the project. Some of the practical problems (regarding requirements & OPNET modeler), in implementing the network in real time would be discussed in this report.
1.4. Project Methodology:
The main aim of the project is to design and implement the WLAN for the Menzies Hotel which is a real time project where we follow the specific project methodology to accomplish and deliver the project in time. "Incremental Process" of methodology is the one we would follow in this project. Incremental Process is the combination of the linear and iterative processes of development. In this process of methodology we would follow series of "Waterfall Process" are followed to complete a piece of work on time before going on to the next level of the process.
In this project the following process is planned:
Gather the requirements à Analyze the requirement specifications à Design the System for the requirements à Implement and Test the System à Analyze the results
From the above analysis get the feed back from the project supervisor and Hotel Management and take an iterative stage by following the changes they specify to make it better
Get the feedback à Analyze the Changes à Change the Design of the System à Implement and test the changed system in the OPNET à Analyze the results
Detailed analysis on the results is made and is discussed against the requirement specifications and the performance indicators. An academic final report is planned to be submitted before the due date by overcoming all the inherent project risks.
1.5. Expected Artifacts:
a) WLAN network model design for the Menzies Hotel from the analyzed requirement.
b) OPNET design model which is the implementation of the network model design.
c) Detailed analysis report of simulation results against performance standards and requirements.
1.6. Structural organization of the project thesis:
This project thesis report is concluded in 7 chapters.
Chapter 1:Introduction: In this section of the report gives the general introduction of the project background and motivation, problem specification, methodology, expected artifacts and structure of the thesis.
Chapter 2:Literature review: In this section of the report we review all technologies used in the project. Review of WLAN and its practical applications and limitations are clearly explained in it. A review on the tools used like OPNET, VM ware is also reported.
Chapter 3:Requirement Analysis and Design of the Network model: In this section of the report we provide the information about the requirement gathering from the Management. The analysis of the raw requirement specifications and providing the specific requirements is reported. These specific requirements are designed into a network model and a WLAN network model design is made.
Chapter 4:Implementation of the network model using OPNET: In this section of report we provide the step by step creation of the network design in the OPNET. All the configuration of the routers, switches, workstations, servers are clearly explained step by step. Simulation results are been taken for this network designed.
Chapter 5:Analysis of the Results: In this section of report, simulation results are analyzed and they are compared against the standards and requirements of the management. The limitations of the network designed are been discussed.
Chapter 6:Conclusion: In this section of the report we conclude the project with its results analyzed.
Chapter 7:Future prospects and recommendations of the project: In this section of the report we present some of the recommendations for the network designed for its betterment.
Chapter 2: Literature review:
Wireless network communication is the rapid growing technology in the modern world where the 70% communication in this modern world is being demanded by it. There are many technologies which are being emerged based on it from day to day life. Some the prevailing technologies like Bluetooth, Infrared, Wireless LANs, Radio frequency communications, etc.., All these technologies are being used by the common man in his every day life. These technologies are being adapted by every business organization and even used in the many educational institutions, major corporations, banking sector, military, scientific research etc.., the boundaries of these technologies cannot be specified. With the demand of these technologies by hardware and users need there is a rapid growth in these fields.
One of the most prominent technologies of Wireless communication is Wireless Local Area Networks (WLANs). There are specified standards for every communication technology as well for the WLAN. These standards are been created by the Institute of Electrical and Electronics Engineers (IEEE).The IEEE extended the 802.3 wired Ethernet standards to wireless domain. For the fist time in June 1997, IEEE created the standard for the WLAN as 802.11 which are named after the group formed to oversee its development. 802.11 standards consist of 3 layers: Logical Link control (LLC), Media Access Control (MAC) and Physical Layer (PHY). The 802.11 standard is widely known as Wi-Fi which is a vernacular of Wireless Fidelity. Wi-Fi Alliance is the independent organization which gives the certification for the IEEE standards. The network bandwidth which is supported by this standard is 2Mbps which is unfortunately very slow for most of the applications. This made the companies to stop manufacturing of the WLAN products. The original 802.11 standards are been extended by IEEE in the next few years stating many other standards every year after.
2.1.1. WLAN Standards:
Every home or business network administrators looking to buy WLAN gears should select a standard from the array of 802.11. There are many products which confirm to the 802.11a, 802.11b, 802.11g or 802.11n Wireless standards know as Wi-Fi technologies. Let us review these standards with there pros and cons:
802.11b- High Rate DSSS in the 2.4GHz band:
This standard is specified by the task group for 802.11b of IEEE in late 1999 by extending the WLAN standard 802.11 for the first time. To provide higher data rates 802.11b uses Complementary Code Keying modulation technique that makes efficient use of the ratio spectrum. This is first time to be more popular as WLAN standard which is adapted many organizations and many products supporting it are also been manufactured.
This supports the 1Mbps, 2Mbps, 5.5Mbps and 11Mbps bandwidth comparable to the traditional Ethernet networks. The boost of this speed from 1Mbps/2 Mbps to 11Mbps is by using DSSS (Direct Sequence Spread Spectrum) modulation. http://www.yourdictionary.com/computer/802-11b. This modulation involves the Baker code chipping sequence where each bit is enclosed into a redundant 11-bit Baker code, with each resulting data object forming a chip.
802.11b uses the same radio frequency spectrum of 2.4GHz as similar to microwave ovens, cordless phones and many other regular appliances. However, installing the 802.11b devices at a reasonable distant from these devices would avoid maximum interference. The chip generated in using DSSS is put into the carrier frequency channel range. This frequency is unlicensed and unregulated which is more often to be adapted by the vendors to manufacture the goods with this standard.
Pros of 802.11b:Obstruction of the signals is low, good signal strength and Low cost.
Cons of 802.11b:Home appliances may interfere in the unregulated frequency band, slowest maximum speed (Slowest range in the maximum transmission speed) .
802.11a-OFDM in the 5GHz Band:
802.11a is a Physical layer (PHY) standard that specifies operating in the 5GHz UNII using Orthogonal Frequency Division Multiplexing (OFDM). This is the standard which is derived while the development of the 802.11b is in the process. These two standards are developed at the same time. But, as 802.11b gained much popularity in short time some of the folks believe that 802.11a is created after the 802.11b. 802.11a uses a Coded Orthogonal frequency Division Multiplexing (COFDM) which sends the streams of data in the massively parallel fashion across multiple sub carriers, each of which is 20 MHz wide and is subdivided into 52 sub carrier channels. Of 52 sub carriers, 48 are used for data transmission and the rest 4 are used for error control. http://www.yourdictionary.com/computer/802-11a
Bandwidth:This supports bandwidth up to 54Mbps. This is much faster than 802.11b in comparison.
Radio Frequency:802.11a transmits the signals in higher frequency of 5GHz. This higher frequency means shorten the range of the 802.11a networks and the probability of obstruction is more (signal penetrating capacity is low).
Pros of 802.11a:Regulated frequency prevents the other appliances interference with the transmission, Fast Maximum speed (Maximum speed in the Maximum transmission range).
Cons of 802.11a:Probability of obstruction is more, highest cost for higher frequency.
802.11g- Higher Rate Extensions in the 2.4GHz Band: (Wi-Fi Delity)
802.11g is the extended from the 802.11b Physical layer with higher speed extension up to 54Mbps. In June 2003 IEEE standard released 802.11g which is backward-compatible to the 802.11b at 2.4GHz radio frequency.
Bandwidth:This can support up to 54Mbps of bandwidth. This can support the higher speed of transmission rate and can be compatible to the 802.11b access point. The data can be transmitted from the access point which is supporting 802.11g to access point of 802.11b and vice versa. It is backward-compatible at every different transmission rate. At 6, 9, 12, 18, 24, 36, 48, and 54 Mbps it uses OFDM which is compatible to 802.11a. At 5.5Mbps and 11Mbps it uses Complementary Code Keying (CCK) which is compatible to 802.11b and at 1Mbps, 2Mbps, it reverts to DSSS and Binary Phase Shift-Keying (BPSK) which is compatible to 802.11a specification. Tri-mode components allow 802.11a/b/g devices to be interoperable but it shows a negative impact on the performance.
Radio Frequency:This operates 2.4GHz frequency band. The RF spectrum is divided in to 14 channels, each of which as a width of 25 MHz. Where in U.S., FCC allows 11 channels, only four can be used in a confined area at any given time without overlap. In France only 4 channels are used, 13 channels are used in U.K. and only 1 channel is used in Japan.
Pros of 802.11g:Not easily obstructed, Good signal strength and range, Fast maximum speed, Backward-compatible to the tri-mode devices.
Cons of 802.11g:Costs more than 802.11b, Probability of interference in unregulated signal frequency.
Table 1: Represents the modulation techniques, code rate, and bits per OFDM symbol for each transmission rate.  (Mahasukhon, 2007)
This is newest IEEE standard in the Wi-Fi category. It is the extension of the 802.11g in the area improving the usage of the higher bandwidth which is supported by utilizing multiple wireless signals and antennas using a technology called Multiple input Multiple output (MIMO) OFDM instead of using one.
Bandwidth:When this standard is finalized it may support 100 Mbps.
Radio Frequency:A better area of coverage is expected than the 802.11g.
Pros of 802.11n:Fastest Maximum speed, Best signal range, more resistant to the signal interference from outside sources.
Cons of 802.11n:Cost is more than 802.11g; interference is more from the nearby 802.11b/g based networks as if using the multiple signals.
Here is the list of the IEEE standards which are in use or development to support the wireless network technologies:-
IEEE 802.11a- 54 Mbps standard, 5 GHz signaling (ratified 1999)
IEEE 802.11b- 11 Mbps standard, 2.4 GHz signaling (1999)
IEEE 802.11c- operation of bridge connections (moved to 802.1D)
IEEE 802.11d- worldwide compliance with regulations for use of wireless signal spectrum (2001)
IEEE 802.11e- Quality of Service (QoS) support (not yet ratified)
IEEE 802.11f- Inter-Access Point Protocol recommendation for communication between access points to support roaming clients (2003)
IEEE 802.11g- 54 Mbps standard, 2.4 GHz signaling (2003)
IEEE 802.11h- enhanced version of 802.11a to support European regulatory requirements (2003)
IEEE 802.11i- security improvements for the 802.11 family (2004)
IEEE 802.11j- enhancements to 5 GHz signaling to support Japan regulatory requirements (2004)
IEEE 802.11k- WLAN system management (in progress)
IEEE 802.11l - skipped to avoid confusion with 802.11i
IEEE 802.11m- maintenance of 802.11 family documentation
IEEE 802.11n- 100+ Mbps standard improvements over 802.11g (in progress)
IEEE 802.11o - skipped
IEEE 802.11p- Wireless Access for the Vehicular Environment
IEEE 802.11q - skipped
IEEE 802.11r- fast roaming support via Basic Service Set transitions
IEEE 802.11s- ESS mesh networking for access points
IEEE 802.11t- Wireless Performance Prediction - recommendation for testing standards and metrics
IEEE 802.11u- internetworking with 3G / cellular and other forms of external networks
IEEE 802.11v- wireless network management / device configuration
IEEE 802.11w- Protected Management Frames security enhancement
IEEE 802.11x - skipped (generic name for the 802.11 family)
IEEE 802.11y - Contention Based Protocol for interference avoidance ,
Types of WLAN:
802.11 wireless networks can be broadly classified into two modes, Infrastructure mode and Ad hoc mode.
Infrastructure mode:In this type of mode all wireless nodes in the network will communicate with the centralized access point (AP), which is in turn connected to the wired LAN to form a Infrastructure Basic Service Set (IBSS). In this mode of WLANs, access points act as the relay stations between wired stations and wireless stations. Such a combination of BSS with a backbone distributed system forms an ESS.
Ad-hoc mode:In this mode of WLANs, wireless stations or nodes communicate with each other without an access point to form an independent BSS. Nodes in one network act as routers that discover and maintain the routes to other nodes -
WLAN provide wireless network communication over short distance using radio frequency or infrared signals rather than using traditional Ethernet cables . Wireless network uses a shared medium which means they use the same unlicensed radiofrequency 2.4 GHz and 5 GHz. These bandwidths are same as the telephone lines and microwaves. These bandwidths are to be coordinated for the better performance the network . These networks are extended to wired local area networks. A typical WLAN consists of a number of wireless clients and access points. These WLANs are connected to the edge of the wired network with the device called "Access Point". These devices acts as small versions of cell phone towers to relay the transmission to the required coverage area needed. All the wireless clients will access the transmitted network and communicate with the wireless access points (APs) . These clients communicate with the help of the wireless network adapters which are similar in functionality with the traditional Ethernet adapters.
2.1.2. Components of a Typical WLAN topology:
Every WLAN uses a channel for the transmission of the data through the medium.
A channel is a range of electromagnetic frequencies over which data is transmitted . Every WLAN will use a channel for the transmission of the data with in its network or to other networks. The data which is transmitted through this channel is been encrypted at the AP and is decrypted at the workstation (Client).
WLANs provide the wireless equivalent of Ethernet, providing seamless connectivity anytime, anywhere. The communication in the network is covered with the access points and these access points are connected to the edge of the wired network (LAN). Thus access points will transmit the signals from the wireless devices to the wired network and vice versa with out any distortion in the data. Every AP will establish its own Basic Service Set (BSS) in its area of radio coverage. Wireless clients that know the name of the BSS (Its SSID) can try to authenticate and associate with the access point . Access points oversee a Distributed Coordination Function (DCF) called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) .
Basic Service Set (BSS):
A BSS is the basic building block of the WLAN. A single access point with all its stations in its coverage area is known as BSS. The area of coverage is known as Basic Service Area (BSA).
Service Set Identifier (SSID):
A SSID is a token which identifies 802.11 WLAN. This is set by the network administrator. This is an alpha numeric, case sensitive string from 2 to 32 characters in length. Every client should know the SSID to connect to the network. Every access point will transmits its SSID with in its coverage area and all the clients in this area can communicate with the AP with its SSID. This SSID is transmitted as a packet header for every packet that is transmitted by the WLAN in its network .Several access points in the same network can share same SSID for enabling the roaming of the clients .
Extended Service Set (ESS):
When a single BSS provides insufficient RF coverage, one or more can be joined through common distribution system into Extended Service Set. In an ESS, one BSS is differentiated from the other by using Basic Service Set Identifier (BSSID) which is the MAC address of the access point serving the BSS. The coverage is the extended service area (ESA).
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA):
This means that clients on a WLAN must sense the medium for energy levels and wait until the medium is free before sending. This process is to be followed by every client on the network for better performance of network and efficient usage of the medium. If access point receives data from the client on the network it will send an acknowledgement to the client stating the data is received. This acknowledgement keeps the clients from assuming that a collision is occurred and avoids the retransmission of the data again. Thus the medium is maintained efficiently. To maintain the channel and prevent the channel from the hidden node problem CSMA/CA is featured with two operations Request To Send (RTS) /Clear To Send (CTS). With the help of these operation access point maintains the network medium efficiently and avoids collision of the data packets that are been transmitted. The same process is followed by every client in the network.
Whenever a workstation moves from the coverage of the access point in the WLAN the workstation leaves a probe message. Access points that cover the new area will respond to this, and the station associates with one of these APs, which it chooses from the factor of signal strength and noise level. This procedure of associating with the new AP is called handoff .
Fig: A model Infrastructure model
A Wireless router is a wired router with a built in wireless access points. So, that we use it either wired or wireless connectivity. It can perform the duties of access point, Ethernet switch and router. Routers isolate network segments into collision domains. Each domain is unaware of collision in other domains. In addition routers are capable to isolate the subnets and networks by using the Network layer in the protocol stack. An entity in the Network layer reads the header of the Network layer in the packet to find its destination and then it looks into the routing table. Routing table is a list of mappings of network addresses to ports that will deliver the packet to the appropriate destination with the best means. The best means could be the shortest path, maximum throughput, minimum time, etc. The routing table for small networks can be done manually but for large networks they are meant to be generated automatically by using the appropriate routing protocols. Thus a router is more specified in network addresses and in getting packets transmitted from one network to other .
Wireless routers are reviewed with built in DSL modem and network software. Such type of router will act as hardware and software security combo box. Wireless router can be called an access point in a single home network where there is no need of extending the network into subnets. All the IP addresses are automatically allocated in the wireless router. In the review of the routers in the present generation there is a introductory of the wireless IP network router. In this network the IP addresses are assigned to the network clients where these are maintained by the network administrator configured in the main router of the network. Routers in real time application play a major role of performance in the network. Routers can be used to connect two different networks in the Wide Area Networks (WAN). Firewalls for the security can be implemented at the routers which serve as the filter for the network from the outside intruders. Outside world can be connected to the home server by using the router connection to the specified network.
In the real time application the routers are selected in prior with there requirement necessity and performance ability. The routers which we did selected in this project are customized devices where it has 4 ethernet ports and WLAN port which is capable to connect to other devices like switches or modems in the network. But in the real time there is broad selection of the routers with inbuilt modem and network software. These combo boxes are higher in cost metric but even higher in performance and network management.
It is a network device which joins multiple computers together within one LAN. A Switch can be considered as a hub. But the switch is more intelligent and slightly higher in cost metric. A network switch operates two layers viz., Data link layer and OSI model layer . Network switches are more capable of inspecting the data packets that are received. It is capable of inspecting the header of the data packet where the information of source and destination of the data packet is present and deliver it to the appropriate destination without any distortion. Network bandwidth is conserved by delivering the messages only to the connected devices on the network and thus it offers better performance than a general hub. The total bandwidth is determined by the number of the ports on a switch (i.e., a switch with 100Mbps and 8 ports can manage until 800Mbps of band width). A Mainstream Network Switch can support either 10/100 Mbps Fast Ethernet or Gigabit Ethernet of 10/100/1000 standards. Switch which manages the transfers in full-duplex mode gives the possibility of doubling the speed of each bond (like bond with 100Mbps can manage to deliver 200Mbps) [-].
Different models of switches can handle different number of devices depending on there capability. In general for the customer usage switches with 4 or 8 Ethernet ports are supplied. But there are many models of switches developed by Cisco and other commercial organizations which are used for commercial purposes rather than for small networks. These commercial switches are 3 layer switches. They can handle more memory on the network i.e., can handle more number of devices in the network. A switch can even be used to prioritize the subnets connected in a single network. The VLAN technology of separating the different subnets in the network with there respective functionalities can be done at switch. The 3 layer switches are organized with the VLAN managing capability.
Switches in the real time applications act as transceivers where the data packets are been transmitted on the network through it stating their destination on the packet header. In the traditional Ethernet based network switches are the heart of the network. But in the modern Wireless networks there are second prioritized after the routers even though they are the intelligent part of the network managing the data transmission on the network. In the WLAN switch transmits all the signals from the router to the access points and vice versa in the network on their priorities of delivery.
Workstations typically make use of the services of all layers of a protocol stack because they process the requests of application programs for information on servers. Every client in the network is a workstation performing some application .
Servers also make use of all layers of the protocol stack because they respond to all requests from the application programs on other computers .
Real time applications (Voice, Audio and Video):
Advantages of WLAN:
WLANs are user flexible built from early stages of the networking. WLANs are efficient compared to traditional wired LANs. Some of the advantages of the WLAN are: Convenience, Productivity, Mobility, Cost, Deployment, Expandability, Maintenance etc..,
Convenience:Wireless network can be accessed from any convenient area near to the coverage of the access point in the network (Home, Office, Organization, Enterprise, etc..,).
Productivity:WLAN network is more productive in every field like connectivity, mobility, cost and performance. Eg., A employee in an organization can accomplish his work even by moving from one place to other, which more productive to the organization.
Deployment:Setting up of the WLAN is more convenient than setting up traditional wired LAN. Setting up of infrastructure based WLAN for the first time in an organization or enterprise requires more than one access point. After designing the network model for the WLAN, deploying it is very convenient compared to wired LAN. The problems like pulling the cables from walls and ceiling are no more effecting parameters.
Expandability:There is no fixed size limited to the WLAN. Any number of clients in the coverage can be increased rapidly sharing the existing infrastructure. Expanding the existing technology is even not a hard task to be accomplished.
Cost:Hardware components of the wireless network are higher at cost than wired networks. But, this potentially increase cost is almost always more than outweighed by the savings in cost and labor associated to running physical cables.
Disadvantages of WLAN:
For every technology there are pros and cons and even WLAN had some of the disadvantages like: Security, Speed, Reliability, Range and QOS in Video/Audio transmission.
Security:Security cannot be guaranteed on the WLAN even lot of countermeasures for the security issues are being evolved on every day. Security can be assigned to the network by configuring some of security protocols like WEP, WPA etc..,.
Range:Transmission range is other issue of WLAN. As transmission of the data packets in a network is done by using RF waves, Infrared waves, due to the obstacles in the pathway of the transmission range of transmission is affected. Range of the transmission can be achieved by using proper access point positioning techniques.
Reliability:As the usage of the unlicensed range of transmission of WLAN networks, interference from the appliances which use the same range is encountered. This is one of the important issues which affect the reliability of the network. This is even out of hands of network administrator. In case of some complex networks this counter measured by using Phase shift keying (PSK) or Quadrature amplitude modulation (QAM), making interference and propagation effects all the more distributing. As a result important network resources like servers cannot be connected wirelessly.
Speed:Most of the WLAN networks are typically connected with transmissions rates of 1-100 Mbits/sec which is slow compared to the wired connected networks transmission. IEEE 802.11 work groups are building new standards for the better transmission rates of 100-200 Mbits/sec in 802.11n WLAN satndard.
QOS in Video/Voice transmission:Due to the usage of the lower range of RF waves of 1.4GHz - 2.4GHz which is unlicensed and been obstructed by many day to day appliances the transmission of higher applications like Video/Voice are experiencing low quality of transmission.
2.2. Review on Simulation Tool:
There are different simulation tools for the designing and testing the network system. Some of the major networks simulators in order as which are used in the research papers are:
1. ns2/ns3- It is a discrete event simulator targeted at research in network which provides a substantial support for simulation of routing, TCP and multicast protocols over the wireless and wired networks. The source code of ns 2 can be downloaded and can be compiled of multiple platforms with most popular flavors of UNIX and Windows. , .
2. OPNET- Products of OPNET combines the predictive modeling and clear understanding of networking technologies. It enables the customers to design, deploy and manage network infrastructure, network equipment and networked applications. OPNET is a development environment, allowing you to design and study communication networks, devices, protocols, and applications. .
3. GloMoSim / QualNet- A scalable environment for wired and wireless network systems. The parallel discrete-event simulation capability provided by Parsec is employed by the GlomoSim. To run GlomoSim we need the latest version of the Parsec compiler. If a user wants to use the GlomoSim he/she should have some familiarity with the Parsec compiler. QualNet is the commercial version of the GlomoSim for the utility of the customers. , .
4. NetSim- It is a comprehensive tool for the computer networking. It contains some modules for network programming and real time packet capture. Aloha, Slotted aloha, Ethernet, Token Ring, Token Bus, WLAN, X.25 Frame Relay, ATM, TCP and devices like switches, routers, access points etc., are covered in the simulation of the NetSim., .
5. OMNeT++- It is a component based, modular and open-architecture simulation environment with strong GUI support and an embeddable simulation kernel. This is used for the modeling of: communication protocols, computer networks and traffic modeling, multi-processors and distributed systems etc. It also supports animation and interactive support. There are some of the extensions of it for real-time simulation, network emulation, alternative programming languages, database integration, SystemC integration and several other functions. Domain framing functionality is provided by model framing which is developed as independent project.,
There are many other network simulators which are being developed and tested in various areas of building the networks.
OPNET in particular is a user development environment which allows the user to design and study the communication networks, devices, protocols and applications. . It is very well known for its functionally rich capabilities for modeling and optimizing network performance and the impact of managing change across the infrastructure. It is one of the best tools for the network simulations where the simulation results can be viewed and analyzed from network level to the nodal level of the network. All the hierarchical levels of the network can be clearly depicted by using this simulator, where the characteristics of those levels can also be analyzed. Simulation results are easily and clearly obtained, which can be analyzed by any user. The GUI interface is very rich such that it helps the user to get all his required devices for designing the network, protocols for designing and can analyze the performance of the network from the simulation results.
Chapter3: Requirement Analysis and Design of the Network:
3.1. Gathering Primary Information (Raw Requirement Data Set):
The first step for starting any project is the collection of requirements from the client. The data collected from the client stating his/its requirements is called Raw Requirement Data Set. This data has got all the requirements of the client including some of the non practical applications. This requirement data set is filtered to form a "Synthesized Requirement Data Set". Synthesized Required Data Set is the requirement data set which is derived by filtering all the non practical applications from the RRDS. This process of forming a SRDS is the important stage of project accomplishment agreement. Once the agreement is signed the project is considered to be started and on its process of completion.
Every requirement data set consists of immediate and future need of the clients and the existing information system. Here is the RRDS for our project "Designing and Implementation of WLAN for Menzies Hotel"
Raw Requirement Data Set:
Cost Metric:The budget is the most important requirement for building any project. The budget for implementation of the WLAN in Menzies Hotel is mentioned as "Free Budget" as it is the conversion of the Wired network to the WLAN. Anyway minimum budget is to be maintained to meet the requirement and better performance of the network.
Time Management:Time is one of the major factors effecting every project completion. This is the model design for the Menzies Hotel to extend there wired LAN into WLAN, thus the time factor is not mentioned for this project. But, the time taken to complete our academic project is considered to complete the project for the client.
Range of Coverage:The WLAN coverage requirement for the Menzies Hotel is to cover all the building area. 100 X 100 feet coverage for total building with 6 Floors of coverage altitude is to be covered. There are 60 room spaces which are to be covered by the WLAN.
Throughput:Throughput is the performance standard which is very dynamic in nature. Every network will deliver its throughput depending on many physical characteristics of the network devices like Access points, Routers, number of users of the network etc.., The throughput for our network is expected to be with the saturated number of users to be at most 10 Mbps for the channel transmission rate of 12Mbps.
Application Software:The application software for the Menzies Hotel is Oracle. The applications that are to be maintained in the network design are:
a) Data base (Oracle),
b) Email service,
c) File Transfer,
d) File print,
e) Video Conferencing,
f) VOIP, and
g) Web browsing.
Privileges to be considered:
1) Management and Reception: Data base, Email, File Transfer, File print, Web browsing, VoIP.
2) Bar and Kitchen: Data base, Email, File Transfer, File print, Web browsing.
3) Banquet Hall: Video Conferencing, File Transfer, VoIP, Web browsing.
4) House Keeping: File Transfer, File print.
5) Staff Live-in: Web browsing, Email.
6) VIP suites: Web browsing, File print.
7) Casual suites: Web browsing.
Operating Systems:Linux is the Operating system that is to be installed in the systems of Menzies Hotel.
Hardware:Hardware depends on the type of technology we are using. We are implementing WLAN 802.11g standard of technology to build the network and all the hardware that supports this technology are used to maintain budget and performance. Any usage of the old systems is also to be considered.
Quality of Service:Quality of Service is expected in every technology used in the network. Like QOS in WLAN, QOS in Video Conferencing, QOS in VOIP and in every other service providing technologies QOS is to be maintained.
Facts to be considered to design a WLAN in real time:
1) Keep in mind that we define the Synthesized Requirement Data Set as if to determine what the WLAN must do, not how it will do it.
2) Selection of the WLAN standard is to be made to meet requirement specification of the client.
3) Maximum number of users i.e., reliability of the network with the maximum load is considered.
4) Proper planning of the project is made for completion of project in date.
5) Positioning of the Access points is the important task for maintaining the coverage of the WLAN in the building .
6) The minimum number of access points that are to be maintained for the proper coverage of the network all through the building.
7) Customers are to be kept on the separate subnet in the network for the data protection.
8) The real time obstacles like walls, glasses, floor, shape of the room, partition of the room are to be considered.
9) Regardless of the size of the network concentrate on the requirement satisfaction for the client.
10) The real time hardware selection is the important part of the network designing, where all the performance criteria would depend on the proper support of these devices for the selected standards.
11) Unwanted selection of hardware is to be omitted to maintain the network in budget.
Considering all the above facts generating Synthesized Data Requirement Set:
1) In the practical implementation of the network, first and the foremost step we take are to filter the RRDS to form the SRDS. This is because requirement analysis is the most important stage of any project to prevent if from having some breaks in the process of development.
2) Time Constraint: With the help of the perfect project management standards we can meet the time constraint and finish the project in time lapse.
3) Cost Metric: Budget is to be as humanly low as possible. Cost is to be balanced against current performance and future expandability.
4) Coverage: With the proper usage of - standards of placing the access point in the network we can provide coverage to the whole building.
5) Throughput: It depends on the distant between the nodes and access point in the infrastructure mode of WLAN. It is the dynamic property of the WLAN which determines the performance of the network designed. Throughput is the number of packets/bits received to transmitted per sec. This can be increased by increase in number of the users and decreases with increase in delay, data drop and increase in the obstacles like concrete floor, glasses, walls etc., .
6) Application Software: Applications which are stated in RRDS can be implemented in the real time and these applications and privileges can be given in the application server.
7) Operating System: Any operating system can be used to implement in the network depended on the hardware support to the network.
8) Hardware: All the advanced hardware with performance priority is used in the network design to deliver a very good network.
9) Maintenance: Maintaining a WLAN is to keep update to the technologies that are being updated in day to day life, which are adapted by the administration. All the network routes, access points, switches, routers and nodal characteristics are to be checked to date by using one of the available network management software.
10) Quality of Service is not restricted to one of network technology used. This can be considered in every technology like:
QOS in WLAN depends on providing the network coverage, throughput, and performance efficiency -.
QOS in Video Conferencing depends on the video clarity of transmission from the other network to our network or vice versa.
QOS in VOIP depends on the clarity of the voice transmission and the decrease of the Jitters in the network.
QOS is not limited any one area of technology, all service providing technologies are to be maintained to give maximum QOS output.
3.2. Architectural Design of the Network model:
This is second phase of project, where we select the proper standard of WLAN and design model network satisfying all requirement specifications using appropriate network devices. All the real time barriers are to be considered for designing the network model, because this is the model design which is going to be implemented in any of the simulation tool for analysis of its performance.
3.2.1. Selecting the WLAN standards according to the client requirements:
There are different WLAN IEEE 802.11 standards, which are defined to satisfy different purposes of the network users. In our project of designing a WLAN for Menzies Hotel as per its requirement specification we use the 802.11g standard which is most common and advanced standard for the indoor WLAN applications. This selection of WLAN standard is very important in designing of WLAN as the next proceeding of the network design will depend on the devices and software that support this standard.
Important specifications of WLAN 802.11g:
a) It uses 2.4GHz range of transmission with bandwidth up to 54 Mbps(1, 2, 6, 9, 11, 12, 24 and 54Mbps).
b) This standard of WLAN is backward-compatible to the 802.11b standard.
c) It uses different modulation techniques for every range of bandwidth of transmission.
d) This is most efficient standard that is being used and adapted by many organizations for indoor WLAN design.
e) Due to use of low range of frequency, probability of interference from doors, walls, ceilings is low.
f) In the survey of calculating "Throughput analysis on WLAN" using all its standards, research members concluded maximum throughput can be obtained under saturated conditions for 802.11g. ,,,
With a conclusion on specifications of the 802.11g WLAN standard and its usage in the real time applications, we use it as a standard to be followed in our project work.
3.2.2. Planning the WLAN: [
Implementing a WLAN that takes the best advantage of resources and delivers the best service requires careful planning. WLAN installations can range from very simple to very complex and intricate designs. A well documented plan must be in place before a wireless network can be implemented. Here we are going to discuss some of the important planning criteria's to be followed for the best plan:
Number of users: Number of users is not a straightforward calculation of the WLAN design. Number of users depends on the geographical layout of your facility. That is "How many devices and users can fit in a space available?"
Data rates: Data rates are most important as per the user expectation. As we are using the shared medium, increase in number of users increases the contention of the Radio Frequency signals.
Non overlapping channels: The use of non overlapping channels by multiple access points in an ESS.
Transmit power: Transmission power (speed) is one of the criteria that are to be planned for designing a WLAN.
dB loss: Construction of the building has a great impact on the Wi-Fi planning. dB loss is the main function of the material used.
We can provide sufficient coverage for our network users with proper planning of the RF coverage in an ESS.
The first step in planning a WLAN is "survey of the site". We start with a map of the area that is to be covered. Then the coverage of the WLAN is to be planned by calculating the approximate position of the Access points.
Positioning of the Access points in the site:
When planning the position of the Access points, we should not just draw the circle of coverage and drop them to cover the area. An approximate calculated circular coverage area is important.
Some of the important point to be considered while placing an Access point:
a) If the old wired LAN connection is to be used to connect Access point on to the backbone of the network we need to consider, how to manage coverage from that point.
b) Position of the access points should be above obstructions.
c) They should be installed vertically near the ceiling in the center of each coverage area, if possible (3 feet above from the reach of human body is expected).
d) They need to be positioned in the user expected areas.
e) "Outside-in": Access points are to be mounted outside the rooms of the guests and shooting transmitter into rooms.
f) "Hallway": Needs a compact discrete form factor with high power.
With the completion of discussion about the position of the AP we need to consider the point "How many APs do you need?"
a) High transmit power and receive sensitivity means less APs. In our project we are going to implement the 802.11g which transmits up to 54Mbps.
b) If the rooms are made of brick or concrete: 15 rooms can be covered by using single AP.
c) If the rooms are drywalls: 25 rooms per AP can be accessed.
Every BSA can cover 5000 square feet of area. The BSA takes its radius diagonally from the center of each square.
Conclusion in respect to our project requirements:
All the area that is to be covered by WLAN for Menzies Hotel is 100 X 100 Feet (10,000 square foot area); where in a real time each BSA can cover 5000 square foot of area. All walls which are occupied by the guests are drywalls. Every floor for guest allotment is with 16 rooms and this implies we can access a single AP which covers the floor.
Coverage of Ground Floor (100X100 feet):Management & Reception area can be covered by one of the AP and Bar & Kitchen area can be covered by another AP.
Coverage of First Floor (75X100 feet):First floor is with Banquet/Conference Hall and House keeping department. Two access points are used one in Hall and other for House keeping.
Coverage of Second Floor (75X100 feet):This floor is allocated for Staff Live-in In and there are 12 rooms which are of concrete build walls. Here we can use single AP for covering all these 12 rooms.
Coverage of Third Floor (75X100 feet):This floor is allocated for occupancy of 10 VIP suites which can be covered by single access point.
Coverage of Fourth Floor (75X100 feet):This floor is allocated for occupancy of 16 Casual suites which can be covered by single access point.
Coverage area planning:
Requirements specify coverage by every AP is 5000 square feet.
Where Area = Z2
From Pythagoras: 2R2 = Z2
R= Sq. root of Z2/2
R= 50 Feet and Z= 70.71 feet.
We need to keep the BSA as overlapping in the following manner:
Two access point coverage is to be overlapped for enabling the roaming of the clients in the network.
5000 Sq. Feet Area 5000 Sq. Feet Area
3.2.3. Defining the number of subnets:
Following the client requirements is very important in selecting the subnets. Here in this project according to the client specification we need to allocate the application privileges to specified departments. Keeping all these requirement specifications in mind we allocate different subnets for every specified area of management:
Ground Floor:We allocate a subnet profile for Management and Reception with an access point in it, next to Bar and Kitchen another subnet profile with an access point in it.
First Floor:We allocate a subnet profile for Banquet/Conference Hall with an access point in it and next to House keeping department with another subnet profile with an access point in it.
Second Floor:We allocate single subnet profile for this floor which is allocated for Staff Live-in.
Third Floor and Fourth:We allocate single subnet profile for these floors which are allocated for VIP Guests and Casual respectively.
3.3. Artifact of the Building:
Management and Reception (Ground Floor):
The access point is positioned at the centre of the calculated area of 50 feet radius circle as per the calculation of positioning access point.
Bar and Kitchen (Ground floor):
The access point is positioned at the centre of the calculated area of 50 feet radius circle as per the calculation of positioning access point.
Banquet/Conference Hall (First Floor):
House keeping (First Floor):
Staff Live-in (Second Floor):
Staff Live-in (Second Floor) is allocated for the Staff. There are 12 rooms in total for occupancy with concrete build walls. The positioning of the access point is specified at the centre of the floor with facing the transmitting antenna into rooms.
VIP Suites (Third Floor):
All the 10 rooms are covered by the access point placed at the centre of the floor. All the walls are drywalls.
Casual Suites (Fourth Floor):
All the 16 rooms are covered by the access point placed at the calculated position of the access point. All the walls of these rooms are drywalls.
3.4. Performance Indicators:
Error bit rate:
Client data rate:
Load of the network.
3.5. Limitations and Exceptions of the project requirements:
There are some of the non practical requirement specifications which are not 100% possible to reach in implementing the project in real time they are:
As time and budget doesn't permit to implement the network design that is the output of this project in real time, I would like to analyze the performance indicators with the project results against the research theoretical calculated values in IEEE papers. The proper functioning of the network can be determined from the simulation results of the network in OPNET. The limitations of the OPNET modeler in the implementation process of the network design are discussed in the Chapter 4.
Chapter 4: Implementing the design model in OPNET:
Chapter 5: Analysis of the results.
5.1. Analysis of the results against the performance standard measures.
5.2. Analysis of the limitations of the project.
Chapter 6: Conclusion:
Chapter 7: Future prospects and recommendations of the project.
WLANS for the 21st Century Library.Full Text AvailableBy: Calamari, Cal. Teacher Librarian, Dec2009, Vol. 37 Issue 2, p40-42, 3p; (AN 47500191)
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