Wireless Network System for an IT Training Centre - Assignment Example

A Case Study Approach To Develop and Implement a Wireless Network System for an IT Training Centre Waquas Mehmood Introduction Wireless LAN is a computer networking technology that uses Radio Frequency (RF) as a connecting medium instead of wires and cables (Khayat, 2002). The need for a wireless LAN arose due to the requirement of mobility of users while staying connected to the network. Users can access the network within a specified range without any physical contact with the main server. This facility has been made available to the users by the introduction of modulation techniques into networking. The information to be shared between the users is made to superimpose on certain radio frequencies acting as carriers. This information is then transmitted through air with the help of a transmitter and received at the other end through a receiver and demodulated. Since both transmission and reception of the signals has to be carried out at the same point, therefore a device known as an 'Access Point' (AP) is used which is a simple transmitter/receiver or transceiver. By assigning different frequencies to different users many users can access the network simultaneously without interfering. As is evident, the access to a wireless network can be gained only if the users are having devices which have wireless facility. These devices such as notebook computers and tablet PC's are widely available in the market and their prices have fallen by large amounts in recent times making them affordable. An access point, ( source dlink.com,2005) Depending on the designing technology used WLAN's are mainly of three types. 'Narrowband wireless LAN's', 'Spread Spectrum wireless LAN's' and 'Infrared wireless LAN's'. Narrowband WLAN's, as is understood from the name, use narrowband signal for communication. Therefore the speeds achieved are low in this case but the problem of interference is greatly reduced as is the case with narrowband signals. The problem of low speeds is solved by the Spread Spectrum WLAN's which use wideband signals. The drawback of this technology is that the number of users accessing an access point is lesser and the security is also weaker than Narrow band WLAN's. However, in spite of these drawbacks it is the most widely used technology. The infrared WLAN's don't find many uses as the speeds as well as the range in this case is very low. Infrared WLAN's are used only when the devices and access points are placed close to each other and when they are in the line of sight. The requirement of devices to be in the line of sight is because RF signals cannot pass through opaque objects. Development and Implementation of a WLAN Standards The leading authority involved in the specification and ratification of technology related standards is the 'Institute of Electrical and Electronics Engineers' (IEEE) (BECTA, 2005). Presently there are three wireless standards originated from IEEE. They are IEEE 802.11a, 802.11b and 802.11g. IEEE 802.11b It is the most widely used wireless network standard. It is used by most public wireless 'hotspots' (Khayat, 2002) . 802.11b standard was ratified by IEEE in 1999. The main features of this standard are as given below. It operates in 2.4 GHz spectrum. It has nominal data transfer rate of 11 Mbps and a practical rate of about 4-7 Mbps. It offers three non-overlapping channels. These features are adequate for most data transfer applications and for accessing internet but might be inadequate for multimedia access. It might also face problems when users in large number access the network from a single access point. The frequency of operation, i.e., 2.4 GHz, coincides with the spectrum used by cordless phones, microwave ovens, etc. Therefore the interference problems are more likely to occur. IEEE 802.11a It was rated by IEEE in 1999. The main features of this standard are as given below. It uses 5 GHz frequency spectrum. It has a nominal data transfer rate of 54 Mbps with a practical rate of 17-28 Mbps. It offers 8 non-overlapping channels. It has a signal range of about 50 metres with data rates tending to drop at 10-15 meter range. It uses 'Orthogonal Frequency Division Multiplexing' (OFDM) which is a technology which when used prevents multi path distortion and has resilience to RF interference. 802.11a suits to the conditions of multiple users accessing the network with high data rates. It is best suited for classrooms where students can access multimedia, digital video or database packages (BECTA, 2005). IEEE 802.11g It was rated in June 2003. It combines the features of both 802.11b and 802.11a and operates in 2.4 GHz spectrum with a speed of 54 Mbps. Its main features are as given below. It operates in 2.4 GHz spectrum. It has a nominal speed of 54Mbps with practical speed of 19-30 Mbps. However in presence of 802.11b equipments the speeds drop to around 60%. It offers three non-overlapping channels. It is less power efficient than 802.11b. Interference with 2.4GHz frequency device is possible. It uses OFDM. Channels 802.11b and 802.11g standards both operating in 2.4 GHz frequency have 13 available channels. However, in order to avoid interference there are only 3 non-overlapping channels available for these standards (usually set to 1, 6 and 11) (BECTA, 2005). All the AP's are set to different channels. Therefore in order to avoid overcrowding only three AP's can be used in parallels. However in case of 802.11a we have 8 non-overlapping channels available enabling more AP's to be used in parallels. Source BECTA, 2005 Design Considerations Planning In order to implement a wireless LAN there are certain factors that need to be considered and planned accordingly. These factors include the use of WLAN, the applications to be run on the network, the number of users, the range to be covered and the location of the area. Also the knowledge of the latest standards is necessary. Sometimes mobile AP's are used instead of fixed AP's. They can be wheeled to the site of operation on a trolley and then connected to AP terminals provided at the site. In this way we can use a lesser number of AP's and reuse them at different places. However it necessitates the installation of fixed network ports at all these places. Site Survey First of all a floor plan is to be designed indicating the areas of network coverage and data transfer rate. According to this, one can design the location and the number of AP's to be used. It is necessary to see whether considerable data transfer rate is achieved even at the edge of the coverage area. The channel designation, signal strength and the population of the area is also to be considered. Depending on the number of users we may need to place more AP's at certain locations. The AP's should be positioned such that it covers the maximum area without many obstacles in between the AP's and the users. Position of AP's The access points should be placed at a higher level for better quality. A better antenna elevation means better connectivity range, with all other things being equal (Khayat, 2002). When AP's are placed at lower levels there are many obstacles that come in the way. Access points use power supply to run. Therefore AP's which are located in some uncomfortable positions should be having remote control facility. Power over Ethernet Many access points now support power over Ethernet (PoE). PoE is a network standard (IEEE 802.3af) for sending DC power over data cabling to provide power for networked devices (BECTA, 2005). PoE makes it possible for WLAN's to be implemented at places very far off from the power supply ports. PoE therefore also reduces cost of installation. Develop and Implement a Wireless Network for an IT Training Centre: Case Study The general procedure to implement a wireless LAN has already been discussed in 'Design Considerations' section. Now let us apply the procedure to the present case, i.e., 'implementing WLAN in an IT Training Centre'. The centre is having a total number of 22 PC's with 2 PC's for staff and managers, and 20 for clients. The centre also has a branch within a few miles. Procedure First of all one of the computers has to act as a server. This is the main computer to which all others are linked in the network. Then a network interface card (NIC) has to be integrated with each computer. Computers, these days are available with inbuilt NIC's. These NIC's are of various forms. NIC's help in recognising different computers and connect them to the wireless network. Then, access points have to be placed at different places depending upon the distribution of users. Also, the capacity of AP's, i.e., the number of users that can access an AP simultaneously has to be taken into consideration. Places like library, classrooms and staffrooms are more likely to get overcrowded and therefore these places must have adequate AP's installed. The setting up of WLAN is described in the step by step method as given below:- 1. Draw the block diagram of the network indicating the positions of AP's and the server in the building of the IT centre. 2. Make 'power' sockets and 'network' ports available at the site of AP's and the server. This will require the pulling of network and power cables through walls or externally fix them to the walls. 3. Connect the AP's with the server through these data (Ethernet) cables by plugging in both AP's and the server in the network ports. 4. Also give power supply to all these components as they require it for their working. 5. Fix the 'network interface cards' (NIC's) into the PC's. Necessary softwares associated with them also have to be installed. 6. Start the systems and enjoy the advantages of Wireless Networking. Source pdamd.com, n.d. Observing the advantages and disadvantages of various available standards of wireless networks, the use of IEEE 802.11a is advised. It has a disadvantage of having lesser coverage area but other features such as frequency of operation (5GHz) and speed make it a better choice. The other two standards operate in 2.4 GHz band and can therefore interfere with cordless phones and other devices operating in the same spectrum. The speed of 802.11a is greater than 802.11b and equal to 802.11g. Further it offers 8 non-overlapping channels which is greater than that of the other two. Most importantly, all the devices should be Wi-Fi approved. The devices with Wi-Fi certification mark are tested for compliance with IEEE standards and are interoperable with other Wi-Fi devices (BECTA, 2005). A NIC, used on a desktop PC (Left), used on a laptop PC (Right), ( source dlink.com,2005). Roaming is the facility for the user to move flawlessly from one access point to the other. To do this, all the AP's should be on the same subnet (To avoid needing to acquire a new IP address) and have same 'Service Set Identifier' (SSID) and encryption keys (BECTA, 2005). In order to provide wireless networking to a far off place which is at a large distance from the main network, as is the case here, a different technology known as 'Wireless Wide Area Network' (WWAN) is used. WWAN's communicate predominantly through the use of radio signals over analog, digital cellular or PCS networks, although the signal transmission through microwaves is also possible (Josh, Rosemary, n.d.). A wireless modem and a wireless network infrastructure is required for WWAN connectivity. The wireless devices send radio signal to a 'Switching Centre' which uses an appropriate network link (Public/private network or other high speed line) to pass the signal to the organisation's existing WLAN infrastructure. This is shown in the given fig. However, there are some interference problems faced by WWAN's. The bad weather conditions and natural hindrances like trees, mountain peaks etc. can cause disturbance, but it is still a safe and reliable means of communication. Diagram showing WWAN (Source pdamd.com, n.d.) Testing the network When you implement the network, it needs to be tested whether it is working or not. First of all the power supply connections are checked so that all the wireless devices are working. After they are turned ON, it needs to be seen whether the AP's are emitting the signal or not. To do this one moves around with a computer notebook in his hand and checks whether it is receiving the signal and whether the data transfer is taking place or not. If there is any problem with the signal, then the network connections in the ports should be checked. If there is any variance in the speed then check if there is any unwanted obstacle in the path. One must move to the edge of the range of an AP to check whether the data speed is alright. Similarly, roaming should be checked by moving around to all the AP's. If one can move to adjacent AP smoothly without being disconnected with the network, then it is working well. Problems faced The various problems faced in implementing a secure wireless network and their solutions are stated below. Security:- Security is one of the issues regarding wireless LAN's which has been discussed for years. The main problem here is the attack threats and vulnerability of the network. The threats to data security have increased throughout the world in many forms. The need is to update the systems with new threats and continuously find solutions to emerging security problems. The presence of a wireless LAN can be detected by a compatible wireless device. Appropriate security measures should be taken in order that no one from outside has access to the network. Complex encryption techniques are used which make it almost impossible for unauthorised persons to get access to the network traffic. Wireless LAN's have a security mechanism called as Wireless Equivalent Privacy (WEP). However a new upgraded standard called Wi-Fi Protected access (WPA) is available these days. It is better to have WPA security certification for the wireless devices before using them. However WEP, which provides relatively weaker security, can also be upgraded to WPA by upgrading the software. The problem of security can be rectified by taking the following steps during installation and afterwards by the network manager:- The security of devices being used should be checked before installation. Wi-Fi certification is must. Educate the users about security and networking. Change the username and password of administrator regularly. Turn OFF the access points when not in use. Use 'Directional Antennas' to restrict the wireless signal only to the area where it is needed. Use a firewall to allow only authorised persons accessing the network. Update the virus detection softwares in order to save the network from internet hackers. Use of virtual private network (VPN) allows users to enter the network only after entering a specified username and password allotted by the administrator. Thus it prevents unauthorised access to the network. This is the job of the network managers to look after the network and make sure that it remains problem free, thus allowing users to take full advantages of this technology. Risks: Health and safety:- Since the wireless networks use Radio Frequency, therefore they may cause health problems for the users. The devices like mobile phones, cordless phones, etc., also emit radiations but the emissions from a WLAN have been found to be very less as compared to the other devices (about 1/10th). This is the reason that WLAN's are used widely in places like hospitals. Applying some of the safety measures however is necessary:- At least 30cm distance is to be kept between the WLAN equipment and the users. The antenna of the AP's should not be touched while operating. Users should be advised not to use laptops in their laps so that the necessary distance remains between the user and the wireless device. Channel overlapping:- As the number of students and faculty gaining access to the network increases the performance starts to degrade. There is a limit to users accessing an access point. Due to this the densely populated areas such as libraries face a problem of connectivity. This requires placing of access points closer to each other which can cause channel overlapping. But this problem is overcome by the use 802.11a which provides 8 non-overlapping channels. These channels are used at places where there is supposed to be overcrowding, by configuration in the software of the devices. Wireless LAN's: Helping academia and business There are a wide range of benefits of wireless LAN's as far as facilitation of education is concerned. WLAN's are equally beneficial to both students as well as faculty. WLAN's offer mobility and convenience to its users. Inside the campus or in classroom users can access any information required at that time particularly related to the subject. Using search engines on the internet users can find on the spot solutions to their problems in academics. Today's world is competitive and by introducing such facilities in universities and colleges, the institutions compete for better students and faculty. Moreover introducing these technologies makes the job of students and faculty full of fun. WLAN's help the business of training centres in a number of ways. First of all the installation cost is nearly the same as for the wired network, but the maintenance cost is very less. So it reduces the overall cost as compared to wired LAN. As mentioned earlier WLAN is easy to handle and use. Moreover today's students are tech-savvy. They like to use new and technologically advanced devices. In case of an IT training centre the students will feel better as it is related to their field of study. Therefore it will help to attract more and more students for admission. The use of latest technology also helps appointment of better teachers, which in turn will again attract the students. Advantages and disadvantages Wireless LAN's have many advantages over wired LAN's as stated below. One can access the network from anywhere within the range of access point allowing the users to remain connected even when they are moving inside the range. It is relatively easy to install a WLAN as compared to wired LAN as minimum cabling is required. A wireless LAN can be installed at places where it is impossible to do wiring. Initially the investment required for WLAN can be higher than LAN but the overall installation and maintenance cost is lesser. A WLAN is advantageous in some cases where the installation is temporary. WLAN does also have some disadvantages. The data transfer rate to each device decreases considerably as the no. of devices attached to the network increases. The security is weaker than wired LAN's. The network can be accessed at a limited distance from the access point. Moreover the solid obstacles between user and access points result in weakening of the signal. So in order to increase the signal strength more access points are needed which in turn increase the installation cost. The data speed depends upon the distance of the user from the access point. The larger the distance, the lesser is the speed. Certain radio frequencies used for WLAN's may interfere with each other as the no. of users increases. With the advancement of technology it becomes necessary to upgrade the devices to higher specifications requiring to change them sometimes. Conclusion Flexibility and mobility of wireless LAN's are the factors making them a favourite choice of users around the world. They are hassle free and have almost all the functionality of wired LAN's. Here we find the simplicity of installation and maintenance. Users find it extremely simple to operate their systems within a wireless network. The fact that users can access the network even when they are having a walk makes it extremely useful. The low cost of ownership and wider range are the added bonus for acquiring a wireless LAN. For all these reasons wireless LAN's are finding extensive use in universities and colleges. They are even used in schools now. Students find learning interesting and innovative, thereby making the job easier. On the other hand teachers access any information regarding their academics easily and within the campus. Therefore it makes both teaching and learning very easy. The students have a role to play in setting up and functioning of this technology. They must learn about the security and use of WLAN's. It is their duty to put WLAN's to a constructive use. Students must use it for their academic benefits and not try to create nuisance by introducing viruses, etc. into the network. How the students handle the network will decide its functioning. The proper or improper functioning of the network will undoubtedly affect the students. To sum up the wireless LAN technology can benefit the users in numerous ways and it finds many uses. However there are some issues like high costs and low speeds which have to be worked upon. With the present rate of advancement in technology these disadvantages will be overcome in the near future. References British Educational Communications And Technology Agency, BECTA. (January 2005). Wireless Local Area Networks (WLAN). Retrieved February, 24, 2006, from http://www.becta.org.uk/leaders/leaders.cfmsection=3_2&id=396 Fischer, Josh & Wang, Rosemary. (n.d.). Wireless Local Area Networks (WLAN). Retrieved March 4, 2006, from http://www.pdamd.com/vertical/features/wireless_3.xml Fischer, Josh & Wang, Rosemary. (n.d.). Wireless Wide Area Networks (WWAN). Retrieved March 4, 2006, from http://www.pdamd.com/vertical/features/wireless_4.xml Khayat, Mike M. (March 12, 2002). Wireless Local Area Network (WLAN). Retrieved February 24, 2006, from Dlink.com (n.d.). Wireless. Retrieved February 24, 2006, from http://www.dlink.com/products/digitalhome/wireless/11b+/ Read More