Hard-Wired Systems and Their Effects - Case Study Example

Methods of Network Delivery Faculty I. Hard-wired Systems a) Twisted-pair Wire b) Co-axial Cable c) Fiber Optics II. Wireless Technology a) Microwave b) Satellite c) Cellular/PCS d) Wireless LAN e) Bluetooth III. Business Uses of Wireless Technology a) Shipment Tracking b) Theft Prevention c) Airline and Maritime Navigation d) Law Enforcement I. Hard-wired Systems Twisted-pair Wire: Twisted pair cable is used for telephone communication and most modern Ethernet networks. In twisted-pair wire, a pair of wires forms a circuit for transmitting data. The pairs (wires) are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. Electrical current flowing through a wire creates a small, circular magnetic field around the wire. Two wires magnetic fields are exact opposite of each other, when they are placed close together in an electrical circuit and hence the two magnetic fields cancel each other out and also cancel out any outside magnetic fields. Twisting the wire enhances this cancellation effect and can effectively provide self-shielding for wire pairs within the network media [CCNA, 2003]. Two types of twisted-pair cable exist and they are unshielded twisted pair (UTP) and shielded twisted pair (STP). Figure 1: Layout of UTP and STP Cables Source: http://en.wikipedia.org/wiki/Twisted_pair In UTP cable, each of the eight individual copper wires in UTP cable is covered by an insulating material and each pair are twisted around each other. It is least expensive than any other type of LAN cable. It provides speed and throughput from 10 to 1000 Mbps up to the maximum cable length of 100 meters. The main advantage of it is that it does not quickly fill up wiring ducts as it is thin and flexible cable. The most commonly used cable is CAT 5 UTP cable. STP cable combines the techniques of shielding, cancellation and wire twisting. In STP, each pair of wires is wrapped in a metallic foil and than the four pairs is wrapped in an overall metallic braid or foil (usually 150-ohm cable). STP reduces electrical noise both within the cable (crosstalk) and from outside the cable (EMI and RFI). It provides speed and throughput from 10 to 100 Mbps up to the maximum cable length of 100 meters. It moderately expensive compared to UTP cables. Figure 2: Layout of Co-axial Cable Co-axial Cable: The layout of co-axial cable is shown in figure 2. It consists of a hollow outer cylindrical conductor that surrounds a single inner wire made of two conducting elements. At the centre of the cable is a copper conductor that surrounded by a layer of flexible insulation. Over insulating material is a woven copper braid or metallic foil that acts both as the second wire in the circuit and as a shield for the inner conductor. This second layer (shield) helps reducing the amount of outside interference from fluorescent lights, motors, and other computers. The metallic shield is covered by the cable jacket [CCNA, 2003]. Co-axial cable is used as a high-frequency transmission line to carry a high-frequency or broadband signal. It provides speed and throughput from 10 to 100 Mbps. It can be run with fewer boosts from repeaters for long distances (up to 500 meter) between network nodes. It is less expensive compared to fiber-optic cable. Fiber-Optics: Fiber-optic system is similar to the copper wire system replaced by fiber-optics. It uses light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting data modulated onto light waves. Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials as shown in figure 3. Figure 3: Fiber-optic Cable Fiber-optic cable can carry more data as compared to metal cables because of greater bandwidth. Fiber optic cable has the ability to transmit signals over much longer distances with greater speeds than coaxial and twisted pair. Thus it can be used for video conferencing and interactive services. It is much thinner and lighter and less susceptible to interference. The data is transmitted digitally rather than analogically by the use of fiber-optic cables. But these cables are expensive to install and are more fragile than wire and are difficult to splice. This is used mainly for LAN but nowadays it is used for all communications purpose. Tables 1 show the comparisons of different media types discussed . Table 1: Comparison of Different Media Types Media Type Maximum Segment Length Speed Cost Advantages Disadvantages UTP 100 m 10 Mbps to 1000 Mbps Least expensive Easy to install; widely available and widely used Susceptible to interference; can cover only a limited distance STP 100 m 10 Mbps to 100 Mbps More expensive than UTP Reduced crosstalk; more resistant to EMI than Thinnet or UTP Difficult to work with; can cover only a limited distance Coaxial 500 m (Thicknet) 185 m (Thinnet) 10 Mbps to 100 Mbps Relatively inexpensive, but more costly than UTP Less susceptible to EMI interference than other types of copper media Difficult to work with (Thicknet); limited bandwidth; limited application (Thinnet); damage to cable can bring down entire network Fiber-Optic 10 km and farther (single-mode) 2 km and farther (multimode) 100 Mbps to 100 Gbps (single mode) 100 Mbps to 9.92 Gbps (multimode) Expensive Cannot be tapped, so security is better; can be used over great distances; is not susceptible to EMI; has a higher data rate than coaxial and twisted-pair cable Difficult to terminate Source: CCNA: Network Media Types, Cisco Systems, Inc II. Wireless Technology Microwave: The term narrowband microwave refers to the use of a microwave radio frequency band for signal transmission, with relatively narrow bandwidth: just wide enough to accommodate the signal, typically 12.5 kHz or25 kHz. Narrow bandwidth combined with high power results in larger transmission distances that are available from 900 MHz or 2.4 GHz spread spectrum systems, which have lower power levels and wider bandwidths. UHF wireless data communication systems normally transmit in the 430 to 470 MHz frequency range, with rare systems using segments of the 800 MHz range. The lower portion of this band 430-450 MHz is often referenced as unprotected (unlicensed) and 450-470 MHz is referred to as the protected (licensed) band. It has a range of approximately 100 meter for indoor and 1 to 2 miles for outdoor. [Guide to Wireless…]. Microwave radio frequency usable for voice, data and video transmission are licensed and coordinated within specific geographic areas to avoid potential interference between systems. The licensed narrowband LAN gives guarantees for interference free communication. The main advantage of UHF is its range. It can provide optimum Low cost solution for large sites with low to medium data throughput requirements. The disadvantage of these technologies (UHF) is its low throughput. These systems are proprietary, and communicate only with devices manufactured by the system vendor. Any interference from outside sources within customer’s bandwidth will disrupt wireless data communications. RF license are required for protected bands which are provided by radio authorities in each country who regulate and license specific frequencies to users. In addition, large radio’s and antenna’s increase wireless client size. Satellite: Satellite communication is comparable in importance to optical fiber in the evolution of telecommunications and data communications. The main part of a satellite communication system is a satellite-based antenna in a stable orbit above the earth. In a satellite communication system, two or more stations on or near the earth communicate via one or more satellite that serve as relay stations in space. The antenna system near or on the earth is referred to as stations. A transmission from an earth station to the satellite is referred to as uplink, whereas transmissions from the satellite to the earth station are downlink. The electronics in the satellite that takes an uplink signal and converts it to a downlink signal is called as transponder. Different ways of categorizing communication satellites are: Coverage Area-Global, regional or national. The larger the area of coverage, the more satellites must be involved in a single networked system. Service Type-fixed service satellite (FS), broadcast service satellite (BSS), and mobile service satellite (MSS). General Usage-commercial, military, amateur and experimental.(Stallings 2002) Cellular: Cellular technology is the foundation of mobile wireless communications and supports users in locations that are not easily served by wired networks. Cellular technology is the underlying technology for mobile telephones, personal communications systems, wireless Internet and wireless Web applications and much more. Cellular radio is a technique that was developed to increase the capacity available for mobile radiotelephone service. A typical system would support about 25 channels with an effective radius of about 80 km. the way to increase the capacity of the system is to use lower-power systems with shorter radius and to use numerous transmitter/receivers. The essence of a cellular network is the use of multiple low-power transmitters, on the order of 100 W or less. Because the range of such a transmitter is small, therefore an area can be divided into cells and served by is own antenna. Each cell is allocated a band of frequencies and is served by a base station, consisting of transmitters, receivers and control unit. Adjacent cells are assigned different frequencies to avoid interference or crosstalk. However, cells sufficiently distant from each other can use the same frequency band. Two types of patterns can be used for cells, square patterns and hexagonal patterns. [Stallings 2002] Wireless LAN: Wireless LANs provide high-speed, reliable data communications in a building or campus environment or in remote areas. Wireless LAN can be installed easily and not incur monthly user fees or data transmission charges. A wireless LAN saves the cost of the installation of LAN cabling and eases the task of relocation and other modifications to network structure. Wireless LANs can be used in buildings with large open areas such as manufacturing plants, stock exchange trading floors, and warehouses, outdoor events, on-site training, historical buildings with insufficient twisted pair and where drilling holes for new wiring is prohibited and small offices where installation and maintenance of wired LANs is not economical. [Stallings 2002] In a peer-to-peer topology (Ad-hoc networking), wireless devices create a LAN by communicating directly with each other. This type of network is setup temporarily to meet some immediate need (figure 4). For example, a group of employees with laptop or mobile devices (Bluetooth) may convene in a conference room for a business or classroom meetings. Access point based topology (figure 5) is also common in which, Wireless LANs do not replace wired LANs, but they extend connectivity to mobile devices. In this type of configuration, wireless devices can connect to the wired LAN backbone for communication with both wired and wireless nodes. Figure 4: Ad-hoc LAN or Peer-to-peer configuration Figure 5: Access Point Configuration Figure 6: Point-to-Point Wireless Bridging and Point-to-Multipoint Wireless Bridge Another commonly used wireless network topology is the point-to-point and point-to-multipoint bridge1 (figure 6). Wireless bridges connect a LAN in one building to a LAN in another, even if the buildings are many miles apart. These connections require a clear line-of-sight2 between the buildings. The line-of-sight range varies based on the type of wireless bridge and antenna used as well as environmental conditions. A point-to-multipoint bridge topology is useful for a campus or nearby buildings. A wireless bridge connects the LAN backbones in separate buildings or locations. Bluetooth: Bluetooth technology is how mobile phones, computers, and personal digital assistants (PDAs), not to mention a broad selection of other devices, can be easily interconnected using a short-range wireless connection. Using this technology, users can have all mobile and fixed computer devices be totally coordinated. [http://www.bluetooth.com/bluetooth/] Bluetooth is an industrial specification for wireless personal area networks (PANs). It provides a way to connect and exchange information between devices such as mobile phones, laptops, printers, computers and digital cameras, over a secure, globally unlicensed short-range (Infrared) radio frequency. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group. Bluetooth is primarily designed for low power consumption, with a short range (100 meters: 100mW, 10 meters : 2.5mW, 1 meters: 1mW) based on low-cost transceiver microchips in each device. Bluetooth devices communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, as long as the received transmission is powerful enough. [Wikipedia: Bluetooth]. Figure 7 shows the Personal Area Network (PAN) using Bluetooth. Figure 7: Personal Area Network (PAN) Using Bluetooth Source: www.cnp-wireless.com/.../2000Q2%20Bluetooth.html The main advantage is that Bluetooth can be implemented in a variety of new products such as phones, laptops, cameras, modems, headsets, etc. It is acceptable for situations when two or more devices are in proximity to each other and do not require high bandwidth. It simplifies the discovery and setup of services. Bluetooth security may lead to disclosure of personal data. There is also possibility of conversation crack on Bluetooth based wireless headsets. Bluetooth devices can be infected with virus and worms. III. Business Uses of Wireless Technology Shipment Tracking: The shipment process is often characterized by a certain amount of mystery. According to Logistics Management & Distribution Report explained: "Within memory of many logistics managers, transportation was often described as a black hole. Freight went into the system, and managers hoped it would emerge at the other end intact and something close to on time." (Shipping and Shipment……) For keeping track of millions of individual packages in shipment different technologies are used. Wireless technology is considered very important for the shipment tracking. Wearable computers and handheld scanners connected by the centralized wireless computer system (Server) can be used by package handlers at distribution hubs and drivers in shipment business. These wireless devices can performs various functions such as the ability to record digital signatures from customers who accepted shipments, notifying workers if they attempted to place packages onto the wrong vehicle, track shipments as they moved from point to point , and updating database regarding the whereabouts of individuals packages. When wireless sensors are placed on trucks could reveal when doors are opened; when trailers are empty, full, or hooked to different cabs; the temperature of perishable shipments like fruits or vegetables; and more. (Shipping and Shipment……) Theft Prevention: Wireless technology can be very useful in case of theft prevention. Different types of cameras, microphones, alarms and sensors and other security related devices when connected with wireless systems can be useful for theft prevention. It can be placed or installed at the location for prevention of theft and can be monitored easily with the wireless devices. For example it can be used for security systems for systems for homes or office buildings. Wireless transmitter can be used to transmit the information concerning the current state of the door or window. Airline and Maritime Navigation: For Airline and Maritime navigation Global Positioning System (GPS) are used these days, which is an application of wireless technology. GPS assists the maritime and airline industry with navigation. It can be used for drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth and safety purposes. GPS displays the map of the surrounding area and sends signal from the GPS satellites to an onboard computer, which contains an application with software that contains a topographical map. The receiver can see the present location in the form of dots in coordinates of map that is updated live as the receiver moves. GPS can be also used for providing communications to the ships with information in harsh weather or provide them a mechanism to call for help. In addition, hhandheld wireless radios such as Maritime VHF radio transceiver can be used for Maritime navigation. Law Enforcement: Wireless technology is very useful for the purpose of law enforcement. Various types of CCTV cameras when connected with wireless systems can be very useful for traffic controls. It can record any traffic violations and accidents on the roads, highways and send it to centralized computer system that is connected wirelessly with these devices. Also the wireless transmitter and sensors can be installed at important places for monitoring the activities remotely. Reference Stallings, W (2002). Wireless Communications and Networks, Pearson Education P. Ltd. Guide to Wireless LAN Technologies, Intermec Technologies Corporation. Retrieved on 8 June 2007 from http://www.utdallas.edu/ir/wlans/whitepapers/wlan_wp.pdf. CCNA: Network Media Types, Cisco Systems, Inc, Mar 14, 2003. Retrieved on 9 June 2007 from http://www.ciscopress.com/articles/article.asp?p=31276&rl=1 The Media: Conducted and Wireless, Chapter 3, Data Communications and Computer Networks: A Business User’s Approach. Retrieved on 9 June 2007 from http://www.ist.psu.edu/faculty_pages/giles/IST220/vghs/Ch3.ppt#291,59,Slide 59 Conducted and Wireless, Chapter 3, Data Communications and Computer Networks: A Business User’s Approach, Third Edition. Retrieved on 8 June 2007 from http://kahuna.clayton.edu/~enda/Slides/book/chapter03.ppt#305,62,Slide 62 http://en.wikipedia.org/wiki/Twisted_pair accessed on 8 June 2007 http://fcit.usf.edu/network/chap4/chap4.htm accessed on 8 June 2007 http://www.webopedia.com/TERM/F/fiber_optics.html accessed on 8 June 2007 http://www.arcelect.com/fibercable.htm accessed on 9 June 2007 http://www.bluetooth.com/bluetooth/ accessed on 9 June 2007 Bluetooth. Retrieved on 8 June 2007 from http://en.wikipedia.org/wiki/Bluetooth Shipping and Shipment Tracking - TRACKING & TRACING. Retrieved on 9 June 2007 from http://ecommerce.hostip.info/pages/937/Shipping-Shipment-Tracking.html Introduction to Wireless: From Past to Present. Retrieved on 8 June 2007 from http://www.syngress.com/book_catalog/152_wan_luc/chapter_01.htm Read More