The enterprise networking

Introduction

I am a student from the International Advanced Diploma In Computer Studies in MCC Computer Training Center. It is offered by NCC Education Center. There are seven subjects in my course. Among them Enterprise Networking is one of my main subject. This assignment is for my Exam Cycle March 2010.

Acknowledgement

We are grateful to have such as great opportunity to participate in practical Enterprise Networking.

Firstly, give much thanks to Lecturers U Aung Thu Thu who teach the Enterprise Networking subject with great care also guide patiently and correct our mistakes during the period of doing our assignment and lecture time.

Secondly, our course manager, Daw Aung Thandar Lynn Myint for supporting carefully from every side such as class timetables, assignment due dates, and exam dates and so on.

Thirdly, thank to all of my classmates who encourages and helps to accomplish this assignment.

Bus network topology

In local area networks where bus topology is used, each machine is connected to a single cable. Each computer or server is connected to the single bus cable through some kind of connector. A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the MAC address or IP address on the network that is the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data does match the machine address, the data is accepted. Since the bus topology consists of only one wire, it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure. If the network cable breaks, the entire network will be down.

Linear bus

The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has exactly two endpoints (this is the 'bus', which is also commonly referred to as the backbone, or trunk) – all data that is transmitted between nodes in the network is transmitted over this common transmission medium and is able to be received by all nodes in the network virtually simultaneously (disregarding propagation delays.

Note: The two endpoints of the common transmission medium are normally terminated with a device called a terminator that exhibits the characteristic impedance of the transmission medium and which dissipates or absorbs the energy that remains in the signal to prevent the signal from being reflected or propagated back onto the transmission medium in the opposite direction, which would cause interference with and degradation of the signals on the transmission medium (See Electrical termination).

Distributed bus

The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission medium – the physical distributed bus topology functions in exactly the same fashion as the physical linear bus topology (i.e., all nodes share a common transmission medium).

Notes:

1. All of the endpoints of the common transmission medium are normally terminated with a device called a 'terminator' (see the note under linear bus).
2. The physical linear bus topology is sometimes considered to be a special case of the physical distributed bus topology – i.e., a distributed bus with no branching segments.
3. The physical distributed bus topology is sometimes incorrectly referred to as a physical tree topology – however, although the physical distributed bus topology resembles the physical tree topology, it differs from the physical tree topology in that there is no central node to which any other nodes are connected, since this hierarchical functionality is replaced by the common bus.

Star network topology

In local area networks where the star topology is used, each machine is connected to a central hub. In contrast to the bus topology, the star topology allows each machine on the network to have a point to point connection to the central hub. All of the traffic which transverses the network passes through the central hub. The hub acts as a signal booster or repeater which in turn allows the signal to travel greater distances. As a result of each machine connecting directly to the hub, the star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding other machines. The primary disadvantage of the star topology is the hub is a single point of failure. If the hub were to fail the entire network would fail as a result of the hub being connected to every machine on the network.

Notes:

1. A point-to-point link (described above) is sometimes categorized as a special instance of the physical star topology – therefore, the simplest type of network that is based upon the physical star topology would consist of one node with a single point-to-point link to a second node, the choice of which node is the 'hub' and which node is the 'spoke' being arbitrary[1].
2. After the special case of the point-to-point link, as in note 1.) above, the next simplest type of network that is based upon the physical star topology would consist of one central node – the 'hub' – with two separate point-to-point links to two peripheral nodes – the 'spokes'.
3. Although most networks that are based upon the physical star topology are commonly implemented using a special device such as a hub or switch as the central node (i.e., the 'hub' of the star), it is also possible to implement a network that is based upon the physical star topology using a computer or even a simple common connection point as the 'hub' or central node – however, since many illustrations of the physical star network topology depict the central node as one of these special devices, some confusion is possible, since this practice may lead to the misconception that a physical star network requires the central node to be one of these special devices, which is not true because a simple network consisting of three computers connected as in note 2.) above also has the topology of the physical star.
4. Star networks may also be described as either broadcast multi-access or nonbroadcast multi-access (NBMA), depending on whether the technology of the network either automatically propagates a signal at the hub to all spokes, or only addresses individual spokes with each communication.

Extended star

A type of network topology in which a network that is based upon the physical star topology has one or more repeaters between the central node (the 'hub' of the star) and the peripheral or 'spoke' nodes, the repeaters being used to extend the maximum transmission distance of the point-to-point links between the central node and the peripheral nodes beyond that which is supported by the transmitter power of the central node or beyond that which is supported by the standard upon which the physical layer of the physical star network is based.

Note: If the repeaters in a network that is based upon the physical extended star topology are replaced with hubs or switches, then a hybrid network topology is created that is referred to as a physical hierarchical star topology, although some texts make no distinction between the two topologies.

Distributed Star

A type of network topology that is composed of individual networks that are based upon the physical star topology connected together in a linear fashion – i.e., 'daisy-chained' – with no central or top level connection point (e.g., two or more 'stacked' hubs, along with their associated star connected nodes or 'spokes').

Ring network topology

In local area networks where the ring topology is used, each computer is connected to the network in a closed loop or ring. Each machine or computer has a unique address that is used for identification purposes. The signal passes through each machine or computer connected to the ring in one direction. Ring topologies typically utilize a token passing scheme, used to control access to the network. By utilizing this scheme, only one machine can transmit on the network at a time. The machines or computers connected to the ring act as signal boosters or repeaters which strengthen the signals that transverse the network. The primary disadvantage of ring topology is the failure of one machine will cause the entire network to fail.

Mesh

The value of fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed's Law.

Fully connected

Note: The physical fully connected mesh topology is generally too costly and complex for practical networks, although the topology is used when there are only a small number of nodes to be interconnected.

Partially connected

The type of network topology in which some of the nodes of the network are connected to more than one other node in the network with a point-to-point link – this makes it possible to take advantage of some of the redundancy that is provided by a physical fully connected mesh topology without the expense and complexity required for a connection between every node in the network.

Note: In most practical networks that are based upon the physical partially connected mesh topology, all of the data that is transmitted between nodes in the network takes the shortest path (or an approximation of the shortest path) between nodes, except in the case of a failure or break in one of the links, in which case the data takes an alternative path to the destination. This requires that the nodes of the network possess some type of logical 'routing' algorithm to determine the correct path to use at any particular time.

Also known as a hierarchical network.

The type of network topology in which a central 'root' node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second level) with a point-to-point link between each of the second level nodes and the top level central 'root' node, while each of the second level nodes that are connected to the top level central 'root' node will also have one or more other nodes that are one level lower in the hierarchy (i.e., the third level) connected to it, also with a point-to-point link, the top level central 'root' node being the only node that has no other node above it in the hierarchy (The hierarchy of the tree is symmetrical.) Each node in the network having a specific fixed number, of nodes connected to it at the next lower level in the hierarchy, the number, being referred to as the 'branching factor' of the hierarchical tree.

1. A network that is based upon the physical hierarchical topology must have at least three levels in the hierarchy of the tree, since a network with a central 'root' node and only one hierarchical level below it would exhibit the physical topology of a star.
2. A network that is based upon the physical hierarchical topology and with a branching factor of 1 would be classified as a physical linear topology.
3. The branching factor, f, is independent of the total number of nodes in the network and, therefore, if the nodes in the network require ports for connection to other nodes the total number of ports per node may be kept low even though the total number of nodes is large – this makes the effect of the cost of adding ports to each node totally dependent upon the branching factor and may therefore be kept as low as required without any effect upon the total number of nodes that are possible.
4. The total number of point-to-point links in a network that is based upon the physical hierarchical topology will be one less than the total number of nodes in the network.
5. If the nodes in a network that is based upon the physical hierarchical topology are required to perform any processing upon the data that is transmitted between nodes in the network, the nodes that are at higher levels in the hierarchy will be required to perform more processing operations on behalf of other nodes than the nodes that are lower in the hierarchy. Such a type of network topology is very useful and highly recommended.

Signal topology

The mapping of the actual connections between the nodes of a network, as evidenced by the path that the signals take when propagating between the nodes.

Note: The term 'signal topology' is often used synonymously with the term 'logical topology', however, some confusion may result from this practice in certain situations since, by definition, the term 'logical topology' refers to the apparent path that the data takes between nodes in a network while the term 'signal topology' generally refers to the actual path that the signals (e.g., optical, electrical, electromagnetic, etc.) take when propagating between nodes.

Logical topology

The logical topology, in contrast to the "physical", is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices. A network's logical topology is not necessarily the same as its physical topology. For example, twisted pair Ethernet is a logical bus topology in a physical star topology layout. While IBM's Token Ring is a logical ring topology, it is physically set up in a star topology.

Classification of logical topologies

The logical classification of network topologies generally follows the same classifications as those in the physical classifications of network topologies, the path that the data takes between nodes being used to determine the topology as opposed to the actual physical connections being used to determine the gutty.

Notes:

1. Logical topologies are often closely associated with media access control (MAC) methods and protocols.
2. The logical topologies are generally determined by network protocols as opposed to being determined by the physical layout of cables, wires, and network devices or by the flow of the electrical signals, although in many cases the paths that the electrical signals take between nodes may closely match the logical flow of data, hence the convention of using the terms 'logical topology' and 'signal topology' interchangeably.
3. Logical topologies are able to be dynamically reconfigured by special types of equipment such as routers and switches.

• UTP, unshielded Twisted Pair is pretty good for lots of data applications, but only goes up to 100 Megabits/sec, while fiber goes to many Gigabytes. Fiber carries more IF YOU NEED IT.
• UTP is cheap and very easy to handle, while fiber is expensive, harder to handle, and you need to make very round corners.
• You can cut UTP with a knife and crimp on a connector easily, but with fiber you need special tools and skill to terminate them.
• Finally, you need power and LEDs to put the electrical signals on fiber, and photodiodes with powered amps to get the signals off the other end.
• In general, fiber optical cable is a great performer, wonderful, and the best thing ever IF YOU NEED THAT MUCH BANDWIDTH. But for most applications UTP is plenty good enough.
• If you need fiber, the plastic is easier to use for short runs, while the glass has higher performance and more difficult to work with.

• Twisted pair’s susceptibility to the electromagnetic interference greatly depends on the pair twisting schemes (usually patented by the manufacturers) staying intact during the installation. As a result, twisted pair cables usually have stringent requirements for maximum pulling tension as well as minimum bend radius. This relative fragility of twisted pair cables makes the installation practices an important part of ensuring the cable’s performance.
• In video applications that send information across multiple parallel signal wires, twisted pair cabling can introduce signaling delays known as skew which results in subtle color defects and ghosting due to the image components not aligning correctly when recombined in the display device. The skew occurs because twisted pairs within the same cable often use a different number of twists per meter so as to prevent common-mode crosstalk between pairs with identical numbers of twists. The skew can be compensated by varying the length of pairs in the termination box, so as to introduce delay lines that take up the slack between shorter and longer pairs, though the precise lengths required are difficult to calculate and vary depending on the overall cable length.

ADSL2+ extends the capability of basic ADSL by doubling the number of downstream bits. The data rates can be as high as 24 Mbit/s downstream and up to 3.5 Mbit/s upstream depending on the distance from the DSLAM to the customer's home.

ADSL2+ is capable of doubling the frequency band of typical ADSL connections from 1.1MHz to 2.2MHz. This doubles the downstream data rates of the previous ADSL2 standard (which was up to 12 Mbit/s), but like the previous standards will degrade from its peak bitrate after a certain distance.

Also ADSL2+ allows port bonding. This is where multiple ports are physically provisioned to the end user and the total bandwidth is equal to the sum of all provisioned ports. So if 2 lines capable of 24 Mbit/s were bonded the end result would be a connection capable of 48 Mbit/s download and twice the original upload speed. Not all DSLAM Vendors have implemented this functionality. ADSL2+ port bonding is also known as G.998.x or G.Bond

Wi-Fi

Wi-Fi (pronounced /'wa?fa?/) is a trademark of the Wi-Fi Alliance that may be used with certified products that belong to a class of wireless local area network (WLAN) devices based on the IEEE 802.11 standards. Because of the close relationship with its underlying standard, the term Wi-Fi is often used as a synonym for IEEE 802.11 technology.[1][2]

The Wi-Fi Alliance is a global, non-profit association of companies that promotes WLAN technology and certifies products if they conform to certain standards of interoperability. Not every IEEE 802.11-compliant device is submitted for certification to the Wi-Fi Alliance, sometimes because of costs associated with the certification process and the lack of the Wi-Fi logo does not imply a device is incompatible with Wi-Fi devices.

WiMAX

WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile internet access. The technology provides up to 10 Mbps [1] broadband speed without the need for cables. The technology is based on the IEEE 802.16 standard (also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX[2] as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL".[3]

Comparisons and confusion between WiMAX and Wi-Fi are frequent because both are related to wireless connectivity and Internet access.

• WiMAX is a long range system, covering many kilometers, that uses licensed or unlicensed spectrum to deliver a point-to-point connection to the Internet.
• Different 802.16 standards provide different types of access, from portable (similar to a cordless phone) to fixed (an alternative to wired access, where the end user's wireless termination point is fixed in location.)
• Wi-Fi is more popular in end user devices.
• WiMAX and Wi-Fi have quite different quality of service (QoS) mechanisms:
• WiMAX uses a QoS mechanism based on connections between the base station and the user device. Each connection is based on specific scheduling algorithms.
• Wi-Fi has a QoS mechanism similar to fixed Ethernet, where packets can receive different priorities based on their tags. For example VoIP traffic may be given priority over web browsing.
• Wi-Fi runs on the Media Access Control's CSMA/CA protocol, which is connectionless and contention based, whereas WiMAX runs a connection-oriented MAC.
• Both 802.11 and 802.16 define Peer-to-Peer (P2P) and ad hoc networks, where an end user communicates to users or servers on another Local Area Network (LAN) using its access point or base station.

Recommendation

Our country have two ISP Services these are Myanmar Post and Tele-communication (MPT) and Yadanapone Teleport. These two provider are distribute to the internet service of our country. I want to suggest that WiMAX technology is the best way of solving the police department. Because that data transfer rate is too large and the connection speed is very strong.

Investigate the methods the Police Department could implement for two-way voice communications. As a minimum include the following information:

How each method works(frequencies, full/half duplex, etc)? 6Marks

GSM (Global System for Mobile communications: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. Its promoter, the GSM Association, estimates that 80% of the global mobile market uses the standard. GSM is used by over 3 billion people across more than 212 countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signaling and speech channels are digital, and thus is considered a second generation (2G) mobile phone system. This has also meant that data communication was easy to build into the system. GSM EDGE is a 3G version of the protocol.

The structure of a GSM network

The ubiquity of the GSM standard has been an advantage to both consumers (who benefit from the ability to roam and switch carriers without switching phones) and also to network operators (who can choose equipment from any of the many vendors implementing GSM). GSM also pioneered a low-cost (to the network carrier) alternative to voice calls, the short message service (SMS, also called "text messaging"), which is now supported on other mobile standards as well. Another advantage is that the standard includes one worldwide emergency telephone number, 112.This makes it easier for international travelers to connect to emergency services without knowing the local emergency number.

Newer versions of the standard were backward-compatible with the original GSM phones. For example, Release '97 of the standard added packet data capabilities, by means of General Packet Radio Service (GPRS). Release '99 introduced higher speed data transmission using Enhanced Data Rates for GSM Evolution (EDGE).

walkie-talkie

A walkie-talkie (more formally known as a handheld transceiver) is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald L. Hings, radio engineer Alfred J. Gross, and engineering teams at Motorola. Similar designs were created for other armed forces, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a push-to-talk (P.T.T) switch that starts transmission. Typical walkie-talkies resemble a telephone handset, possibly slightly larger but still a single unit, with an antenna sticking out of the top. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in the user's immediate vicinity. Hand-held transceivers may be used to communicate between each other, or to vehicle-mounted or base stations.

Some cellular telephone networks offer a push-to-talk handset that allows walkie-talkie-like operation over the cellular network, without dialing a call each time.

Walkie-talkies for public safety, commercial and industrial uses may be part of trunked radio systems, which dynamically allocate radio channels for more efficient use of limited radio spectrum. Such systems always work with a base station that acts as a repeater and controller, although individual handsets and mobiles may have a mode that bypasses the base station.

Multi-band and multi-mode phones

Today, most telephones support multiple bands as used in different countries. These are typically referred to as multi-band phones. Dual-band phones can cover GSM networks in pairs such as 900 and 1800MHz frequencies (Europe, Asia, Australia and Brazil) or 850 and 1900 (North America and Brazil). European tri-band phones typically cover the 900, 1800 and 1900 bands giving good coverage in Europe and allowing limited use in North America, while North American tri-band phones utilize 850, 1800 and 1900 for widespread North American service but limited worldwide use. A new addition has been the quad-band phone, supporting all four major GSM bands, allowing for global use.

There are also multi-mode phones which can operate on GSM as well as on other mobile phone systems using other technical standards or proprietary technologies. Often these phones use multiple frequency bands as well. For example, one version of the Nokia 6340i GAIT phone sold in North America can operate on GSM-1900, GSM-850 and legacy TDMA-1900, TDMA-800, and AMPS-800, making it both multi-mode and multi-band.

Walkie-talkie Frequency Band

Provide a recommendation for how voice communications should be set up and run including reasons for this recommendation. 6Marks

Recommendation

In task 3, I have investigated about the two way voice communication method, data transmission methods, accuracy of the voice communication, additional services and limitations. The categories include Global System of Mobile (GSM) and walkie-talkie. The devices and technologies can use communication of police department. The walkie-talkie to use the voice communication with third party or communicate with each other.

Investigate telephone systems available in your country for single-site organizations like the police department. Pay particular attention to :

The main equipment that would be installed.8mark

A private branch exchange (PBX) is a telephone exchange that serves a particular business or office, as opposed to one that a common carrier or telephone company operates for many businesses or for the general public. PBXs are also referred to as:

• PABX - private automatic branch exchange
• EPABX - electronic private automatic branch exchange

PBXs make connections among the internal telephones of a private organization — usually a business — and also connect them to the public switched telephone network (PSTN) via trunk lines. Because they incorporate telephones, fax machines, modems, and more, the general term "extension" is used to refer to any end point on the branch.

PBXs are differentiated from "key systems" in that users of key systems manually select their own outgoing lines, while PBXs select the outgoing line automatically. Hybrid systems combine features of both.

Initially, the primary advantage of PBXs was cost savings on internal phone calls: handling the circuit switching locally reduced charges for local phone service. As PBXs gained popularity, they started offering services that were not available in the operator network, such as hunt groups, call forwarding, and extension dialing. In the 1960s a simulated PBX known as Centrex provided similar features from the central telephone exchange.

Two significant developments during the 1990s led to new types of PBX systems. One was the massive growth of data networks and increased public understanding of packet switching. Companies needed packet switched networks for data, so using them for telephone calls was tempting, and the availability of the Internet as a global delivery system made packet switched communications even more attractive. These factors led to the development of the VoIP PBX. (Technically, nothing was being "exchanged" any more, but the abbreviation PBX was so widely understood that it remained in use.)

The other trend was the idea of focusing on core competence. PBX services had always been hard to arrange for smaller companies, and many companies realized that handling their own telephony was not their core competence. These considerations gave rise to the concept of hosted PBX. In a hosted setup, the PBX is located at and managed by the telephone service provider, and features and calls are delivered via the Internet. The customer just signs up for a service, rather than buying and maintaining expensive hardware. This essentially removes the branch from the private premises, moving it to a central location.

The features available with each system. 12Marks

Functionally, the PBX performs four main call processing duties:

• Establishing connections (circuits) between the telephone sets of two users (e.g. mapping a dialed number to a physical phone, ensuring the phone isn't already busy)
• Maintaining such connections as long as the users require them (i.e. channeling voice signals between the users)
• Disconnecting those connections as per the user's requirement
• Providing information for accounting purposes (e.g. metering calls)

In addition to these basic functions, PBXs offer many other calling features and capabilities, with different manufacturers providing different features in an effort to differentiate their products. Common capabilities include (manufacturers may have a different name for each capability):

• Auto attendant
• Auto dialing
• Automatic call distributor
• Automated directory services (where callers can be routed to a given employee by keying or speaking the letters of the employee's name)
• Automatic ring back
• Call accounting
• Call Blocking
• Call forwarding on busy or absence
• Call park
• Call pick-up
• Call transfer
• Call waiting
• Camp-on
• Conference call
• Custom greetings
• Customized Abbreviated dialing (Speed Dialing)
• Busy Override

Entel HT952/HT953 Series (ATEX) Version 2.0

For those requiring an entry level portable, the HT900 is a cost effective solution. The new HT900 Series 2.0 has superior build quality and exceptionally loud audio that enables you to communicate in the noisiest environments, making it the choice of the fire & rescue services and major blue-chip petrochem organizations worldwide. This low cost entry level model is simple to use, yet highly specified, offering features such as channel scanning, and local personal attack alarm, with optional Bluetooth communications facility and variable point voice scrambler.

The HT900 Series is of course Fully Submersible and the Version 2.0 radios are visibly tougher than their predecessors. Entel have expanded their radios' capabilities and put time into designing a superior product.

Built to the same standard as the HT900 professional series and with all the same features this is a lot of radio and with no license required it has lower running costs. With the standard 2 year Entel warranty you can have piece of mind that this is a robust, fully submersible and reliable radio all the qualities you would now expect from Entel.

ATEX Approved Intrinsically Safe E Ex i b ll C T3

The new HT900 Series 2.0 has superior build quality and exceptionally loud audio that enables you to communicate in the noisiest environments, making it the choice of the fire & rescue services and major blue-chip petrochem organizations worldwide.

The HT900 Series is of course Fully Submersible and the Version 2.0 radios are visibly tougher than their predecessors. Entel have expanded their radios' capabilities and put time into designing a superior product.

Utilizing the latest intelligent Lithium-Ion battery technology, this radio will display a battery cycle count each and every time you power-on your radio (if dealer enabled). For your convenience it will even alert you to imminent battery life expiration.

Motorola GP340 Ex ATEX

The GP340 EX ATEX replaces the GP900 series of CENELEC radios, which has represented the industry standard for so many years. Smaller with more functions than its predecessor it is simply superb.

Features: Range up to 8km, VOX, Xpand Voice Compression, Whisper Mode, Call Forward, DTMF Encoder Sequences, Dedicated Call Buttons, Call Timer, Stun/un-stun, Lone Worker, Emergency Signalling, Low Battery Level Indicator, Call Status Indications, Escalert, Call reminder Alerts, Monitor, High / Low Output Power, 20ms CCIR, CTCSS & SELCALL Signaling, ATEX Approved.

Dual prong adapter- Connects headset to equipment featuring a plug prong jack (operator console or PBX)- Scroll volume control located on adapter- For use ....

The cost of operating the system.6Marks

Some cellular telephone networks offer a push-to-talk handset that allows walkie-talkie-like operation over the cellular network, without dialing a call each time.

Walkie-talkies for public safety, commercial and industrial uses may be part of trunked radio systems, which dynamically allocate radio channels for more efficient use of limited radio spectrum. Such systems always work with a base station that acts as a repeater and controller, although individual handsets and mobiles may have a mode that bypasses the base station.

There are various accessories available for walkie talkies such as rechargeable batteries, drop in rechargers, multi-unit rechargers for charging as many as six units at a time, and an audio accessory jack that can be used for headsets or speaker microphones.

When headsets are used with voice activation (VOX) capability the user can talk with hands free operation. Several types of audio accessories are available such as speaker microphones that clip near the ear, security type earpieces with a pendant push-to-talk switch and a built-in microphone, a headset that has a push-to-talk switch ear bud that looks more like what you would find on a music player, or a single-ear lightweight behind-the-head headset with boom microphone and pendant push-to-talk switch similar to that worn by a telephone call center agent. Above the cost are expenses into the system.

Recommendation

In task 4, I have investigated about the telephone system, additional services and limitations. The categories include PBX(Public Branch Exchange) and KTS(Key Telephone System). The PBX system to use the wide range communication serves are available to our police department. Our police department require the wide range communication services and to solve the criminal case of our country. The PBX system is more comfortable than KTS service, because the PBX system to apply the IP with communicate to each other. Thus why I was suggested that PBX system is the best solution of our police department.

The police office department in Townsville has been restructured and is shortly opening a new headquarters building. The building will house all the communication and computer system for the police department.

Townsville Police Department covers an area of 100 square kilometers and has a chief Constable who is responsible for the policing of that area. The Chief Constable is assisted by an Assistant Chief Constable who carried out senior duties and takes responsibility for the whole Police Department when the Chief Constable is ill, on holiday, or away from the area.

I have constructed the POLICE Department with Global Positioning System (GPS), General Packet Radio Service (GPRS), Global System of Mobile (GSM) and Geographical Information System (GIS).

In task 1, I have taken the research for the police department paying attention to the two way voice communication method, the accuracy of the data transmission method, the information delivered by the head office to the branch, the method of data transmission from vehicle to centre, the cost per device of using the system, Additional services that the system can provide and limitations of the system. And then to select the topology of network communication, decide which topology to make better than to our police department. The recommendation for task 1 is already shown at the end of task 1.

In task 2, I have investigated the methods of communication service and to select the which one is the best and compare the price and services. Which services are meet with our police department and recommendation for task 2 is already shown at the end of task 2.

In task 3, I have investigated the more detail of two way voice communication method. To find the GSM, walkie-talkie system function and frequencies band width of the each system. The cost per device and which device can use, these devices to implement our police department. The recommendation for task 3 is already shown at the end of task 3.

In task 4, I have investigated the telephone system available of our country for single-site organizations. The police department which telecommunication system to use and I was suggested PBX and KTS system to use our police department. This telecommunication system is the best of our police department. The recommendation for task 4 is already shown at the end of task 4.

Please be aware that the free essay that you were just reading was not written by us. This essay, and all of the others available to view on the website, were provided to us by students in exchange for services that we offer. This relationship helps our students to get an even better deal while also contributing to the biggest free essay resource in the UK!