The term bus is derived from bus bar, found in electromechanical switching devices. A bus bar distributes electrical current to its required location. In electronic devices, the bus or data bus can best be thought of as a data highway joining all the devices together. Network nodes are trapped onto the highway by means of T-connections. At each of the bus is a terminator, sometimes known as a head end, to stop the electrical signals reflecting back from the end of the bus. The terminator may be a simple resister or complex electronic device, depending upon the type of signaling used.
Nodes have equal priority and there is no requirement for a control station. The nodes need to co-operate with each other to use the bus successfully and to avoid corrupting each other's transmissions. Clearly, if two nodes try to transmit at the same time, the signal on the bus will be impossible to read. The meaning of at the same time needs some care, since although signals travel along the bus at the speed of light, the time between nodes can be significant when considering the speed of processors. A node to the start transmitting whilst a signal is in transmits from another node. This would lead to the signal being corrupted. Some mechanism is needed to either avoid these collisions, or to correct the errors if collisions occur.
Star Topology
Because of the problem in troubleshooting and managing a physical bus or ring network and because a signal cable failure can bring down the entire network, these topologies have been largely replaced by the physical star topology. A star topology describes computer connected by cable segments to a central device. Note that the physical star topology doesn't specify how signals should travel from computer to computer, only that cables connect computers to a central device. In fact, the underlying logical topology in a physical star is likely a bus, a ring, or switching. One benefit of a physical star topology is its inherent centralization of resources. However cable installation. A physical bus strings a cable from one computer to the next, but cable installation in a star topology usually involves stringing cable through conduit, under floor, and inside ceilings to get the cable from the computer work area to the connecting device. This installation is usually more labor intensive and requires much more cable.
Ring Topology
Data in a logical ring topology, as its name suggests from one device, or node, on the network to the next device until the data reaches its destination. Token passing is one method for sending data around a ring. A small packet, called a token, pass around the ring to each computer in turn. If a computer has information to send, it modifies the token, adds address information and the data and send, it around the ring. That information travels around the ring until it reaches its destination or returns to the sender. When the intended destination computer receives the information, it returns a message to the sender to acknowledge its safe arrival. The sender then releases the token and sends it around the ring to begin the process again.
Modern logical ring topology use "smart hubs" that recognize a computer's failure and remove the computer form the ring automatically. Another advantage of the ring topology lies in its capability to share network resources fairly. Each computer had an equal opportunity to send data, so no single computer can monopolize the network. This feature is useful in high-traffic and time-critical applications, in which every devices must be able to send data within a given period. A ring topology with token passing guarantees a device's capability to send, whereas a bus topology is a first-served arrangement in which a single device can monopolize the network medium.
Task1. (b)
Copper Cable
The oldest form of media is copper cabling. This comes in a number of different types that can be understood in terms of the history of development. The most common type of copper of copper wiring is used to implement Ethernet, which is based on a bus logical topology. The earliest type of Ethernet cabling was 10Base5. This cabling is usually yellow and marked every 2.5 meters to show where a connection can be made. Thick Ethernet is heavy and difficult to install. It cannot be bent around tight radiuses and the connections to the cable must be made with a 'vampire tap' in which a pin is forced through the insulation to contact the core. Thick Ethernet is now seen only in old installations
Thin Ethernet or 10Base2 uses a much thinner coaxial cable. It is considerably lighter and easy to install. Instead of vampire taps, connection into the cable is made with simple T connectors using BNC bayonet connections. These can be made and unmade very simply and reliably. Unfortunately, the ease of changing connection is one of the scheme's disadvantages, it is very easy to disconnect a part of the bus, rendering the whole of the bus and all of the nodes on it unable to communicate.
Fiber-optic cable
Fiber-optic cable trades electrical pulses for their optical equivalents, which are pulses of light. Because no electrical signals ever pass through the cable, fiber-optic media is as immune to interference as any medium can get. This characteristic also makes fiber-optic cables highly secure. They emit no external signals that might be detected, unlike electrical or broadcast media, thereby eliminating the possibility of electronic eavesdropping. In particular, fiber-optic cable is a good medium for high-bandwidth, high-speed, Long-distance data transmissions because of its lower attenuation characteristics and vastly higher bandwidth. Today, commercial implementations at 10Gbps are in use.
Fiber-optic cable consist of five components: a sender cylinder of glass fiber called the core, surrounded by a concentric layer of glass called the cladding. The fiber is then jacketed in a thin transparent plastic material called the buffer.
Task 1(c).
Recommendation for which topology and medium to use including
We use the Star Topology and Fiber optic cable. In the Star Topology is a central connection point called the hub which is a computer hub or a switch. In a Star Network the best advantage is when there is a failure in cable then only one computer can get affected and not the entire network. A Star Network Topology is very easy to manage because of its simplicity in functionality. The problems can be easily located logically in a Star Topology and therefore is easy to troubleshoot also. The Star Topology is very simple in format so it is very easy to expand on the Star Topology.
Task 2
Task2. (a)
Internet Connection Requirements for the Police Department
Myanmar Teleport and
Broadband with wireless loop
Internet Service require in police department
Wed Mail
HTTP
VOIP
FTP
IP Security Camera and
Video conferencing
(b) Connection speed
Name
need connection speed
Web Mail
HTTP
VOIP
FTP
IP Security Camera
Video Conferencing
100Mbps
100Mbps
1Gbps
1Gbps
1Gbps
1Gbps
1Gbps
(c) For about ISP and Myanmar Teleport
For about Internet Service Provider
To arrange communication services for smooth and easy usage by the general public.
To arrange communication services for smooth and easy usage by the general public.
To satisfy the communication needs of commercial, social, and administrative infrastructures. To establish communication centers and routes in accordance with work requirements.
To monitor communication services in accordance with Laws, Rules and Regulations.
To develop relations with other countries, int'l organizations, regional organizations, and apply the agreements made.
To issue licenses and collect fees for Radio, TV, VCR, and TVRO.
To conduct tests for international radio operators.
To manage and monitor radio frequencies.
To manage standard and quality of communication systems.
To conduct communications related research works and studies.
It started off with a dream. One that would the entire country the best in info-communication, by being the provider that would takes the people of Myanmar into Cyberspace. And now this dream is becoming reality through a team of young and dynamic characters that make up Myanmar Teleport. Multipurpose facility, with built-in full redundancy is the central communication hub of the company. The teleport is the control site for all domestic and international satellite, networks and links. The teleport operator multiple satellite links providing connection to the Internet backbone, through a wide range of earth station equipment and multiple high power antennas. An Internet Data Center provides a secure and 100% reliable environment for web-hosting and co-location services for corporate customers and public sector institutions requiring mission critical operations.
Broadband Wireless
Broadband wireless networks have also been deployed in Yangon and Mandalay, using industry leading technology from Alva ion. The Network with multiple Point-of-Presence will sure uniform converges for the whole of Yangon. This cost effective solution for business and home-users provides high speed internet access and a voice capability using VoIP technology.
(d).Cost of ISP and recommend of ISP
Now you need to ask yourself how much you are willing to pay for Internet services. ISP's have to ways of charging for their services. They can either charge by the hour of usage or they may charge a flat fee for unlimited usage. We recommend that you go with an ISP that charges a flat fee for unlimited usage. Rates for dialup access range from $8 to $30 a month. Shell accounts range from $5 to $20 a month. Cable access ranges from $30 to $100 per month. Dedicated access ranges from $500 to $15000 a month. You do not need to invest in your own web server. Most ISPs have very fast connections to the internet. The ISP's server should offer a very high degree of availability (up time) and reliability. The ISP should have a secure operating environment, high quality virus protection and the latest software patches to ensure the security of your site.
Task 3
Task3. (a) Two-way radio frequencies
Two-way voice communication methods
Conventional versus trunked
Simplex versus duplex channels
Push-to-talk
Analog versus digital
Data over two-way radio
Conventional versus trunked
Conventional radios operate on fixed RF channel. In the case of radios with multiple channels they operate on one channel at a time. The proper channel is selected by a user. The user operates a channel selector or buttons on the radio control panel to pick the channel
In multi-channel system, channels are used for separate purpose. A channel may be reserved for a specific function or for a geographic area. In a functional channel system, one channel may allow City of Springfield road repair crews to communicate with state highway department crews. In a geographic system, a taxi company may use one channel to communicate in the Boston, Massachusetts area and a second channel when taxis are in Providence, Rhode Island. In marine radio operations, one channel is used as an emergency and calling channel, so that stations may make contact then move to a separate working channel for continued communication.
Motorola uses the term mode to refer to channels on some conventional two-way radio models. In this use, a mode consists of a radio frequency channel and all channel-dependent options such as selective calling.
Simplex versus duplex channels
Simplex
Simple channel system use a single channel for transmits and receive. This is typical of aircraft VHF AM and marine radios. Simplex systems are often legacy systems that have existed for years or decades. The architecture allows old radios to work with new ones in a single network. In the case of all ships worldwide or all aircraft worldwide, the large number of radios installed can take decades to upgrade. Simplex systems often use open architecture that allow any radio meeting basic standards to be compatible with the entire system.
Duplex
Duplex means two channels are used one in each direction. Duplex channel system transmits and receive on different discrete channels. This defines system where equipment cannot communicate without some infrastructure such as repeater, base station to Talk-Through Base. Most common in the US is a repeater configuration where a base station is configured to re-transmit the audio received from mobile units. This makes the mobiles, or hand-held's able to communicate amongst one another anywhere within reception range of the base station or repeater. Typically the base or repeater station has a high antenna which allows greater range compared with a ground vehicle or hand-held transceiver.
Duplex systems can be divided into two types. The term half-duplex refers to system where use of a push-to-talk switch is required to communicate. Full duplex refers to system like mobile telephones with a capability to simultaneously receive and transmit.
Push-to-talk
The microphone looked like a normal mobile microphone except that the button rocked either up or down instead of pressing in. Rocking the switch in one direction transmitted duplex on a repeater the other transmitted simplexes on car-to-car. In two-way radios with headsets a push-to-talk button may be included on a cord or wireless electronics box clipped to the user's clothing. In an ambulance or aircraft a button may be present where the corded headset plugs in to the radio wiring. Dispatch consoles often have a hand-operated push-to-talk buttons along with a foot switch or pedal. If the dispatcher's hands are on a computer keyboard the user can step on the foot pedal to transmit. Some systems have muting so the dispatcher can be on a telephone call and the caller cannot hear what is said over the radio. Their headset microphone will mute if they transmit. This relieves the dispatcher of explaining every radio message to a caller.
Analog versus digital
Duplex means two channels are used one in each direction. Duplex channel system transmits and receives on different discrete channels. This defines systems where equipment cannot communicate without some infrastructure such as a repeater, base station or Talk-Through Base. Most common in the US is a repeater configuration where a base station is configured to re-transmit the audio received from mobile units. This makes the mobiles or hand-held's able to communicate amongst one another anywhere within reception range of the base station or repeater. Typically the base or repeater station has a high antenna which allows greater range compared with a ground vehicle or hand-held transceiver.
Data over two-way radio
In some cases two-way radio is used to communicate analog or digital data. Systems can be simplex or duplex and may employ selective calling features such as CTCSS. In full-duplex systems data can be sent real-time between two points. In simplex or half-duplex data can be sent with a time lag between many points. Some two-way digital systems carry both audio and data over a single data stream. The method of encoding and decoding the audio stream is called a codec, such as the AMBE family of codec's. After market GPS tracking and mobile messaging devices can be interfaced with popular two-way radio models providing a range of features.
Types of VoIP Calls
VoIP telephones call can be placed either to other VoIP devices or to normal telephones on the PSTN (Public Switched Telephone Network). Call from a VoIP device to a PSTN device are commonly called "PC-to-Phone" calls even though the VoIP device may not be a PC. Calls from a VoIP device to another VoIP device are commonly called "PC-to-PC" calls even though neither device may be a PC. Voice over Internet Protocol (VoIP) utilizes the internet to carry voice calls to any telephone worldwide. This service is not designed to replace your traditional telephone connection but it's meant to supply you cheaper call rates by taken advantages of Internet technology. You traditional telephone line will still be necessary if you connect to the internet via your telephone like ADSL. It is also necessary in case of an Australian emergency call for example 000. Since all called are made from an Internet server the operator is unable to locate where you are making the call from so in an emergency call you must tell the operator your location
b) Legal Requirements for Operation System
Operating a radio communications network in most countries is subject to licensing by national telecommunications regulators, both for its type of use and the radio frequency spectrum it utilizes, especially as radio frequency spectrum is a scarce resource and needs to be used efficiently.
Operating a commercial mobile radio network practically always requires a specific operating license. In case of private radio networks, i.e. Professional Mobile Radio (PMR), the interpretation of the licensing requirements is country specific and the opinion of the national regulator should thus always be consulted before setting up a radio communication network. In most cases a private radio system requires only a frequency license.
c) Cost
Plan
Monthly FEE (FEC)
Free Email Account
Maximum Attached Devices
Speed (MIR)
Corporate
150
30
12 PC + 2 VoIP
512 kbps
Installation Fee
VoIP Service Fee (Optional)
WiMax Activation Fee
900 FEC
VoIP Activation Fee (Per Line)
80 FEC
WiMax Annual Fee
60 FEC
VoIP Annual Fee (Per Line)
60 FEC
WiMax Equipment Fee
740 FEC
VoIP Adaptor (3 ports)
300 FEC
Total
1,700 FEC
Total
440 FEC
Cost for walkie talkie
Motorola Talkabout® T9680RSAME 25-Mile 2-Way Radios
Model: T9680RSAME
$89.99
d) Limitations of Methods
Conventional versus trunked: Systems make arrangements for handshaking and connections between radios by one of these two methods:
A computer assigns channels over a dedicated control channel. The control channel sends a continual data stream. All radios in the system monitor the data stream until commanded by the computer to join a conversation on an assigned channel.
Electronics embedded in each radio communicate using a protocol of tones or data in order to establish a conversation, (scan-based).
If all physical channels are busy, some systems include a protocol to queue or stack pending requests until a channel becomes available.
Simplex versus duplex channels
As the simplest system configuration, there is reliability from the fact that only two radios are needed to establish communication between them. The simplex configuration offers communication over the shortest range or distance because mobile units must be in effective range of each other. The available channel bandwidth limits the number of simultaneous conversations, since "dead" air time cannot be easily used for additional communication.
Duplex channels usually allow repeater operation which extends range (in most cases due to increased transmit power and improved aerial location / height) - especially where hand-held radios are in use. If a radio cannot reach the repeater, it cannot communicate.
Push-to-talk
In some circumstances, voice-operated transmit (VOX) is used in place of a push-to-talk button. Possible uses are handicapped users who cannot push a button, Amateur radio operators, firefighters, crane operators, or others performing critical tasks where hands must be free but communication is still necessary.
Data over two-way radio
Digital systems typically use data rates in the 1,200-19,200 kilobit-per-second rates and may employ modulation schemes such as frequency shift keying, audio frequency shift keying, or quadrature phase shift keying to encode characters. Modern equipment have the same capabilities to carry data as are found in Internet Protocol. Working within the system's protocol constraints, virtually anything can be sent or received.
Limitation of VoIP
Emergency 000 calls: VoIP service providers are unable to pass your street address details to emergency services at this point in time..
Some VoIP provider do not support calls to Australian 1800, 1900 or 13 numbers.
Power failure at your location will almost certainly render your Internet modem and VoIP device inoperable. Some VoIP devices (e.g. DrayTek 2100 and 2500) can make PSTN calls during power failure.
Network outages: As mentioned above, there is no guarantee of availability or 100% quality, due to communication outages or congestion beyond VoIP's control.
Limitation of walkie talkie
Motorola can be used up to only 25-mile range.
Motorola has only 15 channels with 121 privacy codes.
Motorola can be used list of the same code.
3(d) Recommendation of two-way radio device
Two- way radios can operate on many different frequencies and these frequencies are assigned differently in different countries. Typically channelized operations are used so that operators need not tune equipment to a particular frequency but instead can use one or more pre-selected frequencies easily chosen by a pushbutton or other means. For example in the United States there is a block of 22 channels assigned collectively to the General Mobile Radio Service and Family Radio Service.
In an analog conventional system a frequency or channel serves as a physical medium or link carrying communicated information. The performance of a radio system is partly dependent in the characteristics of frequency band used.
Task 4
4(a).The main equipment of that would be installed
IP PBX
Walkie talkie
VoIP
IP phone
4(b) Feature of PBX
The features of the PBX were somewhat limited and basically consisted of the following capabilities.
To dial other extensions.
To dial outside lines.
To make an enquiry call to another extension whist connected to an external call.
To transfer the external call to the extension where an enquiry call had just been made.
A PBX (Private Branch Exchange) is a small telephone switch owned by a company or organization. PBX reduces the total number of telephone lines you need to lease from the telephone company. Without a PBX, a company will need to lease one telephone line for every employee with a telephone.
More and more companies are making the transition to IPPBX systems because they offer flexibility and cost savings in addition to extra features. IPPBX uses VoIP technology which means it utilizes your broadband for call services and since you already have broadband in your office a lot of calls are indeed free or significantly cheaper. If you have a branch office you can benefit by calling them as an internal call completely free of charge. Remember, the quality of voice very much depends on your broadband service. If your location from BT exchange is far and your broadband is not stable, then IPPBX is not for you.
Give control back to IT with robust communications policies
Comprehensive communication policies help you better manage mobile devices, telecom infrastructure, and track effectiveness.
Manage on a per-user basis
Manage profile attributes
Manage security functions-including access privileges-more easily.
Prioritize communications with classes of service-so important calls get through quickly
Designate call-routing protocols-forcing calls onto the most cost-effective routes
Let end users manage their own devices through user-friendly Web and phone interfaces and converged applications
Users handle "adds, moves, and changes"
Users manage conferencing, notification, polling, and more
Feature of Walkie talkie
Walkie-talkies are widely used in any setting where portable radio communications are necessary, including business, public safety, military, outdoor recreation, and the like, and devices are available at numerous price points from inexpensive analog units sold as toys up to ruggedized (i.e. waterproof or intrinsically safe) analog and digital units for use on boats or in heavy industry. Most countries, at the very least, will allow the sale of walkie-talkies for business, marine communications, and some personal uses such as CB radio, as well as amateur radio designs. Walkie-talkies, thanks to increasing use of miniaturized electronics, can be made very small, with some personal two-way UHF radio models being smaller than a pack of cigarettes (though VHF and HF units can be substantially larger due to the need for larger antennas and battery packs). In addition, as cost come down, it is possible to add advanced squelch capabilities such as CTCSS (analog squelch) and DCS (digital squelch) (often marketed as "privacy codes) to inexpensive radios, as well as voice scrambling and trucking capabilities. Some units (especially amateur HTs) also include DTMF keypads for remote operation of various devices such as repeaters. Some models include VOX capability for hands-free operation, as well as the ability to attach external microphones and speakers.
Consumer and commercial equipment differ in a number of ways; commercial gear is generally ruggedized, with metal cases, and often has only a few specific frequencies programmed into it (often, though not always, with a computer or other outside programming device; older units can simply swap crystals), since a given business or public safety agent must often abide by a specific frequency allocation. Consumer gear, on the other hand, is generally made to be small, lightweight, and capable of accessing any channel within the specified band, not just a subset of assigned channels.
Wide-band receivers, often including radio scanner functionality, for listening to non-amateur radio bands.
Multiple bands; while some operate only on specific bands such as 2 meters or 70 cm; others support several UHF and VHF amateur allocations available to the user.
Since amateur allocations usually are not channelized, the user can dial in any frequency desired in the authorized band.
Multiple modulation schemes: a few amateur HTs may allow modulation modes other than FM, including AM, SSB, and CW, and digital modes such as radio teletype or PSK31. Some may have TNCs built in to support packet radio data transmission without additional hardware.
Feature of VoIP
An IP PBX is a complete telephony system that provides telephone calls over IP data networks. All conversations are sent as data packets over the network. The technology includes advanced communication features but also provides a significant dose of worry-free scalability and robustness that all enterprises seek. The IP PBX is also able to connect to traditional PSTN lines via an optional gateway - so upgrading day-to-day business communication to this most advanced voice and data network is a breeze. With IP PBX deployed, an enterprise can even keep its regular telephone numbers. This way, the IP PBX switches local calls over the data network inside the enterprise and allows all users to share the same external phone lines. Voice over IP (VoIP) was developed in order to provide access to voice communication in any place around the world. In most places, voice communication is quite costly. Consider making a phone call to a person living in a country half the globe away. The first thing you think of in this case is your phone bill! VoIP solves this problem and many others. There are of course a few drawbacks attached to the use of VoIP, as is the case with any new technology, but the advantages largely outbalance these. Let's explore below the benefits of VoIP and see how it can improve your home or business voice communication.
Feature of IP phone
IP Phones are devices which typically resemble your conventional telephone and function in much the same way. The main difference between IP Phones and conventional analog telephones is that the IP Phone converts your voice signal directly into a digital 'data packet' rather than the 'analog' signal produced by your conventional telephone. Again, the majorities of this phone is aimed towards 'high-speed' Internet Users and usually incorporate an RJ45 interface to plug into your high-speed modem or network router.
4(c) cost of equipment
Recommendation of PBX
PBX is a mature technology that offers many benefits for the right type of application. As a minimum multiple extensions in a single office can share the cost of incoming phone lines. It is not necessary to pay for a separate phone line for each extension. Capital costs for the equipment can be amortized and depreciated over time. Even though system management and maintenance continues to add cot after installation today's system are more robust and easier to manage than they have been in the past. Incoming calls are typically free or very low cost. In more expensive systems some level of system expansion is allowed for scalability. Businesses that can reliably predict their needs can usually find a cost-effective system. As feature and function continue to be added a PBX can add productivity to an office environment. Almost ant feature that can be imagined for telecommunications can usually be found somewhere among the many vendors and offerings in this space as long as customers are willing to pay the associated price.
Easy management on line, no need to call engineer if you want to install one extra phone
A central box to install, or a hosted solution if you prefer at our partner telecom company
All you need is a set of IP Phones
You will get clear bills per second with huge savings
You can keep your numbers and integrate that into the new system
Task 5
Task5.
Our network system is using Star network topology. A star Network Topology is structure simple and very easy to manage but the whole working of the network depends on the hub or the switch. The problems can easily troubleshoot. If there are many nodes and the cable is long distance, the network many slow down. We use the fiber optic that can operate at high speed large carrying capacity and greater resistance to electromagnetic noise. But fiber optic cable is very high costs and less to maintain.
Our Internet system data transfer range is 64 kbits per second to 128 kbits per second. Using our internet system is low cost, so connection may slow down at sometimes. Data transmitting cannot send many packets at the same time. We use the two-way communication radio for our station because this system is useful for us. This system has audio accessories such as heads and IP phone. Headsets two-way radios are the walkie talkie type of radio. As ruled by the FCC (Federal Communications Commission) two-way radios have a jack for an audio accessory like a headset or speaker microphone. Our staff shirts or jackets have a special place to clip the walkie talkie on our shoulder so this may not work for a person wearing average clothes. This device has security for our system. Having the walkie talkie near our ear is saved for noisy environment.
Motorola two-way radio mount in a car or truck and we use the vehicle's battery for power. We many have our own antenna but better range is achieved by using an externally mounted antenna. These devices are easy to connect and operate at different carrier frequencies. And then we can use to contact wirelessly. But these devices have travel to limit and only one direction at a time.
PBX makes connections among the internal telephones of a private's organization and also connects them to the public switched telephone network (PSTN) via trunk lines. PBX was cost savings on internal phone calls handling the circuit switching locally reduced charges for local phone service. As PBX gained popularity, they started offering services that were not available in the operator network call forwarding and extension dialing. We need 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. In a hosted setup the PBX is located at and managed by the telephone service then buying and maintaining expensive hardware. This essentially removes the branch from the private premises moving it to a central location. So we make telephone system with PBX.
