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I am one of the enthusiasts, energetic and active student studying IADCS (International Advanced Diploma in Computer Studies). In my second module in this course, I have to do the assignment for Enterprise Networking which demonstrates an understanding of the network, telephone system and two-way voice communications with patrolling police officers.
In this assignment, I have to learn about computer network, telephone system and two-way voice communications for Police Department. This is really a real time process for me. I have to research all the things which will be needed for this assignments and it gave me a lot of knowledge of computer network, telephone system, etc. This assignment is not just an assignment, it is the really implementation of the police department with network.
No work is done properly without getting help, supports, courage, motivation and inspiration. Like so, I got a lot of knowledge-constraints during the development of this assignment. But later, I manage to cope them all with the help and supports from them whom I'd like to acknowledge from the bottom of my heart.
First of all, I'd like to give my thanks to our active, fun-to-be-with and generous Enterprise Networking lecturer, U Aung Thu Thu, who gave me a tremendous supports and courage and make our eyes open to networking world. And I'd like to thanks to our course manager, Tr. Daw Aung Thandar Lynn Myint who makes us ready for every resources we need and care about us.
Finally, I'd like to thank to MCC itself which give me a place to study and to do my assignment in its modern structured computer room with highly specification latest computer. My thanks also go to the teachers and all other staffs who are working in MCC who help us in indirect ways.
Task - 1
Possible Network Topologies
A topology refers to the manner in which the cable is run to individual workstations on the network. The dictionary defines topology as: the configurations formed by the connections between devices on a local area network (LAN) or between two or more LANs.
Computer network topologies can be categorized in the following categories.
Hybrid networks are the complex networks, which can be built of two or more above mentioned topologies.
The bus topology for the use of the backbone of the common all network to connect to a network device to a linear appearance. The function of a single cable communication for sharing devices attached to the media this interface cable connector. The device and Communications, which wants a message, broadcast devices attached to the cable to share as well as the recipient in fact, to allow for message and process. Ethernet bus topology can install easily and don't need to set up the numbers of cable and only major shared cable can be used on the network. The most popular types of Ethernet cable which are used in the bus for topology are 10Base2 and 10BaseT. Moreover, city bus works with a very limited device. Performance issues might have problems in the bus topology if more than 12-15 computers are added to the Bus Network. In fact, when the backbone cable fails, then all are useless, and network communication will fail all computers which is used this method. Unlike with the star topology, if a computer on the network was detached and will not affect to the other computer on the network.
Star topology is the most common computer network topology. The simplest form of a star network includes one central switch, the hub or computer passageway to the transport messages. As a result, the hub and leaf nodes and power lines between them as a form of a graph of stars topology. If the central node is a passive, the original node must be able to do it or not tolerate must be a reception on the echoes delay in the one-way transmission two hours (that is, the central node) Plus delay in the central node. Star network active central node is the means for echo in order to prevent the-related problems.
Star topology reduces the possibility ways that failed to connect all network to a central system node. When communicate with the bus-based networks, the central hub rebroadcasts all the transport every node in the network to another peripheral nodes, sometimes, such as the original node. All peripheral nodes communicate to all others by transferring to and receiving from only with the central node. The failure of a transmission line that will connect any node of outlying dispositive with the central node will be in the isolation of that node of outlying dispositive of all other ones, but the rest of the systems they will be immune.
Ring network in all computer or device have two adjacent to the neighbors for communication. For the ring network, all communications Messages are run in the same directory whether clockwise or anti clockwise. The cable damage of all of the cable or devices can be broken off the entire network. For now, the ring topology almost obsoletes.
It can be used in order that FDDI, an SONET or Token ring technology carries out ring technology. It can be found in an office, a school or a small building the ring topology.
The mesh topology works the routes of the concept. Though a message sent to the destination in mesh topology reaches the destination, I can need any kind of possible easiest route having a shortest it. A message is bus topology in particular, and, by topology and bus in front of the star, it is usually done a broadcast by all computers. Direction namely clockwise or anticlockwise can travel among just one by a ring topology message likewise. The Internet uses the mesh topology and the message finds the route for the destination. The router work that a route finds in an inch reaching the it at the destination of for a message and it. Topology each device is connected to each other equipment was called "full of topology, LAN, each device is indirectly connected to the other equipment.
Tree the composition of the topologies multiple star arranged on a bus. Tree topology integrating a star layout is of a bus. Only hub devices can connect and direct the tree bus and each functions of the Center a root the trees of networking equipment. Such a bus/star/mixed combination support for future scalability of computer network, more than a bus or star.
The choice of one over the other should be based on the strength and less weaknesses. The linear bus consists of a central cable running around the entire length of the network premises. It is the cables that are referred to as the bus. All workstations are directly connected to the bus. The bus is terminated at either end with electrical resistors. What is found worthwhile in this topology is that it is cheaper and easier to install in comparison to all others. The biggest worry being a disadvantage is that should there be a break anywhere in network cabling, the whole network crashes thus bringing everything to a hold. It is even difficult to locate such breaks in some large installation due to line breakage. Certainly, this topology is not suited to very large private installations. In most cases, repeaters are to boost signals if the length of the bus exceeds 185 meters. The university library has suffered setbacks inherent in this architecture. The library option was then to avoid such a bus and adopt a Star Bus architecture that basically consists of the workstations and the file server being connected to a hub. A hub is actually an electric device which channels electric signals from both the file server and workstations to each other. The advantage of the Star Bus is that should a cable connecting a workstation to the hub break, then only that workstation would lose its connection to the network. All other workstation would remain functional. However, should the cable connecting the file server break or should the hub develop a fault, then the whole network would crash. All the same such faults are very easy to detect and verify. This topology is very reliable compared to the others. It involves a lot of cabling to its disadvantage. The library looks forward to a newer similar technology that is more intelligent, for should there be a break, the system would detect the break and ensure that the signals are re-routed. The Ring bus would have been another third network topology for consideration. It is very much like the linear bus except that instead of using electrical resistors to terminate the loose ends, the cable ends are connected to each other to form a ring, hence its name. It involves a co-axial cable being laid round the premises of the network site. All workstations and the file server are connected off the ring. The network would crash should any cable in the network break. Locating such breaks is really tedious and taking a lot of time.
The type of network topology in which each of the nodes of the network is connected to a central node with a point-to-point link in a 'hub' and 'spoke' fashion, the central node being the 'hub' and the nodes that are attached to the central node being the 'spokes' (e.g., a collection of point-to-point links from the peripheral nodes that converge at a central node) - all data that is transmitted between nodes in the network is transmitted to this central node, which is usually some type of device that then retransmits the data to some or all of the other nodes in the network, although the central node may also be a simple common connection point (such as a 'punch-down' block) without any active device to repeat the signals.
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.
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').
The star topology reduces the probability of a network failure by connecting all of the peripheral nodes (computers, etc.) to a central node. When the physical star topology is applied to a logical bus network such as Ethernet, this central node (traditionally a hub) rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, sometimes including the originating node. All peripheral nodes may thus communicate with all others by transmitting to, and receiving from, the central node only. The failure of a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the remaining peripheral nodes will be unaffected. However, the disadvantage is that the failure of the central node will cause the failure of all of the peripheral nodes also. If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way round trip transmission time (i.e. to and from the central node) plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems.
Task - 2
Internet Connection Requirements for the Police Department
- Ministry of Communications, Posts and Telegraphs
- Myanmar Teleport
- Broadband Wireless Local Loop
Internet Services in Myanmar
In Myanmar, we can get many internet services. These services are as follow:
- Web Mail
- Web Cam
- IP-Security Camera
- Video Conferencing
Examples of Internet Services Providers (ISPs)
- Ministry of Communications, Posts and Telegraphs
- Responsibilities of MPT
- Organization communications services harmony and a simple use of the general public.
- To accommodate the commercial, social, and administrative infrastructure.
- To establish communication centers and roads, in accordance with the requirements of work.
- Monitoring communications services in accordance with laws, rules and regulations.
- The two countries' relations that of other countries, INT'L, regional organizations, and to implement the agreements already reached.
- To issue licenses and collect the royalties for radio, TV, VCR and Antennas.
- To conduct tests for international radio operators.
- To manage and monitor radio frequencies.
- Management standards and quality of the communications system.
- The telecommunication-related research and publications research.
About Myanmar Teleport
KEEPING MYANMAR CONTACT TO THE FUTURE OF INFO-COMMUNICATIONS
It has started with a dream.
You will have all the countries; the best Information-Communication although the supplier will take the people of Myanmar in cyberspace. Now those dream a reality of a task force of young, dynamic characteristics, including Myanmar telecommunications.
Network and Infrastructure
- Myanmar Teleport IDC & Teleport
- Versatile, building on fully redundant center, the Center's communications company.
- The telecommunications station's web site of control, all countries and the international satellite, networks and contact. Operator telecommunications satellites Multilink provide a connection Internet backbone, owing to a wide range of earth station equipment and many high-powered antennas.
- A Data Center the Internet to provide a safe and 100 of 100 reliable environments to the Internet hosts and co-location services such as corporate clients, and public-sector institutions the Mission's key operational.
- Versatile, built in full redundancy is the center of center of communication of society.
- Telecommunications station's web site of the internal control and international satellite network and contact. The telecommunications operators a variety of satellite links provide a connection Internet backbone, owing to a wide range of earth station equipment and many high-powered antennas.
- A Data Center the Internet to provide a safe and 100 of 100 reliable environments to the Internet hosts and co-location services such as corporate clients, and public-sector institutions the Mission's key operational.
Broadband Wireless Local Loop
- Broadband Wireless Network was also deployed in Yangon and Mandalay; use the industrial advanced technologies for the Alva Yang. The Network's presence will be several points unified connecting Yangon as a whole.
- Such a solution for cost-effective in companies and home-user with high-speed Internet access and a capable of voice by using VoIP technology.
Recommendation of Choosing ISP
For usual wired LAN connectivity, the immediate cost is high, the installation site requires extra money compared to the WLAN connectivity, this is not to include the wired cable is a lease line, and switched line rates, the actual rates for dedicated leased lines may vary from one country to another. The WLAN protocol is engineered to reduce the demanded bandwidth and maximize the number of wireless network types that can deliver. Multiple WLAN networks within an area can be achieved, with the additional aim of multiple networks. In other words, an IP-networked world will enable the multimedia evolution to optimize the bandwidth required to support the multimedia applications demanded by the marketplace. This will reduce the cost to own or lease a dedicated LAN circuit. The WLAN equipment can go point-to-point (PPP), speed up to 100MB at range of 3000 meters to send and receive e-mail messages, upload and download documents (PowerPoint briefing slides, spreadsheet, etc.) and small data files.
The standard for WLAN networks is IEEE 802.11b. The 802.11b standard specifies the use of DSSS in the 2.4 GHz band. The 802.11b high-rate (HR) Wi-Fi version of the standard increases the throughput to 11 Mbps. The WLAN equipment can theoretically support up to 200 customers. In view of wireless technology, cost reductions of network components will be possible compared to alternative technologies like traditional wired LAN. Cards that plug into PC or laptop are promptly available, and operate either Peer-to-Peer or Peer-to-AP Mode. The WLAN equipment can be configured in a matter of hours while customarily used equipment (hard wire) can take a week to a month if cable between customers is not available. For scalability, WLAN can be installed and configured in a variety of topologies to meet the needs of specific. The WLAN configurations are easily changed and range from peer-to-peer networks suitable for a small number of customers to full infrastructure networks of thousands of customers that enable roaming over a broad area. WLAN security is the most serious issue that a customer must consider. Throughput is the next most critical WLAN issue. WLAN should not be used for critical data transfer without a study on the maximum throughput requirement. The WLAN technology is considered an emerging technology, and therefore should be approached with caution. The technology is largely untested for the secure environment, and it introduces a potential for operational data-loss and yet-unknown security risks. As WLAN technology becomes a more secure and trusted channel by which customers may conduct their financial affairs, the market for WLAN will become even more lucrative.
The Choosing Wireless from MPT
Broadband Wireless gives you anywhere, anytime access and is fantastic for:
- Providing remote access to employees
- Mobilizing my sales force
- Providing access for telecommuting employees
- Field force automation
- Removing the hassle of a phone line
- Temporary office locations
- The travelling worker
A USB modem connection or laptop computer modem card is not a major option for those who really need mobile access, or an office modems can be a more practical solution of a company, often change of venue.
Task - 3
The Methods of Two-Way Voice Communications
- Conventional versus trunked radio system
- Simplex versus duplex channels
- Analog versus digital
- Data over two-way radio
- TErrestrial Trunked Radio (TETRA)
The functions of each method
Conventional versus trunked radio system
Conventional radio system
The conventional operation of the stations fixed radio frequency channels. Under such circumstances, radios with the variety of channels, they affect a channel at the same time. The user selects the appropriate channels. Users using a channel selector or a button radio control panel, select the Canal.
In multi-channel system, the channels are used to separate objectives. A road may be reserved for a specific functions or a geographical region. In functional systems to Canal, the Canal City of Springfield road maintenance staff made a statement, the city's Springfield, the Road Maintenance of office. The second channel may permit repair of roads, the crew members and communication Highway Department crew members. In a radio operations at sea, a channel is used as a matter of urgency and called on Canal, then the site may take linked to a separate working channels of communication, to continue.
Trunked Radio System
In a communications urban Radio System logic, the systems automatically select physical radio channels. This is a protocol, established a relations, radio, and the support radio backbone. The Protocol allows canal to be done automatically.
Digital total system can be at the same time for dialog a physical channel. In this case the radio apparatus clusters, the system is also management position of a single sports channel. The function with talk of a single-channel is for multiplexers.
Simplex versus duplex channels
Simplex chat simply the canal system using a single-channel sends and receive. This is a typical aircraft VHF marine and radios. Simplex chat simple this system is often the traditional system, existed for many years or more 10 years. The architecture allows that old radios work in new ones in an alone net. In this case, all vessels in the world of all the aircraft World, a large number of radios installed, (the installed base) may need a few 10 years of upgrade. The simple systems often use open architectures that allow that any radio that covers the basic censuses is compatible with the whole system.
Duplex means two channels for one in every direction.
Duplex canal systems send and receive on different separated channels. This definition system, such as the device does not communicate without some of the infrastructure, such as transponders, base station or talk about base. The most common United States is a repeaters set in a base station is configured for re-transmission audio received mobile unit. This makes motives or hand-application, able to communicate, among them, in any part of the received radius base station or repeater. Generally, base or repeater stations of have high Antennae, which allowed a more extensive, compare with a ground vehicles or portable radio transceiver.
Duplex system can be divided into two categories. The term half-duplex referred to the system using a push-to-talk switch is necessary communications. Full duplex means that the system such as mobile phone, the capacity to receive and at the same time transmission.
Some systems use combination of both on the radio double-sided use as a default but can communicate simplex chat simply that the canal if Bund.
Push-to-talk (PTT), also known as the you transmit, is a way to converse in a half-duplex communication channels, including two-way radio, use a temporary button with sound patterns of the mode of transmission.
Analog versus digital
One example of analog radios is AM aircraft for communicating with control towers and air traffic controllers. Another is a Family Radio Service walkie-talkie. Equipment is simpler than digital.
Advantage: Equipment of high quality, better ability to communicate in cases where a signal received is low or noisy.
Disadvantage: There is only one session during a time could occur in each channel.
Data over two-way radio
In some cases, two-way radio is used to communicate analogue or digital data. Such a system may simplex chat simple this and duplex and can be used as a selective calling features CTCSS. The full-duplex communication systems can send data real-time two points. In the simplex chat simple or half-duplex, the data may send a gap many of the points.
TErrestrial Trunked Radio
TErrestrial Trunked Radio (TETRA) which is also known as the Pan-European an Integrated Radio, is a commercially dealing mobile radio and transmitters and receivers (mostly known as walkie-talkies) specifications. TETRA is generally designed to use of government organizations, emergency services, military services and railway transportation of staff, transport services.
Not to allow the requirement has no need for our technology and requirement because our police's organization is under the main government force
Licensing costs is no need for our project. Because our organization is under one of the government agency.
Limitations of Methods
Conventional versus trunked radio system
System to organize, in the negotiations and the interrelationship between the Radio One of these two methods:
- A computer assigns channels on a channel of dedicated control. The control channel sends a constant flow of data. All radios in the system monitoring the flow of data until orders for the computer to unite to a conversation on an assigned channel.
- The electronic team embedded in each radio communicates using a protocol of the tones or the data in order to make it / to be it to establish a conversation, (scan-based)
If all of the physical channels are occupied, some system, including a protocol the tails or battery waits for request the canal the existing.
A number of integrated radio-frequency and an additional talk about group or organization-fleet-fleet
Simplex versus duplex channels
Advantage: As the easiest to configure the system, the reliability of the facts, only two radios is necessary to establish communication.
Disadvantages: On the configuration simplex chat simply providing communications in the short-range or distance of mobile units must be broad each of the other. Canal speed limit for the many talks at the same time, as the "dead" air time cannot be easily used to complement communications.
Advantage: Generally allow double-sided channels transponder operation, coverage (in most cases, the appropriate increase air power transmission and improve their websites/height)
Particularly in portable radio, this is used in.
Disadvantage: If a radio cannot achieve transmitters, it does not communicate.
When you use GSM and CDMA network, PTT service is usually not to use in a telephone call minutes regular that can be used for voice calls.
Data over two-way radio
Digital systems use of general data flow of the 200-19, 200-1000 bit every 2nd rate and can employ modulation plans, such as frequency changes, input Audio Input diversion, or orthogonal stage into input character encoding. Modern equipment has the same ability, data and was found in Internet protocol. Within the system of the Protocol constraints, there is little can send or receive.
TErrestrial Trunked Radio
Their common operation is a group calling mode in which a press of single button can communicate one user to the several users in a specific call group and/or a dispatcher. It may become the terminal act as a one-to-one walkie-talkie but the normal range limitation is not defined so the call needs to use the network. If the Subscriber Management allow it, TETRA terminals can be mobile phones (known as cell phones), which can connect to other TETRA Users or the PSTN with a full-duplex direct connection. To the dispatcher, while overriding any other activity taking place at the same time, emergency signals can be transmitted among the users by the use of Emergency buttons which are provided on the terminals. TETRA uses TDMA (Time Division Multiple Access) together with 4 user channels along with one radio carrier and spacing between carries is 25 kHz. So, not only point-to-point and also point-to-multipoint transfer can be used simultaneously. Digital data transmission is also embedded in the standard with a low data rate.
Not only Direct Mode and also Trunked infrastructure, Switching and Management Infrastructure (SwMI) can be used to communicate TERA Mobile Stations which made of TETRA Base Stations (TBS).Direct Mode or DMO has the function of using one of TETRA terminals as relays for a signal while allowing direct conversations in instance where the coverage of network is not available. This type of process is called DMO gateway (which is from DMO to TMO) or also called DMO Repeater (DMO to DMO).This function supports direct conversations underground or in bad coverage areas even in emergency situations. Moreover in voice and dispatch services, the TETRA system enables various types of data communication. Base on the main control channel of system, Status messages and SDS (Short Data Services are enabled while the usage of Packet Data or Circuit switched data transmissions are in the traffic channels.
Authentication Mechanisms of Terminals towards Infrastructure and vice versa are provided by TERA. Over the air encryption and end-to-end encryption is supported so that the eavesdropping is protected.
Task - 4
Recommendation for TETRA Technology
Advantages of TETRA
The main advantages the tetra other technology, such as GSM) is much lower frequency for longer than the so that we can be very high level of geographical coverage, a small number of issuers, thereby reducing costs the infrastructure.
High spectral efficiency-4 channels in 25 kHz and no such detentions band compared with the mobile and 8 channels in 200 kHz and custody band. Soon to appeal the local - one of many of the Panel to the General settings of 0.5 seconds (General less than 250 milliseconds, only one node appeals) compared to the number of seconds (in general, 7 10 type), it is necessary to a GSM network.
The working, high-speed > 400 km/h. TETRA has been used in France High-Speed Record speed in 3 April 2007-574.8 km/h. The system contained a number of mechanisms aimed at protocols and radio parameters, to ensure that communication even success overloading of the (for example, in public events or a disaster situations) and will always have requested through different mobile telephone system. The system is also supporting a series of urgent appeals of the transport. tetra infrastructure are usually separation (but connection) Public (mobile telephone network, and thus the (General) No telephone charges system owners, significantly more diverse and flexible communications and it is easy to customize and integration in data applications (vehicle position, geographic information system databases, scheduling system, etc).
Unlike most mobile technology, tetra networks in general some reserve public transport, such as the capacity of local telephone base station process. So-called "mission-critical network can be built all aspects of the tetra unsafe/multiple superfluous.
Without a network mobile/portable can use a direct" mode, they agreed that direct channels (phone mode).
Gateway mode a single mobile phone, connected to the network could serve as a relay other nearby mobile and less than the infrastructure.
TETRA also provided a point to point function, the traditional analog emergency services radio system did not provide. This enables users to have a comprehensive "the link between the Radios" which does not directly involved in a control room Operator/courier. Unlike the cellular technology, linking a subscriber to another subscriber (one-to-one).
TETRA is based on the one, a, one of many, many in many. These business model is the direct the public security and professional users.
TETRA supported the two air interface encryption and end-encryption rapid deployment (transfer) network solutions are available for relief and the Provisional existing capacity. equipment is available from many suppliers around the world, the welfare of competition network solutions are the two old circuit-switched (telephone) framework and buildings, IP structure and soft (software) switch.
Disadvantages of TETRA
Major shortcoming: need for a linear amplifier respect for the RF technical specifications to enable him to exist and other broadcasting services and equipment more expensive to mobile (about 750 Euros in 2003, about 600 Euros, and the 2006). This is the most difficult technical, economic size a smaller scale and different business models (e.g.: needs security and high-power and durability). However, than the major (team) * competitors technical Air Pollution Control Ordinance, all price >$3000 each aircraft. Tetra price should continue to serve as manufacturers have begun Far East of 2007. Data transmission is effective and long-term (and many kilometres) and the modern standards but slowly in 7.2 Kbit/s time (3.5 Kbit/slot net packet data throughput) while up to 4 beaches to integrate into a single data channels, the rates are relatively high, and in any one 25 kHz channel.
The latest version of standards support 115.2 Kbit/s 25 kHz or up to 2 Kbit/s expanded 150,000 Sheikh Channels. The nature of the pulse tdma are employed in the protocol and more high-power, mobile, merger (only) can sometimes interact, poor design (general old) or sensitive electronic devices for broadcasting (TV) receiver.
This has led some of the problems of users sensitive equipment, such as pacemakers, they did not documented, and if regular spent many ambulance crews. As a caution, the users of these teams should be careful with any RF to transmit equips when they use in intimate vicinities (for example < it distances 1 meter).
Key Voice Services and Facilities:
- Group Call (commonly called 'all in formed net' and 'talk group call')
- Pre-Emptive Priority Call (Emergency Call)
- Call Retention
- Priority Call
- Busy Queuing
- Direct Mode Operation (DMO)
- Dynamic Group Number Assignment (DGNA)
- Ambience Listening
- Call Authorized by Dispatcher
- Area Selection
- Late Entry
- Voice Encryption
This is probably the most basic voice services tetra but still the most complex and supports the effective and efficient. This is because Group calls for:
- Simple use of "Push to Talk" to provide a rapid called for establishing communications group.
- The operation and management of certain methods to optimize network load
- Operate in simplex
- In a "priority" web site best network loading
- A specific regional action (Area selection).
- Very reliable marks for the establishment of the protocol to ensure that all users in a group connected together when a request is the first launch (request that the accused mark is unrealistic Group's request.
- Priority mechanism to ensure that specified that the user in a wide area group, called (covered several based site) is connected together when a network is occupied.
It is that complexity, Support Group's request, the public mobile network is inappropriate, because they were the original purpose is to strengthen "one of an "invitation, on the contrary, tetra the main purpose is to support group called for a primary.
Pre-emptive Priority Call
The Service's appeal, the top priority is an urgent appeal of the highest uplink priority and the highest priority access to the network resources. If a network is busy, lowest priority communication is falling to manipulate the emergency appeal. Contrary to the 911, 112 or 999 calls of emergency of the net initiate (that it can also be supported on TETRA) publics the call of emergency of TETRA can be initiate using a dedicated switch located on the terminal unit. The emergency appeal of Activation automatically alerts affiliated dispatcher Control room terminals and other users that the people talk group.
This call service, that the highest priority is the emergency call, it provides the highest priority of upward link and the highest access of priority for resources of the net. When the emergency appeal is to support to a network, it is of vital importance, only a small number of radio terminal users with such assistance is to maintain important appeal may be lost.
During the periods of maximum acme of the net, this service allows the net to the access for resources to user unit's terminal state of priority appeal. When there are 16 levels of priority in TETRA, this service is very useful in providing it varies levels of levels of service (the intents) (and of the tariff systems) during the periods. For example, official of first line they would be given with the highest priority that the levels of the public's security connect to a net to maintain the highest level in the access of the service then / then routine that users would be provided at the lowest level in the priority.
In a file TETRA is foreseen by lorry in the net of transport of controller during the periods to keep and to direct its calls on one first in the first out) it bases on order for the user level of priority. The advantage is that an user has to begin an order of having called once, knowing that, even in the times of Pointe in that the call will automatically be created as soon as a traffic channel becomes free, reducing the user tension and the frustration therefore, when fights with other users in an inhabited net.
Direct Mode Operation (DMO)
Operation of direct (BMD) Mode gives the possibility for terminal units of radio of TETRA to communicate directly with each independent of the infrastructure of the net of TETRA. BMD is not new and it has been an authorized installation and to use for many user organizations of traditional PMR for several decades. The main requirement for DMO has been provoked by the necessity of balancing the covering of RF, the category of service (the intents) and dependability of a net on the whole with that of the cost of the net. The requirement for DMO makes the inadequate use of cellular public nets.
Dynamic Group Number Assignment (DGNA)
This service allows that the creation of users' unique groups manages the different communication necessity and it can also be accustomed to the group participants in a call in course. This service is considered by many organizations of public security of being extremely useful in Sep up a group of common chat for incident communications. For example selected users of the police, fire and ambulance could be brought together to take a very important emergency where the coordination fences among the three emergency services it is required. In a similar way, DGNA is also considered useful to direct the incidents for other user organizations like services and transport.
A sender can put a terminal unit of radio in the way of atmosphere listening without any sign that are provide to the user of terminal unit of radio. This controlled distant movement allows that the sender listens bottom noises and to conversations inside the reach of the microphone of the terminal unit of radio. This is an important service to use for those people that it transported the important and valuable and/or delicate material that could be the goals of air Kidnapping. Similarly, this is a useful service and the implementation of public service vehicle drivers from the health and safety will also be threatened.
The number of user applications listening service atmosphere in which many, and in many cases, application of the particular. However, it is important to note that, many users may believe that this service occupied an individual's right to privacy, therefore, only those users who need atmosphere of its work listening functions should be for the service.
Call Authorized by Dispatcher
This service allows the dispatcher to verify call requests before calls are allowed to proceed. This is a useful service to utilize when radio user discipline needs to be maintained. This Service also reduces the amount of radio traffic on a network as only essential work related calls are permitted. However, the need for frequent informed all net users group communications between Terminal and the time delay experienced in authorizing calls can make this service unacceptable for some user organizations.
Choice of areas of operation definition, the user can choose to a "call on the basis of. The services are essentially modeling capacity a scheduling; choose different base station, a request, probably in traditional network. It will also help to improve network loading and overall spectrum efficiency the restricted area of operation and the group called selected.
The service provides the incessant calls for Update, let latecomers to a communication channels. This is not a service, but an air interface feature that allows trunked radio terminals acts of similar methods, the conventional force terminal. For example, if a user open its tetra terminal control channel will be automatically transferred the user terminals, a discussion group if a requirement that had been in progress. Also, if the user's terminal has been outside radio, for example, in a tunnel and control channel will divert the user terminals, a discussion group called an appeal was made on the progress made.
TETRA standard support some air tetra algorithm (tea), different types of users, they are permitted use them. The main benefit the encryption is over, it could carry out the software in radio stations and base station equipment, rather than using encryption modules, consumption by the space and cost. TETRA standard also support end to end the encrypted with other encryption algorithm that in the national security organizations need.
The Main Installable Equipments
We find the types of Private Automatic Branch Exchange (PABX) and Electronic Private Automatic Branch Exchange (EPABX). We connect their PABXs for our telephone system. So we can use the telephone and likely using Internet.
PABXs make connections among the internal telephone by private organizations and connect to the public telephone switched network (PSTN) through the lines of trunk.
Because the integration phone, fax machine, a modem, the generic term "extension" that is used to refers to the end of the All. PABX differentiated as the key to the user's system is the key system is choosing they own outgoing choosing good and PABX outgoing automatically.
The Major advantage of PABXs was cost savings on internal phone calls: handling the circuit switching local reduction charges for local telephone services. As PABX gained popularity, they will be begun offering services that do not available in the network operator, call forwarding, and extension dialing. We need by packet switching networks for the data; therefore, using the telephone calls has been tempting, and the availability of the Internet as a delivery system world packet switching communication even more attractive. These factors leading to the preparation of VoIP PABX (on technology, what is "exchange more, but abbreviation PABX such broad understanding, it is still in use.
Another trend is to focus on core competencies. In a host of installing PABX located and management of the telephone service providers and characteristics and requirements through the Internet. We only signs of service and buy expensive hardware and maintenance. This is to delete section from private premises of the Centre.
The PABX performs four main call processing duties:
- Establishing connections (circuits) between two users of telephone sets
- To Maintain such connections as long as the users require them (i.e. channeling voice signals between the users)
- These connections to disconnect the per user's requirements
- Accounting Provides information about the purpose (for example, metering call)
Telephone Systems for Single-Site Organizations
- Car Phone
- Cordless Phone
- Mobile Phone
- Professional Mobile Phone
- Radio Phone
- Satellite Phone
- IP Phone
A car phone is mobile telephone equipment designed specifically for and loaded with a car. The car phones is in the late 1970s and 1980s, more and more people than the regular mobile phone. However, the mobile phone fever in the 1990s, mobile telephone service have become more expensive, car phone suffers a loss, as most people implementation of their mobile phone surrounding the people, including in the car. On the other hand, free of charge hand KITS AVAILABLE now installed many of the cars to make the drivers can be discussed and heard the appeal driving although.
The original car phone services may now referred to as 0 G (zero generation) service, in 1 G (first-generation) is that it was the beginning of modern mobile telephone services. In Finland, car phone service is the first-available in 1971 on zero generation ARP (Autoradiopuhelin, or a car radio-telephone service. This was happened in 1982 by NMT of system of 1G (Nordic wireless telephone), used to the other side of Scandinavia and in other areas often distant. In North America, car phone typically use mobile phone service (MTS), this is the first used in St. Louis or improve mobile services (IMTS) Former giving way to analog mobile telephone services (5A) in 1984. AMPS technology was stopped in the United States in 2008.
As a traditional car phones use a high-power transmitter and external Antenna, it is the ideal of rural or developed regions mobile handset may not work, or at all. However, due to the current US Federal Communications Commission, the carrier must pay a fine, start any equipment, is not an e 911 compatible devices, such as analog.
A cordless telephone or portable telephone is a telephone with a wireless handset that communicates via radio waves with a base station connected to a fixed telephone line, usually within a limited range of its base station (which has the handset cradle. The base station is on the subscriber premises, and attaches to the telephone network the same way a corded telephone does.
The user buildings are distinguishing a cordless telephone from a cellular phone. The current cordless telephone standards, such as PHS and DECT, has become blurred, once it became clear line between rope and mobile phone, the transfer of batteries, Remove the trees of the line once among wireless and movable telephones implementing delivery of cell advanced several characteristics, as the transfer of data and not even, on a limited, international scale to wander. In these models, a commercial mobile network operator maintains the base station and includes users' subscription services.
Different from that record telephone, a cordless phone requires main electricity to power base station. The cordless handset is the one type of the rechargeable battery, which is charged by sitting in its cradle.
The makers announce that the systems of more frequency improve the quality of audio and the extension generally. High-frequency in fact worse by the ideal breeding as basic Friis transmission equation, and the path loss tend to increase loss in higher frequencies. More important influence on the quality and range are signal strength, antenna quality, the method modulation used, and the obstruction, while local varied.
"Plain old telephone services"(POT) landlines designed to divert the audio and a quality, is only the parties enough mutual understanding. Typical bandwidth is 3.6 kHz; only a small part of the frequency, human beings can hear, but is sufficient for Speech Understanding. There is no phones can improve the quality, because it is a restricted the telephone system itself. The telephones of better quality can transfer this sign to the handset with less interference on a bigger extension, however. Most of the wireless telephones, however, what a matter exactly not used the frequency tape or transmission method they are, they will combine with the quality of sound of a quick telephone of good quality fixed to a good line phone hardly ever. Some problems that this kind of check and supervision cause include the following:
- Sidetone: hearing one's own voice echoed in the receiver speaker
- Significant quantities of ongoing background noise (this is not to interfere in from external sources, but the noise level cordless telephone system.
- Frequency response has not been fully frequency response in the existing cable landline telephone.
Most of the manufacturer claims that a series of about 30 meters (100 feet) 2.4GHz and 5.8GHz system, but cheap mode often fail to meet this claim.
However, higher frequency often brings benefits. The 900 MHz and 2.4 GHz band increasingly used as a host of other devices, including the infant Monitor, microwave ovens, Bluetooth wireless LAN; therefore, it is possible, a cordless phones will be interference with the signal broadcast of the equipment. It is there may also be a cordless telephone interfere with the 802.11 a wireless standard, the 802.11 a standard can be configured to at the operational 5.8GHz frequency range. However, this is an easy fixed the configuration of equipment, the work of the 5.320 5.180 GHz to GHz band.
Recently allocated 1.9GHz frequency band has reserved for the phones use dect standards, which should avoid interference problem, more and more to be seen as in the unlicensed 900MHz, 2.4GHz, and 5.8GHz band.
In early next century, most of the cordless phones are digitals. Digital technology will provide to get clear sound and restricted wiretapping. Many cordless phones have a major base station, which can increase three or four additional base. This can give multiple voice paths so that it can be pass three ways conference calls between the bases. This technique also allows multiple uses of mobile phones in the same time, up to 2 handheld devices can be an external conversation.
A mobile phone or mobile phone (also known as neck, mobile phones ) is electronic equipment for mobile telecommunications (mobile phones, newsletter or data transmission) more than one mobile network of specialized base station called mobile communication stations. Mobile telephone different from cordless telephones, providing only telephone services of limited in scope for example, in a home or office, through a fixed route and a base station have a user, also from satellite telephone and radio-telephone. And not a radio-telephone, mobile phones with a full-duplex, automated telephone and paging from a public land mobile network (PLMN) and handoff (handover) in a telephone when a user from a cell (base station area, covering), another. Most of the current mobile connect to a mobile networks, including exchange points and base station (cell sites) have a mobile network operators. In addition, the standard voice capabilities, the existing mobile phone may support many of the additional services, and accessories, such as SMS text messaging, e-mail, packet-switching technology, use the Internet, games, Bluetooth, infrared, cameras and video cassette recorders and mms used to send and receive pictures and video, MP3 player, radio and global positioning system.
Analog cellular telephony (1G)
The first business automation cellular network (1G generation in Japan's NTT in 1979) starts the network covering the whole of urban areas, more than 20 Tokyo residents of the 10,000 a mobile network of 23. In five years, Nippon Telegraph and Telephone Network has been expanded to cover the entire population of Japan to become the first nationwide the second-generation service network.
A number of States at the earliest in middle including the United Kingdom, Mexico and Canada in the early 1980s G fired network. In the United States launch the first 1 G Internet use in 1983, well-known first-hand grip moving Tel Motorola Dynastic is based on the Chicago the Ameritech. In 1984, Bell Laboratories development modern business of cell technology (as the basis, to a large extent, in the last pleased, Perelman patent that use multiple, focus to control station (cell site), a small regional (a cell) each of these provide servo. Cell site will be set up such a cell overlap. In a mobile telephone system, a signal in a base station (cell) and a Terminal (telephone) only strong enough to between the two, therefore, the same channel can use a different dialog that different cell.
The first facilities as well as the first designated medical facilities are based on the Ericsson ax digital exchange node.
Mobile telephone system needs to be some leaps of technology, including handover, which allows for a topic, continue to be a mobile phone travelled from cell, cells. The system includes variable transmission power in the two base stations and telephone (control the base station) which allow scope and cell size. As the system to expand and nearly capacity, so as to reduce transmitted to allow the new cells will increase, resulting in more, small cell, and thus more capacity. The evidence and this growth can still see in many older, tall cell towers, there is no Antenna tower upper part. These places created big cells and therefore the antennae on top of the tower atop towers, the purpose of enabling the system to expand and cell size reduction can lower the antennae.
Digital mobile communication (2G)
At the first "modern" network technology in digital 2 G (the second-generation) mobile technology was launched the Radiolinja (now Elisa group part in 1991 in Finland standards, also marks the introduction of competition mobile telecommunications when Radiolinja challenge incumbent Telecom Finland (now some of the Company) who ran a 1G network.
Wideband mobile communication (3G)
In 2001, the first commercial launches 3G (3G again in the Japanese NTT docomo WCDMA standards.  The second-generation CDMA network to be consistent with the third generation through an amendment to an EV-DO. A revised EV-DO put forward some added that the protocol to maintain it fully compatible with older versions of the EV-DO.
These included a number of new forward link data rate, and the increased maximum burst rate from 2.45 Mbit/s to 3.1 Mbit/s. Also included the Protocol and to reduce a time (called for strengthening MAC channel), the capacity of more than a mobile share the same time slots (Multi-User packets) and the introduction flag QoS. All of which are put to the low latency, low speed communications such as VoIP.
One of the latest 3G technologies for the implementation is High-Speed Downlink Packet Access (HSPA). It is an enhanced 3G (3G) mobile telephone communications protocol in high-speed packet access (''HSPA'') family, creating a 3.5 G 3 G+ or turbo 3G that make the net based on universal mobile telecommunications system (UMTS) for getting higher data transmission speed and power. Current HSDPA deployments support the down-link of 1.8, 3.6, 7.2 and 14.0 Mbit/s. Because of the provider of HSPA +, the speeds are increasing more than 42 Mbit/s receptions and 84 Mbit/s and release 9 of 3 GPP standards.
Broadband Fourth generation (4G)
The next evolution, recently released its fourth generation is also known as the 3G after the literature to provide a broadband wireless access than a nominal data rate of 100 Mbit/s, rapid mobile devices, and 1 Gb/s in the definition of the fixtures ITU-R  4 G systems may be based on a three GPP LTE (long-term evolution) movement, and to provide high rates of 326.4 Mbit/s. It may also be WiMAX-based or flash-OFDM wireless metropolitan area networking technology to ensure wireless broadband access speeds to 233 Mbit/s the mobile phone users. Radio interface, the systems are based on all-IP Packet Exchange, MIMO diversity, many carrier modulation plans, dynamic channels transfer (DCA) and channel-dependent arrangements. A 4G system should be a fully replace the existing network infrastructure and is expected to provide a comprehensive and safe solutions, voice, data, and streamed multi-media also to users in a "Anytime, Anywhere" basis, and more high data rate than previous-generation. Sprint has a 4 G network, select areas. It is expected in 2011, more wireless will be Release 4 G broadband network.
Professional mobile radio (also known as Private Mobile Radio (PMR) in United Kingdom and Land Mobile Radio (LMR) in North America) are in the field radio communication system, use portable, mobile phones, base station, and send console radio. Action team of radio equipment is based on such criteria as MPT-1327, TETRA and Air Pollution Control Ordinance, 25, that is designed to use the specific organizations, or standards, such as NXDM for general commercial use. A typical example is radio systems used by the police and fire brigade. Main feature of the professional Mobile Radio System could include:
- Point to multi-point communications (as opposed to cell phones which are point to point communications)
- Push-to-talk, release to listen — a single button press opens communication on a radio frequency channel
- Large coverage areas
- Closed user groups
- Use of VHF or UHF frequency bands
A wireless phones are communications equipment, allows two or more of the people use of the radio. There are differences of opinion definition. There are some of the contradictions British Use of English, United States Use of English, and historic use. Possible confusion here similar terms wireless phones and mobile phones. A historic event and mobile phone was used for two-way radio has yet to find. However, since 1930s the Federal Communications Commission issued a variety of commercial "radiotelephone operator" licenses and permits, qualified applicants. This makes their installation, services and maintains voice-only radio transmitters system uses the vessels and aircraft.  (Until deregulation in the 1990s, they also needed domestic commercial radio and television broadcast system. As the treaty obligations, we still have to engineer International short-wave radio station; Certificate is issued a general radiotelephone operator license.
As push-to talk
A simple handheld wireless phones are sometimes referred to as "walkie-talkie. CB radio is also a very similar technology. While in recent years, mobile phones have largely replaced radiotelephone the average users, they are still being widely used in many specialist applications, such as Police Communications, emergency services, the taxi service, private mobile radio network (service) and air communications and the plane.
Privacy and selective calling
Often, on a small network system, there are many mobile units and one main base station. This would be typical for police or taxi services for example. To help direct messages to correct the recipients and avoid irrelevant traffic on the network's being a distraction to other units, a variety of means have been devised to create addressing systems.
The crudest and oldest of these is called CTCSS, or Continuous Tone-Controlled Squelch System. This consists of a precise superimposing very low frequency signal tone on the audio. Only tuned to the receiver this specific tone is able to receive the signal: This receiver shuts off the audio when the tone is not present or is a different frequency. Designation of a unique frequency, each mobile, and the private channels can be imposed upon a public network. However, it is only a convenient functions it does not protect privacy.
A more commonly called system is selective calling or recall. It also use audio sound, but this is not restricted, audio sound, sent a short bursts order. The receiver will be programs to respond only a unique tone in a precise sequence, and then they would be open audio lines conversation open channels the base station. This system is much more versatile in CTCSS, relatively few sound produce more and more "addresses". In addition, the special functions (such as playback mode and emergency cover) can be in the design, use of the Special theory and earmarked for the purpose. A mobile units can also broadcast a series of recall its unique a basis for settlement, so that users can know previous appeals, takes up the unit. In practice, many recall system have automatic transponding built-in, which allows the base station "interrogate" a mobile even if an operator does not exist. This transponding system usually have a status code, users can set to show they have done. Features such as this, although it is very simple, is a reason why they are very popular organizations, need to manage the large number of long-range Tactical Unit. Recall is widely used, although it is a place of the more advanced digital system.
A satellite phones, satellite phones, or sat phone is a type of mobile phone, connected to orbit satellite and not land mobile communication stations. Under the framework of a specific system, coverage as a whole may include earth, or only specific areas.
The mobile equipment, also known as a container terminal, has a big difference. Early satellite mobile phones have a size and weight is the same in the late 1980s, in the early 1990s mobile phones, but there is usually a big retractable antenna. More recent satellite phones have the same size, a regular mobile phones, some prototypes satellite telephone no distinction between different the smart phones.   sat phones most popular adventure to remote areas of land mobile services unavailable.
Fixed installations, such as used on-board, possibly including large, rough and frame-installation of an electronic, and a shift toward microwave antennas the mast, auto tracking the indirect satellite. VoIP small devices over two-way satellite broadband services, such as ASTRA2 Connect Maritime Broadband network the costs reached within the context of leisure boat owners. Internet service satellite telephone a well-known poor reception room, although it is likely to be consistent signal nearly a window or on the top floor of a full of building if the roof. The plane is connector of external Antenna, often installed on vehicles and buildings. Some systems are allowed to use repeaters, much like land mobile telephone system.
In some countries rule oppressive regimes such as Myanmar and possession of a satellite phone is illegal.   its signals), will bypass the local telecommunications system; affect the examination and wiretapping attempts. In Australia, residents in remote areas may apply for a government-funded a satellite telephone.
An IP telephony use allows telephone Voice over IP technology made an IP network, such as the Internet, not PSTN system. Calls upon can traverse the Internet, or a private IP network, for example, Session Initiation Protocol, Skinny Client Control Protocol or one of various proprietary protocols such as that used by Skype. IP Phone can be simple software-based soft phones or special hardware device; it is like an ordinary telephone or a cordless telephone. General PSTN telephone was used for IP telephone with analog telephone Adapter (ATA).
It would probably have a lot of features the analog telephone does not support, such as e-mail-like logo of contacts might more easily recall in the name or phone number. Elements of IP telephony:
- DNS client
- STUN client
- DHCP client (not commonly used)
- Signaling stack (SIP, H323, Skinny, Skype, or others)
- RTP Stack
- Codecs (Audio codecs such as G.711, GSM, iLBC, Speex, G.729, G.722, G.722.2 (AMR-WB) etc. Video codecs such as H.263, H.263+ and H.264)
- User interface
Hardware-based IP phone
Total hardware might look like a telephone or mobile phone. IP telephony has the following hardware components.
- Speaker/ear phone and microphone
- Key pad/touch pad to enter phone number and text (not used for ATAs).
- Display hardware feedback user input and show caller-ID/information (and not to Agates).
- General purpose processor (GPP) to process application messages.
- A speech engine or a digital signal processor, the process rtp message. Some IC manufacturers with and DSP, single-chip.
- ADC and DAC converters: To convert voice to digital data and vice versa.
- Ethernet or wireless network hardware, transmit and receive e-mail data networks.
- Power may be a battery or DC power supply. Some IP telephone receiving electricity power, the Ethernet card.
For wireless IP phones
- Wireless network interface controller
Common features of IP phones
- Caller ID
- Dial-Up use of the name/number (unlike speed dial the number is stored in the client)
- Locally stored and network-based directories
- Conference and multiparty call
- Call park
- Call transfer and call hold
- Save the user name/number when choosing a different service provider (not widely supported).
- Applications such as the weather report, schools and offices, life news...
Features available with each system
And then these basic functions, PABXs offer many other calling features and capabilities, with different manufacturers providing different features in an effort to differentiate their products. Common capabilities include:
- 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
- Conference call
- Custom greetings
- Customized Abbreviated dialing (Speed Dialing)
- Busy Override
- Direct Inward Dialing
- Direct Inward System Access (DISA) (the ability to access internal features from an outside telephone line)
- Do not disturb (DND)
The PABX exchange is configured with a list of numbers for our customers. When a call is received, the exchange routes it to each number on the list in turn until either the call is answered or the list is exhausted (at which point the call may be routed to a voice mail system).
- Interactive voice response
- Music on hold
- Night service
- Shared message boxes (where a department can have a shared voicemail box)
- Voice mail
- Voice message broadcasting
- Voice paging (PA system)
- Welcome Message
A mobile PABX is a hosted PABX service that extends fixed-line PABX functionality to mobile devices such as cellular handsets, smartphones and PDA phones by provisioning them as extensions. Mobile PABX services also can include fixed-line phones. Mobile PABX systems are different from other hosted PABX systems that simply forward data or calls to mobile phones by allowing the mobile phone itself, through the use of buttons, keys and other input devices, to control PABX phone functions and to manage communications without having to call into the system first.
An IP PABX handles voice signals under Internet protocol, bringing benefits for computer telephony integration (CTI). An IP-PABX can exist as physical hardware, or can carry out its functions virtually, performing the call-routing activities of the traditional PABX or key system as a software system. The virtual version is also called a "Soft PABX".
Costs of Operation System
In the business, time is of paramount importance. The faster we can make a decision and exchange of information, and raise their chance to ensure that transactions, and to ensure that the customers happy. The company plans to red link broadband services, therefore, we can choose from Suite value and broadband solutions to meet the difficult challenges you. Recommendation 12 PCs, enterprise program is the 10 US, can easily establishment of a large office broadband solutions, and if you have many customers or workstations, although we company package plan most suitable for large office environment 35 PC. Static IP address option should also provide such police station to enhanced features.
The recommendation of professional mobile radios are field radio communications systems which use portable, mobile, base, station and dispatch console radios. They can communicate the point to point communications, push-to-talk and large coverage areas, closed user groups and VHF, HF frequency bands.
The reason or recommendation is the four districts and one of serious crimes squad head require point to point communication and all of police officer user push-to-talk device, walkie-talkie and also police patrols. They can go by using this device anywhere of under main station. Often, on a small network system, there are many mobile units and one main base station. They are still widely used in many more specialist applications, for example police communications, emergency services, taxi services, private mobile radio networks (PMR), and in-flight communications to and from aircraft.
The core technologies used in the TETRA standard, such as Digital, Trucking and Time Division Multiple Access (TDMA) also provide a number of inherent advantages and benefits as follows:
Nowadays, practically everything electronic uses digital technology and wireless communications are no exception. Even though analogue FM PMR communications will remain a viable option for several years, digital radio provides relative advantages and disadvantages in the important performance areas of:
- Voice Quality
- RF Coverage
- Non-Voice Services
Relay technology has been used for many years of switched telephone network. The first systems of communication of radio movable trunked were deployed when early the 70 are in North America with protocols reserved signaling and shortly later in the technology of MPT1327 of similar Europe to use. The main benefit the route is often seen as spectrum efficiency, or more users each RF radio channels and more traditional channels at some level of service (GoS) have automatic and dynamically allocated a small number of channels of communication sharing between a relatively large numbers of users.
The relay system to support more radio users than conventional system, the National Administration actively support for the deployment relay system, which would help to reduce pressure on the team spectrum. However, from one of the radio user operational point of view, spectrum efficiency does not mean. What users want and resolve all the operations of the standing force with, but still retain the simple regular public channels informed all networks. The basic elements of the route, could resolve these traditional team is to use a control channel. Table 1 operational issue in the traditional team, it also shows how to use relay resolve these problems.
It is important to note that the simple conventional force, "All informed the discussion group net communications remains employed rapid call set up "Promoting Talk" (ptt) operating the radio terminals.
Additional Services and Facilities
In Control channel acts as a signal to man the links between the relay system controller and all mobile radio terminal operating system, the trunking controller know the status of the system at any time, and its historic use, which is stored in its memory. For example, the Trunking Controller knows:
- The individual and group identity of all radio units registered on the system
- The individual identity and time radio units registered on the system
- The individual identity and time radio units de-registered from the system
- The individual and group identity, time and duration of all messages
Further information on the radio station and the relay controller and interests of the benefits route can increase. For example, the length of control channel signaling information can be increased by an amount to accommodate the new services and facilities. Also, the trunking can be programmed to manage the calls in to variety of ways like to require for the operator of the system.
Time Division Multiple Access (TDMA)
A four-time through the TDMA technology is tetra provides it with the best solution, to balance the costs of the equipment and support services and facilities the user organizations a medium to high networks provide a single site local RF coverage and/or multiple sites Wide Area RF coverage.
Radio frequency spectrum efficiency is a combination of three main factors are occupied bandwidth per communication channels, frequency to use the carrier factors, the disturbance rate of protection C/I in dB, the trunking technology use. As previously mentioned tetra has also spent the most new route technology. In addition, TDMA technology used in tetra provide 4 independent channels of communication, a 25 kHz beam bandwidth channels so that it twice, effective occupied bandwidth articles as a traditional 12.5 kHz RF broadband site channels. Although site technology is often have a better C/I performance than TDMA tetra, overall spectrum efficiency tetra advantage, especially for medium to high networks.
Due to the use TDMA technology, costs and equipment in the space station base station can greatly reduce and more traditional site technical route solutions. Another use TDMA technology is for new services and facilities are to support the minimum fee. Some examples:
Higher Data Rates
"The Law of physics restrictions with the largest data rate in a particular RF bandwidth. Assumptions in the same modulation plan, the broader channels of bandwidth of high data rate. Because TDMA versatile channels sites other than the integrated data rate in a single RF carrier is further.
Improvement of data throughput of the poor conditions of the RF signal net data rates than TDMA site in poor conditions of the Program launched frequent. This is because auto repeat (ARQ's) shall be the receipt of data is damaged a result of RF gradually disappear. As TDMA in the one that the terminal devices efficiently ARQ's works in both senses they can be efficiently a correspondent after each hole transmission instead of waiting until the end of each vocal transmission, as being generally the box with FDMA.
Bandwidth on Demand
The TDMA any number of time up to the maximum limit of technology has been employed can be combined to increase the data throughput application-specific.
Concurrent Voice and Data
The TDMA time framework is to specify a time, support for voice and the next period of time, supporting data in a two-slot from radio transmission terminals. These capacities to effectively allow for a single radio terminals at the same time transmit or receive voice and data at the same time.
Full duplex Voice Communications
TDMA technology is to support full-duplex communication. Although the duplex voice communications on site can support system needs to be duplex operational needs between RF screening the transmitters and receivers, is also a duplexer allowed for single antenna. That is why the double-sided site radio terminals are usually replace and more expensive, from TDMA pier, and do not need RF screening or to antenna.
Task - 5
By using internet service provider (ISP) in our system, This can solute cost effectiveness for police department and provides high speed internet access and a voice capability using VoIP technology and the Network with multiple Points-Of-Presence will ensure uniform converge for the whole of Yangon. The WLAN protocol is engineered to reduce the demanded bandwidth and maximize the number of wireless network types that can deliver. Multiple WLAN networks within an area can be achieved, with the additional aim of multiple networks. The WLAN equipment can go point-to-point (PPP), speed up to 100MB at range of 3000 meters to send and receive e-mail messages, upload and download documents (PowerPoint briefing slides, spreadsheet, etc.) and small data files. The WLAN equipment can theoretically support up to 200 customers. In view of wireless technology, cost reductions of network components will be possible compared to alternative technologies like traditional wired LAN. Cards that plug into PC or laptop are promptly available, and operate either Peer-to-Peer or Peer-to-AP Mode. WLAN can be installed and configured in a variety of topologies to meet the needs of specific. WLAN technology becomes a more secure and trusted channel by which customers may conduct their financial affairs, the market for WLAN will become even more lucrative. All workstations are directly connected to the bus. The bus is terminated at either end with electrical resistors.
A single button push will connect the user to the users in a selected call group and/or a dispatcher. It is also possible for the terminal to act as a one-to-one walkie talkie but without the normal range limitation since the call still uses the network.
If enabled by the Subscriber Management TETRA terminals can act as mobile phones (cell phones), with a full-duplex direct connection to other TETRA Users or the PSTN. Emergency buttons, provided on the terminals, enable the users to transmit emergency signals, to the dispatcher, overriding any other activity taking place at the same time. TETRA uses Time Division Multiple Access (TDMA) with four user channels on one radio carrier and 25 kHz spacing between carriers. TETRA provides Authentication Mechanisms of Terminals towards Infrastructure and vice versa. For protection against eavesdropping, over the air encryption and end-to-end encryption is available. TETRA provides Authentication Mechanisms of Terminals towards Infrastructure and vice versa. For protection against eavesdropping, over the air encryption and end-to-end encryption is available. For choosing of wireless from MPT, wireless broadband can provide anywhere, anytime. The reason is the four districts and one of serious crimes squad head require point to point communication and all of police officer user push-to-talk device, walkie-talkie and also police patrols. They can go by using this device anywhere of under main station. Its main disadvantages are: requires a linear amplifier to meet the stringent RF specifications that allow it to exist alongside other radio services.
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