Police Station Network Topologies And Media Computer Science Essay

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Ring topology, also known as ring network, is a type of computer network configuration where computers and devices are connected to each other in the form of a large circle (ring). Each computer in the network is called as host that handles every message which flows through the ring. Each host has a unique address. If a host sends packet to another host, the packet is sent around the ring until it reaches its final destination. Signals always travel in only one direction around the ring because the ring network has no end and so the termination is not required. Every computer in the ring is responsible for retransmitting the data. The ring network uses coaxial cable or fiber-optic cable as a transmission media. If one computer fails in the single ring network, the whole network is going to breakdown. The Fiber Distributed Data Interface (FDDI) network overcomes the disruption in the network by sending data in the clockwise and counterclockwise direction on the ring. The FDDI network has two rings. If one ring is failed, the network is still alive with another ring. Token passing is one method for sending data around the ring. A small packet, called a token, passes around the ring to each host. If a host has the information to send, it modifies the token, adds address ad data and sends it around the ring to the destination device or returns to the sender. When the intended device receives the information, it creates a message and returns to the sender to acknowledge for its safe arrival. Modern ring network uses "smart hubs" which recognize the computer's failure and remove the computer from the ring automatically. Each computer has an equal opportunity to send data and so a single computer can't be able to monopolize the network.

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Star Topology

Star topology is a type of network topology in which the computers and devices are connected to each other by using the cables and central connection point such as hub or switch. Typically, the star network needs more cables than the bus network. The cables used in the star network are unshielded twisted pair (UTP) and shielded twisted-pair (STP). If one computer fails in the star network, the failure affects the only one computer and not the entire network. In the star network, the entire network depends on the hub or switch and so if the whole network is breakdown, there could be a problem in the hub or switch. This feature makes easier to troubleshoot because the administrator can fix quickly and easily network problems including a single device or cable without affecting the other devices. Switching technology is used to connect hosts and devices in the star network. In the star network that used hub as a central device, when the computer sends the signal, the hub receives it and retransmits it through every cable to all of the hosts and devices which are connected to the hub. All hosts have the signal and check the destination address but only the host that the signal is addressed processes the data. In the star network that used switch as a central device, when the computer sends the signal, the switch takes it and retransmits it to one of its port where the intended computer is connected. In this method, the multiple computers can connect simultaneously without affecting each other. The star network that used switch is faster than the star network that used hub. Star network configurations are 100-Base-T and 1000-Base-T local area networks.

(b) Advantages of coaxial cable

Has a sufficient frequency range to support multiple channels

Each multiple channel offers substantial capacity

Provides greater bandwidth for each channel

Supports mixed range of services

Improves noise immunity and has slightly better performance than twisted-pair cable.

Promotes compatibility and interoperability of different vendors' equipments.

Resists electromagnetic interference.

Disadvantages of coaxial cable

The bus topology which uses coaxial cable is susceptible to congestion, noise and security risks.

May be damaged by lightning strikes.

Installation costs are high.

Is heavy and bulky and has high attenuation and so it would have need to implement repeaters.

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Is difficult to install.

Is difficult to troubleshoot.

Can't be bent around tight radiuses

Can't be tolerant to fault.

Advantages of unshielded twisted-pair (UTP) cable

Limit signal degradation caused by electromagnetic interference (EMI) and radio frequency interference (RFI).

Can carry data at a faster speed.

Less expensive than other type of network media.

Is easy to install.

Is easy to troubleshoot.

Is easy to move and change.

Can be used with most of the major networking architectures.

Disadvantages of unshielded twisted-pair (UTP) cable

The distance between signal boosts is shorter than it is for coaxial and fiber-optic cables.

Sensitive to noise.

(c) I recommend star topology and switch and twisted-pair cable to use. Because the star topology is easy to manage for its simplicity in the functionality. The problems in the star network are easy to troubleshoot. The star topology has very simple format and so it is very easy to expand on the network. If one host fails in the network, it affects only the failure host and not the entire network. It has good performance and it is also very easy to replace, install or remove hosts or other devices. When the computer sends signal to another computer, the switch receives it and transfers it directly to the destination computer and so it is fast in speed. The twisted-pair cable can carry data at a faster speed. If the switch is safe, very computer in the network is safe. So, this type of network conveys more privacy than any other networks.

Task 2

(a) The internet services that may be required are

Sending Email from one police department to the another police department.

Sending the sensitive message from one department to another by using the internet connection.

Watching the websites to know about the news of all over the world.

To announce the new policies of the department.

(b) The suitable connection speeds for these services are 512 kbps because it is high bandwidth, high speed and it can use securely.

(c) The ISPS that can meet these requirements in my country are MPT and Red Link.

MPT offers the plans for ADSL service as following.

Plan

Activation Fee (FEC)

Monthly Fee (FEC)

Free E-mail Accounts

Maximum Attached Devices

Speed (kbps)

Data Limit (MB)

Consumer (Data only)

840

35

1

1 PC

128

400

Consumer

840

45

1

1 PC + VoIP

128

400

Enterprise

840

75

3

4 PC + VoIP

256

2,000

Corporate

840

130

25

12 PC + VoIP

512

10,000

VPN

840

100

-

-

512

10,000

Red Link offers the plans for Wi-max service as following.

Plan

Monthly Fee (FEC)

Free Email Account

Maximum Attached Devices

Speed (MIR)

Consumer

45

1

1 PC + 1 VoIP

128 Kbps

Enterprise

75

3

4 PC + 1 VoIP

256 Kbps

Corporate

130

25

12 PC + 2 VoIP

512 Kbps

Installation Fees

Wi-max Activation Fee= 840 FEC

Wi-max Annual Fee = 60 FEC

Wi-max Equipment Fee= 600 FEC

Total Fee = 1,500 FEC

VoIP Service (Optional)

VoIP Activation Fee = 50 FEC

VoIP Annual Fee = 60 FEC

VoIP Adapter (3 ports) = 250 FEC

Total Fee =360 FEC

(d) I recommend to choose the MPT as the internet service provider because it is the best internet service provider in my country. In the connection speed, I recommend to choose the ADSL with the corporate plan because it has 512 kbps with the reasonable cost and it is enough to use the required internet services for the police department.

Task 3

(a) I investigate GSM and walkie-talkie as the two methods of the two-way voice communications that could be implemented by the police department. I am going to explain how each method works.

How GSM works

Global System for Mobile Communications (GSM) is an international standard and can use in the many parts of the world. GSM operates with 900 MHz band (890 MHz-960MHz) in Europe and Asia and 1900 MHz band in United States. GSM network consists of three major systems; the Switching System (SS), the Base Station System (BSS) and the Operation and Support System (OSS).

Switching System (SS)

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The switching system performs call processing and subscriber related functions. SS has five databases to perform different functions. These databases are Home Location Register (HLR), Mobile Services Switching Center (MSC), Visitor Location Registration (VLR), Authentication Center (AUC) and Equipment Identity Register (EIR).

Home Location Register (HLR)

HLR performs storing and managing information of subscribers and consists of subscriber server profile, status of activities, information about locations and permanent data of all sorts. When the subscribers use new connection, the subscribers are registered in HLR of mobile phone companies.

Mobile Services Switching Center (MSC)

MSC handles technical end of telephony and performs switching functionality of the entire system. It controls the calls from same networks and calls from other networks. It is responsible for toll ticketing, common channel signaling, network interfacing, etc.

Visitor Location Register (VLR)

VLR performs dynamic tasks and stores temporary data regarding subscribers which is needed by MSC. VLR is connected to MSC directly. When subscriber moves to different MSC location, VLR integrates to MSC of current location and requests the data of subscriber from HLR. When the subscriber makes a call, VLR already has the required information for making call and doesn't require connecting to HRL again.

Authentication Center (AUC)

AUC handles the security end of the system. The major task is to authenticate and encrypt the parameters which verify user's identification and so the subscriber can make a call confidentiality. It makes sure that the mobile operators are safe from different frauds.

Equipment Identity Register (EIR)

EIR stores crucial information regarding mobile equipments. It provides in restricting for calls been stolen, mal functioning of any Mobile Station (MS) or unauthorized access. ELR and AUC are either stand-alone nodes or sometimes work together as combined AUC/EIR nodes for optimum performance.

Base Station System (BSS)

BSS is very important in mobile communication. It is out door units which consists of iron rods and is usually high length. It is responsible for connecting subscribers to mobile networks. All communication is made in radio transmission. It can be divided into two systems, Base Transceiver Station (BTS) and Base Station Controller (BSC).

Base Transceiver Station (BTS)

Mobile phones connect to the mobile network through BTS. BTS handles communication using radio transmission with mobile station. BTS is the radio equipment that receives and transmits voice data at the same time.

Base Station Controller (BSC)

BSC controls many cells, it registers subscribers and responsible for MS handovers, etc. BSC creates physical link between subscriber (MS) and BTS and controls functions of BTS. BSC performs the function of high quality switch by handover over the MS to next BSC when MS goes out of the range of BTS, BSC helps in connecting to next in range BTS to keep the connection within the network. BSC also performs the functions such as cell configuration data and control radio frequency in BTS. After BSC done its processes, data moves to MSC. MSC is a switching center that acts like a bridge between different mobile networks.

Operation and Support System (OSS)

OSS implements Operations and Maintenance Center (OMC) which is designed to connect to equipment of MSC and BSC. OSS monitors and controls the complex systems in the mobile networks. The basic reason of OSS is to provide users a cost effective support and solutions. OSS helps in managing, centralizing, local and regional operational activities required for the GSM networks. The important aspects of OSS are maintaining mobile network organization, provide overview of network, support and maintenance activities.

How Walkie-Talkie works

Walkie-talkie is a two-way radio transceiver. It is handheld, portable and has a half-duplex channel. While the user talks with the walkie-talkie, the user has to simply push and hold the button on the walkie-talkie. Then the sound is transmitted through the air by using the radio waves. These radio waves go to another walkie-talkie and then convert into the sound. There are basically six parts on the common walkie-talkies. They are;

Transmitter- It sends voice to another walkie-talkie after converting voice into radio waves.

Receiver- It receives radio waves sent by transmitter.

Speaker- It amplifies the sound received by receiver.

Microphone- It attains the sound and converts it into electric signal.

Crystal - It is also called channel, sets the frequency used for communication.

Power Source- It is usually from the batteries.

Most walkie-talkies have option to change channels. This prevents people from using the same channel for communication.

(c)License Cost for GSM

The licensing cost for GSM is 1,500,000 kyats.

Rates in Kyats

Rate of US $

Annual Charges

12000.00

600.00

Local Call Fees (Per Minute)

25.00

0.30

Trunk Call Fees (Per Minute)

35.00

0.30

Value Added Services

Call Line Identification Services

Call Waiting Service

Call Forwarding Service

Three Ways Call Service

Shifting Fees

Reconnection Fees

6000.00

6000.00

5000.00

200.00

120.00

120.00

120.00

120.00

30.00

30.00

Short Message Services (SMS)

(Per message- maximum 160 characters)

25.00

25.00

Equipment cost for GSM

Brand

Nokia

Model No.

Nokia 6220

Network Communication

GSM850/900/1800/1900

HSDPA900/2100 (for 3G network)

Weight and height

108 x 47 x 15 mm, 90g

Memory

Internal memory=128 MB

Micro SD Card (over 8GB)

Connection

Bluetooth 2.0 with A2DP, USB 2.0, EDGE, GPRS, WAP2.0

Multimedia

MP3, MP4, FM, TV output built in GPS, Office application, Java application

Type of Camera

5 mega pixel, Resolution= 2592 x 1944 pixel

OS

Symbian OS 9.3

Messaging

SMS, MMS, Email, Instant Messaging

Cost

190,000 kyats

Brand

Sony Ericsson

Model No.

Sony Ericsson K810

Network Communication

GSM850/900/1800/1900

Weight and height

104 x 43 x 10.5 mm, 80g

Memory

Internal memory=14 MB

Micro M2 Card= 512 MB (over 4 GB)

Connection

Bluetooth 2.0 with A2DP, USB 2.0, EDGE, GPRS

Multimedia

Game, voice memory, Walkman player, Track ID music, Java application

Type of Camera

1.3 mega pixel, Resolution= 1280 x 1024 ( can't shot video)

OS

Java phone

Messaging

SMS, EMS, MMS, Email, Instant Messaging

Cost

200,000 kyats

Equipment cost for Walkie-Talkie

Brand

Motorola

Model No.

Motorola T9680R

Available Range

28 miles

Available Channel

22 channels

Cost

$ 47.50

Brand

Motorola

Model No.

Motorola FV300R

Available Range

10 miles

Available Channel

22 channels

Cost

$ 25.00

(d) Although each method has the advantages on the communication, they also have the limitations too.

Limitations of GSM

Coverage occurs in rural areas and places like tunnels. The transmission from GSM may disturb the electronic devices. The interference from GSM is both radio frequency interference (RFI) and electromagnetic interference (EMI). The maximum range for the standard GSM is 35 km.

Limitations of Walkie-Talkie

The communication range of walkie-talkie can be reduced by the rugged terrain and can be affected by weather conditions. The sound quality is not good. The speaker is too loud so that the other person can hear the voice from the walkie-talkie. If your walkie-talkie is on the same channel with someone, he can listen to your voice.

(e) I recommend to use the walkie-talkie for communication. Because walkie-talkies are license free and don't cost any charges for calling. This reduces the cost of police fund. The walkie-talkies are very cheap and easily buy. They are portable and so the policemen can carry them together in their pockets and can communicate each other easily.

Task 4

(a) The telephone systems available in my country that is appropriate for single-site organization are private branch exchange (PBX) and key telephone system (KTS)

Private Branch Exchange (PBX)

PBX makes the connections among the internal telephones within the organization and also connects them to the public switched telephone network (PSTN) via trunk lines. The lines are connected to PBX and PBX makes connection to the central office and then it transfers the call to the other extensions when the outside number is dialed. PBX system includes the land line, PBX, phones and phone cables. In the PBX system, it contains internal switching network, microcomputer for data processing, control and logic, lines, switchboard and uninterruptable power supply (UPS).

Key Telephone System (KTS)

KTS is a premises telephone system that have buttons for calling inside an organization or outside through the public telephone network. KTS relies on the telephone company switching equipment. KTS doesn't require to dial a number to make an outside call because all lines are connected directly to the telephone company central office. KTS contains the equipment such as phone and land lines. The land lines connect each phone per line.

(b) The features of PBX

Auto Attendent

Auto Dialing

Automatic Call Distributor

Automatic Ring Back

Call Accounting

Call Blocking

Call Forwarding

Call Parking

Call Pick-up

Call Transfer

Call Waiting

Conference Call

Speed Dialing

Direct Inward Dialing

Night Service

Voice Mail

The features of KTS

Remote Supervision

Automatic Call Accounting

Speed Dialing

Caller ID

Static-specific Limitation

Selection of Signaling Sounds

(c) The cost of equipment for PBX

Panasonic KX-TDA100

Panasonic KX-TDA100 is a hybrid IP-PBX system and it provides up to 96 ports, 64 CO's and can wire up to 64 phones. Its cost is about $ 352.33. Its cost is about $ 352.33. Its features are

Up to 96 ports

Up to 64 CO's

Up to 64 phones

Multi-Cell Wireless

Maximum Cell Stations Up to 16

Maximum Doorphones are Up to 8

Maximum Door Opener Contacts are Up to 8

Maximum Voice Message (OGM) Channels are Up to 8

Maximum Voice Processing Systems contain 2 units

two BGM/MOH (Music on Hold) Inputs

two External Paging Outputs

one RS232C/SMDR Outputs

one USB Ports

Ethernet (10 BaseT) for CTI/Programming one port

Voice Over IP Gateway

Incoming Call Distribution

Universal Call Distribution

Panasonic KX-T7020 Speakerphone

Panasonic KX-T7020 is a speakerphone and it contains twelve programmable line buttons. It can automatically redial. It contains mute key, hold key, flash key, redial key, configuration key, transfer key, auto-answer key and message waiting key. Its price is about $ 64.99.

Philips Phone Cable

Philips phone cable is long about 50 ft and the connectors are 1x RJ-11-male.

Installation cost for PBX

The installation cost for PBX is about $ 1,000.

The cost of equipment for KTS

Panasonic KX-TDA100 telephone and Philip phone cable can use for the KTS.

(d) The cost of operating the system

For local call- 15 kyats per minute

For trunk call- 25 kyats per minute

(e) I recommend to purchase the Private Branch Exchange system PBX allows all users to share phone lines and so reduce the telecommunication expenses than KTS. PBX system is totally programmable. PBX system contains a lot of useful features. It is easy to install and configure than traditional telephone system. It is low cost to operate. When the users make the call within the organization, it is free of charge. It can handle addition phone connections and extensions without disturbing the efficiency of the network.

Task 5

I write the report describing my network recommendations including the details of tasks 1-4 and the estimated cost throughout the assignment. In task (1)

Task (1)

(a) Investigate the possible network topologies and media appropriate for police department

How topologies operate

(a) I investigate the network topologies and media that can use to create the appropriate with the police station. I write about star topology and ring topology. I also write the coaxial cable and unshielded-twisted pair for the media of the network.

Ring Topology

Ring topology, also known as ring network, is a type of computer network configuration where computers and devices are connected to each other in the form of a large circle (ring). Each computer in the network is called as host that handles every message which flows through the ring. Each host has a unique address. If a host sends packet to another host, the packet is sent around the ring until it reaches its final destination. Signals always travel in only one direction around the ring because the ring network has no end and so the termination is not required. Every computer in the ring is responsible for retransmitting the data. The ring network uses coaxial cable or fiber-optic cable as a transmission media. If one computer fails in the single ring network, the whole network is going to breakdown. The Fiber Distributed Data Interface (FDDI) network overcomes the disruption in the network by sending data in the clockwise and counterclockwise direction on the ring. The FDDI network has two rings. If one ring is failed, the network is still alive with another ring. Token passing is one method for sending data around the ring. A small packet, called a token, passes around the ring to each host. If a host has the information to send, it modifies the token, adds address ad data and sends it around the ring to the destination device or returns to the sender. When the intended device receives the information, it creates a message and returns to the sender to acknowledge for its safe arrival. Modern ring network uses "smart hubs" which recognize the computer's failure and remove the computer from the ring automatically. Each computer has an equal opportunity to send data and so a single computer can't be able to monopolize the network.

Star Topology

Star topology is a type of network topology in which the computers and devices are connected to each other by using the cables and central connection point such as hub or switch. Typically, the star network needs more cables than the bus network. The cables used in the star network are unshielded twisted pair (UTP) and shielded twisted-pair (STP). If one computer fails in the star network, the failure affects the only one computer and not the entire network. In the star network, the entire network depends on the hub or switch and so if the whole network is breakdown, there could be a problem in the hub or switch. This feature makes easier to troubleshoot because the administrator can fix quickly and easily network problems including a single device or cable without affecting the other devices. Switching technology is used to connect hosts and devices in the star network. In the star network that used hub as a central device, when the computer sends the signal, the hub receives it and retransmits it through every cable to all of the hosts and devices which are connected to the hub. All hosts have the signal and check the destination address but only the host that the signal is addressed processes the data. In the star network that used switch as a central device, when the computer sends the signal, the switch takes it and retransmits it to one of its port where the intended computer is connected. In this method, the multiple computers can connect simultaneously without affecting each other. The star network that used switch is faster than the star network that used hub. Star network configurations are 100-Base-T and 1000-Base-T local area networks.

(b) Advantages of coaxial cable

I investigate the advantages of the coaxial cable as following.

Has a sufficient frequency range to support multiple channels

Each multiple channel offers substantial capacity

Provides greater bandwidth for each channel

Supports mixed range of services

Improves noise immunity and has slightly better performance than twisted-pair cable.

Promotes compatibility and interoperability of different vendors' equipments.

Resists electromagnetic interference.

I also investigate the disadvantages of this medium.

Disadvantages of coaxial cable

The bus topology which uses coaxial cable is susceptible to congestion, noise and security risks.

May be damaged by lightning strikes.

Installation costs are high.

Is heavy and bulky and has high attenuation and so it would have need to implement repeaters.

Is difficult to install.

Is difficult to troubleshoot.

Can't be bent around tight radiuses

Can't be tolerant to fault.

Advantages of unshielded twisted-pair (UTP) cable

I write about the advantages of unshielded twisted pair (UTP) cable as following.

Limit signal degradation caused by electromagnetic interference (EMI) and radio frequency interference (RFI).

Can carry data at a faster speed.

Less expensive than other type of network media.

Is easy to install.

Is easy to troubleshoot.

Is easy to move and change.

Can be used with most of the major networking architectures.

Disadvantages of unshielded twisted-pair (UTP) cable

I also write the disadvantages of unshielded twisted pair as following.

The distance between signal boosts is shorter than it is for coaxial and fiber-optic cables.

Sensitive to noise.

(c) I recommend star topology and switch and twisted-pair cable to use. because the star topology is easy to manage for its simplicity in the functionality. The problems in the star network are easy to troubleshoot. The star topology has very simple format and so it is very easy to expand on the network. If one host fails in the network, it affects only the failure host and not the entire network. It has good performance and it is also very easy to replace, install or remove hosts or other devices. When the computer sends signal to another computer, the switch receives it and transfers it directly to the destination computer and so it is fast in speed. The twisted-pair cable can carry data at a faster speed. If the switch is safe, very computer in the network is safe. So, this type of network conveys more privacy than any other networks.

Task (2)

Investigate internet connection requirements

(a) Required Internet services for the police department

The internet services that may be required are

Sending Email from one police department to the another police department.

Sending the sensitive message from one department to another by using the internet connection.

Watching the websites to know about the news of all over the world.

To announce the new policies of the department.

(b) Suitable connection speeds for these requirements

The suitable connection speeds for these services are 512 kbps because it is high bandwidth, high speed and it can use securely.

(c) ISPs that can meet these requirements

The ISPS that can meet these requirements in my country are Myanmar Post and Telecommunication (MPT) and Red Link.

Myanmar Post and Telecommunication office offers the plans for ADSL service as following.

Plan

Activation Fee (FEC)

Monthly Fee (FEC)

Free E-mail Accounts

Maximum Attached Devices

Speed (kbps)

Data Limit (MB)

Consumer (Data only)

840

35

1

1 PC

128

400

Consumer

840

45

1

1 PC + VoIP

128

400

Enterprise

840

75

3

4 PC + VoIP

256

2,000

Corporate

840

130

25

12 PC + VoIP

512

10,000

VPN

840

100

-

-

512

10,000

Red Link offers the plans for Wi-max service as following.

Plan

Monthly Fee (FEC)

Free Email Account

Maximum Attached Devices

Speed (MIR)

Consumer

45

1

1 PC + 1 VoIP

128 Kbps

Enterprise

75

3

4 PC + 1 VoIP

256 Kbps

Corporate

130

25

12 PC + 2 VoIP

512 Kbps

Installation Fees

Wi-max Activation Fee= 840 FEC

Wi-max Annual Fee = 60 FEC

Wi-max Equipment Fee= 600 FEC

Total Fee = 1,500 FEC

VoIP Service (Optional)

VoIP Activation Fee = 50 FEC

VoIP Annual Fee = 60 FEC

VoIP Adapter (3 ports) = 250 FEC

Total Fee =360 FEC

(d) I recommend to choose the MPT as the internet service provider because it is the best internet service provider in my country. In the connection speed, I recommend to choose the ADSL with the corporate plan because it has 512 kbps with the reasonable cost and it is enough to use the required internet services for the police department.

Task (3)

Investigate two-way voice communications could be implemented for police department

(a) How full duplex and half duplex work

(a) I investigate GSM and walkie-talkie as the two methods of the two-way voice communications that could be implemented by the police department. I am going to explain how each method works.

How GSM works

Global System for Mobile Communications (GSM) is an international standard and can use in the many parts of the world. GSM operates with 900 MHz band (890 MHz-960MHz) in Europe and Asia and 1900 MHz band in United States. GSM network consists of three major systems; the Switching System (SS), the Base Station System (BSS) and the Operation and Support System (OSS).

Switching System (SS)

The switching system(SS) performs call processing and subscriber related functions. SS has five databases to perform different functions. These databases are Home Location Register (HLR), Mobile Services Switching Center (MSC), Visitor Location Registration (VLR), Authentication Center (AUC) and Equipment Identity Register (EIR).

Home Location Register (HLR)

The home location register (HLR) performs storing and managing information of subscribers and consists of subscriber server profile, status of activities, information about locations and permanent data of all sorts. When the subscribers use new connection, the subscribers are registered in HLR of mobile phone companies.

Mobile Services Switching Center (MSC)

The mobile services switching center (MSC) handles technical end of telephony and performs switching functionality of the entire system. It controls the calls from same networks and calls from other networks. It is responsible for toll ticketing, common channel signaling, network interfacing, etc.

Visitor Location Register (VLR)

The visitor location register (VLR) performs dynamic tasks and stores temporary data regarding subscribers which is needed by MSC. VLR is connected to MSC directly. When subscriber moves to different MSC location, VLR integrates to MSC of current location and requests the data of subscriber from HLR. When the subscriber makes a call, VLR already has the required information for making call and doesn't require connecting to HRL again.

Authentication Center (AUC)

The authentication center (AUC) handles the security end of the system. The major task is to authenticate and encrypt the parameters which verify user's identification and so the subscriber can make a call confidentiality. It makes sure that the mobile operators are safe from different frauds.

Equipment Identity Register (EIR)

The equipment identify register (EIR) stores crucial information regarding mobile equipments. It provides in restricting for calls been stolen, mal functioning of any Mobile Station (MS) or unauthorized access. ELR and AUC are either stand-alone nodes or sometimes work together as combined AUC/EIR nodes for optimum performance.

Base Station System (BSS)

The base station system (BSS) is very important in mobile communication. It is out door units which consists of iron rods and is usually high length. It is responsible for connecting subscribers to mobile networks. All communication is made in radio transmission. It can be divided into two systems, Base Transceiver Station (BTS) and Base Station Controller (BSC).

Base Transceiver Station (BTS)

Mobile phones connect to the mobile network through the base transceiver station (BTS). BTS handles communication using radio transmission with mobile station. BTS is the radio equipment that receives and transmits voice data at the same time.

Base Station Controller (BSC)

The base station controller (BSC) controls many cells, it registers subscribers and responsible for MS handovers, etc. BSC creates physical link between subscriber (MS) and BTS and controls functions of BTS. BSC performs the function of high quality switch by handover over the MS to next BSC when MS goes out of the range of BTS, BSC helps in connecting to next in range BTS to keep the connection within the network. BSC also performs the functions such as cell configuration data and control radio frequency in BTS. After BSC done its processes, data moves to MSC. MSC is a switching center that acts like a bridge between different mobile networks.

Operation and Support System (OSS)

The operation and support system (OSS) implements Operations and Maintenance Center (OMC) which is designed to connect to equipment of MSC and BSC. OSS monitors and controls the complex systems in the mobile networks. The basic reason of OSS is to provide users a cost effective support and solutions. OSS helps in managing, centralizing, local and regional operational activities required for the GSM networks. The important aspects of OSS are maintaining mobile network organization, provide overview of network, support and maintenance activities.

How Walkie-Talkie works

Walkie-talkie is a two-way radio transceiver. It is handheld, portable and has a half-duplex channel. While the user talks with the walkie-talkie, the user has to simply push and hold the button on the walkie-talkie. Then the sound is transmitted through the air by using the radio waves. These radio waves go to another walkie-talkie and then convert into the sound. There are basically six parts on the common walkie-talkies. They are;

Transmitter- It sends voice to the another walkie-talkie after converting voice into radio waves.

Receiver- It receives radio waves sent by transmitter.

Speaker- It amplifies the sound received by receiver.

Microphone- It attains the sound and converts it into electric signal.

Crystal - It is also called channel, sets the frequency used for communication.

Power Source- It is usually from the batteries.

Most walkie-talkies have option to change channels. This prevents people from using the same channel for communication.

(c)License Cost for GSM

The licensing cost for GSM is 1,500,000 kyats.

Rates in Kyats

Rate of US $

Annual Charges

12000.00

600.00

Local Call Fees (Per Minute)

25.00

0.30

Trunk Call Fees (Per Minute)

35.00

0.30

Value Added Services

Call Line Identification Services

Call Waiting Service

Call Forwarding Service

Three Ways Call Service

Shifting Fees

Reconnection Fees

6000.00

6000.00

5000.00

200.00

120.00

120.00

120.00

120.00

30.00

30.00

Short Message Services (SMS)

(Per message- maximum 160 characters)

25.00

25.00

Equipment cost for GSM

Brand

Nokia

Model No.

Nokia 6220

Network Communication

GSM850/900/1800/1900

HSDPA900/2100 (for 3G network)

Weight and height

108 x 47 x 15 mm, 90g

Memory

Internal memory=128 MB

Micro SD Card (over 8GB)

Connection

Bluetooth 2.0 with A2DP, USB 2.0, EDGE, GPRS, WAP2.0

Multimedia

MP3, MP4, FM, TV output built in GPS, Office application, Java application

Type of Camera

5 mega pixel, Resolution= 2592 x 1944 pixel

OS

Symbian OS 9.3

Messaging

SMS, MMS, Email, Instant Messaging

Cost

190,000 kyats

Brand

Sony Ericsson

Model No.

Sony Ericsson K810

Network Communication

GSM850/900/1800/1900

Weight and height

104 x 43 x 10.5 mm, 80g

Memory

Internal memory=14 MB

Micro M2 Card= 512 MB (over 4 GB)

Connection

Bluetooth 2.0 with A2DP, USB 2.0, EDGE, GPRS

Multimedia

Game, voice memory, Walkman player, Track ID music, Java application

Type of Camera

1.3 mega pixel, Resolution= 1280 x 1024 ( can't shot video)

OS

Java phone

Messaging

SMS, EMS, MMS, Email, Instant Messaging

Cost

200,000 kyats

Equipment cost for Walkie-Talkie

Brand

Motorola

Model No.

Motorola T9680R

Available Range

28 miles

Available Channel

22 channels

Cost

$ 47.50

Brand

Motorola

Model No.

Motorola FV300R

Available Range

10 miles

Available Channel

22 channels

Cost

$ 25.00

(d) Although each method has the advantages on the communication, they also have the limitations too.

Limitations of GSM

Coverage occurs in rural areas and places like tunnels. The transmission from GSM may disturb the electronic devices. The interference from GSM is both radio frequency interference (RFI) and electromagnetic interference (EMI). The maximum range for the standard GSM is 35 km.

Limitations of Walkie-Talkie

The communication range of walkie-talkie can be reduced by the rugged terrain and can be affected by weather conditions. The sound quality is not good. The speaker is too loud so that the other person can hear the voice from the walkie-talkie. If your walkie-talkie is on the same channel with someone, he can listen to your voice.

(e) I recommend to use the walkie-talkie for communication. Because walkie-talkies are license free and don't cost any charges for calling. This reduces the cost of police fund. The walkie-talkies are very cheap and easily buy. They are portable and so the policemen can carry them together in their pockets and can communicate each other easily.

Task (4)

Investigate telephone systems available in my country for single-site organization

(a) Main equipment that would be installed

Public Branch Exchange (PBX)

PBX makes the connections among the internal telephones within the organization and also connects them to the public switched telephone network (PSTN) via trunk lines. The lines are connected to PBX and PBX makes connection to the central office and then it transfers the call to the other extensions when the outside number is dialed. PBX system includes the land line, PBX, phones and phone cables. In the PBX system, it contains internal switching network, microcomputer for data processing, control and logic, lines, switchboard and uninterruptable power supply (UPS).

Key Telephone System (KTS)

KTS is a premises telephone system that have buttons for calling inside an organization or outside through the public telephone network. KTS relies on the telephone company switching equipment. KTS doesn't require to dial a number to make an outside call because all lines are connected directly to the telephone company central office. KTS contains the equipment such as phone and land lines. The land lines connect each phone per line.

(b) Features of these systems

The features of PBX

Auto Attendent

Auto Dialing

Automatic Call Distributor (Automatic Call Directory services)

Automatic Ring Back

Call Accounting

Call Blocking

Call Forwarding

Call Parking

Call Pick-up

Call Transfer

Camp-on

Custom greetings

Busy override

Call Waiting

Conference Call

Speed Dialing

Direct Inward Dialing

Night Service (department can have the shared message boxes.)

Voice Mail

Direct Inward Access (DISA) [ability to access the internal features from the outside phone lines.

Do not Disturb (DND)

Interactive voice response

Music on hold

Voice message broadcasting

Voice paging

Welcome message

The features of KTS

Remote Supervision

Automatic Call Accounting

Speed Dialing

Caller ID

Static-specific Limitation

Selection of Signaling Sounds

(c) The cost of equipment for PBX

Panasonic KX-TDA100

Panasonic KX-TDA100 is a hybrid IP-PBX system and it provides up to 96 ports, 64 CO's and can wire up to 64 phones. Its cost is about $ 352.33. Its features are

Up to 96 ports

Up to 64 CO's

Up to 64 phones

Multi-Cell Wireless

Maximum Cell Stations Up to 16

Maximum Doorphones are Up to 8

Maximum Door Opener Contacts are Up to 8

Maximum Voice Message (OGM) Channels are Up to 8

Maximum Voice Processing Systems contain 2 units

two BGM/MOH (Music on Hold) Inputs

two External Paging Outputs

one RS232C/SMDR Outputs

one USB Ports

Ethernet (10 BaseT) for CTI/Programming one port

Voice Over IP Gateway

Voice Over IP Extension

SD Card, it is used for storing system software and local database information

TAPI 2.1 Compliant, Telephone Application Programming Interface Compliant

Automatic Callback Busy (Camp On)

System Speed Dialing 1000 Numbers and 32 Digits each per tenant

Account Codes

Conferencing, 3 to 8 parties per conference (32 parties total)

Incoming Call Distribution

Universal Call Distribution

Panasonic KX-T7020 Speakerphone

Panasonic KX-T7020 is a speakerphone and it contains twelve programmable line buttons. It can automatically redial. It contains mute key, hold key, flash key, redial key, configuration key, transfer key, auto-answer key and message waiting key. Its price is about $ 64.99.

Philips Phone Cable

Philips phone cable is long about 50 ft and the connectors are 1x RJ-11-male.

Installation cost for PBX

The installation cost for PBX is about $ 1,000.

The cost of equipment for KTS

Panasonic KX-TDA100 telephone and Philip phone cable can use for the KTS.

The installation cost for KTS is about $ 200.

(d) The cost of operating the system

The cost of operating these telephone systems are as following.

For local call- 15 kyats per minute

For trunk call- 25 kyats per minute

(e) I recommend to purchase the Private Branch Exchange system PBX allows all users to share phone lines and so reduce the telecommunication expenses than KTS. PBX system is totally programmable. PBX system contains a lot of useful features. It is easy to install and configure than traditional telephone system. It is low cost to operate. When the users make the call within the organization, it is free of charge. It can handle addition phone connections and extensions without disturbing the efficiency of the network.

Estimate Cost

The estimate cost throughout the network is as following.

Implementing star topology

with unshielded twisted pair $ 100

Internet Service (ADSL) $ 1,000

Walkie-talkie $ 50 (per item)

PBX $ 1,500 (including installation cost, central unit, cables and ten telephones)

Total Estimated Cost $ 2,650

throughout the assignment

Assumption

I have a lot of knowledge about the network by doing this assignment. In task (1), I have a lot of knowledge about how topologies work including the media used to connect. I also know the details of star and ring topologies and the coaxial and unshielded twisted pair cable. In task (2), I know a lot of information about the internet services offered by the internet service providers in my country. In task (3), I know about how Global System for Mobile Technology (GSM) and walkie-talkie work, cost of setting up and operating each method and limitations of the GSM and walkie-talkie. In task (4), I have a lot of knowledge about the private branch exchange (PBX) and key telephone system(KTS) including the features, the cost of equipment and the cost of installation and the cost of operating the PBX and KTS.

Conclusion

I try this assignment very hard by watching the internet and going to the library. So, I have a lot of knowledge about the network and telecommunication.