china news: Global system for mobile communications

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

Introduction of GSM

GSM (Global System for Mobile Communications) is the most popular form of mobile phones in the world. It's legal license promoter, the GSM Organization, predicts that 80% of the global communications across the mobile network uses the standard.

How does GSM network work?

GSM uses a series of radio transmitters so called Base Stations (BS) to make a connection between the cells phone and the nearest cellular network. Each BS can be termed as a cell as it covers a definite range within an allocated area (cell). Base Stations used in the GSM network are supposed to be all interconnected, which is why we can move from one cell to another- that process is also called "hand-over". Each cell phone can be connected from one another via individual SIM card for one digit number. The combination of a cell phone and the SIM card can creates a special digital termed as signature- that includes your subscriber number which is being sent from your cell phone to the it's nearest BS to confirm that your reach is in a range form of frequencies within a definite allocation. The request you demand is passed on along the network of BSs to the main target of a cellular by the name of the Mobile Switching Center (MSC). The MSC also find the routes all your incoming and outgoing phone calls to and from the fixed phone line networks from which various cellular network can be connected and operated with each others.

HLR uses as a restrictive tools for administrative information required to authenticate, register and if your subscription is on the current , the MSC will send back a message contained an description to your connected phone bye the use of network of BSs that describes that you are allowed to use the network. The name or code of the cell network you demand will be appeared soon on the screen of your portable mobile device. The entire log-one process normally takes just a few seconds.

Polling - Every from now on and again and again, the cell phone will send a message automatically to the network indicating where it is without letting you know, a process named Polling.

Hand Over - whilst you are driving and making a phone in the network area of A, and finally your call ended in the area of B, base station of A will be transferred your continued to B - that process is called Hand Over.

Multiplexing - All BS (base station) uses digital techniques to enable numerous phones to simultaneously be connected to it and calling and receiving two calls or more than can be happened via digital jugging ability called Multiplexing.

Mail Box- if you are unavailable for some connection problems or out of area, the messages sent to you will be stored in the Mail Box of your unique at the base station - that device is called Mail Box.

In our country, GSM 900 is most used by nearly all in business sectors uses the circa of 900Mhz band From the moment of collecting the information, the frequency band used is definitely 935-960MHz (base transmit) and 890-915MHz (mobile transmit).To enable this maximum number of users GSM access, each sector (allocation of network range) is subdivided into 124 carrier signal frequencies spaced 200 kHz apart, bye the use of FDMA techniques.

How does Walky Talky work?

A walkie-talkie known as a handheld transceiver is a hand-held portable, two- way radio transceiver. Especially, it includes a half-duplex channel which goes that only one person at a time can talk, but other on the same frequency will have to listen. There is a push-to-talk button to start the transmission. Generally, walkie-talkies has come as a small handset that you can use at the time of walking and talk in the small LAN.

Walkie-talkies, to be in the most basic form, transmit the signal on a frequency from an antenna. Walkie-talkies just only work on a half duplex channel. However, this means that only one person at a time can talk, but everyone on the same frequency channel just will have to listen. On every walkie-talkie has a push-to-talk button that starts the transmission. While you have the switch on, only you have to talk and everyone else in the group will have listen. Basically, walkie-talkies has come as a small handset to our world that you can walk and talk with--hence, the name.

GSM telephone license require permit from Government.
GSM telephone license require waiting around 2 month to get the permit.
Licensed users or organizations require following Government policy.

Walkie-talkies (PTMR) are hand-used for keeping in particular contact within a interconnected group. They can operate at either 27 MHz or 409 MHz and do not require a legal complicated license as long as they meet the technical requirements ruled by the Office of the Telecommunications Authority. Especially, walkie-talkies that operate at 409 MHz are usually smaller, and more suited to short-range communication.

PTMR system require permit from Government.
Registration the PTMR needs to wait around 1 month to get permit.
Register customer or organization has to show true information for registration.

Costs of setting up and operating the system, including licensing costs, equipment cost Cost of Setting up and operating the system for GSM

There are typically three types of systems for the main components of Global System for Mobile Communication (GSM).

The Switching System

Home Location Register (HLR) - A database which deals with data about GSM subscribers, including the Individual Subscriber Authentication Key for each Subscriber Identity Module (SIM).

Mobile Services Switching Center (MSC) - Just one of the network element which works for the telephony switching network functions for the GSM network. The MSC is used for common net channel toll ticketing, interconnected network interfacing, common toll ticketing.

Visitor Location Register (VLR) - Used as a database which stores to access the temporary information about mobile roaming network GSM subscribers.

Authentication Center (AUC) - A database which stores to access the International Mobile Subscriber Identity (IMSI) the Subscriber Authentication key (Ki), and the defined algorithms for encryption.

Equipment Identity Register (EIR) - A database which contains the detailed information about the identity of mobile equipment with the hope of preventing calls from stolen, unauthorized usage, or defective mobile stations.

For each amount of above requirements are supposed to be in one amount of need.

Components of Switching System Unique Cost of fee ( Assumption)

The Base Station System (BSS)

Base Station Controller (BSC) - Used as one of the network element which offer all the controlling network functions and physical layer links between the MSC and BTS. The BSC offers some functional services such as cell configuration data, handover, and take responsibility for controlling of radio frequency (RF) power levels in Base Transceiver Stations (BTS).

Base Transceiver Station (BTS) - one of important network element which maintains the radio signal interface at the mobile station (MS).

The BTS is the radio digital equipment (transceivers and antennas) required to make a service each cell in the particular network.

The Operation and Support System (OSS)

Message Center (MXE) - Just a network element which offers the service of Short Message Service (SMS), paging, email, fax mail, voice mail.

Mobile Service Node (MSN) _ Just a network element which handles mobile intelligent interconnected network (IN) services.

Gateway Mobile Services Switching Center (GMSC) - A network element is supposed to interconnect within two GSM networks.

GSM Inter-working Unit (GIWU)_ Used as a portable network element which interfaces to different data networks.

The amount of each components of assumption for the Police Department is described in the detail of following recommendations. The systems can combine all required components (BTS, BSC and MSC) to provide the private and public GSM network in one unique cabinet. The GSM network can be in the combination of over several sites and network interconnected configurations, offering a wide range variety of customized services to the end users.

Cost of setting up should be supposed to be around total $ 2000 for GSM and $ 3000 for Walky Talky (PTMR)

Most GSM networks work on 900 MHz or 1800 MHz bands.

GSM networks work in a numerous different frequency ranges (separate in GSM frequency ranges for 2G and UMTS frequency bands for 3G.). Common 2G GSM networks operate in the frequency form of 900 MHz or 1800MHz bands which can be enhanced up to 2100 for some occasions.

The maximum range of a GSM network depends on the type of locations, surfrace to be penetrated, and the barrier access. Basically, GSM has a fixed limited maximum range of about 40km (around 25) miles which is assumed by technical limitations. As simple surface, no high buildings at all are expected to get around till to 30 miles. Depending on the type of weather and other air circumstances, GSM Tower can be replaced within 2 and 50 miles of wiring for a fixed wireless network. For a huge network, some repeater or re-transmitter stations can be used to adjust the distance. But for our police department, it doesn't need to power up the signal again as it is worked within a city.

The network available distance is around 12 miles depending on the type of network.

The communication range of walkie-talkies can be deteriorated by the adverse terrain through which you are traveling, and can be affected by gloomy weather conditions. So we won't get a reliable satisfaction and should always be prepared for possible hurry emergencies in which you cannot rely on walkie-talkies alone. It is crucial to prepare a full-backup such as a mobile phone, and you should always learn about the locations of public general pay phones and free emergency help-lines that will be nearby before you go out

First of all, to set up the voice communication network, the police department should be make some important legal aid from the local community service from which further aid should be continued. After accepting the legal requirement, we have to think about setting up the required accessories for the voice com network. Each cost of setting up in GSM and Walky Talky are shown above from that it is very noticeable the price between GSM and Walky Talky ( PTMR).

There are two way of using GSM and Walky Talky detailed described above. For some general purposes of using in Police department, mostly personal Walky Talky are being offered by the department these days. However, for some reasons highlighted above, for each district or some short convenience use, Walky Talky are more suited than GSM. One disadvantages is GSM is not available in all countries or may not be available at every geographical point in a GSM country. Moreover , some buildings are designed in such a way that the GSM signal cannot reach into the building.

Cost of setting up should be supposed to be around total $ 2000 for GSM and $ 3000 for Walky Talky (PTMR)

In our country, GSM 900 is most used by nearly all in business sectors uses the circa 900Mhz band

The frequency band used is 890-915MHz (mobile transmit) and 935-960MHz (base transmit). To allow this maximum number of users GSM access, each band is subdivided into 124 carrier frequencies spaced 200 kHz apart, using FDMA techniques.

Most GSM networks work on 900 MHz or 1800 MHz bands.

The maximum range of a GSM network depends on the type of locations, surfrace to be penetrated, and the barrier access. Basically , GSM have a fixed maximum range of 40km (around 25) miles which is imposed by technical limitations. As a simple surface , no high buildings at all are expected to get around till to 30 miles. Depending on terrain and other circumstances, a GSM Tower can be replaced between 2 and 50 miles of cabling for fixed wireless networks. For a huge network, some repeater or re-transmitter stations can be used to adjust the distance. But for our police department, it doesn't need to power up the signal again as it is worked within a city.

The network available distance is around 12 miles depending on the type of network.