What is GSM and how does it work?
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What is GSM and how does it work?
Advantages and Disadvantages of GSM?
GSM surveillance cameras?
GSM installation and configuration?
WCDMA vs GSM differences?
What is GSM and how does it work?
What does GSM mean and what is it for? When picking up a new phone or studying news, the user periodically sees the GSM 800/900/1800/1900 line in the features. Naturally, you may have questions "GSM: what's in the phone?" and “What do these numbers mean?”
GSM (from Groupe Special Mobile, later renamed Global System for Mobile Communications) is a digital communication standard developed in the late 1980s. GSM should be attributed to the second generation networks, i.e. 2G: digital cellular communications.
The standard got its name in honor of the analysis group that created the standard (Groupe Special Mobile). Its development began in 1982. The goal is to build a single cellular system for all European countries in the 900 MHz band. Commercial GSM networks began operating in mid-1991.
GSM is the most widely used communication standard in the world. It represents more than 80% of the entire global mobile communications market.
GSM (Global System for Mobile Communications) is a second-generation 2G international communication standard, a digital network used by mobile operators to transmit data on it. It is used all over the world and is compatible with almost all mobile phones. Data is transmitted wirelessly, so no channels are needed.
Main parts of the GSM system?
The simplest part of the block diagram, a portable phone, consists of two parts: the "phone" itself: ME (mobile equipment, a mobile device) and a smart card SIM (subscriber identity module, subscriber identification module), obtained by concluding a contract with an operator. Just as any car is equipped with a unique body number, a cell phone has its own number: IMEI (International Mobile Equipment Identity - International Mobile Device Identity), which can be transmitted to the network to order (more details on The IMEI can be found here ). SIM , in turn, contains the so-calledIMSI _ I think the difference between IMEI and IMSI is clear: IMEI corresponds to a specific phone and IMSI , to a specific subscriber.
The "central nervous system" of the network is the NSS (Network and Switching Subsystem), and the component that performs the functions of the "brain" is called MSC (Mobile services Switching Center). It is the latter in vain that they call (sometimes aspirated) the "switch", and also, in case of communication problems, blame him for all mortal sins. There may be more than one MSC in the network (in this case, the analogy with multiprocessor computing systems is very appropriate) Beeline was implementing a second switch (manufactured by Alcatel). master handles call routing, generates data for the billing system, manages many procedures: it is easier to say what is NOT the responsibility of the switch than lists all its functions.
The next most important network components, also included in NSS , are the so-called HLR (Home Location Register) and VLR (Visitor Location Register - motion log). Pay attention to these parts, in the future we will refer to them frequently. HLR , in general terms, is a database of all subscribers who have signed a contract with the network in question. Stores information about user numbers (the significant numbers, firstly the IMSI mentioned above and secondly the so-called MSISDN). -mobile subscriber ISDN, ie telephone number in its usual sense), a list of available services and much more; Later in the text, parameters located in the HLR .
Unlike HLR , which is one on the system, there can be multiple VLRs; each of them controls their part of the network. The VLR contains data about subscribers who are in your territory (and only in it!) (and not only your subscribers are served, but also registered roamers on the network). As soon as the user leaves the coverage of a VLR, the information about him is copied to the new VLR and deleted from the old one. In fact, between what there is of the subscriber in VLR and in HLR, there is a lot in common: look at the tables where the list of long-term (Table 1) and temporary (Tables 2 and 3) data about the users stored in these records. I once again draw the reader's attention to the fundamental difference between HLR and VLR : the first contains information about all network subscribers, regardless of their location, and the second contains data only about those who they are in the territory subordinate to this VLR. In the HLR , for each subscriber, there is always a link to the VLR that is currently working with him (the subscriber) (in this case, the VLR can belong to a foreign network located, for example, at the other end of the earth).
NSS contains two more components: AuC (Authentication Center - Authorization Center) and EIR (Equipment Identity Registry - Equipment Identification Registry). The first block is used for user authentication procedures, and the second, as its name implies, is responsible for allowing only authorized cell phones to operate on the network. The operation of these systems will be discussed in detail in the following section on the registration of subscribers in the network.
The executive, so to speak, part of the cellular network is BSS (Base Station Subsystem - a subsystem of base stations). If we continue the analogy with the human body, then this subsystem can be called the extremities of the body. BSS consists of several "arms" and "legs" - BSC (Base Station Controller - Base Station Controller), as well as many "fingers" - BTS (Base Transceiver Station - base station). Base stations can be observed everywhere: in cities, countryside in fact, it is just these transceivers that contain from one to sixteen emitters. Each BSC controls an entire BTS group and is responsible for managing and distributing channels, power level of base stations, and the like. Usually there is not a BSC in the network, but rather a whole set (there are hundreds of base stations in general).
The operation of the network is managed and coordinated by OSS (Operating and Support Subsystem, a management and support subsystem). OSS consists of all kinds of services and systems that control work and traffic; In order not to overload the reader with information, the work of the OSS will not be considered below.
How does the GSM Module work?
GSM unlike the same CDMA offers more opportunities for international roaming. Since it represents 80% of the entire market. In addition, the technology allows you to transfer data and make calls simultaneously.
It operates at one frequency: 800/900/1800/1900 MHz. Almost all modern phones support these frequencies without problems. The signal extends to a distance of 35 km from the base station/tower. And the average data transfer rate is up to 20kbps.
Includes add-ons: GPRS and EDGE. They allow you to transfer data in batch format and increase the transfer speed. They are also called 2.5G and 2.75G. It is with their help that you can access the World Wide Web from your phone. Two elements are involved in the transmission of signals between subscribers:
GSM module in the phone: transmits / receives a radio signal from the operator's base station.
1.- Base station: connects with other users, verifies the authenticity of the SIM card, protects the radio from listen.
2.- GSM communication works as follows:
2.1.- The radio module in the phone scans the air.
2.2.- The base station sends a random number generated by the algorithm to the module.
2.3.- The phone generates a response and returns it.
2.4.- If the response code is correct, then it connects to the mobile network.
With the proper settings in the GSM, the base station checks the IMEI of the device and can deny access if it is on the banned or monitored list.
3.- This and the previous 3 stages take place when the device is turned on,before receiving + sending SMS, making calls, reconnecting to another base station.
4.- An encrypted connection is established between the elements. The phone and the base station exchange information. At the end of the exchange, the connection is disconnected and the device continues to listen to the radio.
Services provided by GSMMain services:
1.- Transmission of speech information.
2.- Sending SMS messages.
3.- Send fax messages.
4.- Data transfer.
5.- Additional services include:
6.- Voice message.
7.- Definition of incoming numbers.
8.- Call waiting.
9.- Voice communication with several subscribers (conference).
10.- Prohibition of certain services.
GSM Services StandardsWhat does GSM mean and what is it for? Contents [ hide ] [ hide ] What does GSM mean? The evolution of GSM or what is 2.5G and 2.75G Communication capabilities GSM how it works Advantages and disadvantages of GSM What does GSM mean? GSM (Global System for Mobile Communications) or 2G is an international standard for digital mobile communications. Developed by the staff of the European Telecommunications Standards Institute in the 1980s.
It uses radio channels with a frequency of 800/900/1800/1900 MHz to transmit information. Mobile phones released after 2000 featured this standard.
Mobile phones are launched with support for 4 frequencies: 850 MHz, 900 MHz, 1800 MHz and 1900 MHz.
Phones are divided into classes based on the number of bands the devices support. For example, a phone that operates on one frequency is called a single band, and one that operates on three frequencies is called a tri-band. On some models, you can select a specific frequency.
Note.- The channel frequency varies depending on the region. In Australia, Asia, Africa, Europe, these are 900 and 1800 MHz. In North and South America: 850 and 1900 MHz. The reason for the difference is that at the time the standard was changed in the USA. and Canada, European frequencies were already in use.
Information transfer rate: up to 19.5 kbps. The maximum distance between the phone and the base station is 35 kilometers. If necessary, it can be increased with the help of repeaters, amplifiers up to 120 kilometers.
Evolution of GSM which is 2.5G and 2.75GGPRS (General Packet Radio Service) or 2.5G is a complement to the GSM standard. The information it contains is transmitted in the form of packets: messages containing information about the sender, the recipient and the transmitted data. A fragment of a photograph, for example.
EDGE (Enhanced Data Rates for GSM Evolution) or 2.75G is an enhanced version of GPRS that uses 8PSK modulation. The technology increases the transmission speed up to 270 kbps.
Packets allow participants to exchange data not only with each other, but also send/receive from the Internet. Transmission speed - 85-100 kbps.
Advantages and Disadvantages of GSM?
Advantages GSM Services1.- Smaller size and weight than phones that use analog standards.
2.- Good communication quality.
3.- Great network capacity.
4.- Good protection against eavesdropping and illegal use.
5.- Compared to the AMPS-800 (1G) standard , GSM-enabled phones are smaller and consume less power because the base station controls the signal strength of the subscriber's device. If it is above a certain level, the station orders to reduce it.
6.- Roaming capability.
Disadvantages GSM services1.- Possible speech distortion during digital processing and data transmission.
2.- Ability to communicate at a distance of no more than 120 km from the nearest station.
Note.- We can say about GSM communication that this standard reduced the phones, increase battery life, improve the quality of communication and the security of the information transmitted.
How are GSM surveillance cameras?
Using a SIM card allows you to use other options. Thus, for example, a residential or office security system can transmit an alarm signal to a mobile device (tablet, smartphone) or remote control panel, including equipment monitored by a rapid response team. A video surveillance camera with a GSM module allows you to access a number of different services that are in demand in the operation of various security systems
1.- Automatic sending of SMS and MMS notifications.
2.- Transmit video and audio online.
3.- Connection established with the remote archive of video recordings.
4.- Remote control of the security system.
Characteristics of GSM video surveillanceBy design, a video camera with such a module differs significantly from analogs in terms of the method of data delivery.
So, in analog devices, the video signal comes through a coaxial cable, unlike them, digital models transmit it through a twisted pair. The GSM camera is equipped with a SIM card port, which is used to send information.
The SIM card is used the same as for telephone communication, it has its own identification number, and the surveillance system can be created in three ways
1.-The use of cameras equipped with a GSM module.
2.- Connection of classic digital or analog devices to the module block with GSM.
3.- Use of IP cameras with GSM extension.
Installation of cameras with GSM
In such a security system, the camera sends a text message or MMS to the configured number and does not transmit the video stream continually.
If a motion or smoke sensor is triggered in the system, the video camera can capture the reporting area and send a photo as a message.
You can set the camera to trigger either by a sensor signal, or according to a schedule, or when an event occurs.
GSM video cameras are a way out of a situation where there is no Internet on the premises. With the advent of 3G\4G Mimo boosters, problems with unstable mobile internet connection are a thing of the past. So, if you have a pretty good internet, then it is more important to take a step towards 3D Self-Monitoring.
For stable operation of a 3G video camera, the required output Internet speed in a protected installation should be 1 Mb\s.
Connection to the unit with GSMThe second way to create an alarm or surveillance system based on such equipment is based on connecting a base unit with a module of wireless communication and a SIM card slot - classic design video cameras are connected. These can be analog or digital type devices.
A striking example of such a system is the Sapsan 3G\MMS design. Strictly speaking, this scheme is not a video surveillance system, since its functionality is limited to taking pictures of the monitored area and sending the pictures taken to a preprogrammed number.
It is possible to send a message to any mobile device that is equipped with a SIM card with the desired number. The kit includes 4 cameras and a motion sensor per Therefore, each device is equipped with its own sensor, which allows you to establish uninterrupted control over a specific area.
Video cameras have built-in microphones - due to this, remote wiretapping of the controlled area is possible.
In addition, the system allows you to configure notifications so that they are not sent to one, but to several numbers.
There are also devices that combine an alarm and a video camera in a single case, a striking example of this design is the "Guardian MMS Black".
GSM module cameras
Devices have a built-in flash drive that can store images, storage capacity may vary.
These cameras are often equipped with the following important components:
1.- Built-in microphone.
2.- Memory card.
3.- IR illumination.
4.- Motion sensor.
A modern IP video camera with a GSM module is a rather expensive device that often plays an important role in a security system. surveillance or alarm.
Any mode can be set, therefore, in order to save free disk space, scheduling is allowed, as a result of which the camera will turn on once in a certain period of time or from a triggered sensor.
Infrared lighting allows you to conduct video surveillance around the clock, regardless of the lighting level.
The main criterion for creating a security system with GSM equipment is the presence of a cellular signal, while the quality is not affected by the choice of any provider.
GSM systems for surveillance in the countryIf the user needs to create a video surveillance system in the country with remote access, when you can get a picture from the camera at any moment and view it from the screen of a laptop, tablet or phone, the best is a device with a suitable GSM module for this purpose.
The disadvantage of the system are just the periodic failures of cellular communication and the possible signal deterioration: most of the time this happens due to problems with the tower or bad weather.
Without However, even in the case of an initially weak signal, the system it is quite possible to implement, but you will need to request 3G or 4G connection amplifiers.
To install such a scheme, you will have to pay monthly for access to Internet, because without it the camera simply cannot work and send images or a video stream.
The advantages of such devices include installation options widespread, even in places where it is impossible to implement systems with a different design.
GSM video surveillance is also relevant if you want to create a system with remote access and online viewing, since the use of IP cameras classical is impractical due to the great economic expenses and the more complex installation.
Such a surveillance system can be created both for a country house and for a garage or the entire site, the most important thing is that the equipment captures the signal constantly and the number of cameras is selected with the calculation of the area of the site
Very often, on remote sites, including summer cottages, they are used remote systems with the ability to control the operation of the remote camera via high-speed Internet.
In addition to GSM cameras, you can mount a system based on a 3G network router.
The cameras are equipped with an internal disk: it allows to work autonomously.
A 220 V network, a battery, built-in batteries or even a generator can be used as a power source.
Among modern systems, the most popular options are the use of cameras that connect through the 3G mobile Internet network.
GSM Outdoor Camcorders
Therefore, outdoor video devices are often equipped with a special case, so that they are not afraid of temperature changes.
Universal boxes have a built-in temperature sensor, a heater and a mini fan; when the thermal indicators change, an automatic adjustment is performed.
Outdoor cameras are often equipped with sensors auxiliaries, can be mounted on a swivel frame with electric drive, which allows changing the viewing angle of the device.
The model with GSM unit and motion sensor can be used for protect a country house, a car park, a parking space, a summer house and other objects.
Outdoor cameras must necessarily film in color, it is desirable that are equipped with an infrared sensor or a backlight to Surveillance can be carried out in the dark.
How are 4G outdoor camerasAmong the devices that belong to the middle price category and that allow to create a system that operates in a 4G network, the KARKAM model KAM-004G is popular.
This equipped with an integrated LTE modem and can send notifications snapshots in the form of a message or call if the motion sensor is activated movement.
The camera has a high-performance TI DaVinci DSP DM365 processor, a matrix responsive and supports free cloud storage option of the streaming video, in addition to recording on media.
The device has a slot for flash cards up to 128 GB, which allows you to save all the necessary data.
Have powerful infrared illumination, so it is possible to shoot in darkness at a distance of up to 50 meters, and the filter is equipped with an automatic transmission.
Also, the manufacturer has provided for the use of a wide range of innovations for noise reduction, white balance stabilization, glare removal and other technologies.
Installation and configuration GSM cameras?
By In general, security and surveillance systems that use equipment GSM can be installed by yourself, no need to contract professionals for this.
The most popular are cameras with autonomous power supply: their installation is the simplest, without the need to pull a cable, and the central power grid is used.
The GSM devices are modest in size, can be installed in tight space conditions and adjust in terms of angle of vision so that the entire territory or the widest possible area falls inside the frame.
In mode standby, the camera works up to 10-20 days continuously, the exact period depends on the volume and condition of the battery. By Of course, when sending SMS or MMS, more power is consumed, and if the sensors are activated frequently or if you configure the regular sending of images, the battery will drain faster.
Finally, it should be noted that the fact of video surveillance must be notified to everyone in the room; this is usually done with the help of plates with appropriate inscriptions or symbols.
Using covert surveillance systems creates problems with law enforcement because it violates privacy laws.
WCDMA vs GSM: What's the difference?On some smartphones, you may see multiple network support modes at the same time, including GSM, WCDMA, or WCDMA/GSM. Which of these modes should be selected when the device is running? Let's look for an answer.
How does GSM work?GSM refers to so-called second generation communication (2G) - digital cellular communication. Mobile phones are available with support for 4 frequencies: 850 MHz, 900 MHz, 1800 MHz and 1900 MHz. Many models support several types of frequencies at the same time.
If you select the GSM network support mode, know that it handles calls and sending/receiving SMS messages better. But the data transmission is carried out by GPRS; this is a plugin about GSM. The maximum data transfer speed is only 171.2 kbps, which is extremely low in modern realities. However, there is another type of add-on - EDGE, whose maximum data transfer speed is already 474 kbps, which, however, is still not much.
But GSM mode allows you to save battery power. Therefore, if you decide to go camping, where you can not even dream of the Internet, then you should use the GSM mode.
How does WCDMA work?WCDMA refers to third generation (3G) cellular communications. WCDMA is an air interface technology that uses wideband code division multiple access. It is WCDMA that has been chosen by many cellular operators to provide broadband radio access to support 3G services.
What WCDMA does best is data transfer, as speeds can reach up to 3.6 Mbps. This is enough not only for uploading images to the web or visiting sites, but even for watching videos online.
This mode should be used if you use the Internet and communications at the same time. For example, for the city, this is the most optimal mode. It is true that the load consumption will be slightly higher compared to GSM.
How is WCDMA/GSM?Universal cellular communication mode, set by default. In general, it can be called optimal, since it provides high-quality voice communication and data transfer at maximum speed. Its only drawback is that the battery discharge rate will be a little higher than if you use only one mode.
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What is GSM and how does it work?
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