GSM is currently the most widely used network technology in Internet of Things (IoT) applications for its simplicity, low complexity cellular communications for IoT devices in a way that conserves energy.
What is GSM for IoT? NB-IoT and GSM Overview
GSM for IoT: NB-IoT
NB-IoT refers to Narrow Band Internet of Things (Narrow Band Internet of Things) technology, which is a low-power wide-area (LPWA) network technology standard based on cellular technology for connecting various smart sensors and devices using wireless cellular networks. , focusing on the Low Power Wide Coverage (LPWA) Internet of Things (IoT) market, is an emerging technology that can be widely used worldwide.
2.1 Low power consumption
Low power consumption is an important indicator for IoT applications, especially for devices and occasions where batteries cannot be replaced frequently. NB-IoT focuses on small data volume and low rate applications, so the power consumption of NB-IoT devices can be very small, and the battery life of the device can be greatly increased from the past few months to several years.
2.2 Low cost
NB-IoT is a technology based on the LTE network, so by transforming it on the basis of the existing LTE network, the network can be established quickly and the coverage can be expanded quickly. At present, major operators are still vigorously promoting the construction of LTE networks, which is also conducive to the improvement of NB-IoT coverage.
2.3 Strong connection
In the case of the same base station, NB-IoT can provide 50-100 times the number of accesses than existing wireless technologies. One sector can support 100,000 connections, supporting low latency sensitivity, ultra-low equipment cost, low equipment power consumption and optimized network architecture. In a small space, more devices can be placed without interfering with each other. NB-IoT is enough to easily meet the needs of a large number of devices in the future smart home.
2.4 Wide coverage
NB-IoT has strong indoor coverage, with a 20dB gain compared to LTE, which is equivalent to a 100-fold increase in coverage area capability. Not only can it meet the needs of wide coverage in rural areas, but it is also suitable for applications that require deep coverage such as factory areas, underground garages, and manhole covers.
3. Communication protocol
NB-IoT is a communication technology. The devices that use the NB-IoT network and the IoT platform to communicate generally have to comply with a certain communication protocol. It is equivalent to two people making a phone call, and the sound is transmitted through radio waves, but the language used by the two people is The call must be in a language the other party can understand.
4. Application scenarios of NBIOT
4.1 Public utilities: smart water meters, smart water services, smart gas meters, and smart heat meters.
4.2 Smart city: smart parking, smart street lights, smart trash cans, smart cellar covers.
4.3 Consumer electronics: independent wearable devices, smart bicycles, chronic disease management systems, management of the elderly and children.
4.4 Equipment management: equipment status monitoring, white goods management, large-scale public infrastructure, safety monitoring of pipelines and tunnels.
4.5 Intelligent buildings: environmental alarm system, central air conditioning supervision, elevator Internet of Things, and air defense space coverage.
4.6 Command logistics: cold chain logistics, container tracking, fixed asset tracking, financial asset tracking.
4.7 Agriculture and Environment: Agricultural Internet of Things, animal husbandry, real-time monitoring of air, and real-time monitoring of water quality.
4.8 Other applications: mobile payment, smart community, smart home, cultural relics protection.
GSM for IoT: GSM
The Global System for Mobile Communications, abbreviated as GSM, is a digital mobile communication standard formulated by the European Telecommunications Standards Organization ETSI. Its air interface adopts time division multiple access technology. Since it was put into commercial use in the mid-1990s, it has been adopted by more than 100 countries around the world. GSM standard equipment occupies more than 80% of the current global cellular mobile communication equipment market. Since GSM is the second generation of mobile communication technology relative to analog mobile communication technology, it is referred to as 2G for short.
2.1 Spectral efficiency
Due to the adoption of high-efficiency modulators, channel coding, interleaving, equalization and speech coding techniques, the system has high spectral efficiency.
Due to the increase of the transmission bandwidth of each channel, the requirement of the co-frequency multiplexing to interference ratio is reduced to 9dB, so the co-frequency multiplexing mode of the GSM system can be reduced to 4/12 or 3/9 or even smaller (the analog system is 7/21). ); coupled with the introduction of half-rate speech coding and automatic traffic allocation to reduce the number of handovers, the capacity efficiency of the GSM system (the number of channels per megahertz per cell) is 3 to 5 times higher than that of the TACS system.
2.3 Voice Quality
In view of the characteristics of digital transmission technology and the definition of air interface and voice coding in GSM specification, when the threshold value is above, the voice quality always reaches the same level and has nothing to do with the wireless transmission quality.
2.4 Open Interface
The open interface provided by the GSM standard is not limited to the air interface, but also directly between the newspaper network and between various equipment entities in the network, such as the A interface and the Abis interface.
The purpose of security is achieved through the use of authentication, encryption and TMSI numbers. Authentication is used to verify the user's right to access the network. Encryption is used on the air interface and is determined by the SIM card and the key of the network AUC. TMSI is a temporary identification number assigned by the business network to the user to prevent someone from tracking and revealing their geographic location.
2.6 Interconnection with ISDN, PSTN, etc.
Interconnection with other networks usually utilizes existing interfaces such as ISUP or TUP.
Roaming is implemented on the basis of SIM card. Roaming is an important feature of mobile communication, which means that users can automatically enter another network from one network. GSM can provide global roaming, but of course requires some agreement between network operators, such as billing.
GSM for IoT: Comparison of NB-IoT and GSM
1. Wide coverage
Compared with traditional GSM, a base station can provide 10 times the area coverage. An NB-IOT base station can cover a range of 10km, and a single base station in a small county can cover it. At the same time, NB-IoT has a gain of 20dB higher than that of LTE and GPRS base stations. It can cover places where signals are difficult to reach, such as underground garages, basements, and underground pipes. It is impossible to make calls underground, but NB-IoT can still communicate. .
2. Massive connections
A frequency of 200KHz can provide 100,000 connections. The more connections you provide, the fewer base stations you build, and the fewer base stations you build, the more money you save! A teacher can teach 200 students at the same time, and another teacher can take 20 students. In this way, on the premise of taking 1,000 students, a teacher with 200 students can only hire 5 students, and the latter teacher will hire 50 students. indivual.
3. Low power consumption
It can work for ten years with AA batteries (AA batteries) without recharging. 10 years without charging! You are not lying to me, are you? My phone needs to be charged every day! NB-IoT introduces eDRX power saving technology and PSM power saving mode, which further reduces power consumption and prolongs battery life. In PSM mode, the terminal is still registered on the network, but the signaling is unreachable, so that the terminal stays in deep sleep for a longer time to save power. The eDRX power-saving technology further extends the sleep period of the terminal in idle mode, reduces unnecessary startup of the receiving unit, and greatly improves the downlink accessibility compared to PSM.
4. Mobility is simplified
Unlike our mobile phones, which are often used in cars and high-speed trains, the signal on the high-speed train is not good, because the speed is too fast. The mobile phone keeps switching base stations, just like a relay race. Lost, calls are intermittent or even dropped.
Most scenarios of using NB-IOT for IoT terminals are static, such as smart meter reading, which can reduce the complexity of the protocol and reduce the cost of modules.
5. Insufficient NB-IOT
5.1 The deployment frequency is authorized and must be deployed by the operator!
5.2 The cost of the module is still high (compared to the mature GPRS module, wifi module), which should gradually decrease with the increase in usage.
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