Cellular networks provide the backbone for many things we know and love, enabling us to access the Internet, take a bus, contact friends, shop, watch videos and so on. It is well known that in addition to the continuous development of cellular applications, the Internet of things also plays a vital role in many applications.
In some past articles, we have discussed other connection technologies, including WiFi, Bluetooth and lpwan. The reason why we have so many connection options is that IOT applications may be very different, which means that the requirements will be different.
There is always a trade-off between bandwidth and power consumption. In the past, cellular connectivity has focused on range and bandwidth at the cost of power consumption, which means it can send a lot of data over long distances, but it will soon run out of battery power. This is a good choice for devices that are connected to the power supply or can be charged frequently (such as your mobile phone), but it is not feasible for IOT applications that require remote sensors and devices to be used for months or years.
But that’s not all about cellular networks. You may have heard of 2G, 3G and 4G, but new cellular technologies such as NB IOT and lte-m are specifically for IOT applications. 5g may also prove beneficial and transformative for the Internet of things.
How does a cellular network work?
When we make phone calls, send text messages or access the Internet through mobile devices, we are sending signals wirelessly to the nearby mobile phone transmission tower. These cellular towers receive our signals and send them back to us. Cellular tower is a part of the base station. The base station has wired connection with other base stations and the Internet, which helps to transfer information over a greater distance than a single cellular tower.
Like all wireless communication technologies, cellular networks use electromagnetic waves to send information. Just as your radio has different frequency bands that can be tuned (for example, tuning to 101.1 means you are listening to 101.1mhz), wireless communication technology also has a specific frequency band in which it works.
If all wireless communications try to use the same frequency, there will be too much noise and interference for clear communication. Therefore, the FCC specifies the frequency bands that can be used by who, and the cellular carriers each have specific frequency bands that allow them to work (for example, Verizon in the 746-757mhz and 776-787mhz frequency bands).
However, even if it has its own designated frequency band, operators still need to consider interference. If the operator’s two base stations are close to each other and operate at the same frequency, their signals will interfere with each other and cause problems for people trying to use the network in the area.
The solution to this problem is also the answer to the next question.
Why is it called a “cellular” network?
It is called cellular network because the network operator divides the area into “cells”. Each cell has a cell tower, and its working frequency is different from that of adjacent cell towers. For example, if you use hexagonal arrangement, it means that you only need 7 different frequencies to ensure that the same frequency will not be used in adjacent cells.
The area of each cell depends on the use density. In cities, the distance of each community may be only half a mile, while in rural areas, the distance may be as high as five miles.
When users move between cells, their frequency will automatically change to switch to the new cell tower. There is still a lot of work to be done behind the scenes to manage the large number of users using the same network on the move at the same time.
What does g mean?
Even if all of the above is new to you, you’ve almost certainly heard of terms like 3G or 4G. These refer to the third and fourth generation respectively.
Each generation is a set of standards and technologies defined by a standards body called itu-r. The organization is responsible for managing international RF spectrum and standards, which helps to ensure the effective use of spectrum. Without such institutions and rules to control who can use what spectrum, different companies and organizations may interfere with each other and reduce the overall service level.
However, it should be noted that even under the same standard, there may still be different technologies. For example, UMTS (universal mobile telecommunications system) is a 3G technology mainly used in Europe, Japan and China, while CDMA2000 System is used in North America and South Korea.
So what’s the difference between 1g, 2G, 3G and 4G?
Starting with the 1g system launched in the early 1980s, a new generation will be launched about every 10 years. Each generation brings new frequency bands, higher data rates and new transmission technologies (not backward compatible).
Because each generation is different, which is why you may not have 4G coverage on your phone, but there is still 3G (and why you may not be able to access the Internet, but you can make calls and send text messages).
Several operators have announced that they will shut down their 2G networks to release radio spectrum for other purposes. Any machine using 2G radio needs to replace its radio with a new generation radio in order to continue working.
Is cellular connection a good choice for the Internet of things?
It all depends on your specific use case. As mentioned in the introduction, cellular has not been suitable for many Internet of things applications because it consumes a lot of power and the unit cost may be high. This limits cellular connections to applications that have direct power, need to send large amounts of data, do not involve a large number of devices, and are located in densely populated areas.
For use cases that require sensors / devices to be battery powered, there is no need to send a large amount of data. With thousands of devices, or possibly remote, cellular phones are not a suitable choice. But some things are changing.
Operators are promoting new cellular technologies such as NB IOT and lte-m specifically for the Internet of things. Although you still need to be in densely populated areas (near cellular towers), these technologies will provide low-cost, low bandwidth and low-power connectivity, which will make many new Internet of things use cases that are currently expensive possible.
As many operators are about to launch their services, please pay attention to these cellular technologies.