At present, more than 100 million devices in the world support Bluetooth technology, of which more than 50% are used on mobile phones. Bluetooth technology is a solution for wireless transmission of consumer electronic products. More than half of consumers have at least one device that supports Bluetooth technology, and most consumers around the world can recognize this brand logo.
1、 Comparison of wireless network data transmission protocols
We are familiar with zigee, WiFi and Bluetooth (great changes have taken place in traditional Bluetooth and the new generation of Bluetooth). The relationship between them can be seen from the figure below.
It can be seen from the above figure that different wireless data transmission protocols have their own application ranges in data transmission rate and transmission distance. ZigBee, Bluetooth and WiFi standards are wireless communication standards working in the 2.4GHz frequency band. Let’s briefly compare ble with traditional Bluetooth and WiFi standards to help readers quickly understand.
The traditional Bluetooth data transmission rate is less than 3mbps, and the typical data transmission distance is 2-10M. The typical application of Bluetooth technology is to transmit a small amount of data between two mobile phones. The maximum data transmission rate of WiFi can reach 50Mbps, and the typical data transmission distance is 30-100m. WiFi technology provides an internet wireless access technology.
2、 Bluetooth 4.0
Bluetooth wireless technology is one of the most widely used global short-range wireless standards. The new Bluetooth 4.0 version combines three Bluetooth technologies (namely traditional Bluetooth, high-speed Bluetooth and low-power Bluetooth Technology). It integrates the inherent advantages of Bluetooth technology in wireless connection, and adds the characteristics of high-speed Bluetooth and low-power Bluetooth. These three specifications can be used in combination or alone.
Low power Bluetooth, or ble, is the core specification of Bluetooth 4.0. The biggest feature of this technology is that it has ultra-low operating power consumption and standby power consumption. Bluetooth low-power devices can work continuously for several years with a button battery. They can be applied to wireless solutions with strict requirements on cost and power consumption, and will have a wider field with the development of intelligent machines.
In May 2016, the international Bluetooth Technology Alliance proposed the Bluetooth technology standard.
3、 Bluetooth ble
Low power Bluetooth technology Bluetooth low energy, a standard Bluetooth wireless protocol adopted by the international Bluetooth Alliance (bt-sig).
The ble specification defines two basic configuration files: gap (generic access profile) and GATT (generic attribute). The gap layer in the protocol is responsible for the device access mode and process, including device discovery and connection establishment. Terminate the connection. Initialize security features and device configuration. The GATT layer in the protocol stack is used for data communication between connected Bluetooth devices.
Ble is a standard, which defines a series of communication protocols required for short-range and low data transmission rate wireless communication. The working frequency bands used by ble based wireless networks are 868mhz, 915MHz and 2.4GHz, and the maximum data transmission rate is 250kbps.
4、 Relationship between Bluetooth 4.0 and traditional Bluetooth
What is the relationship between smart ready, smart and traditional Bluetooth? Please see the figure below:
Smart ready can connect and communicate with smart ready, traditional Bluetooth and smart. Traditional Bluetooth can connect and communicate with smart ready and traditional Bluetooth. Smart can connect and communicate with smart and smart ready
5、 Dual mode equipment
1: Basicrate (BR), 2: Bluetooth low energy (ble). The devices that support both BR and ble are dual-mode devices, that is, smart ready discussed here. Smart ready is the main body of Bluetooth 4.0. Generally, devices with stable power supply, such as mobile phones and PCs, adopt dual-mode Bluetooth chips.
Single mode equipment
So what is smart? Smart is the trademark of low-power Bluetooth in Bluetooth 4.0, that is, Bluetooth low energy, abbreviated as Le or ble. On the Internet, a button battery in Bluetooth 4.0 can be used for one year for ble. Smart ready still consumes a lot of power. It needs a stable power supply, such as mobile phones, PCs and other devices. Because of its low power consumption, smart is usually powered by batteries or button batteries.
Characteristics of ble
In general, ble technology has the following characteristics:
High reliability
For wireless communication, because the electromagnetic wave is easily disturbed by many factors in the transmission process, such as obstacles, weather conditions, etc., the wireless communication system has inherent unreliability in the data transmission process. When specifying Bluetooth 4.0 specification, sig of Bluetooth technology alliance has taken into account the inherent uncertainty in the process of data transmission. Reliability measures are adopted in RF, baseband protocol and link management protocol, including error detection and correction, data encoding and decoding, data noise, etc., which greatly provides the reliability of Bluetooth wireless data transmission. In addition, adaptive frequency modulation technology is used, Minimize crosstalk with other 2.4G radio waves.
Low cost and low power consumption
Low power Bluetooth supports two deployment modes: dual-mode and single-mode. Generally, dual-mode is adopted on intelligent machines, and ble single-mode is generally adopted for peripherals.
Low power design: Bluetooth version 4.0 strengthens the low power performance of Bluetooth in data transmission, and the power consumption is 90% lower than that of traditional Bluetooth.
The standby power consumption of traditional Bluetooth devices has always been one of its defects, which is closely related to the fact that the traditional Bluetooth technology uses 16-32 channels for broadcasting, while low-power Bluetooth is only applicable to three broadcasting channels, and the RF on time during each broadcasting is also reduced from the traditional 22.5ms to 0.6 ~ 1.2ms. The changes of these two protocol specifications greatly reduce the standby power consumption caused by broadcast data.
The low-power Bluetooth design uses the deep sleep state to replace the idle state of the traditional Bluetooth. In the deep sleep state, the host is in the ultra-low load cycle state for a long time, which is only started by the controller when it needs to operate. Because the host consumes more energy than the controller, this design also saves more energy.
Quick start, instant connection
Previously, the startup speed of Bluetooth version was very slow. The Bluetooth startup connection of version 2.1 took 6S, while the Bluetooth 4.0 version only took 3MS, which was almost an instant connection.
Great transmission distance
The transmission distance of traditional Bluetooth is generally 2-10M, while the effective transmission distance of Bluetooth 4.0 can reach 60 ~ 100m, and the transmission distance is increased by 10 times, which greatly opens up the application prospect of Bluetooth technology.
High security
In order to ensure the security of data transmission, AES-128 CCM encryption algorithm is used for data packet encryption authentication.
Communication channel analysis of ble wireless network
Antenna is very important for wireless communication system. Various antennas can be seen in daily life, such as mobile phone antenna, TV receiving antenna, etc. the main function of antenna can be summarized as follows: complete the transmission and reception of radio waves. When transmitting, the high-frequency current is converted into electromagnetic wave and transmitted; When receiving, the electromagnetic wave is converted into high-frequency current.
How to distinguish different waves?
In general, different radio waves have different spectrum. The spectrum of wireless communication system ranges from tens of megahertz to thousands of megahertz, including the band used by radio, mobile phone and satellite TV. These radio waves use air as the transmission medium. In order to prevent mutual interference between different applications, it is necessary to manage the communication channel of wireless communication system.
Each country has its own radio management structure, such as the Federal Communications Commission (FCC) of the United States and the typical Standards Commission (ETSI) of Europe. China’s radio management organization is called China Radio Management Commission, which is mainly responsible for the division, allocation and assignment of radio frequencies, coordination and management of satellite orbital positions, radio monitoring, detection and interference investigation, Coordinate and deal with electromagnetic interference and maintain air wave order.
Generally, the use of a specific frequency band requires the permission of the radio management department. Of course, the radio management departments of various countries also stipulate that some frequency bands are open to the public and can be used without permission to meet different application needs. These frequency bands include ISM (industrial, scientific and medical-i) frequency band.
In addition to ISM frequency band, in China, the frequency band below 135KHz is also free in North America, Japan and other places. The management of radio spectrum in various countries not only stipulates the frequency of ISM frequency band, but also specifies the transmission power used in these frequency bands. In the process of project development, it is necessary to consult relevant manuals, such as the regulations on the management of micro power (short distance) radio equipment issued by the Ministry of information industry of China.
Ble works in the ISM band and defines two bands, 2.4GHz band and 896 / 915MHz band. A total of 27 channels are specified in IEEE 802.15.4:
In the 2.4GHz frequency band, there are 16 channels in total, and the channel communication rate is 250kbps:
In the 915MHz frequency band, there are 10 channels in total, and the channel communication rate is 40kbps:
In the 868mhz frequency band, there is one channel, and the channel communication rate is 20kbps.
Ble works in the 2.4GHz frequency band and is only applicable to three broadcast channels. It is applicable to the adaptive FM technology common to all Bluetooth specification versions.
Adaptive frequency modulation technology is a combination of frequency self-use and power adaptive control based on automatic channel quality analysis. It can automatically avoid the interfered frequency points in the process of frequency modulation communication, and achieve the purpose of maintaining high-quality communication on the non-interference frequency modulation channel for a long time with the minimum transmission power and the lowest interception probability.
Application fields of ble Technology
For a long time, the application of Bluetooth technology in accessories has attracted more attention, but with the rapid development of the mobile era, ble will be more useful. In fact, ble’s low-power technology focuses on special markets such as medical and health monitoring at the beginning of its design. In general, the development direction of Bluetooth 4.0 will be sports management, medical and health care, smart meters, smart home and various Internet of things related applications.
In the field of health care
In the past, many health applications were based on Bluetooth 2.1 protocol, but they failed to stir up too much waves due to power consumption. After ble solved this problem, the market was strongly activated. For example, the continua Health Alliance, initiated by Intel and established by many different medical technology and health care institutions, has decided to include ble in the future standard transmission technology.
At present, there are many medical products with Bluetooth 2.1 specification in the market, such as sphygmomanometer and blood glucose meter. In the future, there will be more and more medical products with Bluetooth 4.0 specification officially certified by continua Health Alliance. In terms of health application, ble also has a broad market space, which can be seamlessly combined with fitness equipment. When people use fitness equipment, they can transmit and record sports through relevant equipment such as pedometer and pulse machine, enter mobile devices and save personal health information.
In the field of Internet of things
At present, all smart devices in the market are the driving force for the ecological development of the Internet of things, but ble can play a node role in opening up the “joint” between the Internet of things and sensor devices, which will promote the real development of the Internet of animals in a key sense. Because Bluetooth technology has always paid attention to the upper application and has unified standards, although a variety of bottom hardware come from different manufacturers, they can be interconnected, form a perfect ecological environment, and create a good environment for themselves and the Internet of things product market.
Some analysts believe that when ble turns everyone’s Android or other mobile devices into a sensor tag, what it can do will not only find things through application software, but will have great scalability. For example, it can build a P2P network through app and sensors to simulate the function of GPS. In short, when ble sensors are everywhere, there must be huge business opportunities.
Intelligent lighting
At present, most of the traditional intelligent lights in the market are controlled by wire, or there must be a remote controller to control the lights. The control distance is limited and not flexible enough. Low power Bluetooth intelligent mesh lamp uses low-power Bluetooth technology and mesh networking technology. Just install an app on your smart phone to realize the intelligent networking control of light, which is more convenient and flexible. At the same time, it supports remote control equipment.
Set top box, intelligent remote control
With the development of smart TV, the traditional remote controller can not meet the needs of users, and voice remote control is gradually becoming standard. Using our intelligent voice remote control scheme to control smart TV and other devices through voice, users can select their favorite programs more quickly and effectively.
Hid equipment application
Using low-power Bluetooth technology, compared with the traditional Bluetooth keyboard and mouse, it has the characteristics of lower power consumption and faster and convenient pairing connection. Ble can be added to the customer’s existing mouse and keyboard to realize the rapid upgrading of products.
Small household appliances
In traditional small household appliances, such as soymilk machines and rice cookers, low-power Bluetooth control is added to upgrade them to more intelligent small household appliances. Small household appliances can be controlled through smart phones, such as switching and reservation. Small household appliances can also be self inspected and firmware upgraded, bringing a different experience to life.
Beacon application
Beacon sends information to mobile phones based on Bluetooth broadcasting, which can help businesses optimize business strategies and provide services by using users’ geographical location. Businesses can use beacon devices to inform consumers of new products and provide vouchers to encourage consumers’ impulsive consumption. We can also use the data obtained by beacon technology, such as geographical location and purchase records, to provide more consumer satisfaction information and better provide services.
In the scene of finding parking space in the parking lot, you don’t have to take out your mobile phone. The vibration feedback on your watch can help you find vacant space and love your car. It is also an ideal application for beacon. Intelligent message push, product advertising and indoor positioning and navigation are gradually becoming a trend. To realize these functions, beacon products, as the basic hardware equipment, are indispensable. At the same time, apple ibeacon, wechat shake, Alibaba and other Internet giants are also promoting the development of beacon applications.
