The stationary use of information and communication technology is becoming less important. Nowadays, it is important that information be available at any time, any place, whether in a professional or private environment.
Computers are becoming smaller and more compact, and since the invention of digital watches, the idea of wearing a mobile computer on the wrist is playing an increasingly important role. Therefore, many companies have thought about how computers and wristwatches or wristband can be combined with each other and brought some models on the market. The generic term for these portable computers is Wearable Computing. Wearable computers have already gained a lot of importance in our everyday lives. In order for smooth communication between the terminals to take place, standards are needed that are used between the devices. The aim of this article is to provide an overview of today’s possibilities of communication between the terminals. This article is mainly about the communication between the mobile devices. Thus, various communication techniques such as NFC, Bluetooth Low Energy (BLE), Ant +, etc. are explained. This aticle will not evaluate the advantages and disadvantages as well as opportunities to keep the topic shorter.
Communication standards for wearable computing
Communication and technology standards are playing an increasingly important role in today’s world. Without them, various devices with different architecture and from different manufacturers could not communicate together. Since man is an individual, there will always be devices from different providers. In order to guarantee a functioning communication between these devices, they must be coupled with each other. The systems should work together smoothly and be able to communicate both physically and logically. To guarantee this, there must be standards that enable an unrestricted exchange of data and information across manufacturers. Wearables manufacturers should be careful when planning. In addition, wireless networking techniques serve not to restrict the user’s freedom of movement.
NFC
---
Similar to the radio technologies RFID or Bluetooth, the communicating devices in NFC or near-field communication must be kept very close together in a possible transmission. The short distance is the true strength of this technology. Which data is transmitted and which actions are executed depends on the remote site. This can be another NFC-enabled device or an NFC tag. This NFC tag is a chip that can contain specific information. Therefore, if an NFC-enabled device scans or touches such an NFC tag, information may be read or, for example, a transaction may be executed. NFC is already integrated in many devices today. In a supermarket, you could attach an NFC tag to the front door, which displays all the reduced items on the device to be received when scanning. You could also use a day in a cafe to connect to the in-house wifi network or to download coupons.
Bluetooth Low Energy (BLE)
Many new wireless applications in the areas of sports, fitness, medicine and sensor technology are made possible by BLE. BLE is a standard for transmitting sensor values and control data and is also known as Bluetooth Smart Ready. Bluetooth Low Energy is part of the Bluetooth 4.0 standard. It operates in the 2.4 GHz band with 40 channels between 2.402 GHz and 2.483 GHz, of which the three channels 0, 12 and 39 are reserved as signaling channels. The channel width is 1 MHz. BLE uses the Gaussian Frequency Shift Keying (GFSK) frequency hopping technique (FHSS) as a modulation technique, which sends 1,600 frequency hops per second between the predetermined frequency channels. The method is latency-free, so it has no latency. The effective bandwidth is 1 MHz, the data rate is 1 Mbit / s. The bridgeable distance is about 10 m. During the transmission mode, the transmitter needs a maximum of 10 mA. The duty cycle between the transfer mode and the idle state is 0.25%. This means that the average power consumption is in the micro-ampere range. For data security, Bluetooth Low Energy uses the 128-bit Advanced Encryption Standard (AES).
Ant+
Ant+ is a flexible, low-power wireless technology that is not yet standardized. With this technology, scalable Wireless Sensor Networks (WSN) can be set up as ad-hoc networks for a variety of close-to-body monitoring tasks. It can be used to implement many applications in the areas of healthcare, sports and fitness, as well as in patient monitoring. All measurements can be transmitted via these Wireless Sensor Networks. These include the measurement of blood pressure or heart rate, heart rate or body temperature, as well as the weight or body mass index. ANT+ operates in the license-free 2.4 GHz frequency band, the ISM band, between 2.403 GHz and 2.480 GHz. It is transmitted on 78 selectable RF channels, modulated in Gaussian Frequency Shift Keying (GFSK). ANT networks consist of standalone ANT devices, these are sensors with ANT modules that capture the data and transmit it over the WSN network. ANT networks can adopt different topologies and operate as peer-to-peer networks or meshed networks. You do not have a central master. The channels support unidirectional and bidirectional ANT communications, broadcasts and burst operation. The power consumption is extremely low and depends on the operating condition. In idle waiting mode, the power consumption is a few microwatts, in the active state when sending the data or when receiving the power consumption of ANT devices is between 10 mA and 20 mA. The mean value is about 30 μA. After sending, the device switches directly back to the power-saving sleep mode. With this low power consumption ANT devices can be operated over several years with button cells. To ensure secure data transmission, 64-bit data and information is encrypted. In addition, the data to be transmitted is checked by a cyclic redundancy check (CRC). Security is ensured by 64-bit encryption. In addition, there is a cyclic redundancy check (CRC) with which the transmitted data is validated. The nets have high immunity to crosstalk because they have a power budget of +95 dB. Depending on the operating mode, data rates of up to 20 kbit / s can be achieved during operation. ANT + facilitates the collection and transmission of sensor data for processing and monitoring purposes. The data transmission takes place with the ANT protocol.
WiBree
For short-range radio communications, there are various techniques such as Near Field Communication (NFC), which is in the centimeter range, Short Range Devices (SRD), Bluetooth, which is used for distances up to 10 meters, and another with Wibree, developed by Nokia technology, which is also used in the home, but is characterized by a significant power consumption compared to Bluetooth. Wibree targets the wireless exchange of data between keyboards and mice, watches and sensors used in sports or in robots. Communication takes place between the mentioned devices and the mobile phone or the desktop. The transmission takes place in the ISM band at 2.4 GHz with a data rate of up to 1 Mbit/s. The bridgeable distance is 10 m. The Wibree approach targets either a single-chip solution or a dual-chip solution with built-in Bluetooth capabilities.
IEEE 802.15.4
IEEE 802.15.4 targets low-bit-rate Wireless Personal Area Networks (WPAN) with extremely low power requirements, such as those used in wireless sensor networks (WSN). The focus is on battery life. In addition to the normal version, Low Rate Wireless Personal Area Network (LR-WPAN) offers a special low-speed version. Possible applications for 802.15.4 include sensor technology, interactive games, intelligent ID cards, remote controls and building automation. 802.15.4 uses the license-free ISM bands at 2.45 GHz or 868 MHz resp. 915 MHz. As a modulation method, the spread spectrum technique with parallel sequence spread spectrum (PSSS) with a symbol transmission rate of 62.5 symbols/s is used in 802.15.4; in the 2, 4GHz band is done with quadrature phase shift keying (QPSK). Due to a deterministic access method with a fixed time frame, isochronous transfers are possible. In addition, you can configure star-shaped mesh networks that support routing. In such network configurations, there are full function stations, Full Function Devices (FFD), which are responsible for communication and those with limited functionality, Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4. Due to a deterministic access method with a fixed time frame, isochronous transfers are possible. In addition, you can configure star-shaped mesh networks that support routing. In such network configurations, there are full function stations, Full Function Devices (FFD), which are responsible for communication and those with limited functionality, Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4. Due to a deterministic access method with a fixed time frame, isochronous transfers are possible. In addition, you can configure star-shaped mesh networks that support routing. In such network configurations, there are full function stations, Full Function Devices (FFD), which are responsible for communication and those with limited functionality, Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4. In addition, you can configure star-shaped mesh networks that support routing. In such network configurations, there are full function stations, Full Function Devices (FFD), which are responsible for communication and those with limited functionality, Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4. In addition, you can configure star-shaped mesh networks that support routing. In such network configurations, there are full function stations, Full Function Devices (FFD), which are responsible for communication and those with limited functionality, Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4. and those with limited functionality, the Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4.] and those with limited functionality, the Reduced Function Devices (RFD). The latter form the endpoints, for example the sensors from a sensor network, which communicate via the FFD stations. 802.15.4 is used in ZigBee and MeshScape, among others. In the ZigBee protocol stack, the physical layer (PHY) and the medium access control (MAC) correspond to 802.15.4.
ZigBee
ZigBee is a standardized radio procedure. The technology behind it is comparable with wireless technology according to 802.11 and Bluetooth (IEEE 802.15.1). It was developed for low-speed wireless local area networks (LR-WPAN). Unlike the other two techniques, ZigBee transmits only small amounts of data. The transmission speed is slower in comparison, but the low power consumption is a significant advantage of this method. The resumption of functionality after a sleep mode is much faster. Zig-Bee uses the frequencies of license-free ISM bands around the ranges 868 MHz, 915 MHz and 2.4 GHz. Depending on the transmission power, the technology can bridge between 10 and 75 meters. There are several sensors for using ZigBee. For example, over a nasal cannula and a pressure sensor, the patient’s breathing can be monitored. Especially when used in sleep diagnostics, this sensor component makes an important contribution to the detection of nocturnal respiratory arrest phases.
These are the key features of the ZigBee technology:
– Overall data rate 250 kbit/s or useful data rate ~ 128 kbit / s
– Low latency in the connection setup
– Small size of the protocol stack
– Excellent network properties
– Low power consumption
