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Glossary
1 - What is IEEE802.15.4?
TWELITE is a wireless microcontroller module compliant with IEEE802.15.4.
It features low power consumption and stable communication performance.
Features
The features of IEEE802.15.4 are as follows.
International Standard
IEEE802.15.4 is a standard established by IEEE (Institute of Electrical and Electronics Engineers), headquartered in the United States. Being a standard means that products based on the specification are supplied by multiple vendors rather than relying on a single proprietary standard, ensuring stability. When using the 2.4 GHz ISM band, it can be sold not only in Japan but worldwide.
Two-Way Digital Communication
IEEE802.15.4 adopts Offset Quadrature Phase Shift Keying (O-QPSK) as the modulation method in the 2.4 GHz band and Direct Sequence Spread Spectrum (DSSS) as the spreading method, making it resistant to interference noise and enabling stable two-way digital communication.
Encrypted Communication
IEEE802.15.4 ensures data communication security using strong encryption technology, 128-bit AES encryption, which is also used in internet banking and online shopping.
Low Power Consumption
The design philosophy of IEEE802.15.4 emphasizes low power consumption. It enables operation for years without battery replacement, operation with coin batteries, or even operation powered by energy harvesting devices that extract power from light, heat, vibration, etc. This makes wireless use possible in locations that were previously difficult to install.
Low Speed
Compared to wireless LAN or Bluetooth, IEEE802.15.4 limits communication speed. This is to optimize the communication speed (250 kbps) for wireless sensor networks, achieving low power consumption and high communication sensitivity. Although described as low speed, it provides sufficient speed for building sensor networks.
Standard Protocol
IEEE802.15.4 is adopted as the physical layer for wireless communication by many standardization organizations such as the ZigBee Alliance, Thread Group, and IETF. Various standard communication protocols are implemented on top of IEEE802.15.4. This flexibility in protocol selection is also a characteristic of IEEE802.15.4, allowing it to flexibly support wireless sensor networks.
Specifications
| Operating Frequency | 2.4 GHz | Usable worldwide |
| Number of Channels | 16 | 16 channels can communicate simultaneously |
| Modulation Method | O-QPSK, DSSS | Resistant to noise |
| Data Rate | 250 kbps | Optimized for sensor networks |
| Current Consumption (During Communication) | <30 mA | Low power consumption |
| Encryption | AES-128 bit | Strong security available |
| Network Node Capacity | 65,535 | Supports large-scale networks |
IEEE802.15.4 Data Frame
Below is the packet structure defined in the IEEE 802.15.4 data frame.
| PHY Header (SHR, PHR) | PHY Payload (PSDU) Maximum 127 bytes | |||||||
| OCTET | 4 | 1 | 1 | 2 | 1 | 4~20 | n | 2 |
| Contents | Preamble Sequence | Frame Delimiter Start Position | Frame Length | Frame Control | Sequence Number | Address Information | MAC Payload | FCS |
OCTET is a unit representing data volume, defined as 1 OCTET = 8 bits.
While not common nowadays, some systems do not treat 1 byte as 8 bits, so the byte unit can be ambiguous. In communication definitions, OCTET, defined as 8 bits, is used.
- When programming using the IEEE802.15.4 MAC API, the areas to be aware of are frame control, address information, and data.
- The sequence number is automatically assigned by the MAC layer, so users cannot obtain or set this value.
- LQI (Link Quality Indicator) information is not included in the packet information. It is obtained from the receiver circuit at packet reception.
- The maximum packet length is 127 OCTETs (PHY payload: PSDU).
- In typical communication, when address information is 8 OCTETs (16-bit short addresses for both sender and receiver), the data area (MAC payload) can be up to 127 - 2 (frame control) - 1 (sequence number) - 8 (address) - 2 (FCS) = 114 OCTETs.
- In stacks like ZigBee PRO, headers used by the stack reduce the data area available to users.
- Communication time for maximum packet length is about 4.3 ms.
- The composition of address information consists of the following combinations:
- Source (Src) PAN ID (2 OCTET)
- Source (Src) address (0: no address, 2: short address, 8: extended address)
- Destination (Dst) PAN ID (2 OCTET)
- Destination (Dst) address (0: no address, 2: short address, 8: extended address)
- Typically, the structure is Src PAN ID, Src short address, Dst PAN ID, Dst short address, totaling 8 OCTETs.
- It is also possible to use the MAC address only for the Src address. In this case, the total is 14 OCTETs: Src PAN ID, Src MAC address, Dst PAN ID, Dst short address.
| Addressing Mode | Address Area Size |
| No source or destination address (PAN ID only) | 4 |
| 118 | |
| Source and destination use 16-bit short addresses | 8 |
| 114 | |
| Source and destination use 64-bit extended addresses | 20 |
| 102 |
Addressing modes other than the above combinations are also possible.
What is IEEE802.15.4g?
IEEE802.15.4g is a communication method intended for smart meter communication. The frequencies usable with IEEE802.15.4g vary by country; in Japan, the 920 MHz band physical layer (PHY) can be used. The MAC layer is also being standardized as IEEE802.15.4e. Neither is compatible with IEEE802.15.4. In Japan, IEEE802.15.4g is expected to be a standard mainly for enabling automatic gas meter reading.
What is IEEE802.15.4k?
IEEE802.15.4k is a communication method intended for smart grid communication. It is called Low Energy Critical Infrastructure Monitoring (LECIM) and aims to provide reliable communication over low speed and long distances.
Wireless Microcontroller Connecting Things: TWELITE
There are many everyday situations where you want to operate something remotely or monitor something. Wireless is suitable when you want to know the status of a distant object or control it remotely. However, when making things wireless, various constraints such as battery life, communication distance, simultaneous connections, and size make it difficult to realize with conventional wireless technologies. Thus, wireless technology to connect things was born.
Our company offers TWELITE, a wireless microcontroller compliant with IEEE802.15.4, optimal for building wireless sensor networks, supporting customers in simplifying communication function development for wireless sensor network-related devices and accelerating time to market.
It is aimed at those who want to easily use wireless functions to create devices for collecting various sensor information wirelessly or creating various remote controls but find it too challenging. Using TWELITE DIP, you can easily acquire wireless functionality.
It supports a wide range of users from hobbyists and learners to various prototyping and small-lot production.
Evaluation and Development of Wireless Sensor Networks (IEEE802.15.4 Compliant)
Our company also provides development tools for monitoring various sensor information wirelessly applicable to wireless sensor networks and for conducting communication quality measurements.