| DASH7 | |
| Standard: | Based on ISO/IEC 18000-7 |
| Developer: | DASH7 Alliance |
| Version: | v1.1 (Jan 2017) |
| Industry: | Automation, industrial, military |
DASH7 Alliance Protocol (D7A) is an open-source wireless sensor and actuator network protocol, which operates in the 433 MHz, 868 MHz and 915 MHz unlicensed ISM/SRD band. DASH7 provides multi-year battery life, range of up to 2 km, low latency for connecting with moving things, a very small open-source protocol stack, AES 128-bit shared-key encryption support, and data transfer of up to 167 kbit/s. The DASH7 Alliance Protocol is the name of the technology promoted by the non-profit consortium called the DASH7 Alliance.
DASH7 Alliance Protocol originates from the ISO/IEC 18000-7 standard describing a 433 MHz U.S. Department of Defense announced the largest RFID award in history, a $429 million contract for DASH7 devices, to four prime contractors, namely Savi Technology, Northrop Grumman Information Technology, Unisys and Systems & Processes Engineering Corp. (SPEC).[1]
In March 2009, the DASH7 Alliance, a non-profit industry consortium to promote interoperability among DASH7-compliant devices, was announced, and as of July 2010 has more than 50 participants in 23 countries. It was meant to be similar to what the Wi-Fi Alliance does for IEEE 802.11, for wireless sensor networking.
In April 2011, the DASH7 Alliance announced adoption of DASH7 Mode 2, based on the ISO 18000-7 standard that makes better use of modern silicon to achieve faster throughput, multi-hop, lower latency, better security, sensor support, and a built-in query protocol.
In March 2012, the DASH7 Alliance announced that it was making the DASH7 Mode 2 specification available to non-members.
In July 2013, the DASH7 Alliance announced the DASH7 Alliance Protocol Draft 0.2.
In May 2015, the DASH7 Alliance publicly released v1.0 of the DASH7 Alliance Protocol.
In January 2017, the DASH7 Alliance publicly released the v1.1 of the DASH7 Alliance Protocol. The version constitutes a major update of v1.0, in particular in the area of security and interoperability.
Compared with other wireless data technologies:[2]
| Global standard used | Frequency bands | Channel width | Range | Frequencies available globally (yes/no) | Maximum end node transmit power | Packet size | Data rate (uplink/downlink) | Topology | End node roaming allowed | Governing body | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| DASH7 Alliance Protocol 1.x | 433/868/915 MHz ISM/SRD | 25 kHz or 200 kHz | 0–5 km | 433 MHz: +10dBm868/915 MHz: +27dBm | max. 256 bytes/packet | 9.6 kbit/s, 55.55 kbit/s or166.667 kbit/s / 9.6 kbit/s, 55.55 kbit/s or166.667 kbit/s | Node-to-node, Star,Tree | Yes | DASH7 Alliance | ||
| IEEE P802.11ah (low power Wi-Fi) | Unlicensed Sub-1 GHz bands (excluding TV whitespace) | 1/2/4/8/16 MHz | Up to 1 km (outdoor) | Dependent on RegionalRegulations (from 1 mW to 1 W) | Up to 7,991 Bytes (w/oAggregation), up to65,535 Bytes (withAggregation) | 150kbit/s ~ 346.666 Mbit/s/150 kbit/s ~ 346.666 Mbit/s | Star, Tree | Allowed by other 802.11 amendments (like 802.11r) | IEEE 802.11 working group | ||
| Ingenu RPMA | 2.4 GHz ISM | 1 MHz (40 channels available) | >500 km LoS | to 20 dBm | 6B–10kB | AP aggregates to 624 kbit/sper Sector (Assumes 8channel Access Point)/AP aggregates to 156 kbit/sper Sector (Assumes 8channel Access Point) | Typically Star. Treesupported with an RPMAextender | Yes | Ingenu | ||
| LTE-Cat M | Cellular | 1.4 MHz | 2.5–5 km | 100 mW | ~100 -~1000 bytestypical | ~200 kbit/s/~200 kbit/s | Star | Yes | 3GPP | ||
| LoRaWAN | 433/868/780/915 MHz ISM | EU: 8x125 kHz, US 64x125 kHz/8x125 kHz, Modulation: Chirp Spread Spectrum | 2–5 km (urban), 15 km (rural), 702 km LoS tested,[3] 1500 km Link Budget[4] | EU:<+14 dBm,US:<+27 dBm | User defined | EU: 300 bit/s to 50 kbit/s/300 bit/s to 50 kbit/s, US:900bit/s-100 kbit/s/900bit/s-100 kbit/s | Star on Star | Yes | LoRa Alliance | ||
| nWave | Sub-1 GHz ISM | Ultra narrow band | 10 km (urban), 20–30 km (rural) | 25–100 mW | 12 byte header, 2-20 byte payload | 100 bit/s/- | Star | Yes | Weightless SIG | ||
| SigFox | 868/902 MHz ISM | Ultra narrow band | 30–50 km (rural), 3–10 km (urban),1000 km LoS | 10μW to 100 mW | 12 bytes (payload) | 100 bit/s to 140messages/day/max. 4 messages of 8bytes/day | Star | Yes | SigFox | ||
| Weightless-W | 400-800 MHz (TV whitespace) | 5 MHz | 5 km (urban) | 17 dBm | 10 byte min. | 1 kbit/s to10 Mbit/s/1 kbit/s to10 Mbit/s | Star | Yes | Weightless SIG | ||
| Weightless-N | Sub-1 GHz ISM | Ultra narrow band (200 Hz) | 3 km (urban) | 17 dBm | Up to 20 bytes | 100 bit/s/- | Star | Yes | Weightless SIG | ||
| Weightless-P | Sub-1 GHz ISM | 12.5 kHz | 2 km (urban) | 17 dBm | 10 byte min. | 200 bit/s to100 kbit/s/200 bit/s to100 kbit/s | Star | Yes | Weightless SIG |
Networks based on DASH7 differ from typical wire-line and wireless networks utilizing a "session". DASH7 networks serve applications in which low power usage is essential and data transmission is typically much slower and/or sporadic, like basic telemetry. Thus, instead of replicating a wire-line "session", DASH7 was designed with the concept of B.L.A.S.T.:
D7A utilizes the 433, 868 and 916 MHz frequencies,[5] which are globally available and license-free.
Sub 1-GHz is ideal for wireless sensor networking applications, since it penetrates concrete and water, but also has the ability to propagate over very long ranges without requiring a large power draw on a battery. The low input current of typical tag configurations allows operating on coin cell or thin-film batteries.
Unlike most active RFID or LPWAN technologies, DASH7 supports tag-to-tag communications.
Localization techniques can be applied to DASH7 endpoints. An accuracy of 1 m using DASH7 beacons at 433 MHz has been achieved in a lab experiment.[6]
DASH7 supports a built-in query protocol that minimizes "round trips" for most messaging applications that results in lower latency and higher network throughput.
DASH7 provides a link budget of up to 140 dB with 27 dBm transmission power, which positions the technology as medium-range, compared to short-range (Bluetooth, Wi-Fi, ...) and long-range (LoRaWAN, SigFox). Note that higher ranges are always obtained at the expense of per-bit power consumption and transmission duration. Low-power long-range technologies are generally not truly bi-directional, as the regular scanning duty is pretty high. In this context, DASH7 is a very good compromise between range, power consumption, and bi-directionality and is very suitable for industrial applications with effective range of 100 to 500 m.
In line-of-sight situations, DASH7 devices today advertise read ranges of 1 kilometer or more, however, ranges of up to 10 km have been tested by Savi Technology and are easily achievable in the European Union, where governmental regulations are less constrained than in the USA.
The DASH7 Alliance is currently working on a certification program that functionally tests the DASH7 devices. The certification is composed of a set of test scenarios covering transactions in different stack configurations (channel, QoS, security). The physical wireless interface is not covered by the certification and will have to comply to local radio regulations.
The DASH7 Alliance policy forbids the addition of proprietary or licensable modulation techniques in the official DASH7 Alliance Protocol. However, the layered structure of the protocol allows simple integration of alternative modulations, such as LoRa, under the network layer (D7ANL).
Similar to other networking technologies that began with the defense sector, e.g., the Defense Advanced Research Projects Agency (DARPA) funding ARPANET, the precursor to the Internet, DASH7 is similarly suited to a wide range of applications in development or being deployed, including:
The goal of the project is to provide a reference implementation of the DASH7 Alliance protocol.[9] This implementation should focus on completeness, correctness and being easy to understand. Performance and code size are less important aspects. For clarity, a clear separation between the ISO layers is maintained in the code. The project is available on GitHub Welcome and is licensed under the Apache License, version 2.0.
DASH7 Mode 2 developers benefit from the open-source firmware library called OpenTag, which provides developers with a "C"-based environment in which to develop DASH7 applications quickly. So in addition to DASH7 (ISO 18000-7) being an open source, ISO standard, OpenTag is an open-source stack that is quite unique relative to other wireless sensor networking (e.g. ZigBee) and active RFID (e.g. proprietary) options elsewhere in the marketplace today. Even though OpenTag is an open-source project, people may not be able to use it free of charge. As of August 2015, there is no evidence to suggest that OpenTag bears a royalty, although current versions of OpenTag license do include a provision permitting RAND licensing.
DASH7 developers receive support from the semiconductor industry including multiple options, with Texas Instruments, ST Microelectronics, Silicon Labs, Semtech and Analog Devices all offering DASH7-enabled hardware development kits or system-on-a-chip products.
Many companies are members of the DASH7 Alliance to produce DASH7-compliant hardware products: