|International standard||ISO/IEC 18000-7|
|Developed by||DASH7 Alliance|
|Industry||Automation, industrial, military|
DASH7 is an open source RFID-standard for wireless sensor networking, which operates in the 433 MHz unlicensed ISM band/SRD band. DASH7 provides multi-year battery life, range of up to 2 km, indoor location with 1 meter accuracy, 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 200 kbit/s. DASH7 is the name of the technology promoted by the non-profit consortium called the DASH7 Alliance.
- 1 International standard
- 2 Technical summary
- 3 Applications
- 4 Developer support
- 5 The ISO/IEC 18000-7 air interface standard
- 6 See also
- 7 External links
DASH7 is based on the ISO/IEC 18000-7 open standard for the license-free 433 MHz ISM band air interface for wireless communications. 433 MHz is available for use worldwide, except certain countries where it is considered a restricted or licensed band such as India and Japan. The wireless networking technology was originally created for military use and has been re-purposed for mainly commercial applications in place of proprietary protocols like ZigBee or Z-Wave.
In January 2009, the U.S. Department of Defense announced the largest RFID award in history, a $429 million contract for DASH7 devices, to four prime contractors: Savi Technology, Northrop Grumman Information Technology, Unisys and Systems & Processes Engineering Corp. (SPEC).
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 fifty participants in twenty-three countries. Similar to what the WiFi Alliance does for IEEE 802.11, the DASH7 Alliance is doing for the ISO 18000-7 standard for wireless sensor networking.
In April 2011, the DASH7 Alliance announced adoption of DASH7 Mode 2, a next-generation version of 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 it was making the DASH7 Mode 2 specification available to non-members on an open source basis.
In July 2013, the DASH7 Alliance announced the Dash7 Alliance Protocol Draft 0.2.
Note that "Range" is highly dependent on many factors including the transmitter's output power, such that higher power transmitters will be able to communicate at further distances at the immediate cost of increased power consumption. In addition, "Range" is also affected by the communication data-rate, such that higher data-rates (e.g. 200-250kbit/s) will yield a lower communication distance than 10kbit/s. Lower data-rates are more immune to channel-noise, thus effectively increasing signal-to-noise ratio and receiver sensitivity, as a result. The "Average Power Draw" also depends heavily on the communication duty cycle, i.e. how often the radio and micro-controller wake-up to send a packet. In addition to duty cycle, the average power draw is almost entirely dependent on the silicon-chip manufacturer's implementation, and has nothing to do with the choice of frequency (i.e. 433 MHz or 2.4 GHz). For example, CC2530 consumes 29mA at +1dBm transmit power, JN5148 consumes 15mA at +3dBm, and ATmega128RFA1 14.5mA at 3.5dBm. Sleep currents of the micro-controller with RAM retention is also equally important. How often you consume energy is application dependent.
|Technology||Global standard used||Frequencies used||Globally available frequency(ies)?||Rain Penetration||Location Granularity||Range||Average power draw||Average latency||Device cost||Multi-hop capabilities||Sensor and Security support||Interference from 802.11n||Maximum bit rate|
|DASH7||ISO/IEC 18000-7||433.92 MHz||(No)||Higher||1 meter||1,000 m||Lower with remote wake-ups||2 seconds worst case||$10+||2-Hops||Yes||No||200 kbit/s|
|ZigBee||IEEE 802.15.4 (partial)||2.4 GHz, 915 MHz, 868 MHz||2.4 GHz – yes; 915 MHz – no; 868 MHz – no||Lower||10+ meters||30–500 m||Higher with synchronous listening||varies from seconds to potentially minutes||$10+||Yes||Yes||Yes||250 kbit/s|
DASH7 utilizes the 433.92 MHz frequency, which is globally available and license-free. 433.92 MHz is ideal for wireless sensor networking applications since it penetrates concrete and water, but also has the ability to transmit/receive over very long ranges without requiring a large power draw on a battery. The low input current of typical tag configurations allows for battery powering on coin cell or thin film batteries for up to 10 years.
Note that 433.92 MHz is the same as 13.56 multiplied by the number 32, or 2^5th power, which effectively means DASH7 radios can utilize the same antennae used by 13.56 MHz radios including Near Field Communications, FeLiCa, MiFare, and other near-field RFID protocols.
Unlike most active RFID technologies, DASH7 supports tag-to-tag communications which, combined with the long range and signal propagation benefits of 433 MHz, makes it an easy substitute for most wireless "mesh" sensor networking technologies. DASH7 also supports sensors, encryption, IPv6, and other features.
BLAST networking technology
Networks based on DASH7 differ from typical wire-line and wireless networks utilizing a "session". DASH7 networks serves 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 BLAST:
- Data transfer is abrupt and does not include content such as video, audio, or other isochronous forms of data.
- For most applications, packet sizes are limited to 256 bytes. Transmission of multiple, consecutive packets may occur but is generally avoided if possible.
- DASH7's main method of communication is by command-response, which by design requires no periodic network "hand-shaking" or synchronization between devices.
- DASH7 does not need periodic beaconing to be able to respond in communication.
- A DASH7 system of devices is inherently mobile or transitional. Unlike other wireless technologies DASH7 is upload-centric, not download-centric, thus devices do not need to be managed extensively by fixed infrastructure (i.e. base stations).
Integrated query protocol
DASH7 Mode 2 supports a unique, built-in query protocol that minimizes "round trips" for most messaging applications that results in lower latency and higher network throughput.
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.
DASH7 devices use a single global frequency, which simplifies deployment and maintenance decisions relative to specifications using multiple frequencies. A neutral, third party testing authority also conducts conformance and interoperability testing under the DASH7 Certified program.
Similar to other networking technologies that began with defense sector (e.g. DARPA funding the Internet), DASH7 is similarly suited to a wide range of applications in development or being deployed including:
- Building Automation, Access Control, Smart Energy . DASH7's signal propagation characteristics allow it to penetrate walls, windows, doors, and other substances that serve as impediments to other technologies operating at 2.45 GHz, for example. For smart energy and building automation applications, DASH7 networks can be deployed with far less infrastructure than competing technologies and at far lower total cost of ownership.
- Location-Based Services DASH7 is being used today for developing new location-based services using a range of DASH7-enabled devices including smartcards, keyfobs, tickets, watches and other conventional products that can take advantage of the unique small footprint, low power, long range, and low cost of DASH7 relative to less practical and high-power wireless technologies like WiFi or Bluetooth. Using DASH7, users can "check in" to venues in ways not practical with current check-in technologies like GPS, that are power-intensive and fail indoors and in urban environments. Location-based services like Foursquare, Novitaz, or Facebook can exploit this capability in DASH7 and award loyalty points, allow users to view the Facebook or Twitter addresses of those walking past, and more.
- Mobile advertising DASH7 is being developed for "smart" billboards and kiosks, likewise "smart" posters that can be ready from many meters (or even kilometers) away, creating new opportunities for both tracking the effectiveness of advertising spend but also creating new e-commerce opportunities. DASH7's potential to automate check-ins and check-outs provides essential infrastructure to location-based advertising and promotions
- Automotive DASH7 is increasingly seen as the next-generation tire pressure monitoring system given its operation at the same frequency (433 MHz) as nearly all proprietary TPMS systems today. DASH7-based TPMS will provide end users with more accurate tire pressure readings, resulting in greater fuel economy, reduced tire wear and tear, and greater safety. DASH7 products are also being designed and used for other automotive applications like supply chain visibility.
- Logistics DASH7 is being used today for tracking the whereabouts of shipping containers, pallets, roll cages, trucks, rail cars, maritime vessels, and other supply chain assets, providing businesses with unprecedented visibility into their everyday operations. Also cold chain management (vaccines, fresh produce, cut flowers, etc.), whereby DASH7 is used for monitoring the in-transit temperature and other environmental factors that can impact the integrity of sensitive products.
Since NATO militaries continue to deploy DASH7 infrastructure, defense suppliers (see Classes of Supply) are expected to also deploy DASH7 infrastructure given NATO requirements for supply chain visibility beyond just physical boundaries of a given military and deep into the supply chains of an array of suppliers around the world. DASH7 is expected to be adopted similar to the way barcoding was rapidly adopted by commercial companies, many of whom are also defense suppliers, following the LOGMARS barcoding mandate from the U.S. Department of Defense in 1981.
DASH7 is being used extensively by the U. S. Department of Defense (DoD) and other militaries. In January 2009, DoD awarded a $429 million contract for DASH7 devices, making it one of the largest wireless sensor networking deployments in the world, especially when combined with DoD's $500 million + installed base of non-DASH7 infrastructure which DoD is upgrading to DASH7.
Commenting on the U.S. Department of Defense's move to an RFID III multi-vendor contract earlier this year, Lt. Col. Pat Burden, the DoD's Product Manager Joint-Automatic Identification Technology, stated, "This is a significant milestone for DoD in that this migration will not only give DoD and other Federal agencies' customers best-value solutions at competitive prices, but it moves us to ISO 18000-7:2008 compliant products, thus broadening interoperability with DoD and our coalition partners."
NATO military forces are required to interoperate with DoD's DASH7 network and are required to deploy interoperable infrastructure. All NATO militaries are deploying or in the process of deploying DASH7 infrastructure.
OSS-7: Dash7 Open Source Stack
The goal of the project is to provide a reference implementation of the DASH7 Alliance protocol. 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  and uses the LGPL v2.1 licence.
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. That is because the current versions of OpenTag OpenTag License says:
4. RAND LICENSING
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OpenTag is a very purpose-built OS that offers a low level radio driver, PHY & MAC control system, event and session manager (OS-like), network protocols (M2NP, M2DP, M2AdvP) routing, raw data, group synchronization transport protocols (M2QP) query / data acquisition, data transfer filesystem read, write, create, delete, etc. C API library functions (Programming apps in C on the same device), Serial API(s) Client-Server (Communicating the apps via another device).
Semiconductor industry support
DASH7 developers receive support from the semiconductor industry including multiple options, with Texas Instruments, ST Microelectronics, Melexis, Semtech and Analog Devices all offering DASH7 enabled hardware development kits or system-on-a-chip products. Texas Instruments also joined the DASH7 Alliance in March 2009 and announced their CC430 system-on-a-chip product for DASH7 in December 2009. Analog Devices also announced their ADuCRF101 single chip solution for DASH7 in November 2010.
One semiconductor industry approach is the combination of DASH7 with MEMS sensing products:
"We strongly believe that the next big wave in sensors will be driven by the combination of the sensing function with wireless transmission – and ISO 18000-7 is the right solution for security and asset monitoring applications," said Benedetto Vigna, group vice president and general manager of the MEMS and Healthcare Product Division at STMicroelectronics in the company's announcement. "The Smart Web-Based Sensor HDK is a best-in-class development platform that will help the adoption of wireless sensors across the industry."
Another semiconductor industry approach focuses on automotive:
"There is a great potential for DASH7 technology in the automotive area," said Gilles Cerede, Product Line Manager for Wireless Automotive & Sensing at Melexis. "We see a perfect fit between DASH7 features and performance and the requirements of wireless safety applications. For example the ultra low power consumption matches the TPMS life time constraints, while the "multi-kilometer" communication range is perfectly suited for car-to-car and car-to-infrastructure applications. Last but not least, DASH7 is compatible from a frequency point of view with existing Remote Keyless Entry systems."
- DH Technology
- Evigia Systems
- Identec Solutions
- Lyngsoe Systems
- DASH7 Alliance members
The ISO/IEC 18000-7 air interface standard
The original ISO 18000-7 standard was ratified in 2004 then modified in 2008. According to ISO:
ISO/IEC 18000-7:2009 defines the air interface for radio frequency identification (RFID) devices operating as an active RF tag in the 433 MHz band used in item management applications. It provides a common technical specification for RFID devices that can be used by ISO technical committees developing RFID application standards. ISO/IEC 18000-7:2009 is intended to allow for compatibility and to encourage inter-operability of products for the growing RFID market in the international marketplace. ISO/IEC 18000-7:2009 defines the forward and return link parameters for technical attributes including, but not limited to, operating frequency, operating channel accuracy, occupied channel bandwidth, maximum power, spurious emissions, modulation, duty cycle, data coding, bit rate, bit rate accuracy, bit transmission order, and, where appropriate, operating channels, frequency hop rate, hop sequence, spreading sequence, and chip rate. ISO/IEC 18000-7:2009 further defines the communications protocol used in the air interface.
- DASH7 Alliance
- Near Field Communication
- RuBee wireless technology
- Bacheldor, Beth (January 9, 2008). "U.S. Defense Department Picks Four for RFID III". RFID Journal. Retrieved 2009-09-04.
- ReadWrite – DASH7: Bringing Sensor Networking to Smartphones
- Digital In-Store Ad Network Works With RFID - RFID Journal
- Savi Technology (March 18, 2009). "Alliance to Promote Greater Use of the ISO 18000-7 Wireless Data Standard Formed". RF Globalnet. Retrieved 2009-09-04.
- O'Connor, Mary Catherine (December 7, 2005). "NATO Rolling Out System for Sharing Data" (PDF). RFID Journal. Retrieved 2009-08-31.
- [dead link] "Leading Technology Users and Providers to Form DASH7 Alliance to Advance Wireless Data Technology" (PDF). DASH7 Alliance. March 18, 2009. Retrieved 2009-09-04.
- Albright, Brian (May 12, 2009). "STMicroelectronics Offers Active RFID Development Kit". RFID Update. ALX Technologies. Retrieved 2009-09-04.
- Swedberg, Claire (January 12, 2007). "Seven Companies Sign Up for Savi IP License". RFID Journal. Retrieved 2009-09-04.
- Savi Technology (August 6, 2007). "Savi Announces Six RFID E-Seal IP Licensees". RFID Update. ALX Technologies. Retrieved 2009-09-04.
- ISO/IEC 18000-7:2008 - Information technology - Radio frequency identification for item management - Part 7: Parameters for active air interface communications at 433 MHz
- DASH7 Alliance
- OpenTag wiki
- DASH7 technical white paper
- DASH7 vs. ZigBee: A Comparison of Two Wireless Data Protocols
- U.S. Department of Defense RFID homepage