dash7 alliance protocol technical presentation

Dash7 Alliance Protocol

ISO/IEC 18000-7

DASH7 Alliance Protocol 2

The Dash7 Alliance Protocol is based on the ISO/IEC 18000-7

ISO/IEC 18000 is an international standard that describes a series of diverse RFID technologies, each utilizing a unique frequency range.

ISO/IEC 18000-7 describes the parameters for active air interface communications at 433 MHz (2008 - 2009)

DASH7 Alliance Protocol

Active RFID Standard for 433 MHz.

• Build on top of asynchronous WSN MAC.

• High level functionality optimized for RFID.

• Defines full functional RFID tag.

• Can be extended to non RFID applications.

Supports Tag to Tag communication.

DASH7 Alliance Protocol is designed to support fixed and mobile nodes that need to upload or retrieve small chunks of information


History


OSI Model


IEEE 802.15.4

ZigBee WirelessHart ISA100.11a DASH7 Alliance

Protocol

Wireless Available Solutions


Technology Comparison


Node Types


Transmit Receive Complete

Feature set

Wake-on

Scan Cycle

Always-on

Receive

Blinker X

Endpoint X X X

Subcontroller X X X X

Gateway X X X X

Spectrum and Modulation


Dash 7 band: 433.056 Mhz - 434.784 Mhz • Modulation GFSK • 8 non overlapping normal rate channels (55 kbs) • 7 hi-rate channels (4 non overlapping) (200 kbs)

DASH7 band available worldwide


433MHz band regulations


Unlicensed ISM/SRD bands USA/Canada • 260-470 MHz (FCC Part 15.231; 15.205)

Europe: • 433.050 - 434.790 MHz (ETSI EN 300 220)

Frequency vs Range


Network Topology


Tree Mesh Star

Passive RFID


Tags can only be read in the immediate proximity of a reader

Active RFID


Longer range interrogators - Master/Slave

Mesh WSN


Range depends on number of router nodes Congestion - Routing complexity

Latency due to propagation through the network Routers need to be powered and add to the overall consumption of the system

DASH7


Range of Gateway can be extended by subcontrollers Simple routing (2 hops)

Subcontrollers need to be powered but only a few are needed Tag-2-Tag communication

BLAST networking technology


Bursty: Data transfer is abrupt and does not include content such as video, audio, or other isochronous forms of data

Light: For most applications, packet sizes are limited to 256 bytes. Transmission of multiple, consecutive packets may occur but is generally avoided if possible.

Asynchronous: DASH7's main method of communication is by command-response, which by design requires no periodic network "hand-shaking" or synchronization between devices.

Stealth: DASH7 does not use discovery beacons, end nodes can chose to respond only to pre-approved devices.

Transitive: 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) to respond only to pre-approved devices.

Communication Model

Pull

To obtain spontaneous data

Push

For alarms and periodic data


Asynchronous communication


DASH7 supports asynchronous communication using the advertisement protocol

Query


Query based addressing by data content (id, sensor values, location, metadata, …)

In contrast to address based addressing in other technologies.

I want to know all nodes with a temperature above 15°C

I want to know all the person tags within proximity of the LivingRoomNode.

All nodes respond with your temperature.

All nodes with subnet X send me your RSSI.

Global & Local Querying


Global addressing enables the notification of a big group that a query will shortly follow and then selectively query a local group.

1. Ad-hoc synchronization is used to notify all endnodes of coming query.




2. Global query activates all endnodes with temperature sensor. Others go in sleep mode (red).





3. Local query asks response of all endnodes with T > 25° (yellow). Other go in sleep mode till next local query period (orange).






4. Next local query for endnodes with T < 25° and T >10° (yellow). Remaining go in short sleep mode (orange).






4. Next local query for endnodes with T < 25° and T >10° (yellow). Remaining go in short sleep mode (orange).

5. Remaining nodes are queried.

Tag to Tag communication


At any time an endnode can communicate to another endnode. E.g. Proximity based events can trigger communication

www.dash7.org


Open Standard

Very Low

Power

Security Privacy

Large Number Of Nodes

Low Bitrate

Low Cost

Long

Range