About the Jennic RF network

This section summarizes the underlying architecture used for a network of devices represented in Niagara by a SedonaJen6lpNetwork. Some oversimplifications exist. For more complete details about Jennic 802.15.4 wireless communications, refer to Jennic documentation. At the time of this document, one URL for accessing this information is: www.jennic.com/support/user_guides

Jennic-based device protocol stack

Jennic-based devices use a protocol stack, that from “bottom up” use the following:

  • IEEE 802.15.4 at the bottom physical layer and MAC (media access control) layer above—using wireless RF in the 2.4Ghz frequency range. This protocol defines the lower layers of a WPAN (wireless personal area network), including 16 “channels” and the definition of one node being a “full function” type with PAN “coordinator” ability, that is, in charge of the whole network.

  • “JenNet”, the Jennic protocol that manages network formation and message routing, is the next layer up. A JenNet network has nodes that all use the same “PAN ID” (a two byte hexadecimal number).

    JenNet uses a “self healing tree” network structure, where all messaging goes up and down the tree. Nodes can have only one parent, but may have one or more children. Peer nodes do not communicate directly with each other, but rather through their parent.

    Every 802.15.4 network has a single coordinator node plus one or more routers and/or end devices. In a Jennic-based network, the JACE is always the coordinator, at the top of tree. Routers are continuously powered Jennic-based devices capable of relaying messages between nodes (typically in addition to performing other application functions). End devices cannot relay messages, and may be Jennic-based hibernating devices.

    Nodes maintain “PAN info” about any children, and routers also maintain this information about their parent. End devices do not store any “PAN info”. In the Niagara station, this “PAN info” is available graphically as a view on the SedonaJen6lpNetwork, and numerically in properties of some components. For details in this document, see Pan Sheet. For more details, see the engineering notes document Jennic Network Visualization (Pan Sheet).

  • Above the JenNet protocol layer is the 6LoWPAN layer, which the Jennic-based device uses to establish an IPv6 address. Through the operation of the JACE coordinator and Jennic-based driver, each child node under the coordinator also automatically has a mapped IPv4 “private network” address. The IPv4 address is used to support Workbench “tunneled Sox” connections to devices.

  • Sedona Framework is the application layer, which includes protocols DASP (Datagram Authentication Session Protocol) and the Sox protocol, along with other parts of the Sedona Framework.

Jennic radio operation notes

Because Jennic-based devices operate in the 2.4Ghz band spectrum, common to other wireless devices like 802.11 WiFi, Bluetooth, cordless phones, and baby monitors, a few guidelines may help when configuring a Jennic-based network, to minimize interference. Additional considerations can also help optimize throughput.

Location of devices

Jennic-based devices, including the JACE with Sedona Jennic option card, should not be located near noise-generating equipment such as microwave ovens. Other devices based on personal area networks (PAN) may also cause interference, as well as devices previously mentioned.

Use of an antenna extension cable is often required, for a number of possible reasons—often more than one. Examples include to relocate the device’s antenna outside of a metal enclosure that houses it, to distance it from the antenna of another device, and/or to optimize reception and transmission.

Acceptable distances between the (JACE) coordinator and nodes will vary with a number of factors, including building structure makeup, sources of interference, and so on. Use of the Pan Sheet view on the SedonaJen6lpNetwork can help diagnose the JenNet tree structure and the link qualities between nodes.

SedonaJen6lpNetwork (Sedona Jennic option card) configuration

Several network properties can affect radio operation; one example is Channel selection. For more details, see SedonaJen6lpNetwork coordinator properties.