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Hybrid mesh networks combine wireless, PLC

Posted: 07 Sep 2015 ?? ?Print Version ?Bookmark and Share

Keywords:Greenvity Communications? wireless? PLC? mesh network? IoT?

Have you ever noticed that real-world obstacles are usually made of concrete? I'm not just referring to impediments that make our trip or journey less smooth. Concrete walls mean no man can pass, and the same is true for wireless signals.

In industrial and building automation applications, traditional wireless mesh networking faces some significant barriers that are made of concrete. Technologies such as ZigBee and Wi-Fi are great in open spaces, but can suffer severe signal attenuation when they need to pass through concrete walls. Greenvity Communications may have solved this problem by offering a unique hybrid wireless networking approach that can use powerline communications (PLC) to bypass such barriers.

"There are a lot of products for building automation using ZigBee or Wi-Fi," said Greenvity CEO Hung Nguyen. "But wireless in building automation has a problem, especially in Asia and Europe, where there are thick walls. The signals cannot penetrate very well." An alternative for building networking is PLC, Hung explained, but that technology has difficulty bridging across different circuits. The Greenvity approach blends the two technologies to form a single mesh network.

Greenvity, a 4-year-old, privately-held company headquartered in Silicon Valley, started life as a chip vendor creating devices for ZigBee and PLC communications. But they quickly realised, Hung said, that their customers working on industrial and building automation applications involving the Internet of Things (IoT) needed more than chips; they needed full solutions. In introducing its patented hybrid mesh technology, then, Greenvity is providing not only chips, but will also offer also endpoint-device modules, gateways, and even cloud and mobile device apps for specific applications. Its initial focus application is lighting control.

The wireless portion of Greenvity's hybrid mesh network uses IEEE 802.15.4 radio technology, the same as ZigBee, and PLC technology based on the HomePlug Green PHY. The company's unique addition is to seamlessly bridge the two networks. According to Hung, the company's Hybrii-XL GV7011 chip has both interfaces and the intelligence to decide when to hop as well as which medium to use when communicating with adjacent nodes in the mesh. If the wireless channel is unreliable, perhaps due to signal attenuation through walls, it uses the PLC link. If PLC isn't available, it uses wireless. Messages can undergo multiple hops and several changes of mode automatically as they propagate across the network. (A PLC-only chip is also available.)

Greenvity Hybrid Mesh network

Greenvity Hybrid Mesh network

The Greenvity Hybrid Mesh network is self-forming and self-healing, able to support as many as 1000 nodes. Communications are bidirectional with data rates to 100Kb/s, to an aggregate of 1Mb/s. Peer-to-peer messaging is possible, although the lighting control modules Greenvity provides are configured to route all communications through a central hub. "That's for security," Hung said. "While the modules have AES128 encryption built in it's still too easy to hack into a peer-to-peer network. The hub offers much stronger security."

While Greenvity's technology is proprietary, it is open to the possibility of developing industry standards for equipment and applications based on the approach so that an ecosystem of interoperable devices can emerge.

- Rich Quinnell
??EE Times





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