The original version of Z-Wave used a security algorithm called triple Data Encryption Algorithm (DES) with 56-bit key, which is a cipher developed by IBM and then selected as an official standard for the United States in 1976. However, Later on Z-Wave gave up this security layer. According to John Walters, Z-Wave Alliance vice president, "The Z-Wave 100 series single chips had triple DES, but not a single customer used it", said Walters. "When we were developing the 200 series we asked our customers about security and everyone said it was not need it."
People get worried about the security issues of Z-Wave without the security layer. John Adams, voice chair of the ZigBee Alliance "is okay for hobby-type tools. But once home automation becomes the way we expert thing to be, then Z-Wave's lack of security becomes a horrible impediment." He then mentioned that since there is no encryption for the Z-Wave messages, someone could set up a sniffer and watch any message and see the addresses of source and destination;he can then becomes that device and spoof a message.
Having realized this issue, Zensys announced the launch of its fourth generation Z-Wave single chip on January 7, 2008. The new generation chip supports 128-bit security encryption called Advanced Encryption Standard (AES), which is a cipher selected by the United States as an official standard. AES is much more reliable than DES. Recently DES has been superseded by the AES.
Monday, June 23, 2008
Saturday, June 21, 2008
Z-Wave network overview
Wireless mesh networking technology is applied in the Z-Wave. Mesh networking means that all the nodes can participate in routing data and nodes connect to each other via multiple hops . Mesh network is a "self configuring" network; a new node can be added automatically into network without needing any adjustments. It is also a "self healing" network, since the network automatically finds the fastest and most reliable paths to send data, even if nodes are blocked or lose their signal. Mesh network supports Non-Line-of-Sight (NLoS) network configurations where wireless signals are intermittently blocked, because the data is able to get around obstacles and reach the destination via other nodes.
The picture gives an example for routing method in the z-wave mesh network. The user in living room want to control the lamp A in the dining room. However the straight transmission is blocked by reflection from the oven in the kitchen. Z-Wave automatically selects an alternative signal route and ensure the command is carried out.
From:http://www.z-wavealliance.com
The Z-Wave network contains two kinds of nodes: controller nodes and slave nodes. Controller nodes are responsible for sending out the commands to other nodes. The routing table is recorded in the controller nodes and kept updated constantly. The primary controller has the capability to include or exclude nodes in the network. The examples of controllers are remotes controllers and internet gateways. Slave nodes reply on and execute the commands. They both can be used for routing data.
Each Z-Wave network has a unique identifier called Home ID to seperate itself from others. The Home ID is a 32 bit unique identifier that is pre programmed in all controller nodes. Each node also has its own unique 8 bits Node ID assigned by the controller.
The picture gives an example for routing method in the z-wave mesh network. The user in living room want to control the lamp A in the dining room. However the straight transmission is blocked by reflection from the oven in the kitchen. Z-Wave automatically selects an alternative signal route and ensure the command is carried out.
From:http://www.z-wavealliance.com
The Z-Wave network contains two kinds of nodes: controller nodes and slave nodes. Controller nodes are responsible for sending out the commands to other nodes. The routing table is recorded in the controller nodes and kept updated constantly. The primary controller has the capability to include or exclude nodes in the network. The examples of controllers are remotes controllers and internet gateways. Slave nodes reply on and execute the commands. They both can be used for routing data.
Each Z-Wave network has a unique identifier called Home ID to seperate itself from others. The Home ID is a 32 bit unique identifier that is pre programmed in all controller nodes. Each node also has its own unique 8 bits Node ID assigned by the controller.
Friday, June 20, 2008
Z-Wave protocol stack overview
From: http://www.zen-sys.com
Z-Wave started as a proprietary wireless protocol oriented to the residential control anutomation market. Z-Wave protocol is a low bandwidth half duplex protocol intended to offer reliable wireless communication in a low cost control network in the house. The protocol is not designed to transfer large amounts of data or to transfer any kind of streaming.
The protocol consists of 4 layer as figure shows, the MAC layer, the Transfer layer, the Routing layer and the application layer.
The protocol consists of 4 layer as figure shows, the MAC layer, the Transfer layer, the Routing layer and the application layer.
The MAC layer controls the radio frequency medium. The data stream is manchester coded and use FSK modulation. A standard collision-avoidance method is applied in this layer which prevents nodes from starting to transmit while other nodes are transmitting. If media is busy, the transmission is delayed by a random number of milliseconds.
The Transfer layer controls the transfer of data between two nodes including retransmission, checksum check and acknowledgements. This layer contains 4 basic frame formats, which are singlecast frame, multicast frame, broadcast frame and transfer acknowledge frame. Different types of frames are identified in the frame header. If frame is successfully received, ACK frame is sent back to the source node. However, multicast and broadcast frames don't get ACK so these types of frames cannot be used for reliable communication. The solution is to send a singlecast frame to each destination node following multicast and broadcast frame.
The routing layer controls the routing of frames from one node to another in the network. The Z-Wave network contains two kinds of nodes: controller node and slave node, which will be described later. Both controllers and slaves can participate in routing of frames in case they're always listening and have a fixed position. The layer is responsible for routing a frame and ensuring that the frame is repeated from node to node. In the case of the controller device, the routing layer is also responsible for scanning the network topology and maintaining a routing table.
The routing layer controls the routing of frames from one node to another in the network. The Z-Wave network contains two kinds of nodes: controller node and slave node, which will be described later. Both controllers and slaves can participate in routing of frames in case they're always listening and have a fixed position. The layer is responsible for routing a frame and ensuring that the frame is repeated from node to node. In the case of the controller device, the routing layer is also responsible for scanning the network topology and maintaining a routing table.
The application layer is responsible for decoding and executing commands in a Z-Wave network.
Tuesday, June 10, 2008
Z/IP Program: As a big step to broaden adoption
As an accelerator for the adoption of Z-Wave wireless home-control technology, the Z/IP program drives convergence of Z-Wave and TCP/IP. As with all previous Z-Wave protocol advances, Z/IP remains backwards compatible with existing Z-Wave products while adding compliant TCP/IP services to Z-Wave nodes and allows the use of Z-Wave device and command classes in TCP/IP networks.
Compatibility with the Internet Protocol’s Transmission Control Protocol (TCP/IP) enables remote access to a Z-Wave home-control system in a standardized way from the Web browser of any PC or cellphone without loading special software applications onto them, said Zensys marketing EVP Lew Brown. Compatibility also simplifies the integration of Z-Wave systems into increasingly popular IP-based control systems, he said.
"Using TCP/IP transmission will help to accelerate the adoption of applications for multiple uses of Z-Wave around the home, as well as interoperability among multiple vendors," added Martin Manniche, a senior director at Cisco’s Linksys division. Cisco is an investor in Zensys.
With a converged Z-Wave/IP standard, "all Z-Wave network nodes would be addressable from any browser in the world, and all devices in the home would be on a single IP network," a spokeswoman continued. The advanced standard “will remain backwards compatible with existing Z-Wave products while adding compliant TCP/IP services to Z-Wave nodes,” she noted.
In the future, we can use Z-Wave/IP technology to select remotely Z-Wave devices in the home to stream Internet content from the Web, Brown noted. That capability will become more important as Zensys transitions from its current-generation technology, which delivers control commands wirelessly at up to 40kbps, to a 200kbps version in chips meant for the U.S. market, he noted. Z-Wave started out as a 9.6kbps technology.
Compatibility with the Internet Protocol’s Transmission Control Protocol (TCP/IP) enables remote access to a Z-Wave home-control system in a standardized way from the Web browser of any PC or cellphone without loading special software applications onto them, said Zensys marketing EVP Lew Brown. Compatibility also simplifies the integration of Z-Wave systems into increasingly popular IP-based control systems, he said.
"Using TCP/IP transmission will help to accelerate the adoption of applications for multiple uses of Z-Wave around the home, as well as interoperability among multiple vendors," added Martin Manniche, a senior director at Cisco’s Linksys division. Cisco is an investor in Zensys.
With a converged Z-Wave/IP standard, "all Z-Wave network nodes would be addressable from any browser in the world, and all devices in the home would be on a single IP network," a spokeswoman continued. The advanced standard “will remain backwards compatible with existing Z-Wave products while adding compliant TCP/IP services to Z-Wave nodes,” she noted.
In the future, we can use Z-Wave/IP technology to select remotely Z-Wave devices in the home to stream Internet content from the Web, Brown noted. That capability will become more important as Zensys transitions from its current-generation technology, which delivers control commands wirelessly at up to 40kbps, to a 200kbps version in chips meant for the U.S. market, he noted. Z-Wave started out as a 9.6kbps technology.
Sunday, June 8, 2008
Home Automation Market
With the increase in population, rising per capita income and elevated standards of living, it is little surprising that the demand for home automation is also on the rise. With home automation, home-life becomes more convenient and luxurious just by the touch of a button. In today's fast moving world, individuals are forced to lead a busy lifestyle, leaving little time for daily household chores. People generally tend to miss out on simple day-to-day tasks such as turning off lights and fans, lowering thermostat level and activating security system. Thus, busy homeowners yearn for a simple yet powerful system to take charge of the entire home and by automating various home appliances. A home automation system or home control system is one such system available in the present day, which ties up all the individual gadgets and provides the residents with all the benefits of an automated house.
World home automation market is expected to witness robust growth and reach US$2.4 billion by 2010, according to the new market research report of Electronics.ca Publications. The strengthening of existing markets in Europe and the emergence of new markets in Asia, South America and Africa is set to sustain the growth momentum over the next five years. Housing slump in the US is expected to hinder market growth of home automation in North America in the near term.
In order to have a mass-markt for home automation, some issues should be addressed:
Cost: Thousands of nodes are needed to disperse over a building to provide automation, which make the investment quite expensive and unaccessible to middle-class families. Recent technological developments focus on the wireless sensor network (WSN) which reduces the cost of the complicated wiring networks.
Energy: Due to the high node count in the system, having to change or charge the batteries of each wireless sensor evey few days is not feasible. It ask to achieve battery lifetimes of at least several months, better years.
Installation complexity: It is very important to realize that it is the average homeowner or a semi-skilled installer who typically installs the system. The technology must provide simple intuitive installation and require no network management by the user during the lifetime of the installation. Finally the technology must be enable different product types from various vendors to seamless communicate with each other and use each other’s features.
Functionality: Because the current technology didn't offer all the functionally people desired to justify the cost. No one could justify the cost of a system that basically turning lights on and off automatically or control the temperature in the home.
World home automation market is expected to witness robust growth and reach US$2.4 billion by 2010, according to the new market research report of Electronics.ca Publications. The strengthening of existing markets in Europe and the emergence of new markets in Asia, South America and Africa is set to sustain the growth momentum over the next five years. Housing slump in the US is expected to hinder market growth of home automation in North America in the near term.
In order to have a mass-markt for home automation, some issues should be addressed:
Cost: Thousands of nodes are needed to disperse over a building to provide automation, which make the investment quite expensive and unaccessible to middle-class families. Recent technological developments focus on the wireless sensor network (WSN) which reduces the cost of the complicated wiring networks.
Energy: Due to the high node count in the system, having to change or charge the batteries of each wireless sensor evey few days is not feasible. It ask to achieve battery lifetimes of at least several months, better years.
Installation complexity: It is very important to realize that it is the average homeowner or a semi-skilled installer who typically installs the system. The technology must provide simple intuitive installation and require no network management by the user during the lifetime of the installation. Finally the technology must be enable different product types from various vendors to seamless communicate with each other and use each other’s features.
Functionality: Because the current technology didn't offer all the functionally people desired to justify the cost. No one could justify the cost of a system that basically turning lights on and off automatically or control the temperature in the home.
Zensys company
Zensys is the one of the providers of embedded wireless technologies for control and status-reading applications. The company focuses itself on the development of the Z-Wave technology, a wireless RF-based communications technology designed for home automation control. Its products include embedded networking software, integrated MCU (Micro Controller Unit)/Tranceiver chips , reference designs and tools that are used for the development and deployment of intelligent wireless devices.
Zensys also licenses designs, stack software and APIs (Application programming interfaces) to chip manufacturers interested in entering the home control space, with Z-Wave porting services that assure quality and accelerate product development. Z-Wave's industry-leading device specifications are available royalty free, based on a RAND-Z model, and the Z-Wave certification program ensures interoperability between all products.
The company is headquartered in Fremont, California, with R&D in Copenhagen and sales in the New York City region. It retains a partnership strategy with key telecom, utility, and industrial leaders, and participates in a number of co-development projects with major OEMs. These relationships have already resulted in a broad range of award-winning home control products, and will continue to extend Z-Wave's position as the standard in wireless control.
Zensys also licenses designs, stack software and APIs (Application programming interfaces) to chip manufacturers interested in entering the home control space, with Z-Wave porting services that assure quality and accelerate product development. Z-Wave's industry-leading device specifications are available royalty free, based on a RAND-Z model, and the Z-Wave certification program ensures interoperability between all products.
The company is headquartered in Fremont, California, with R&D in Copenhagen and sales in the New York City region. It retains a partnership strategy with key telecom, utility, and industrial leaders, and participates in a number of co-development projects with major OEMs. These relationships have already resulted in a broad range of award-winning home control products, and will continue to extend Z-Wave's position as the standard in wireless control.
Thursday, June 5, 2008
Z-Wave Alliance
Zensys, which developed the Z-Wave mesh technology for wireless controls, announced on Jan 2005 the formation of the Z-Wave Alliance. Zensys licensed Z-Wave to the Alliance to "create multiple sources for the technology in the industry," according to the announcement. This has turned Z-Wave into an open standard. Nowadays, Z-Wave Alliance has grown up to more than 160 members who create products and services based on Z-Wave --the standard in wireless control, including a impressive list of industry leaders: FAKRO, Cooper Wiring Device, Danfoss, Intel, Intermatic, Leviton, Logitech, Universal Electronics, Wayne-Dalton and Zensystem.
Picture, Z-Wave logo (above); Z-Wave Alliance's symbol (below)
The mission of the Z-Wave Alliance is:
- Promote consumer awareness and recognition of the Z-Wave technology as the trusted standard for wireless home control.
- Ensure interoperability between systems and devices from all members.
- Provide processes for collaboration on future products and services.
Products which use this technology, all labeled clearly with a Z-Wave logo to show interoperability between products and vendors.
Picture, Z-Wave logo (above); Z-Wave Alliance's symbol (below)
Overview of Z-Wave
Z-Wave is a wireless RF-based communications technology designed for control and status reading applications in residential and light commercial environments. Z-Wave delivers reliable wireless networking at a fraction of the cost of other similar technologies, by focusing on narrow bandwidth applications and substituting costly hardware. Z-Wave transforms any stand-alone device into an intelligent network node that can be controlled and monitored wirelessly.
Applications for Z-Wave intelligence include home entertainment systems, lighting and appliance control, HVAC systems, security and access control, meter reading and digital home health care.
Radio specifications
Bandwidth: 9,600 bit/s or 40 Kbit/s, fully interoperable
Modulation: GFSK
Range: Approximately 100 feet (or 30 meters) assuming "open air" conditions, with reduced range indoors depending on building materials, etc.
Frequency band: The Z-Wave Radio uses the 900 MHz ISM band: 908.42MHz (USA); 868.42MHz (Europe); 919.82MHz (Hong Kong); 921.42MHz (Australia/New Zealand).
Radio specifics
In Europe, the 868 MHz band has a 1% duty cycle limitation, meaning that a Z-wave unit can only transmit 1% of the time. This limitation is not present in the US 908 MHz band, but US legislation imposes a 1 mW transmission power limit (as opposed to 25 mW in Europe). Z-wave units can be in power-save mode and only be active 0.1% of the time, thus reducing power consumption dramatically.
Topology and routing
Z-wave uses an intelligent Mesh network topology and has no master node. A message from node A to node C can be successfully delivered even if the two nodes are not within range providing that a third node B can communicate with nodes A and C. If the preferred route is unavailable, the message originator will attempt other routes until a path is found to the "C" node. Therefore a Z-wave network can span much further than the radio range of a single unit. In order for Z-wave units to be able to route unsolicited messages, they cannot be in sleep mode. Therefore, most battery-operated devices will opt not to be repeater units. A Z-wave network can consist of up to 232 units with the option of bridging networks if more units are required.
Applications for Z-Wave intelligence include home entertainment systems, lighting and appliance control, HVAC systems, security and access control, meter reading and digital home health care.
Radio specifications
Bandwidth: 9,600 bit/s or 40 Kbit/s, fully interoperable
Modulation: GFSK
Range: Approximately 100 feet (or 30 meters) assuming "open air" conditions, with reduced range indoors depending on building materials, etc.
Frequency band: The Z-Wave Radio uses the 900 MHz ISM band: 908.42MHz (USA); 868.42MHz (Europe); 919.82MHz (Hong Kong); 921.42MHz (Australia/New Zealand).
Radio specifics
In Europe, the 868 MHz band has a 1% duty cycle limitation, meaning that a Z-wave unit can only transmit 1% of the time. This limitation is not present in the US 908 MHz band, but US legislation imposes a 1 mW transmission power limit (as opposed to 25 mW in Europe). Z-wave units can be in power-save mode and only be active 0.1% of the time, thus reducing power consumption dramatically.
Topology and routing
Z-wave uses an intelligent Mesh network topology and has no master node. A message from node A to node C can be successfully delivered even if the two nodes are not within range providing that a third node B can communicate with nodes A and C. If the preferred route is unavailable, the message originator will attempt other routes until a path is found to the "C" node. Therefore a Z-wave network can span much further than the radio range of a single unit. In order for Z-wave units to be able to route unsolicited messages, they cannot be in sleep mode. Therefore, most battery-operated devices will opt not to be repeater units. A Z-wave network can consist of up to 232 units with the option of bridging networks if more units are required.
about this blog
In this blog i will mainly focus on Z-Wave standards. The content refers to the introduction of those standard, institution enviorment, Z-Wave's development and commercial benifit. Finally, my own opinions will be given.
It is the first time for me to make a blog myself. I am trying to keep them updated.
It is the first time for me to make a blog myself. I am trying to keep them updated.
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