A key component of the ZigBee protocol is the ability to support mesh networking. In a mesh network, nodes are interconnected with other nodes so that multiple pathways connect each node. Connections between nodes are dynamically updated and optimized through sophisticated, built-in mesh routing table.
Mesh networks are decentralized in nature; each node is capable of self-discovery on the network. Also, as nodes leave the network, the mesh topology allows the nodes to reconfigure routing paths based on the new network structure. The characteristics of mesh topology and ad-hoc routing provide greater stability in changing conditions or failure at single nodes.
ZigBee Applications
ZigBee enables broad-based deployment of wireless networks with low-cost, low-power solutions. It provides the ability to run for years on inexpensive batteries for a host of monitoring and control applications. Smart energy/smart grid, AMR (Automatic Meter Reading), lighting controls, building automation systems, tank monitoring, HVAC control, medical devices and fleet applications are just some of the many spaces where ZigBee technology is making significant advancements.
Digi ZigBee Technology
Digi is a member of the ZigBee Alliance and has developed a wide range of networking solutions based on the ZigBee protocol. XBee and XBee-PRO modules and other XBee-enabled devices provide an easy-to-implement solution that provides functionality to connect to a wide variety of devices.
Monday, March 29, 2010
ZigBee protocol features include:
* Support for multiple network topologies such as point-to-point, point-to-multipoint and mesh networks
* Low duty cycle – provides long battery life
* Low latency
* Direct Sequence Spread Spectrum (DSSS)
* Up to 65,000 nodes per network
* 128-bit AES encryption for secure data connections
* Collision avoidance, retries and acknowledgements
* Low duty cycle – provides long battery life
* Low latency
* Direct Sequence Spread Spectrum (DSSS)
* Up to 65,000 nodes per network
* 128-bit AES encryption for secure data connections
* Collision avoidance, retries and acknowledgements
802.15.4 – ZigBee Physical Layer
ZigBee is a wireless technology developed as an open global standard to address the unique needs of low-cost, low-power wireless M2M networks. The ZigBee standard operates on the IEEE 802.15.4 physical radio specification and operates in unlicensed bands including 2.4 GHz, 900 MHz and 868 MHz.
The 802.15.4 specification upon which the ZigBee stack operates gained ratification by the Institute of Electrical and Electronics Engineers (IEEE) in 2003. The specification is a packet-based radio protocol intended for low-cost, battery-operated devices. The protocol allows devices to communicate in a variety of network topologies and can have battery life lasting several years.
The ZigBee Protocol
The ZigBee protocol has been created and ratified by member companies of the ZigBee Alliance. Over 300 leading semiconductor manufacturers, technology firms, OEMs and service companies comprise the ZigBee Alliance membership. The ZigBee protocol was designed to provide an easy-to-use wireless data solution characterized by secure, reliable wireless network architectures.
The ZigBee Advantage
The ZigBee protocol is designed to communicate data through hostile RF environments that are common in commercial and industrial applications.
The 802.15.4 specification upon which the ZigBee stack operates gained ratification by the Institute of Electrical and Electronics Engineers (IEEE) in 2003. The specification is a packet-based radio protocol intended for low-cost, battery-operated devices. The protocol allows devices to communicate in a variety of network topologies and can have battery life lasting several years.
The ZigBee Protocol
The ZigBee protocol has been created and ratified by member companies of the ZigBee Alliance. Over 300 leading semiconductor manufacturers, technology firms, OEMs and service companies comprise the ZigBee Alliance membership. The ZigBee protocol was designed to provide an easy-to-use wireless data solution characterized by secure, reliable wireless network architectures.
The ZigBee Advantage
The ZigBee protocol is designed to communicate data through hostile RF environments that are common in commercial and industrial applications.
ZigBee/IEEE802.15.4 - Typical Traffic Types Addressed
* Periodic data
* Application defined rate (e.g., sensors)
* Intermittent data
* Application/external stimulus defined rate (e.g., light switch)
* Repetitive low latency data
* Application defined rate (e.g., sensors)
* Intermittent data
* Application/external stimulus defined rate (e.g., light switch)
* Repetitive low latency data
ZigBee/IEEE 802.15.4 - General Characteristics:
* Dual PHY (2.4GHz and 868/915 MHz)
* Data rates of 250 kbps (@2.4 GHz), 40 kbps (@ 915 MHz), and 20 kbps (@868 MHz)
* Optimized for low duty-cycle applications (<0.1%)
* CSMA-CA channel access Yields high throughput and low latency for low duty cycle devices like sensors and controls
* Low power (battery life multi-month to years)
* Multiple topologies: star, peer-to-peer, mesh
* Addressing space of up to:
- 18,450,000,000,000,000,000 devices (64 bit IEEE address)
- 65,535 networks
* Optional guaranteed time slot for applications requiring low latency
* Fully hand-shaked protocol for transfer reliability
* Range: 50m typical (5-500m based on environment)
* Data rates of 250 kbps (@2.4 GHz), 40 kbps (@ 915 MHz), and 20 kbps (@868 MHz)
* Optimized for low duty-cycle applications (<0.1%)
* CSMA-CA channel access Yields high throughput and low latency for low duty cycle devices like sensors and controls
* Low power (battery life multi-month to years)
* Multiple topologies: star, peer-to-peer, mesh
* Addressing space of up to:
- 18,450,000,000,000,000,000 devices (64 bit IEEE address)
- 65,535 networks
* Optional guaranteed time slot for applications requiring low latency
* Fully hand-shaked protocol for transfer reliability
* Range: 50m typical (5-500m based on environment)
ZigBee The ZigBee logo
The ZigBee specification is a combination of HomeRF Lite and the 802.15.4 specification. The spec operates in the 2.4GHz (ISM) radio band - the same band as 802.11b standard, Bluetooth, microwaves and some other devices. It is capable of connecting 255 devices per network. The specification supports data transmission rates of up to 250 Kbps at a range of up to 30 meters. ZigBee's technology is slower than 802.11b (11 Mbps) and Bluetooth (1 Mbps) but it consumes significantly less power.
What is ZigBee
The mission of the ZigBee Working Group is to bring about the existence of a broad range of interoperable consumer devices by establishing open industry specifications for unlicensed, untethered peripheral, control and entertainment devices requiring the lowest cost and lowest power consumption communications between compliant devices anywhere in and around the home.
The ZigBee membership includes Philips, Honeywell and Invensys Metering Systems, and others and is responsible for defining and maintaining higher layers above the MAC. The alliance is also developing application profiles, certification programs, logos and a marketing strategy. Philips Semiconductors and other chip vendors plan to launch their first ZigBee products as early as 2003. ZigBee was formerly known as PURLnet, RF-Lite, Firefly, and HomeRF Lite.
The ZigBee membership includes Philips, Honeywell and Invensys Metering Systems, and others and is responsible for defining and maintaining higher layers above the MAC. The alliance is also developing application profiles, certification programs, logos and a marketing strategy. Philips Semiconductors and other chip vendors plan to launch their first ZigBee products as early as 2003. ZigBee was formerly known as PURLnet, RF-Lite, Firefly, and HomeRF Lite.
Nintendo® Wi-Fi Connection puts you in touch with players
Nintendo® Wi-Fi Connection puts you in touch with players everywhere - from across the room to across the globe. Use Friend Codes to play online with specific people, or compete anonymously through worldwide matchmaking. With millions of people online, there's always someone ready to play!
wi-fi defenition its certification uses and versions
wi-fi defenitions
Wi-Fi (short for "wireless fidelity") is a term for certain types of wireless local area network (WLAN) that use specifications in the 802.11 family. The term Wi-Fi was created by an organization called the Wi-Fi Alliance, which oversees tests that certify product interoperability. A product that passes the alliance tests is given the label "Wi-Fi certified" (a registered trademark).
Originally, Wi-Fi certification was applicable only to products using the 802.11b standard. Today, Wi-Fi can apply to products that use any 802.11 standard. The 802.11 specifications are part of an evolving set of wireless network standards known as the 802.11 family. The particular specification under which a Wi-Fi network operates is called the "flavor" of the network. Wi-Fi has gained acceptance in many businesses, agencies, schools, and homes as an alternative to a wired LAN. Many airports, hotels, and fast-food facilities offer public access to Wi-Fi networks. These locations are known as hot spots. Many charge a daily or hourly rate for access, but some are free. An interconnected area of hot spots and network access points is known as a hot zone.
Unless adequately protected, a Wi-Fi network can be susceptible to access by unauthorized users who use the access as a free Internet connection. The activity of locating and exploiting security-exposed wireless LANs is called war driving. An identifying iconography, called war chalking, has evolved. Any entity that has a wireless LAN should use security safeguards such as the Wired Equivalent Privacy (WEP) encryption standard, the more recent Wi-Fi Protected Access (WPA), Internet Protocol Security (IPsec), or a virtual private network (VPN).
Wi-Fi (short for "wireless fidelity") is a term for certain types of wireless local area network (WLAN) that use specifications in the 802.11 family. The term Wi-Fi was created by an organization called the Wi-Fi Alliance, which oversees tests that certify product interoperability. A product that passes the alliance tests is given the label "Wi-Fi certified" (a registered trademark).
Originally, Wi-Fi certification was applicable only to products using the 802.11b standard. Today, Wi-Fi can apply to products that use any 802.11 standard. The 802.11 specifications are part of an evolving set of wireless network standards known as the 802.11 family. The particular specification under which a Wi-Fi network operates is called the "flavor" of the network. Wi-Fi has gained acceptance in many businesses, agencies, schools, and homes as an alternative to a wired LAN. Many airports, hotels, and fast-food facilities offer public access to Wi-Fi networks. These locations are known as hot spots. Many charge a daily or hourly rate for access, but some are free. An interconnected area of hot spots and network access points is known as a hot zone.
Unless adequately protected, a Wi-Fi network can be susceptible to access by unauthorized users who use the access as a free Internet connection. The activity of locating and exploiting security-exposed wireless LANs is called war driving. An identifying iconography, called war chalking, has evolved. Any entity that has a wireless LAN should use security safeguards such as the Wired Equivalent Privacy (WEP) encryption standard, the more recent Wi-Fi Protected Access (WPA), Internet Protocol Security (IPsec), or a virtual private network (VPN).
How to Retrieve a Cookie Value?
The "Request.Cookies" command is used to retrieve a cookie value.
In the example below, we retrieve the value of the cookie named "firstname" and display it on a page:
<% fname=Request.Cookies("firstname") response.write("Firstname=" & fname) %>
Output: Firstname=Alex
In the example below, we retrieve the value of the cookie named "firstname" and display it on a page:
<% fname=Request.Cookies("firstname") response.write("Firstname=" & fname) %>
Output: Firstname=Alex
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