Beacon or Non-beacon Networks

In beacon networks, routers will transmit periodically to establish their location with the other nodes allowing the nodes to “sleep” between transmissions. Extended periods between beacons and low duty cycle data transmissions require the timing of the devices to be highly accurate, conflicting with the need to keep product cost down. Beacon networks are used where the routers are battery operated.

Non-beacon networks have routers that are always active consuming more power. A good example of this would be where a control device (HVAC controller) is enabled as a router and is connected to a power main constantly listening for transmissions from remote end devices (temperature, humidity sensors).  The end devices will employ CSMA for initiating a transmission and will sleep between transmissions. CSMA is a collision avoidance mechanism where the transmitting node will listen first to insure the line is clear before sending, similar to people in a conversation. Beacon networks can decrease latency delays.

ZigBee

ZigBee is a low-power Wireless Personal Area Network (WPAN) networking standard incorporating the OSI model in a software stack. The ZigBee stack builds upon the IEEE 802.15.4 wireless networking standard which provides the lower physical layer and the media access component of the data-link layer. ZigBee was developed by a consortium of manufacturers who came together to provide a wireless standard for applications requiring low-power with low cost wireless connectivity.1

The ZigBee standard is different because it has been designed to meet key requirements not satisfied in other wireless standards: Low data rate, low duty cycle and device interoperability. Low data-rate refers to the transmission rate of the data or speed, low duty-cycle refers to the frequency that a device will transmit, the longer the period between transmissions à lower duty-cycle. Device interoperability refers to devices from multiple manufacturers coexisting without any extra overhead or configuration. Meeting these three requirements makes ZigBee desirable for monitoring and control applications in building automation, industrial control, and health care.

IEEE 802.15.4

IEEE 802.15.4 is a standard which specifies the physical layer and medium access control for low-rate wireless personal area networks (LR-WPAN's). As of 2007, the current version of the standard is the 2006 revision. It is maintained by the IEEE 802.15 working group.2
Incorporated within 802.15.4 are:

• Multiple levels of security
• Multiple channels across three unlicensed radio bands
• Message acknowledgement and optional beacon messaging
• CSMA/CA – carrier sense multiple access / collision avoidance
• Two addressing schemes

En Ocean

EnOcean manufactures and markets world-leading energy harvesting technology, sensors, and RF (radio frequency) communication in a single solution for building and home automation, lighting, industrial, automated meter reading and environmental applications.EnOcean is the key to the "Intelligent Green Building":

• Building automation optimizes energy savings and reduces operating costs by lowering total cost of ownership. Furthermore, it enhances security, protection and convenience.
• Wireless radio technology is essential to the success of building automation. It permits the required number, functionality and flexibility of the necessary sensors. Radio technology minimizes installation times and reduces system costs.
• No battery requirement is mandatory for larger installations. The cost to monitor, replace and recycle batteries increases with the number of installed nodes. Battery-free EnOcean radio solutions are eco-friendly, comply with the principles of building biology, and save key resources.3

CDMA

Code division multiple access (CDMA) describes a communication channel access principle that employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code). In communications technology, there are only three domains that can allow multiplexing to be implemented for more efficient use of the available channel bandwidth and these domains are known as time, frequency and space. CDMA divides the access in signal space. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency. CDMA is a form of "spread-spectrum" signaling, since the modulated coded signal has a much higher bandwidth than the data being communicated.

CDMA is also the current name for the cellular technology originally known as IS-95. Developed by Qualcomm and enhanced by Ericsson, CDMA is characterized by high capacity and small cell radius.

CDMA also refers to digital cellular telephony systems that use this multiple access scheme, as pioneered by QUALCOMM, and W-CDMA by the International Telecommunication Union (ITU), which is used in GSM’s UMTS.2

GPRS

General Packet Radio Service (GPRS) is a Mobile Data Serviceavailable to users of Global System for Mobile Communications (GSM) and IS-136 mobile phones. GPRS data transfer is typically charged per kilobyte of transferred data, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user has actually transferred data or has been in an idle state. GPRS can be used for services such as Wireless Application Protocol (WAP) access, Short Message Service (SMS), Multimedia Messaging Service (MMS), and for Internet communication services such as email and World Wide Web access.

2G cellular systems combined with GPRS is often described as "2.5G", that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate speed data transfer, by using unused Time division multiple access (TDMA) channels in, for example, the GSM system. Originally there was some thought to extend GPRS to cover other standards, but instead those networks are being converted to use the GSM standard, so that GSM is the only kind of network where GPRS is in use. GPRS is integrated into GSM Release 97 and newer releases. It was originally standardized by European Telecommunications Standards Institute (ETSI), but now by the 3rd Generation Partnership Project (3GPP).2

Bluetooth

Bluetooth is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, laptops PCs, printers, digital cameras, and video game consoles over a secure, globally unlicensed short-range radio frequency. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group. 2

1 From the ZigBee Alliance web site http://www.zigbee.org/en/index.asp
2 From www.wikipedia.com
3 From www.EnOcean.com