Project MEMS - January 2009 - (Page 12) feature message to all the nodes in the network cell, in a flat hierarchy. This multi-hop, bidirectional scheme actually reduces setup time, the network management overhead, and packet size (since messages only have data, not routing information). DPM also overcomes the “broadcast storm problem” of flooding schemes by using simulcast, where messages of each node are relayed by surrounding nodes using controlled timing. Retransmission of messages through the network is synchronized to sub-bit level, with TDMA as the mater framework. Virtual Extension is submitting this architecture for standardization, and it has already been deployed by Israel Electric (IEC) for meter reading and Mafil in self-service copy machines. green Power GreenPeak Technologies looked to solve a major concern with WSNs power consumption with the Emerald GP500C, said to be the only IEEE 802.15.4-compliant communications controller that operates at extremely low power. This capability enables it to operate with energy-harvesting techniques rather than with batteries that require field maintenance. The chip integrates a transceiver with an integrated communications layer and on-chip energy manager. This makes the chip an autonomous transceiver, able to drive and control communication instead of being driven by a microcontroller (see Fig. 2). The chip consumes only 10% to 25% the energy of traditional designs by using a lower peak current, an ultra-low leakage current, and very short transmission times using just-in-time transmission scheduling. As a result, users can build wireless sensor modules with a peak operating current of 20 mA or so and sleep-mode current of less than 100 nA. Microchip Technology introduced Project Contents Viewpoint MeMS Solutions for Testing MEMS Devices on the Wafer Level Wireless Sensor Networks Have Arrived Choosing the Right Material for RF Packaging Home Page Product Training Module Online Ordering Suppliers Catalog Fig. 2. The gP500C communications controller from greenPeak takes control to reduce energy consumption in WSNs. 1 2 | P r o j E C T M E M S | vo L . 1 / N o . 1 http://ad.doubleclick.net/clk;210306059;32013581;o?http://www.digikey.com/ http://ad.doubleclick.net/clk;210306059;32013581;o?http://www.digikey.com/ http://ad.doubleclick.net/clk;210306136;32013581;k?http://digikey.com/PTM/PTMMaster.page?site=us&lang=en http://ad.doubleclick.net/clk;210306155;32013581;l?http://ordering.digikey.com/ordering/addpart.aspx?site=US&source=search http://www.greenpeak.com http://ad.doubleclick.net/clk;210306414;32013581;j?http://digikey.com/Suppliers/SupplierIndex.page?site=us&lang=en http://www.microchip.com http://ad.doubleclick.net/clk;210306629;32013581;r?http://dkc1.digikey.com/us/en/pdf/Current.html
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