PowWow

• the MAC layer is based on an asynchronous rendezvous scheme initiated by the receiver,
• architectural and circuit level optimizations were performed such as power management, frequency and voltage scaling and FPGA co-processing for low power,
• the software stack is very light uses event-driven programming and is currently derived from the Protothread library of Contiki.

  Hardware

Processing motherboard

• TI MSP430 low-power microcontroller
• MSP430F1612 version, 8 MHz clock
• 55 KB of flash memory, 5 KB of on-chip RAM
• 330uA at 1 MHz and 2.2 V in active mode, 1.1uA in standby mode
• P1, P2 connectors for extension
• JTAG, RS232 and I2C interfaces

  Radio Board

• TI CC2420 RF transceiver
• *Digital direct sequence spread spectrum baseband modem
• * Single-chip 2.4 GHz IEEE 802.15.4 compliant
• * Spreading gain of 9 dB, data rate of 250 kbit/s
• Hardware support for packet handling, data buffering, burst transmissions, data encryption, data authentication, clear channel assessment, link quality indication and packet timing information

  Co-processing Board

• Power Mode Management
• * Low-Power Programmable Timer for Wake-up period
• * MAX6370, 8uA
• Dynamic Voltage and Frequency Scaling
• * Programmable Clock
• ** LTC6930, 490uA
• ** 8 MHz divided by 1 to 128
• * Programmable DC/DC converter
• ** TPS62402/TPS61030
• FPGA co-processing
• * Low-power Igloo FPGA from Actel
• * AGL125: 130 nm, 125 kgates, 32 kbits on-chip RAM, 1 kbits Flash, PLL for clock management.
• * Supply voltages 0 to 1.65V
• * Power consumption: 2.2 uW, 16 uW, 1 to 30 mW in sleep, freeze, run modes
• * e.g. Viterbi decoder for link layer implemented on the FPGA consumes 5 mW

  Networking

• MAC layer: preamble sampling protocol

• Multi-hop routing
• Geographical routing

• * Each node has coordinates
• * Next node for hop transmission is chosen in the neighbors as the nearest to the destination

• Neighbor table management
• * A neighbor is a node in the radio range of a node
• * Neighbors are discovered at power-up and on regular time period
• Transmission modes
• *Broadcast
• **Direct transmission to, no ACK
• *Flooding
• **Broadcast a packet to all network nodes, no ACK
• *Direct Hop with/without ACK
• **Direct transmission to a specific neighbors with/without ACK
• *Robust Multi-Hop
• **Multi-hop transmission to a specific node in the network
• **Each hop is with ACK
• **Uses node address

  Software

• Memory efficiency: 6 Kbytes + 5 Kbytes
• Over-the-air re-programmation

  Development Tools

• Currently based on
• Compiling with gcc for MSP430 is also possible
• Energy estimation methodology

  Availability