Modified OSI Architecture for Low-Power Wireless Networks Jay Bruso Mike Matranga

OSI Model Review Data Link Layer Encodes and decodes data packets into bits ‘101001’ Provides transmission protocols Provides flow control and frame synchronization Manages and handles errors in the Physical Layer Physical Layer Conveys the bits stream across the channel Provides the hardware for sending and receiving data across the channel

Problem with OSI Model Applying standard OSI model to Wireless Networks results in poor energy utilization Physical Layer lacks knowledge of data being sent across the channel Data Link Layer performs work that should really be done in Physical Layer For true energy optimization, Physical Layer must know start and stop of packets to smartly know when to shutdown

Transceiver Block Diagram

Example of Problem Receiving packets of unknown length Data Link Layer (CPU) must be activated to inspect incoming data stream to determine end of packet. Once end of packet determined, Data Link Layer (CPU) sends command to disable receiver A/D converters in receiver are active longer than necessary CPU is unnecessarily activated during data reception

Proposed Solution Move the following Data Link Layer functionality into Physical Layer Packet framing information Character based framing (ESC,STX…ESC,SPX) Character count (packet length) End of packet detection Intelligent frequency hopping No data receive time out Provide data ready interrupt to Data Link Layer

Stating the Obvious … Moving Data Link Layer functionality into Physical Layer still requires power Our hypothesis is that the energy consumed in the Physical Layer performing these functions is much lower than performing it in the Data Link Layer

Project Objectives Measure and characterize energy consumption using standard OSI model and compare it to our improved approach Implement and test several standard protocols using COTS transceivers ChipCon CC2400 Implement and test various applications Streaming media … remote sensing Report final power savings comparing both methods

CC2400 Test Article