Department of Computer Science and Engineering, University of California, Riverside.

1. RISE & Co-S: A high performance Co-proceSsing Sensor architecture for offloading sensing and data processing Anirban Banerjee, Abhishek Mitra, Walid Najjar, Demetrios Zeinalipour-Yazti, Vana Kalogeraki, Dimitrios Gunopulos Department of Computer Science and Engineering, University of California, Riverside. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

2. Roadmap • Problem Addressed • Motivation • Contribution • Sense and Store • RISE:Storage • RISE:Processing • Experimental Results • Conclusions • Future Work IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

3. Problem Addressed • To design a sensor platform satisfying the following constraints: • Small form factor • Energy frugal operation • High computational capability • Gigabyte scale data storage IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

4. Motivation • The need for a powerful sensor to match requirements for CCB, UCR. • Ecological monitoring • CO2, Temperature, Humidity • Live species monitoring • Bird call patterns using spectrograms • There is a clear need for a sensor platform which can balance both energy frugalness and computational capability. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

5. Contribution • Developed the RISE (RIverside SEnsors) platform. • Supplement the RISE with a CoS (Co-proceSsing architecture). • Propose and implement “Sense and Store” paradigm. • Developed Gigabyte-scale Storage Board with indexing capability. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

6. RISE Co-S Architecture IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

7. Sense and Store • Pre-defined queries, e.g. max, min, top-k, avg…. • Store queried values. • Retrieve Queries from the index. • Archive Data for offline processing. • NAND Flash memory for bulk data • NOR Flash memory for index IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

8. Sense and Store (Motivation) Graph depicting the Energy expended for a particular Store Vs Send ratio. Comparison of the Energy expended while transferring data using wireless and various storage options. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

9. Sense and Store (Motivation) 128 POINT FFT BENCHMARK RESULTS IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

10. RISE:Storage • Design / Features • Upto 2GB SD-Card / NAND • Data archival, avoids expensive erasure operation throughout lifetime of node • 1 MB on-board byte programmable NOR • Index stored on NOR Flash • Avoids need to preserve it onto the volatile SRAM • Software Driver • SPI Bus Interface • SD-Card • NOR Flash • Archival of sensory data • Fast retrieval / search using index • Updating the index • Updating Top-k values in the index IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

11. Local Access Methods • Flash Card stores temporal data [ (ts,val1,val2,….),(ts,val1,val2,….),…,(ts,val1,val2,….) ] • Example Query: “Find the timestamps on which val1 (the temperature) was 95F?” • Naïve Solution: Linear Scan over all pages on flash Card. • Problem:Too expensive to search all pages. E.g. a 256MB Flash Card features 500,000 pages! • Our Solution: MicroHash - which is an access method (index) deployed directly on the flash card to assist query evaluation. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

12. MicroHash Overview • An efficient access method that provides random and sorted access to records stored on the flash medium. • Data and Index Pages are sequentially stored on Flash in a heap (sorted by timestamp). • A buffer in SRAM / NOR keeps in memory the directory, index and data pages with the highest hit ratio. • MicroHash structure provides a built-in wear leveling mechanism (evenly distributes page writes) and also minimizes number of expensive random page deletions. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

13. Read Performance Improvements • Pages are read in 512B blocks • When pages are not fully occupied (i.e. index pages) then a lot of padding is transferred to SRAM. • Since read can be performed at any granularity, we perform a Two-Phase Page Read (2PPR). • 2PPR - Phase 1: Read 8 byte Header and determine useful size of page. • 2PPR - Phase 2: Read in SRAM the useful bytes identified in Phase • Note: To initiate a read we need a 9-byte SD-Transaction. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

14. RISE:Processing • Reduce Phonetic renderings of bird songs into unique harmonics • 128 point FFT on 16-bit data sampled at 10Ksps • Calculate power spectral density • Indexing the occurrence of harmonics • USART interface from the M16C to the Chipcon CC1010 host IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

15. FFT / Harmonics Extraction IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

16. Energy Graph – FFT on Node Energy required to sample, Calculate FFT, Extract, Store and Transmit Harmonics, as compared to transmitting raw audio samples IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

17. Conclusions • Developed RISE - CoS: a powerful, energy frugal platform. • Propose and Implement “Sense and Store” paradigm. • Developed Giga-scale STB for in-situ data logging. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

18. Future Work • 32-bit, ARM-7 uC onto the CoS. (Preliminary results are encouraging) • Integrate Microscopic, sub-surface camera equipment onto RISE. • Make use of on-chip, security features of SD Card. IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra

19. Thank You Anirban Banerjee, Abhishek Mitra, Walid Najjar, Demetrios Zeinalipour-Yazti, Vana Kalogeraki, Dimitrios Gunopulos (anirban, amitra, najjar, csyiazti, vana, dg) @cs.ucr.edu IEEE SECON-2005, Tue, September 27, 2005 (C) Anirban Banerjee and Abhishek Mitra