Saving energy is gradually becoming a trend because of the aggravating consequences of the greenhouse effect on our lives. Saving 10% of energy can reduce the production of carbon dioxide by 10%. Portable devices use power from battery cells. Since energy is limited, we should be concerned about energy consumption to achieve goals.

In this thesis, the system architecture and logic design of the Link Layer (LL) of Bluetooth Low Energy (BT-LE) are proposed. The proposed system contains an LL controller, data stream, interface with PHY, and interface with host.

We define the operation mode for BT-LE by analyzing the protocol. The power mode is used to estimate energy consumption. Furthermore, we use the result of the analysis to program the estimation software for energy consumption.

After understanding the protocol, we propose four methods. We find the timeout mechanism inefficient and propose a method to improve its efficiency. Thus, we propose a new timeout mechanism with 89% efficiency when the timeout window is changed and timeout is adapted. We also propose the method of putting devices into idle or power-down mode which saves energy when BT-LE enters the sleep state. Another method involves adjusting the duration of advertisements by considering the number of nearby scanners. This method achieves 80% efficiency. The last method which adapts timeout when the link is established, the data rate is adjusted by SNR. When the SNR is higher than the threshold, we raise the data rate to increase the sleep time. This achieves 49% efficiency. In conclusion, this study may improve the energy consumption of BT-LE through a simple method.

[1] 97 Annual Electricity Emission Factor in Taiwan. [Online]. Available: http:
//www.taipower.com.tw/TaipowerWeb//upload/les/1/d98060501.pdf.
[2] Zigbee alliance. [Online]. Available: http://www.ZigBee.org/.
[3] Z-wave alliance. [Online]. Available: http://www.Z-Wavealliance.org/.
[4] Bluetooth Specication Version 4.0 [Vol 6], Bluetooth SIG Std. v4.0, Dec. 2009.
[5] IEEE Std 1902.1-2009, pp. 1{25, Apr. 2009.
[6] \IEEE Standard for Information Technology - Telecommunications and Information
Exchange Between Systems - Local and Metropolitan Area Networks - Specic Re-
quirement Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer
(PHY) Specications for Low-Rate Wireless Personal Area Networks (WPANs),"
IEEE Std 802.15.4a-2007 (Amendment to IEEE Std 802.15.4-2006), pp. 1{203,
2007.
[7] B. Calhoun, D. Daly, N. Verma, D. Finchelstein, D. Wentzlo, A. Wang, S.-H.
Cho, and A. Chandrakasan, \Design Considerations for Ultra-Low Energy Wireless
Microsensornodes," IEEE Transactions on Computers, vol. 54, no. 6, pp. 727{740,
Jun. 2005.
[8] A. E. Fawal, J. L. Boudec, R. Merz, B. Radunovic, J. Widmer, and G. Maggio,
\Trade-o Analysis of PHY-Aware MAC in Low-Rate Low-Power UWB Networks,"
IEEE Communications Magazine, vol. 43, no. 12, pp. 147{155, 2005.
[9] J. Ma, W. Lou, Y. Wu, X.-Y. Li, and G. Chen, \Energy Ecient TDMA Sleep
Scheduling in Wireless Sensor Networks," in IEEE INFOCOM, 2009, Apr. 2009,
pp. 630{638.
[10] E. Arvelo, \Open-loop Power Control Based on Estimations of Packet Error Rate
in a Bluetooth Radio," in IEEE Wireless Communications and Networking, 2003,
vol. 3, 2003, pp. 1465{1469 vol.3.
[11] Bluetooth Specication Version 2.1 + EDR, Bluetooth SIG Std. v2.1 + EDR, Oct.
2004.
[12] \IEEE Standard for Information Technology - Telecommunications and Information
Exchange Between Systems - Local and Metropolitan Area Networks - Specic
Requirements. - Part 15.1: Wireless Medium Access Control (MAC) and Physical
Layer (PHY) Specications for Wireless Personal Area Networks (WPANs)," IEEE
Std 802.15.1-2005 (Revision of IEEE Std 802.15.1-2002), pp. 1{580, 2005.
[13] \IEEE Recommended Practice for Information Technology - Telecommunications
and Information Exchange Between Systems - Local and Metropolitan Area Net-
works - Specic Requirements Part 15.2: Coexistence of Wireless Personal Area
Networks With Other Wireless Devices Operating in Unlicensed Frequency Bands,"
IEEE Std 802.15.2-2003, pp. 1{115, 2003.
[14] nRF24L01+ Single Chip 2.4GHz Transceiver Preliminary Product Specication,
NORDIC Std. v1.0, 2008.
[15] R. Oliveira, L. Bernardo, P. Pinto, and R. Dinis, \A Load-adaptive Timeout for
Beaconing-based Link Protocols in Ad Hoc Networks," in 14th European Wireless
Conference, 2008, pp. 1{7.
[16] SMIMS VeriLink User Guide v.2.0.0, SMIMS Corporation.
[17] LE Controller Specication, Bluetooth SIG Std. D09R08, Feb. 2009.