A Wireless Sensor Node SoC with a Profiled Power Management Unit for IR Controllable Digital Consumer Devices Dong-Sun Kim, Member, IEEE, Byung-Soo Kim, Kwang-Ho Won and Min-Soo Kang 2282 IEEE Transactions on Consumer Electronics, Vol. 56, No. 4, November 2010

OUTLINE Introduction Architecture of wireless sensor network IR sensor Profiled power management for WSN SoC Experimental results Conclusion

INTRODUCTION Today, one of the promising consumer applications is the wireless sensor network, which satisfies the market's need for a cost-effective and flexible wireless network within the private sphere and industrial environment. This paper presents a wireless sensor node SoC with a profiled power management unit for reducing active power consumption of a battery operated interactive home remote controller

Network enabled digital technology increases the connectivity of consumer devices within the home for the purpose of remote control and monitoring of network enabled devices. such as a high definition television (HDTV), digital audio system, entertainment system and home automation technologies Power line communication (PLC), Wi-Fi, Bluetooth and ZigBee as wired or wireless networks are used to transfer the control information for the network enabled consumer devices in addition to IR-based control technology

ARCHITECTURE OF WIRELESS SENSOR NODE SoC RF transceiver Mainly consists of three blocks: Packet detection block : checks the signal power and preamble data for starting demodulation. Synchronization block : estimate frequency error by preamble, and phase compensation block works for phase rotation. Modulator with DAC and demodulator with ADC for transmitting or receiving the radio frequency signals.

Dedicated hardware blocks These blocks support: Four programmable timers : to check the timing violations such as ACK response time MAC frame block : to generate the transmitted data frame and parses the information from received frames AES-128 function block :to support the encryption of transmitted data CRC : to check the cyclic redundancy check

IR Sensor Infrared radiation is an electronic radiation which have a range of frequency between 1 up to 430 TB Advantages: Low power requirements , it provides a high security, simple circuitry, low cost circuitry Disadvantages :it needs direct line of sight between Tx , Rx, it will be blocked by common materials like People or walls, it provides short ranges, light, wither sensitive, data rate transmission is low

PROFILED POWER MANAGEMENT FOR WIRELESS SENSOR NODE SoC The basic idea of the profile driven frequency scaling is to identify profitable phases at each operation of WSN SoC such as data transmission state. Coarse power management Fine power management

Coarse power management which tries to adjust operating clock speed and enabled block as identified WSN SoC tasks I.e data transmission, data reception, dedicated hardware operation and sleep operation This block controls four types power mode to reduce the power consumption as specified in the next table, It automatically switches the operation mode to have maximum freedom of transferring non-functional units into sleep mode and scaling operation frequency.

Fine power management Whose goal is to adaptively decide the power supplying block by available power level that is indicated from battery management analog block of WSN SoC. High processing performance for handling several tasks is achieved via the highest frequency at maximum voltage. Stable operation of WSN SoC cannot be guaranteed as the battery power supply is decreased.

Designing the configurable phase locked loop (PLL)for clock generator and four channel regulator for fine power management. Estimating the power reduction ratio using commercial electronic design automation (EDA) tools for power estimation and test vectors for achieving coverage of above 90%

Using an independent power supply scheme Such power supply scheme can separately isolate major power consumption blocks and independently control the power supply Dividing to four power supply groups according to functional dependencies and memory controller checks the unused memory block during the user program downloading state

Independent power supply scheme

Independent power supply scheme In the embedded memory block configuration state, memory controller checks the downloaded memory region during the system software download state. In case of emergency handling state, register information of peripheral blocks are stored in embedded 1 Kbyte flash memory and automatically restored in case of wake up state.

EXPERIMENTAL RESULTS To evaluate the performance of a proposed power management unit they measure the average lifetime of eight sensor nodes and build the evaluation platform board, which consists of WSN SoC, 2.4 GHz antenna and a 3.3V 230mAh rechargeable battery Platform board for evaluation

The experiment shows that proposed power management method improves the average power efficiency about 18%. Lifetime comparison result

For the validation of wireless sensor node SoC, they also organize an experimental sensor network for universal remote controller Sensor nodes with electric lamp, robot toy and television are associated with the universal remote controller and send status information to control sensor node of universal remote controller. Control sensor node sends the operation of consumer devices according to the received information.

Universal remote controller system

CONCLUSION This paper introduced a wireless sensor node SoC including the profiled power management unit for universal remote controller. A profiled power management technique has newly applied that incorporates the frequency scaling and the selective power supplying scheme for dynamic power management. The power management mode was divided into two categories. One is coarse power management, which tries to adjust operating clock speed and enabled block as identified WSN SoC tasks. The other is fine power management, whose goal is to adaptively decide the power supplying block by available power level that is indicated Experimental results show that it reduces active power consumption about 18%..

Also it realized that a sensor network for home automation system based on universal remote controller can control the various CE devices such as television, electric lamp and robot toys. From these results, it verified that it can be successfully applied in various future consumer applications based on wireless sensor networks.

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