Edge computing is currently one of the main research topics in the field of Internet of Things. Edge computing requires lightweight and computationally simple algorithms for sensor data analytics. Sensing edge devices are often battery powered and have a wireless connection. In designing edge devices the energy efficiency needs to be taken into account. Pre-processing the data locally in the edge device reduces the amount of data and thus decreases the energy consumption of wireless data transmission. Sensor data compression algorithms presented in this paper are mainly based on data linearity. Microclimate data is near linear in short time window and thus simple linear approximation based compression algorithms can achieve rather good compression ratios with low computational complexity. Using these kind of simple compression algorithms can significantly improve the battery and thus the edge device lifetime. In this paper linear approximation based compression algorithms are tested to compress microclimate data.

A global system for mobile communication (GSM)/enhanced data rates for GSM evolution (EDGE)/wideband code division multiple access (WCDMA) modulator with a 14-bit on-chip digital-to-analog (D/A) converter is presented. The modulator consists of several digital signal processing building blocks, including a programmable pulse shaping filter, interpolation filters, resampler, cordinate rotation digital computer (CORDIC) rotator, programmable output power level controller and ramping unit, and x/sinx filter. The precompensation filter, which compensates the sinc droop above the Nyquist frequency, makes it possible to use WCDMA signal images for up-conversion. The new programmable up/down unit allows power ramping on a time-slot basis as specified for GSM, EDGE and time division duplex (TDD)-WCDMA. The multistandard modulator meets the spectral, phase and error vector magnitude (EVM) specifications. The die area of the chip is 22.09 mm 2 in 0.35-m CMOS technology. Power consumption is 1.7 W at 3.3 V with 110 MHz.Index Terms-Cordinate rotation digital computer (CORDIC), current steering digital-to-analog (D/A) converter, multicarrier, multistandard modulator, power control, power ramping, resampler.

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Internet of Things is evolving heavily in these times. One of the major obstacle is energy consumption in the IoT devices (sensor nodes and wireless gateways). The IoT devices are often battery powered wireless devices and thus reducing the energy consumption in these devices is essential to lengthen the lifetime of the device without battery change. It is possible to lengthen battery lifetime by efficient but lightweight sensor data analysis in close proximity of the sensor. Performing part of the sensor data analysis in the end device can reduce the amount of data needed to transmit wirelessly. Transmitting data wirelessly is very energy consuming task. At the same time, the privacy and security should not be compromised. It requires effective but computationally lightweight encryption schemes. This survey goes thru many aspects to consider in edge and fog devices to minimize energy consumption and thus lengthen the device and the network lifetime.

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