Enhancing Energy Efficiency and Ranging Accuracy in IoT Networks
We consider an IoT network and try to address some of the issues and limitations of this new wireless system paradigm. Some of the issues come from the design requirements of IoT devices such as low cost, low energy consumption, and extended battery lifetime. These requirements limit the ability of such devices to operate at large bandwidth or use complex receiver circuitry that consume high energy. We focus on these two problems and investigate possible solutions to overcome such issues. We address the problem of receiver power consumption by introducing the usage of low-resolution Analog to Digital Converters (ADCs) under Differential-Phase Shift Keying (D-PSK) modulation. Outage-constrained receiver energy efficiency is then used as our metric to ensure low power consumption while operating at reasonable rates which are reflected in achieving low transmission latency values. Additionally, the effects of bandwidth limitations on ranging accuracy are taken into consideration. The idea of Channel Frequency Response (CFR) stitching is applied to expand the bandwidth, where two-way CFR is introduced to ensure CFR coherency upon stitching. Two-way CFR is further studied in details highlighting its advantages and disadvantages. Moreover, two alternative approaches are proposed to overcome two-way CFR’s accuracy degradation drawback by working with one-way response instead. The first techniques is a two-way to one-way CFR conversion where we apply signal processing techniques to detect and correct any phase errors in the CFR after conversion. While the second approach utilizes the novel idea of frequency overlap-based CFR alignment to mitigate the system’s impairments we experience while operating with the one-way approach. Significant ranging accuracy gains were achieved by the proposed techniques and verified by means of accurate system simulation as well as hardware prototyping.