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With the rapid development of social economy, excessive discharge of industrial sewage leads to water pollution, and it also affects the quality of domestic water. Therefore, it is necessary to monitor the water quality. A practical and convenient water quality monitoring system is designed in this paper, which is based on the MCU (Micro-programmed Control Unit) and Bluetooth technology. This design takes the Arduino development board based on ATMega328P chip as the core, and uses sensors to collect pH, turbidity, conductivity and water temperature. The measured data is sent to the smart phone via Bluetooth, and abnormal parameters are prompted. The test results show that the system can obtain the water quality parameters in time and accurately, and the overall operation of the system is stable, which is suitable for many occasions of water quality monitoring.

By separately transmitting data and control signals from different tiers, dual connectivity (DC) delivers a potential solution to the handover and load balancing challenges brought by small cell deployment. In this paper, a tractable framework is developed for the downlink performance analysis of DC assisted heterogeneous cellular networks (HetNets). Based on a stochastic geometry model, accurate expressions of data-control joint coverage probability and average rate for a typical DC capable UE are derived and investigated under DC mode and single connectivity (SC) mode. It is observed that operating parameters like cell association bias and transmit power will change the optimum node density ratio to reach the maximum coverage probability and average rate, but they have little impact on the levels of maximum coverage and rate performance. Numerical results also reveal that better coverage and rate performance can be expected in scenarios with higher small cell path loss exponent.