5G networks aim to improve capacity, reliability, and energy efficiency while reducing latency and increasing connection density. A vital goal is enabling real time communication, which demands extremely low latency, particularly within Dynamic Cloud Radio Access Network (DC-RAN) architectures designed for high coverage density. The FrontHaul (FH) link is a critical component for achieving this, as different FH technologies directly impact performance, latency and coverage in dense areas. This paper focuses on latency budgeting within a DC—RAN, analysing how FH technologies – millimetre wave (mmWave), optical fiber; and Free Space Optics (FSO) – affect overall End-to-End delay (E2E) and Round-Trip Time (RTT). By calculating the propagation and processing delays for various cell types, the analysis provides a comparative performance evaluation. The key finding is that, while processing delay dominates the total latency, the choice of FH link significantly influences performance and practicality. mmWave and FSO are suitable for short-range, dense deployments, whereas optical fiber offers stable, low latency over longer distances. Thus, the optimal FH selection depends on specific network objectives, including coverage, density, and weather conditions; toward meeting Ultra-Reliable Low-Latency Communication (URLLC) targets.
Photovoltaic cells are one of the renewable energy sources that have been employed to produce electrical energy from solar radiation falling on them, but not all incident radiate will produce electrical energy, part of those radiate cause the panel temperature to rise, reducing its efficiency and its operational life, unless an attempt is made to employ one of the traditional cooling methods or innovating other methods to cooling it to reduce this effect, which it represented in the active and passive cooling method. In fact, it is difficult to compare the active method with the passive method, as each method has its Advantages and disadvantages that may suit one region without another. But in general, there are basic factors through which at least a comparison between the two methods can be made. Relatively the passive method is less expensive, in addition to no need for additional parts such as pumps and controllers, there is no energy consumption because it does not require power. But it is less effective and efficient than the active method, while the active method has the ability to disperse the heat higher than the passive method. However, it necessitates the use of electricity and is frequently costlier than the passive strategy. In this review, the most common active and passive cases were reviewed, and the pros and cons of each case are summarized in discussion due to the difficulty to list them. The review recommends that future studies should focus on active water cooling and heat-sink, both of which are viable cooling strategies.