Green Communication: Reducing Energy Consumption in Wireless Networks

By definition, green communication is the practice of selecting energy efficient communications and networking technologies and products, minimizing resources used whenever possible in all branches of communication. It aims at addressing the exploration of sustainability regarding environmental conditions, energy efficiency and the communication purpose on mobile devices mainly. This is to strengthen corporate responsibility towards the environment, motivating an ecological generation of network equipment and systems. 

According to IJERT, recent ideas of mobile technology involve the growth in the number of equipment exploited, initiating the need to innovate in the field of energy efficient communication. Traditional communication systems and infrastructures, from data centers to networking hardware, have been high energy consumers and great carbon emitters. The increased demand for data and connectivity has challenged to find solutions balancing ecological responsibility and technological advancement. The high consumptions and emissions affect not only the environment but also the sustainability of the community and businesses. There is a great challenge for example in Wireless Sensor Networks, where the devices use batteries as the sources of power. Having that the batteries are characterized by limited lifespans, where they are either disposed or recharged. Having that the WSNs are used in military surveillances, disaster, structural, environmental, health, security, wildlife and habitat monitoring as well as in precision agriculture, with so much limited battery lifetimes, it’s a major concern. Several nodes might die due to the batteries. On the other hand, considering the environmental-friendly solutions a lot has to be considered, including water pollution, soil quality, air pollution, protection of the ozone layer, waste reduction and use of natural resources. Telecommunications equipment contains a great number of scarce materials and heavy metals where now the extraction of the materials and treatment of the waste is a great challenge.

According to several researches that have been done, all data centers spend approximately 30 billion dollars on power and cooling purposes. Here, there are a lot of electricity consumptions and increased carbon compounds into the atmosphere. As a result of a higher demand of data, the data centers are increasing the servers’ requests, commonly participating in turning up the diesel generators that generate high amounts of nitrogen oxides into the atmosphere.

With the rapid development of wireless communication technology such as smartphones, smart watches, smart glasses, personal wearable communication devices and health care devices, the lack of co-operation among the mobile nodes not only affects the quality of communication, but also results in unbalance in resource utilization, increasing the energy consumption of the devices. The ICT is responsible for about 3% of energy consumption and 2% - 4% of carbon dioxide emissions all over the world. Within the wireless cellular networks, the Base Stations (BS) occupy a significant portion of about 60% - 80% meaning that there needs a breakthrough to decrease the energy consumption. It has been noticed as well that the 5G mobile communication network consumes 10 times more energy than the predecessor, 4G network.

To reduce energy consumption by going green is by being energy-efficient, energy sustainable and environment-friendly. There’s need to take a holistic approach rather than only focus on the transmission layer or the Radio Access Network (RAN) parts. Based on analyses of the energy supply and energy consumption situations in various parts of the information systems, it has been convinced that there’s a great potential in reducing energy wastes by making information systems more adaptive to traffic demands and QoS requirements. For example, the under-utilized base stations can be turned off or switched to sleep mode whenever the neighboring or upper-layer BSs can accommodate the traffic by cell zoning or other traffic steering methods. The service mode can as well be turned down to low-resolution if user’s QoS requirement has been stepped down. In addition to ultra-dense deployment of base stations, it can be foreseen that 6G needs to further deploy a large number of edge computing facilities to support task offloading and machine learning algorithms for smarter, ultra-reliable and low-latency communications (uRLLC).

To conserve energy in WSNs, the major components in the sensor node must be controlled. The lifetime of the node, which is the lifetime of the network is dependent on, is an indication of how much energy is consumed and the amount of energy available for use. The lifetime depends on activities of the various components such as the sensing, processing, radio and power supply units. Energy conservation on these is based on networking and sensing.

Networking comprises of managing the sensor nodes and the design of the networking protocols while sensing is based on the techniques of reducing the frequency of sensing. One of the methods that can be used is the radio optimization technique. Having that the radio module is responsible for wireless communication, techniques such as cooperative communication schemes, sleep/wake-up schemes, duty cycling and parameters such as radio coding and modulation techniques, and power transmission control can be used to conserve energy. Other methods include the data reduction, aggregation, data compression and data prediction. By reducing the number of transmissions and maintaining the quality of measurements, a trade-off between the number of transmissions and the reliability of the channel is always made.

According to another research, another method known as cognitive radio based in wireless sensor networks (CR-WSNs) can be used to reduce the energy consumption. Cognitive Radio has four components, Primary Users (PUs), Base Station for PUs, Cognitive Radio Users or Secondary Users (SUs) and Base Station for SUs. The PUs are the main users who have the license as they are authorized to use the channel spectrum by the PU-base station. The SUs are not regular users as they must request channel spectrum from the CR-base station. 

Cognitive radio allows the communication devices to use some of the unoccupied frequencies in the white space (unused space) without any interference to the users that use occupied frequencies in the black space (used space). One of the characteristics of CR-WSNs, spectrum management, consists of four components that allow wireless sensor networks to dynamically access the available channels and benefit from the opportunistic channels. They include spectrum sensing, spectrum decision, spectrum sharing and spectrum mobility. Since we said that the life time of a sensor is determined by the life time of the network, this method increases the network life time which saves on energy in the WSNs.