The fourth generation wireless communication systems have been deployed or are soon to be deployed in many countries. However, with an explosion of wireless mobile devices and services, even 4G systems cannot adequately address issues such as the spectrum crisis and high energy consumption. Wireless system designers have been facing demand for increasingly higher data rates. 5Th generation (5G) wireless systems will address these needs and more and are expected to be deployed by 2020. This article proposes cellular architectures that separate indoor and outdoor scenarios. In addition, it discusses various promising technologies for 5G wireless communication systems, such as massive MIMO, energy-efficient communications, cognitive radio networks, and visible light communications.
There are several challenges for 5G designers. One of the most crucial challenges is the physical scarcity of radio frequency (RF) spectra allocated for cellular communications. These frequency spectra have been used heavily, and there is no more to spare in the existing cellular bands. Another challenge is the deployment of advanced wireless technologies comes at the cost of high energy consumption. In addition to environmental concerns, it has been reported by cellular operators that the energy consumption of base stations contributes to over 70% of their electricity bill. Other challenges include but are not limited to: increasing spectral efficiency, high data rate coupled with high mobility requirements, seamless coverage, diverse quality-of-service (QoS) requirements, and fragmented user experience (incompatibility of different wireless devices/interfaces and heterogeneous networks).
What will the 5G network, which is expected to be standardized around 2020, look like? It is now too early to define this with any certainty. However, it is widely agreed that compared to the 4G network, the 5G network should achieve 1000 times the system capacity, 10 times the spectral efficiency, energy efficiency and data rate (i.e., peak data rate of 10 Gb/s for low mobility and peak data rate of 1 Gb/s for high mobility), and 25 times the average cell throughput. The aim is to connect the entire world, and achieve seamless and ubiquitous communications between anybody (people to people), anything (people to machine, machine to machine), wherever they are (anywhere), whenever they need (anytime), by whatever electronic devices/services/networks they wish (anyhow). This means that 5G networks should be able to support communications for some special scenarios not supported by 4G networks (e.g., for high-speed train users who can travel up to 500 km/hour). This articles proposes a potential 5G cellular architecture and discuss some promising technologies that can be deployed to deliver 5G requirements.
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