The Role of 5G Technologies: Challenges in Smart Cities and Intelligent Transportation Systems

Abstract

The new mobile technology, 5G, challenges the current scenario in communications by overcoming the flaws of currently working 4G. Such new technology offers to smart cities and intelligent transportation systems a new way to become fully integrated by allowing massive simultaneous connections and ubiquity of network, even under high mobility situations or dense populated areas. In this way, 5G will become a key enabler for real Internet of Things and its corresponding Internet of Vehicles. This discussion is aimed at providing, in a comprehensive manner, how 5G technology will impact on smart cities, intelligent transportation systems –including autonomous or semi-autonomous vehicles– and vehicular communications, its technical, economic and legal challenges, in the following years.

Scaling Laws of Scheduling Gain for Uplink Massive MIMO Systems: Is User Scheduling Still Beneficial for Massive MIMO?

“…where µ R and σ 2 R are the mean and variance of R, respectively. According to (15), the maximum scheduling gain by the optimum algorithm is approximately 2σ 2 R log N K . Hereafter, we investigate the variance of the sum rate σ 2 R to understand the achievable scheduling gain with respect to the number of antennas.…”

“…According to (15), the maximum scheduling gain by the optimum algorithm is approximately 2σ 2 R log N K . Hereafter, we investigate the variance of the sum rate σ 2 R to understand the achievable scheduling gain with respect to the number of antennas. Using the results in [25], the second-order joint cumulant moment of R can be expressed as…”

“…Thus, a metric for user selection can be calculated by the estimated channel, and the BS can select several users to be served based on the calculated metrics. Accordingly, it can be observed from (15) that the achievable scheduling gain follows 2σ 2 R log N K , whereR = ∑ kRk corresponds to the estimated sum rate derived from the estimated SINR in (2), after replacing h withĥ. Therefore, we can expect that there is no difference between the scaling laws of scheduling gain with imperfect and perfect CSI.…”

“…For simplicity, we assume that the exact SINR in (20) is available at the BS and used for the user selection metric in the case of near-ideal CSI availability. Then, it is observed from (15) that the achievable scheduling gain under near-ideal CSI availability can be obtained by 2σ 2 R log N K , whereR is derived from the exact SINR in (20). In this case, two different SINRs γ 1 and γ 2 in (16) are not independent of each other, even for the ZF receiver, because, unlike perfect CSI, there is residual multiuser interference under imperfect CSI.…”

“…With the development of 5G NR, the performance and functionality of cellular mobile communications have reached an unprecedented level [1]. Compared to the fourth-generation (4G) long-term evolution (LTE), the NR supports faster data rates, lower latency, higher reliability, and new spectrum bands for enabling a wide range of use cases, such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC) [2,3].…”