A Survey on the Roadmap to Mandate on Board Connectivity and Enable V2V-Based Vehicular Sensor Networks <s> 5G <s> Future cellular systems will employ the so-called big three technologies: UDN, massive MIMO, and mmWave (and/or terahertz) communications. The goal is to support the explosive demands for mobile broadband services foreseen for the next decade. In this work, we investigate the joint impact of the three technologies. Using system-level simulations, we evaluate the performance of two-tier cellular networks with μ Wave macrocells and densely deployed mmWave small cells. Our results show that much higher capacity can be realized with UDNs than in macrocell-only setups. The results also reveal that performance does not scale proportionally with increase in the employed mmWave bandwidth. The corresponding increase in noise (due to larger bandwidths) reduces the SINR. Outdoor users experience promising data rates notwithstanding, but the throughputs of indoor users are highly degraded. This is due to the additional wall and indoor losses (on top of the inherently high path loss at mmWave frequencies), which further reduce the SINR of indoor users. Therefore, techniques that significantly enhance the SINR are highly import ant design considerations in unleashing the amazing prospects and potentials of mmWave UDNs. <s> BIB001 </s> A Survey on the Roadmap to Mandate on Board Connectivity and Enable V2V-Based Vehicular Sensor Networks <s> 5G <s> The 3rd Generation Partnership Project (3GPP) is in the process of developing the next generation radio access technology, named New Radio (NR), which will be proposed as a candidate technology for IMT-2020. This article outlines the wide bandwidth operation of NR, among other new features being considered, based on the up-to-date discussions and decisions made in 3GPP standardization meetings. The much wider channel bandwidth of NR, compared to LTE, enables more efficient use of resources than the existing carrier aggregation framework at lower control overhead. The support of multiple sub-carrier spacing options allows NR to operate in a wide range of carrier frequency from sub-6 GHz band to mmWave band with appropriate handling of multi-path delay spread and phase noise depending on the carrier frequency. In addition, the introduction of the new bandwidth part concept allows to flexibly and dynamically configure User Equipment's (UE's) operating bandwidth, which will make NR an energy efficient solution despite the support of wide bandwidth. Other NR wideband operation related issues, such as the support of UEs with limited radio frequency (RF) capability and frequency domain resource indexing, are also explained in this article. <s> BIB002
The roadmap of vehicular communications is marked by the evolution toward 5G, which is typically addressed as the future technology that will provide three main requirements: peak data rates faster than 10 Gbps, device density higher than 1 million per km 2 and latency lower than 1 ms. A new radio technology, called NR, is being developed to this aim. The three major players for 5G NR standardization are the International Telecommunication Union (ITU), 3GPP and IEEE. Candidate technologies are being evaluated by ITU Radiocommunication Standardization Sector (ITU-R) through its 5D Working Party (WP) BIB001 . 3GPP's 5G standards are expected to be finalized with Release 15 (Phase 1) and Release 16 (Phase 2) by September 2018 and late 2019, respectively, and it is the Release 16 that includes the draft standard for 5G V2X BIB002 . 5G works, as LTE, in frequency bands up to 6 GHz, but new frequency are also considered at 28 GHz and 39 GHz. 3GPP is also identifying regulatory requirements of direct communications between vehicles in the spectrum beyond 6 GHz in different regions: 63-64 GHz and 76-81 GHz. Hence, 3GPP is working to manage the allocation of mmWave spectrum for 5G cellular applications and it is expected to be fixed by 2018. As an evolution of LTE, in its first phase, 5G will be based on OFDM with subframe duration fixed to 1 ms and the frame length to 10 ms. Subcarrier spacing is 15 kHz * 2n, hence each symbol length (including cyclic prefix) of 15 kHz equals the sum of the corresponding 2n symbols of the subcarrier spacing. A slot is 7 or 14 OFDM symbols (for subcarrier spacing up to 60 kHz) and 14 OFDM symbols (for subcarrier spacing higher than 60 kHz). Future development of 5G will also include a viable option to halve the subframe duration (so far, LTE-V2X supports only a fixed subframe of 1 ms) and reduce the latency. In addition, non orthogonal multiple access (NOMA) is also being studied. The wide channel bandwidth and multiple subcarrier spacing options enable the 5G NR system to efficiently and flexibly operate from sub-6 GHz band to mmWave band with appropriate handling of multi-path delay spread and phase noise depending on the carrier frequency. As anticipated in Section 4.4, IEEE has recently undertaken a 5G track to enhance existing standards and to evolve new technologies for the mmWave unlicensed bands. These efforts include IEEE 802.11ad/aj/ay, IEEE 802.15.3c, ECMA-387, among the others. The standardization is expected to be completed by late 2019, ahead of the much-anticipated 2020 timeline for commercial deployment BIB001 .