A Survey on the Roadmap to Mandate on Board Connectivity and Enable V2V-Based Vehicular Sensor Networks <s> MmWave Communications <s> Current cellular spectrum at below 3 GHz bands is experiencing severe shortage and cannot keep up with the dramatic proliferation of mobile traffic in the near future, requiring the search for innovative solutions to enable the 5G era. mmWave communications, with a possible gigabit-per-second data rate, have attracted great attention as a candidate for 5G broadband cellular communication networks. However, a complete characterization of mmWave links for 5G wireless networks still remains elusive and there are many challenges and research areas that need to be addressed. In this work we discuss several key elements to enable mmWave communications in 5G: · Channel characteristics regarding mmWave signal attenuation due to free space propagation, atmospheric gaseous and rain are explained. · The hybrid (digital plus analog) beamforming architecture in mmWave system is discussed. · The blockage effect in mmWave communications due to penetration loss and possible approaches are presented. · The application of mmWave transmission with narrow beams in non-orthogonal device-todevice communication is proposed. · mmWave transmission in the booster cell of heterogeneous anchor-booster networks. · mmWave transmission for small cell backhaul is further discussed. <s> BIB001 </s> A Survey on the Roadmap to Mandate on Board Connectivity and Enable V2V-Based Vehicular Sensor Networks <s> MmWave Communications <s> Millimeter-wave communication is a promising technology for future 5G cellular networks to provide very high data rate (multi-gigabits-persecond) for mobile devices. Enabling D2D communications over directional mmWave networks is of critical importance to efficiently use the large bandwidth to increase network capacity. In this article, the propagation features of mmWave communication and the associated impacts on 5G cellular networks are discussed. We introduce an mmWave+4G system architecture with TDMA-based MAC structure as a candidate for 5G cellular networks. We propose an effective resource sharing scheme by allowing non-interfering D2D links to operate concurrently. We also discuss neighbor discovery for frequent handoffs in 5G cellular networks. <s> BIB002 </s> A Survey on the Roadmap to Mandate on Board Connectivity and Enable V2V-Based Vehicular Sensor Networks <s> MmWave Communications <s> This work investigates the feasibility of opportunistic target detection in mmWaves vehicular networks employing the IEEE 802.11ad standard. The beacon signals transmitted during the network discovery phase are exploited to detect the presence of possible obstacles in the surrounding environment and to estimate their position and velocity. The detection problem is formulated as a composite hypothesis test and two detectors are derived and investigated. <s> BIB003 </s> A Survey on the Roadmap to Mandate on Board Connectivity and Enable V2V-Based Vehicular Sensor Networks <s> MmWave Communications <s> Millimeter-wave (mmWave) radar is widely used in vehicles for applications such as adaptive cruise control and collision avoidance. In this paper, we propose an IEEE 802.11ad-based radar for long-range radar (LRR) applications at the 60 GHz unlicensed band. We exploit the preamble of a single-carrier physical layer frame, which consists of Golay complementary sequences with good correlation properties that make it suitable for radar. This system enables a joint waveform for automotive radar and a potential mmWave vehicular communication system based on the mmWave consumer wireless local area network standard, allowing hardware reuse. To formulate an integrated framework of vehicle-to-vehicle communication and LRR, we make typical assumptions for LRR applications, incorporating the full duplex radar operation. This new feature is motivated by the recent development of systems with sufficient isolation and self-interference cancellation. We develop single- and multi-frame radar receiver algorithms for target detection as well as range and velocity estimation for both single- and multi-target scenarios. Our proposed radar processing algorithms leverage channel estimation and time–frequency synchronization techniques used in a conventional IEEE 802.11ad receiver with minimal modifications. Analysis and simulations show that in a single-target scenario, a gigabits-per-second data rate is achieved simultaneously with cm-level range accuracy and cm/s-level velocity accuracy. The target vehicle is detected with a high probability (above 99.99 $\%$ ) at a low false alarm rate of 10 $^{-6}$ for an equivalent isotropically radiated power of 40 dBm up to a vehicle separation distance of about 200 m. The proposed IEEE 802.11ad-based radar meets the minimum accuracy/resolution requirement of range and velocity estimates for LRR applications. <s> BIB004
MmWave communication is a promising technology for also providing a very high data rate for mobile devices. MmWave works with wavelength on the order of millimeters and includes the frequency band [30 300 ] GHz BIB001 . As for VLC, the propagation loss is much higher than in traditional radio frequency bands. Specifically, in this case, the free space propagation loss is proportional to the square of the carrier frequency. With a wavelength of about 5 mm, for example, the free space propagation loss at 60 GHz is 28 dB higher than at 2.4 GHz BIB002 . In addition, the oxygen absorption in the 60 GHz band has a peak, ranging from 15 to 30 dB/km. Hence, transmissions can easily be blocked by obstacles. This aspect implies on the one hand that signals could be limited in roads, but, on the other hand, the system has limited coverage and reliability. In spite the challenging issues related to the higher frequencies, mmWave communications are highly considered for future VSNs with the aim to provide a very high capacity. More than one international organization worked on its standardization, including the European computer manufacturers association (ECMA)  , IEEE 802.15.3 Task Group 3c (TG3c)  , IEEE 02.11ad standardization task group  and consortia, such as the WirelessHD consortium, and the Wireless Gigabit Alliance (WiGig). As far as IEEE 802.11ad is concerned, it specifies the PHY and MAC layer in the 60 GHz band. In the physical layer, two operating modes are defined: the first is based on OFDM for high performance applications and high data rate, the second is based on a single carrier (SC) for low power and low complexity implementation. At the MAC layer, a hybrid multiple access of CSMA/CA and time-division multiple access (TDMA) are adopted: CSMA/CA is more suitable for bursty traffic and reduced latency, while TDMA is more suitable to support high quality of service (QoS). MmWave radar is widely used in vehicles for applications such as adaptive cruise control and collision avoidance BIB004 or for opportunistic target detection and parameter estimation BIB003 . MmWave communications are also considered for future 5G systems. In fact, as it will be better detailed in Section 4.5, 5G new radio (NR) allows a cellular-based system to operate in a wide range of carrier frequencies from a sub-6 GHz band to an mmWave band with appropriate handling of a multi-path delay spread and phase noise depending on the carrier frequency.