G radio for millimeter-wave (mm-wave) and beyond-5G concepts at 0.1-1 THz can exploit angle and delay measurements for localization through an increased bandwidth and large antenna arrays, but they are limited in terms of blockage caused by obstacles. Reconfigurable intelligent surfaces (RISs) are seen as a transformative technology that can control the physical propagation environment in which they are embedded by passively reflecting radio waves in preferred directions and actively sensing this environment in receive and transmit modes. While such RISs have mainly been intended for communication purposes, they can provide great benefits in terms of performance, energy consumption, and cost for localization and mapping. These benefits as well as associated challenges are the main topics of this article. ApplicationsThe interaction between the digital and physical worlds relies on high-definition situational awareness, i.e., the ability of a device to determine its own location as well as that of objects and other devices in the operating environment. Applications include automated vehicles and robots, in general, as well as health care, highly immersive virtual and augmented reality, and new human-to-machine interfaces. Situational awareness can be achieved with a variety of technologies, depending on the application and requirements, including lidar, inertial measurement units, and cameras. Additional technologies include radio-based ones such as satellite positioning, radar, ultrawideband, cellular, and Wi-Fi. Such technologies are attractive because they can have dual communication and sensing functionalities and are often less susceptible to environmental factors, such as poor lighting.Since 4G, dedicated localization reference signals have been considered part of communications system design and standardization. These can enable location accuracy levels on the order of 10 m. With 5G, the use of larger bandwidths and higher carrier frequencies, in combination with antenna arrays in user equipment (UE) and base stations (BSs), is expected to further improve location accuracy to roughly 1 m. Within beyond-5G systems, the trend is to operate at much higher frequencies

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A fully electronically reconfigurable 400-element transmitarray is studied numerically and experimentally in Xband. The array operates in linear polarization and consists of 20×20 unit-cells. A 1-bit phase resolution has been selected for the unit-cell in order to reduce the complexity of the biasing network and steering logic, the insertion loss and the overall cost of the antenna system. The unit-cell stack-up is simple and is made of four metal layers: active side, biasing lines, ground plane and passive side. Two p-i-n diodes are integrated on the active side of each cell in order to control its transmission phase. The active array contains 800 diodes in total. It demonstrates experimentally pencil beam scanning over a 140×80-degree window over a 15.8% fractional bandwidth, with a maximum gain of 22.7 dBi at broadside. We also show that the same antenna array can be used for beam shaping applications (flattop beam). The experimental results presented between 8 and 12 GHz are in good agreement with the theoretical performance calculated using full-wave electromagnetic simulations and an inhouse CAD tool based on analytical modeling.

An electronically reconfigurable unit cell with 1-bit phase quantization (0 /180 ) is proposed for -band linear polarization transmit arrays. It consists of two rectangular patch antennas loaded by U-and O-slots and connected by a metallized via-hole. The transmission phase is controlled using two p-i-n diode switches integrated in the O-slot. An equivalent lumped-element circuit model is implemented and compared successfully to fullwave simulations. The numerical results are validated experimentally using an ad-hoc waveguide simulator. The prototype exhibits low insertion loss (1.8 dB) with the same level for both phase states, a broad 3-dB transmission bandwidth (14.7%), a 1-dB compression point of 13-15 dBm, and a gain of 5 dBi at 9.75 GHz. The performance and simplicity of the proposed unit cell make it attractive to build electronically steerable transmit arrays in -band.Index Terms-Active transmit-array antennas, active unit cell, discrete lens, reconfigurable antennas.

Various visions on the forthcoming sixth Generation (6G) networks point towards flexible connect-and-compute technologies to support future innovative services and the corresponding use cases. 6G should be capable to accommodate ever-evolving and heterogeneous applications, future regulations, and diverse user-, service-, and location-based requirements.A key element towards building smart and energy sustainable wireless systems beyond 5G is the Reconfigurable Intelligent Surface (RIS), which offers programmable control and shaping of the wireless propagation environment.Capitalizing on this technology potential, in this article we introduce two new concepts: i) wireless environment as a service, which leverages a novel RIS-empowered networking paradigm to trade off diverse, and usually conflicting, connectivity objectives; and ii) performance-boosted areas enabled by RISbased connectivity, representing competing service provisioning areas that are highly spatially and temporally focused. We discuss the key technological enablers and research challenges with the proposed networking paradigm, and highlight the potential profound role of RISs in the recent Open Radio Access Network (O-RAN) architecture.

SUMMARYWireless engineers and business planners commonly raise the question on where, when, and how millimeter-wave (mmWave) will be used in 5G and beyond. Since the next generation network is not just a new radio access standard, but also an integration of networks for vertical markets with diverse applications, answers to the question depend on scenarios and use cases to be deployed. This paper gives four 5G mmWave deployment examples and describes in chronological order the scenarios and use cases of their probable deployment, including expected system architectures and hardware prototypes. The first example is a 28 GHz outdoor backhauling for fixed wireless access and moving hotspots, which will be demonstrated at the PyeongChang Winter Olympic Games in 2018. The second deployment example is a 60 GHz unlicensed indoor access system at the Tokyo-Narita airport, which is combined with Mobile Edge Computing (MEC) to enable ultra-high speed content download with low latency. The third example is mmWave mesh network to be used as a micro Radio Access Network (µ-RAN), for cost-effective backhauling of small-cell Base Stations (BSs) in dense urban scenarios. The last example is mmWave based Vehicular-to-Vehicular (V2V) and Vehicular-to-Everything (V2X) communications system, which enables automated driving by exchanging High Definition (HD) dynamic map information between cars and Roadside Units (RSUs). For 5G and beyond, mmWave and MEC will play important roles for a diverse set of applications that require both ultra-high data rate and low latency communications. key words: millimeter wave, MEC, 28GHz, 60GHz, mesh network, V2V/V2X, automated driving, future forecast

International audienceDual-band transmitarray antennas are demonstrated at Ka-band with the capability of forming independent linearly polarized beams with a given polarization in each frequency band, while sharing the same radiating aperture. The proposed three-layer unit-cell is based on identical narrow microstrip patches printed on both receiving and transmitting layers and connected by a metallized via hole. The metal layers are printed on two identical substrates bonded with a thin film, and the designed unit-cell exhibits a 180 degrees phase resolution (i.e., 1-b phase quantization). The dual-band dual-polarized property of the transmitarray is achieved by interleaving unit-cells operating in the down-link and up-link frequency bands. Four different prototypes are characterized to demonstrate the relevance of the proposed concepts. A good agreement is obtained between the radiation patterns, gain curves, and cross-polarization levels measured and computed in both frequency bands and polarizations

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