Fifth-generation (5G) cellular networks will almost certainly operate in the high-bandwidth, underutilized millimeter-wave (mmWave) frequency spectrum, which offers the potentiality of high-capacity wireless transmission of multi-gigabit-per-second (Gbps) data rates. Despite the enormous available bandwidth potential, mmWave signal transmissions suffer from fundamental technical challenges like severe path loss, sensitivity to blockage, directivity, and narrow beamwidth, due to its short wavelengths. To effectively support system design and deployment, accurate channel modeling comprising several 5G technologies and scenarios is essential. This survey provides a comprehensive overview of several emerging technologies for 5G systems, such as massive multiple-input multiple-output (MIMO) technologies, multiple access technologies, hybrid analog-digital precoding and combining, non-orthogonal multiple access (NOMA), cell-free massive MIMO, and simultaneous wireless information and power transfer (SWIPT) technologies. These technologies induce distinct propagation characteristics and establish specific requirements on 5G channel modeling. To tackle these challenges, we first provide a survey of existing solutions and standards and discuss the radio-frequency (RF) spectrum and regulatory issues for mmWave communications. Second, we compared existing wireless communication techniques like sub-6-GHz WiFi and sub-6 GHz 4G LTE over mmWave communications which come with benefits comprising narrow beam, high signal quality, large capacity data transmission, and strong detection potential. Third, we describe the fundamental propagation characteristics of the mmWave band and survey the existing channel models for mmWave communications. Fourth, we track evolution and advancements in hybrid beamforming for massive MIMO systems in terms of system models of hybrid precoding architectures, hybrid analog and digital precoding/combining matrices, with the potential antenna configuration scenarios and mmWave channel estimation (CE) techniques. Fifth, we extend the scope of the discussion by including multiple access technologies for mmWave systems such as non-orthogonal multiple access (NOMA) and space-division multiple access (SDMA), with limited RF chains at the base station. Lastly, we explore the integration of SWIPT in mmWave massive MIMO systems, with limited RF chains, to realize spectrally and energy-efficient communications.

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A Comprehensive Survey on Millimeter Wave Communications for Fifth-Generation Wireless Networks: Feasibility and Challenges

Wireless 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 instead 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 paper starts with 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 ({\\mu}-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.

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Where, When, and How mmWave is Used in 5G and Beyond

Millimetre wave frequency band as a candidate spectrum for 5G network architecture : a survey

Millimeter-wave (mmw) frequency bands, especially 60 GHz unlicensed band, are considered as a promising solution for gigabit short range wireless communication systems. IEEE standard 802.11ad, also known as WiGig, is standardized for the usage of the 60 GHz unlicensed band for wireless local area networks (WLANs). By using this mmw WLAN, multi-Gbps rate can be achieved to support bandwidth-intensive multimedia applications. Exhaustive search along with beamforming (BF) is usually used to overcome 60 GHz channel propagation loss and accomplish data transmissions in such mmw WLANs. Because of its short range transmission with a high susceptibility to path blocking, multiple number of mmw access points (APs) should be used to fully cover a typical target environment for future high capacity multi-Gbps WLANs. Therefore, coordination among mmw APs is highly needed to overcome packet collisions resulting from un-coordinated exhaustive search BF and to increase the total capacity of mmw WLANs. In this paper, we firstly give the current status of mmw WLANs with our developed WiGig AP prototype. Then, we highlight the great need for coordinated transmissions among mmw APs as a key enabler for future high capacity mmw WLANs. Two different types of coordinated mmw WLAN architecture are introduced. One is the distributed antenna type architecture to realize centralized coordination, while the other is an autonomous coordination with the assistance of legacy Wi-Fi signaling. Moreover, two heterogeneous network (HetNet) architectures are also introduced to efficiently extend the coordinated mmw WLANs to be used for future 5 Generation (5G) cellular networks.

Millimeter-Wave Wireless LAN and Its Extension toward 5G Heterogeneous Networks

For millimeter-wave networks, this paper presents a paradigm shift for leveraging time-consecutive camera images in handover decision problems. While making handover decisions, it is important to predict future long-term performance—e.g., the cumulative sum of time-varying data rates—proactively to avoid making myopic decisions. However, this study experimentally notices that a time-variation in the received powers is not necessarily informative for proactively predicting the rapid degradation of data rates caused by moving obstacles. To overcome this challenge, this study proposes a proactive framework wherein handover timings are optimized while obstacle-caused data rate degradations are predicted before the degradations occur. The key idea is to expand a state space to involve time-consecutive camera images, which comprises informative features for predicting such data rate degradations. To overcome the difficulty in handling the large dimensionality of the expanded state space, we use a deep reinforcement learning for deciding the handover timings. The evaluations performed based on the experimentally obtained camera images and received powers demonstrate that the expanded state space facilitates (i) the prediction of obstacle-caused data rate degradations from 500 ms before the degradations occur and (ii) superior performance to a handover framework without the state space expansion.

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Handover Management for mmWave Networks With Proactive Performance Prediction Using Camera Images and Deep Reinforcement Learning

LTE/WiGig RAN-Level Interworking Architecture for 5G Millimeter-Wave Heterogeneous Networks

LTE-WLAN aggregation architecture, which is under discussion in the 3GPP Release-13, can be extended to LTE-WiGig aggregation provided the millimeter-wave (mm-wave) small cell discovery and beamforming (BF) mechanism can be redesigned for the application of this aggregation architecture. In this paper, we propose a novel macro-controlled BF protocol using mm-wave beam databases for LTE-WiGig aggregation in mm-wave heterogeneous networks. This protocol enables an mm-wave access point (AP) to communicate with user equipment (UE) using the best beam under the control of LTE macro eNBs (evolved Node B). In this protocol, the locations of UEs and mm-wave beam information, including mm-wave AP identification (ID), beam ID, received beam power, etc., are collected by UEs and sent to LTE eNBs. LTE eNBs process all the data and construct the location and mm-wave beam databases for all mm-wave APs. Therefore, just by matching the current UE location with the pre-stored information in the databases, the LTE eNBs can allocate the best mm-wave AP and its best beam to the UE at its current location. Simulation results show that the proposed protocol can select the best beam with more than 90% accuracy and achieve more than 18% higher average throughput when the size of the databases is large enough compared to the exhaustive searching scheme due to the decrease in setup time.

Macro-Controlled Beam Database-Based Beamforming Protocol for LTE-WiGig Aggregation in Millimeter-Wave Heterogeneous Networks

Heterogeneous networks (HetNet) with different radio access technologies have been deployed to support a range of communication services. To manage these HetNets efficiently, some interworking solutions such as MIH (media independent handover), ANQP (access network query protocol) or ANDSF (access network discovery and selection function) have been studied. Recently, the millimeter-wave (mm-wave) based HetNet has been explored to provide multi-gigabits-per-second data rates over short distances in the 60 GHz frequency band. WiGig is one of the available radio access technologies using mm-wave. However, the conventional interworking solutions are not sufficient for the implementation of LTE/WiGig HetNets. Since the coverage area of WiGig is very small due to the high propagation loss of the mm-wave band signal, it is difficult for UEs to perform cell discovery and handover if using conventional LTE/WLAN interworking solutions, which do not support specific techniques of WiGig, such as beamforming and new media access methods. This paper proposes a RAN (radio access network)-level coupled LTE/WiGig interworking architecture and a LTE/WiGig protocol adaptor to process and transfer control signaling and user data traffic. The proposed extended control plane can assist UEs to discover and access mm-wave BSs successfully and support LTE macro cells to jointly control the radio resources of both LTE and WiGig, so as to improve spectrum efficiency. Simulation results show that LTE/WiGig HetNets with the proposed interworking solution can decrease inter-cell handover and improve user throughput significantly.

Extended user/control plane architectures for tightly coupled LTE/WiGig interworking in millimeter-wave heterogeneous networks

PROBLEM TO BE SOLVED: To prevent a communication device which can perform cooperative communication in a plurality of radio communication systems from continuously transmitting information related to the device which cannot perform the cooperative communication.SOLUTION: A base station device in a radio communication system which can apply a communication device which can perform parallel communication of first communication between the communication device and the base station device and second communication between the communication device and a second opposite device belonging to a second radio communication system different from the first radio communication system under control of the base station device belonging to the first radio communication system. The base station device notifies the communication device of connection object information for specifying one or more devices to be connected for parallel communication in the second radio communication system, and transmits limitation information not specified in the connection object information and for limiting the device subject to measurement report of radio quality in the second radio communication system to the communication device.SELECTED DRAWING: Figure 5

Peng Hailan

Papers

Millimeter-Wave Wireless LAN and Its Extension toward 5G Heterogeneous Networks

LTE/WiGig RAN-Level Interworking Architecture for 5G Millimeter-Wave Heterogeneous Networks

Macro-Controlled Beam Database-Based Beamforming Protocol for LTE-WiGig Aggregation in Millimeter-Wave Heterogeneous Networks

Extended user/control plane architectures for tightly coupled LTE/WiGig interworking in millimeter-wave heterogeneous networks

Base station device, communication device, control method, and program