What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

What Will 5G Be

The global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm-wave) frequency spectrum for future broadband cellular communication networks. There is, however, little knowledge about cellular mm-wave propagation in densely populated indoor and outdoor environments. Obtaining this information is vital for the design and operation of future fifth generation cellular networks that use the mm-wave spectrum. In this paper, we present the motivation for new mm-wave cellular systems, methodology, and hardware for measurements and offer a variety of measurement results that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.

Millimeter Wave Mobile Communications for 5G Cellular: It Will Work!

The vision of next generation 5G wireless communications lies in providing very high data rates (typically of Gbps order), extremely low latency, manifold increase in base station capacity, and significant improvement in users’ perceived quality of service (QoS), compared to current 4G LTE networks. Ever increasing proliferation of smart devices, introduction of new emerging multimedia applications, together with an exponential rise in wireless data (multimedia) demand and usage is already creating a significant burden on existing cellular networks. 5G wireless systems, with improved data rates, capacity, latency, and QoS are expected to be the panacea of most of the current cellular networks’ problems. In this survey, we make an exhaustive review of wireless evolution toward 5G networks. We first discuss the new architectural changes associated with the radio access network (RAN) design, including air interfaces, smart antennas, cloud and heterogeneous RAN. Subsequently, we make an in-depth survey of underlying novel mm-wave physical layer technologies, encompassing new channel model estimation, directional antenna design, beamforming algorithms, and massive MIMO technologies. Next, the details of MAC layer protocols and multiplexing schemes needed to efficiently support this new physical layer are discussed. We also look into the killer applications, considered as the major driving force behind 5G. In order to understand the improved user experience, we provide highlights of new QoS, QoE, and SON features associated with the 5G evolution. For alleviating the increased network energy consumption and operating expenditure, we make a detail review on energy awareness and cost efficiency. As understanding the current status of 5G implementation is important for its eventual commercialization, we also discuss relevant field trials, drive tests, and simulation experiments. Finally, we point out major existing research issues and identify possible future research directions.

Next Generation 5G Wireless Networks: A Comprehensive Survey

Millimeter-wave (mmW) frequencies between 30 and 300 GHz are a new frontier for cellular communication that offers the promise of orders of magnitude greater bandwidths combined with further gains via beamforming and spatial multiplexing from multielement antenna arrays. This paper surveys measurements and capacity studies to assess this technology with a focus on small cell deployments in urban environments. The conclusions are extremely encouraging; measurements in New York City at 28 and 73 GHz demonstrate that, even in an urban canyon environment, significant non-line-of-sight (NLOS) outdoor, street-level coverage is possible up to approximately 200 m from a potential low-power microcell or picocell base station. In addition, based on statistical channel models from these measurements, it is shown that mmW systems can offer more than an order of magnitude increase in capacity over current state-of-the-art 4G cellular networks at current cell densities. Cellular systems, however, will need to be significantly redesigned to fully achieve these gains. Specifically, the requirement of highly directional and adaptive transmissions, directional isolation between links, and significant possibilities of outage have strong implications on multiple access, channel structure, synchronization, and receiver design. To address these challenges, the paper discusses how various technologies including adaptive beamforming, multihop relaying, heterogeneous network architectures, and carrier aggregation can be leveraged in the mmW context.

Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges

Communication at millimeter wave (mmWave) frequencies is defining a new era of wireless communication. The mmWave band offers higher bandwidth communication channels versus those presently used in commercial wireless systems. The applications of mmWave are immense: wireless local and personal area networks in the unlicensed band, 5G cellular systems, not to mention vehicular area networks, ad hoc networks, and wearables. Signal processing is critical for enabling the next generation of mmWave communication. Due to the use of large antenna arrays at the transmitter and receiver, combined with radio frequency and mixed signal power constraints, new multiple-input multiple-output (MIMO) communication signal processing techniques are needed. Because of the wide bandwidths, low complexity transceiver algorithms become important. There are opportunities to exploit techniques like compressed sensing for channel estimation and beamforming. This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.

An Overview of Signal Processing Techniques for Millimeter Wave MIMO Systems

Systems and techniques are described for scheduling communication by half-duplex devices. One or more half-duplex devices informs a base station that it is capable only of half-duplex operation. For each such device, the base station configures a transmit/receive pattern comprising sequences of uplink and downlink subframes and applies the pattern to the device. The half-duplex device may receive during a downlink subframe and may transmit during an uplink subframe. Uplink and downlink subframes within a pattern are separated by an offset based at least in part on a number of hybrid automatic repeat request processes.

Half duplex scheduling

A method, an apparatus, and a computer program product to support sub-PRB allocation on the Physical Uplink Shared Channel in a wireless communications system, a new resource allocation method is described, where available physical resource blocks (PRBs) in each subframe or narrowband are reorganized into a number of sub-PRBs, which would apply to user equipment in both in CE Mode A and CE Mode B while also supporting sub-PRB allocation in Msg3 as part of early data transmission during random access, so that a user equipment, which is previously configured for using physical uplink shared channel sub-PRB resources, upon receiving an indication, will then use or determine whether to use a sub-PRB resource allocation based on the received indication

Resource allocation method for sub-prb uplink transmission

Embodiments of the disclosure provide a method, device and computer readable medium for data transmission without RRC connections. According to embodiments of the present disclosure, the segments of data packet may be transmitted without the establishment of the RRC connection by introducing semi-persistent scheduling into the early transmission, thereby saving the consumption of signaling.

Methods, devices and computer readable medium for data transmission without rrc connections

Radio resource management (RRM) relaxation has been introduced in 3GPP NR Release 16 as a key feature for optimizing UE power saving. It can be applied for UEs under “low mobility” and “cell edge” criteria. In this study, we investigate its benefit in addition to discontinuous reception (DRX) for reduced capability (RedCap) new radio (NR) UEs, a new type of low-cost device, for which the power saving is a key requirement. We provide comprehensive simulation results that quantify energy saving by applying RRM relaxation for stationary and pedestrian RedCap UEs with different “cell edge” criteria and DRX settings. In addition, we evaluate the impact in terms of handover failures and packet delay. The simulation analysis shows that dynamic adjustment of “cell edge” criteria of RRM relaxation is a more power-efficient solution that can achieve up to 64% to 96% RRM measurement energy saving.

Energy Efficient RRM Relaxation for Reduced Capability UEs in 5G Networks

Improved mechanisms for wireless cellular access using coverage extension techniques are described. A UE needing to use coverage extension to request access to a prospective serving cell detects cells (other than the prospective serving cell) on its frequency, and then investigates each such cell (for example, by attempting to read its system information block and, if the system information block can be read, determining if the cell supports access using coverage extension. If detected cells do not support coverage extension, the UE does not use coverage extension techniques to request access, but if all detected cells support coverage extension, the UE requests access using coverage extension techniques.

Rapeepat Ratasuk

Papers

Half duplex scheduling

Resource allocation method for sub-prb uplink transmission

Methods, devices and computer readable medium for data transmission without rrc connections

Energy Efficient RRM Relaxation for Reduced Capability UEs in 5G Networks

Methods and apparatus for control of coverage extension techniques for access to prospective serving cells