It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

There is considerable pressure to define the key requirements of 5G, develop 5G standards, and perform technology trials as quickly as possible. Normally, these activities are best done in series but there is a desire to complete these tasks in parallel so that commercial deployments of 5G can begin by 2020. 5G will not be an incremental improvement over its predecessors; it aims to be a revolutionary leap forward in terms of data rates, latency, massive connectivity, network reliability, and energy efficiency. These capabilities are targeted at realizing high-speed connectivity, the Internet of Things, augmented virtual reality, the tactile internet, and so on. The requirements of 5G are expected to be met by new spectrum in the microwave bands (3.3-4.2 GHz), and utilizing large bandwidths available in mm-wave bands, increasing spatial degrees of freedom via large antenna arrays and 3-D MIMO, network densification, and new waveforms that provide scalability and flexibility to meet the varying demands of 5G services. Unlike the one size fits all 4G core networks, the 5G core network must be flexible and adaptable and is expected to simultaneously provide optimized support for the diverse 5G use case categories. In this paper, we provide an overview of 5G research, standardization trials, and deployment challenges. Due to the enormous scope of 5G systems, it is necessary to provide some direction in a tutorial article, and in this overview, the focus is largely user centric, rather than device centric. In addition to surveying the state of play in the area, we identify leading technologies, evaluating their strengths and weaknesses, and outline the key challenges ahead, with research test beds delivering promising performance but pre-commercial trials lagging behind the desired 5G targets.

5G : A tutorial overview of standards, trials, challenges, deployment, and practice

This paper provides an overview of the features of fifth generation (5G) wireless communication systems now being developed for use in the millimeter wave (mmWave) frequency bands. Early results and key concepts of 5G networks are presented, and the channel modeling efforts of many international groups for both licensed and unlicensed applications are described here. Propagation parameters and channel models for understanding mmWave propagation, such as line-of-sight (LOS) probabilities, large-scale path loss, and building penetration loss, as modeled by various standardization bodies, are compared over the 0.5–100 GHz range.

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Overview of Millimeter Wave Communications for Fifth-Generation (5G) Wireless Networks—With a Focus on Propagation Models

Millimeter wave (mmWave) communications have recently attracted large research interest, since the huge available bandwidth can potentially lead to the rates of multiple gigabit per second per user Though mmWave can be readily used in stationary scenarios, such as indoor hotspots or backhaul, it is challenging to use mmWave in mobile networks, where the transmitting/receiving nodes may be moving, channels may have a complicated structure, and the coordination among multiple nodes is difficult To fully exploit the high potential rates of mmWave in mobile networks, lots of technical problems must be addressed This paper presents a comprehensive survey of mmWave communications for future mobile networks (5G and beyond) We first summarize the recent channel measurement campaigns and modeling results Then, we discuss in detail recent progresses in multiple input multiple output transceiver design for mmWave communications After that, we provide an overview of the solution for multiple access and backhauling, followed by the analysis of coverage and connectivity Finally, the progresses in the standardization and deployment of mmWave for mobile networks are discussed

Millimeter Wave Communications for Future Mobile Networks

In this paper, we present an experiment- and simulation-based study to evaluate the use of full duplex (FD) as a potential mode in practical IEEE 802.11 networks. To enable the study, we designed a 20-MHz multiantenna orthogonal frequency-division-multiplexing (OFDM) FD physical layer and an FD media access control (MAC) protocol, which is backward compatible with current 802.11. Our extensive over-the-air experiments, simulations, and analysis demonstrate the following two results. First, the use of multiple antennas at the physical layer leads to a higher ergodic throughput than its hardware-equivalent multiantenna half-duplex (HD) counterparts for SNRs above the median SNR encountered in practical WiFi deployments. Second, the proposed MAC translates the physical layer rate gain into near doubling of throughput for multinode single-AP networks. The two results allow us to conclude that there are potentially significant benefits gained from including an FD mode in future WiFi standards.

Design and Characterization of a Full-Duplex Multiantenna System for WiFi Networks

In this paper, a channel measurement campaign is introduced, which utilizes direction-scan-sounding to capture the spatial characteristics of 28-GHz wave propagation channels with 500-MHz sounding bandwidth in office environments. Both line-of-sight and non-line-of-sight scenarios were considered. Measurements were performed by fixing a transmit pyramidal horn antenna, and rotating another one in the receiver site at 10° steps in azimuth. The antenna outputs are viewed as array signals, and a space-alternating generalized expectation-maximization (SAGE) algorithm is applied to estimate delay and angular parameters of multipath components. Benefiting from high resolution achieved by using the SAGE and deembedding of antenna radiation pattern and system responses, more multipath clusters with less spreads in delay and azimuth are found per channel compared with existing works on 28-GHz propagation. The statistics of channel parameters extracted here constitute a preliminary stochastic multipath-cluster spatial channel model.

Experimental Multipath-Cluster Characteristics of 28-GHz Propagation Channel

https://onlinelibrary.wiley.com/doi/pdf/10.4218/etrij.16.2716.0050

Measurement-Based Propagation Channel Characteristics for Millimeter-Wave 5G Giga Communication Systems

https://onlinelibrary.wiley.com/doi/pdf/10.4218/etrij.2017-0188

Field-Measurement-Based Received Power Analysis for Directional Beamforming Millimeter-Wave Systems: Effects of Beamwidth and Beam Misalignment

In this paper we investigate millimeter-wave block- age characteristics based on measurements collected in a typical vehicle- to-vehicle (V2V) environment at 28 GHz Our mea- surement data were obtained with a wideband millimeter-wave channel measurement system We installed an omni-directional antenna for propagation loss and a steerable directional an- tenna for multipath characteristics in the receiver side The measurement campaigns were carried out in an open area to consider the blockage effects caused only by a vehicle between a transmitter and a receiver Based on the measurement data, we analyzed characteristics of the blockage loss with respect to various receiver positions Furthermore, we estimated delay and angular spreads using a correlogram-based multipath component extraction algorithm

Millimeter Wave Vehicular Blockage Characteristics Based on 28 GHz Measurements

To meet the increasing demand for 5G high datarate communications, millimeter-wave frequency bands are expected to be utilized. However, the existing channel models are not applicable to predict channel behaviors in these frequency bands. In this paper we investigate millimeter-wave channel model parameters including path loss exponents, delay and angular spread, and clustering parameters based on measurements collected in urban microcell environments at 28 and 38 GHz. Our measurement data were obtained with a wideband millimeter-wave channel sounder equipped not only an omnidirectional antenna and but also a steerable direction antenna. The measurement campaigns were held in Dunsan District area in Daejeon City, Korea, which is a typical downtown area surrounded with high-rise buildings. From our analysis, fitting results indicate that a path loss exponent of LoS is close to the free space path loss exponent of 2. In NLoS, the path loss exponent is about 3 at both frequencies. Furthermore, we observe that delay and angular spread, and clustering parameters at 28 GHz are similar to those at 38 GHz. We believe that these analysis results will facilitate developing millimeter-wave band 5G wireless systems.

Myung-Don Kim

Papers

Experimental Multipath-Cluster Characteristics of 28-GHz Propagation Channel

Measurement-Based Propagation Channel Characteristics for Millimeter-Wave 5G Giga Communication Systems

Field-Measurement-Based Received Power Analysis for Directional Beamforming Millimeter-Wave Systems: Effects of Beamwidth and Beam Misalignment

Millimeter Wave Vehicular Blockage Characteristics Based on 28 GHz Measurements

Millimeter-wave channel model parameters for urban microcellular environment based on 28 and 38 GHz measurements