Wireless Communications

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

This paper provides an overview of the Internet of Things (IoT) with emphasis on enabling technologies, protocols, and application issues. The IoT is enabled by the latest developments in RFID, smart sensors, communication technologies, and Internet protocols. The basic premise is to have smart sensors collaborate directly without human involvement to deliver a new class of applications. The current revolution in Internet, mobile, and machine-to-machine (M2M) technologies can be seen as the first phase of the IoT. In the coming years, the IoT is expected to bridge diverse technologies to enable new applications by connecting physical objects together in support of intelligent decision making. This paper starts by providing a horizontal overview of the IoT. Then, we give an overview of some technical details that pertain to the IoT enabling technologies, protocols, and applications. Compared to other survey papers in the field, our objective is to provide a more thorough summary of the most relevant protocols and application issues to enable researchers and application developers to get up to speed quickly on how the different protocols fit together to deliver desired functionalities without having to go through RFCs and the standards specifications. We also provide an overview of some of the key IoT challenges presented in the recent literature and provide a summary of related research work. Moreover, we explore the relation between the IoT and other emerging technologies including big data analytics and cloud and fog computing. We also present the need for better horizontal integration among IoT services. Finally, we present detailed service use-cases to illustrate how the different protocols presented in the paper fit together to deliver desired IoT services.

Internet of Things: A Survey on Enabling Technologies, Protocols, and Applications

Millimeter wave (mmWave) signals experience orders-of-magnitude more pathloss than the microwave signals currently used in most wireless applications and all cellular systems. MmWave systems must therefore leverage large antenna arrays, made possible by the decrease in wavelength, to combat pathloss with beamforming gain. Beamforming with multiple data streams, known as precoding, can be used to further improve mmWave spectral efficiency. Both beamforming and precoding are done digitally at baseband in traditional multi-antenna systems. The high cost and power consumption of mixed-signal devices in mmWave systems, however, make analog processing in the RF domain more attractive. This hardware limitation restricts the feasible set of precoders and combiners that can be applied by practical mmWave transceivers. In this paper, we consider transmit precoding and receiver combining in mmWave systems with large antenna arrays. We exploit the spatial structure of mmWave channels to formulate the precoding/combining problem as a sparse reconstruction problem. Using the principle of basis pursuit, we develop algorithms that accurately approximate optimal unconstrained precoders and combiners such that they can be implemented in low-cost RF hardware. We present numerical results on the performance of the proposed algorithms and show that they allow mmWave systems to approach their unconstrained performance limits, even when transceiver hardware constraints are considered.

Spatially Sparse Precoding in Millimeter Wave MIMO Systems

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

Embodiments described herein address the desire to have a method for uplink rate control signaling that is able to achieve increased sector and user throughput with relatively high uplink spectrum efficiency. Rate control signaling embodiments are disclosed that use two common persistence values (404, 408) to update the allocated portion of RoT margin for each UE device, and thus, reduce the variation of the RoT. In addition, SHO information is used to control the inter-sector/cell interference and improve the sector throughput. In such embodiments, each UE determines (412) the data rate and time to transmit according to these common persistence values, SHO status and buffered data. Throughput comparable to that of time and rate schedulers, which require significantly more signaling and information, can be achieved by some of these embodiments while also exhibiting less sensitivity to delay, speed of the UE, and burstiness of the traffic.

Method for rate control signaling to facilitate ue uplink data transfer

Initial deployments of millimeter wave (mmWave) cellular networks are likely to be enabled with self-backhauling. In this work, we propose a random spatial model to analyze uplink (UL) and downlink (DL) SINR distribution and mean rates corresponding to different access-backhaul and UL-DL resource allocation schemes in a self-backhauled mmWave cellular network with Poisson point process (PPP) deployment of users and base stations. In particular, we focus on heuristic implementations of static and dynamic time division duplexing (TDD) for access links with synchronized or unsynchronized access-backhaul (SAB or UAB) time splits. We propose PPP approximations to characterize the distribution of the new types of interference encountered with dynamic TDD and UAB. These schemes offer better resource utilization than static TDD and SAB, however potentially higher interference makes their choice non-trivial and the offered gains sensitive to different network parameters, including UL/DL traffic asymmetry, user load per BS or number of slave BSs per master BS. One can harness notable gains from UAB and/or dynamic TDD only if backhaul links are designed to have much larger throughput than the access links.

Performance of Dynamic and Static TDD in Self-backhauled mmWave Cellular Networks

Massive machine type communication (mMTC) has been identified as an important use case for 5G New Radio wireless technology In 4G Long-Term Evolution (LTE), 3GPP has previously introduced LTE-M for low-power, wide-area networks supporting the Internet of Things Rel-13 specifications for LTE-M were completed in 2016 Rel-14 enhancements were completed in 2017 while Rel-15 enhancements are ongoing and expected to be completed in 2018 In this paper, we provide an overview of LTE-M and describe its evolution in subsequent releases The features of the technology that have specifically been designed for mMTC are discussed In addition, we present evaluations of LTE-M against 5G performance targets and show that mMTC requirements can be satisfied by LTE-M To meet the 5G mMTC requirements, 3-dB power spectral density boosting is used in the downlink In addition, for some requirements, 4 receive antennas at the eNB are required instead of the more typical 2 receive antennas Thus, LTE-M will comprise an important component of 5G New Radio technology

LTE-M Evolution Towards 5G Massive MTC

A method and apparatus for determining the location of a communication unit in a CDMA system includes in a first embodiment, sending a location request via a spread spectrum signal to the subscriber (140), and receiving in return a subscriber signal including a response message showing a receive time of a particular symbol of the base's spreading sequence and a transmit time of a particular symbol of the subscriber's spreading sequence. The base (130), along with other receiving base(s) (140), also receives a predetermined symbol of the subscriber spreading sequence, and each determines a respective receive time of the predetermined symbol. The received information is then processed, along with known base location and delay information, to determine the subscriber location. If insufficient number of bases are capable of communicating with the subscriber, for example due to high loading/interference, auxiliary bases (121) are also provided for receiving from or transmitting to the subscriber.

Method and apparatus for location finding in a wireless communication system

Base stations (101, 102) utilize a spreading code that is dependent upon whether the particular base station (101) is operating in a synchronized, or an unsynchronized mode. Unsynchronized base stations (102) within the communication system (100) utilize a long code unique to the particular base station (102), and base stations (101) operating in a synchronized mode utilize a time shifted version of the same long code. To reduce the search time for remote units (113) within the communication system (100), a group identification code (GIC) (305) is broadcast during a time period that the long code is masked. The GIC (305) indicates a (spreading code) long code group to which the long code of each base station belongs. Additionally, each base station (101, 102) within the communication system (100) determines its synchronization status and utilizes a particular GIC (305) and long code based on the base station's synchronization status.

Amitava Ghosh

Papers

Method for rate control signaling to facilitate ue uplink data transfer

Performance of Dynamic and Static TDD in Self-backhauled mmWave Cellular Networks

LTE-M Evolution Towards 5G Massive MTC

Method and apparatus for location finding in a wireless communication system

Method and apparatus for transmitting information regarding the synchronization status of a base station