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

There is an expected explosion in the number of users which will be connected to future wireless networks with the continued expansion of the Internet of Things. New technologies are needed in order to keep up with this connectivity demand. Non-orthogonal multiple access (NOMA) is one technology which seeks to improve spectral efficiency and allow for more connected users. NOMA seeks to overload resources in order to allow more users to access the same time and frequency resource blocks. There have been various proposals on how to realize NOMA in the network, including power domain non-orthogonal multiple access (PD-NOMA), interleave division multiple access(IDMA), and sparse code multiple access (SCMA). This paper investigates these three proposals and simulates them in the uplink setting in order to analyze their performance and compare them. Advantages and disadvantages for each technique are discussed with an emphasis on practical considerations.

Investigation of Non-Orthogonal Multiple Access Techniques for Future Cellular Networks

A transmitter comprises functionality (101, 103) for generating a block of input modulation symbols for example from received data bits. An M-point discrete Fourier transform (105) is applied to the block of input modulation symbols resulting in a frequency domain symbol block. This block is fed to an N-point inverse discrete Fourier transform (105) (N>M) thereby generating a time domain transmit signal. In addition, the transmitter (200) comprises an inter-symbol processor (201) which determines inter-symbol values corresponding to inter-symbol times of the time domain transmit signal and an attenuation processor (203) which attenuates at least one of the input modulation symbols in response to the inter-symbol values. By attenuating selected input modulation symbol(s) a significantly reduced amplitude variation and specifically peak-to-average amplitude variation can be achieved.

A transmitter, cellular communication system and method of transmitting therefor

Verfahren zur Leistungssteuerung für CDMA Kommunikationssysteme

Un emetteur transmet le signal desire a l'aide d'un cycle de fonctionnement en continu a des vitesses de transmission inferieures a la pleine vitesse L'energie utilisee dans chaque groupe de commande de puissance est liee a la vitesse de transmission En repetant les groupes de commande de puissance, on obtient une diversite de division dans le temps Dans le recepteur, les groupes de commande de puissance recus sont analyses et compares a plusieurs niveaux de seuil d'energie (73, 75, 77, 79) Les resultats des comparaisons sont convertis en un signal de commande de puissance (74, 76, 78, 80, 81) puis sont retournes au poste mobile Les postes mobiles peuvent selectionner le bit adapte et regler leur puissance En option, un indicateur de la vitesse de transmission peut etre achemine en avance sur la trame Le recepteur compare une estimation de puissance avec le seuil pour la vitesse de transmission indiquee

Commande de puissance pour des systemes de communication (a acces multiple par division de code) cdma

The case study in this paper compares various options for deploying picocells in a three-carrier LTE macrocell network in a suburban North American city. Beginning with a single carrier macrocell network on a 5 MHz FDD carrier in LTE band 25 (2 GHz), a 20 MHz TDD carrier in band 41 (2.6 GHz) is added to significantly increase capacity. An additional 5 MHz FDD carrier in band 26 (875 MHz) enhances coverage. The picocell deployment options include placing picocells in band 25, in band 41, or on a dedicated band 41 20 MHz TDD carrier. In addition, picocells may be split between the FDD carrier and the dedicated TDD carrier to simulate a phased rollout as spectrum becomes available. Since the band 41 carrier has a larger bandwidth, network capacity is higher when picocells are placed on this carrier (compared to band 25) even though the number of picocells required to maintain a constant network outage is similar. Dedicated band picocell deployment requires fewer picocells and has higher capacity due to reduced interference.

Amitava Ghosh

Papers

Investigation of Non-Orthogonal Multiple Access Techniques for Future Cellular Networks

A transmitter, cellular communication system and method of transmitting therefor

Verfahren zur Leistungssteuerung für CDMA Kommunikationssysteme

Commande de puissance pour des systemes de communication (a acces multiple par division de code) cdma

A Picocell Deployment Case Study in a Mixed Multicarrier LTE Network