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

A method and corresponding system for controlling uplink timing in a communication network ( 100 ) is described. The method comprises of scheduling a mobile device ( 104 ) to transmit a preamble over a physical random access channel. The mobile device ( 104 ) is scheduled to transmit the preamble over a physical random access channel at a selected random access slot. The method then includes receiving the preamble transmitted by the scheduled mobile device ( 104 ). The preamble is received over the physical random access channel. The method further comprises measuring a timing offset at which the preamble is received from the scheduled mobile device ( 104 ) and determining a timing adjustment value in uplink transmission timing based on the measured timing offset. The method then comprises transmitting a timing advance command comprising the determined timing adjustment value in a control message to the mobile device ( 104 ) for controlling uplink transmission timing at the mobile device ( 104 ).

Method and apparatus for controlling uplink transmission timing in a communication network

A method is provided of discerning a signal of a desired user on a channel having a desired user and a plurality of interfering users, each, upon occasion, transmitting an identifiable, known pilot symbol. The method includes the steps of determining a channel response of the desired user and each of the interfering users and calculating a metric equal to the squared difference between a received signal and a sum of the products of transmitted signals and channel responses for the desired user and each of the plurality of interfering users. The method also includes the step of discerning the signal of the desired user based, at least in part, upon a minimum metric.

Method and apparatus for trellis decoding in a multiple-access system

Various embodiments are described which can serve to mitigate interference between the control channel signaling of adjacent sectors/cells. Potentially, these techniques may have the benefit of reducing the system resource drain caused by control channels, particularly control channels in high frequency-reuse, OFDMA systems. A transmitting device (101) transmits primary control channel information to a plurality of user devices (102). The primary control channel information includes an indication that a first OFDMA resource region (e.g., 320 or 330) is assigned to at least one user device of the plurality of user devices. The transmitting device correspondingly transmits secondary control channel information to the at least one user device using the first OFDMA resource region.

Method and apparatus for conveying control channel information in ofdma systems

A method and apparatus for assigning a communication resource is disclosed. The method includes allocating a channel by a base station or Node B 102. The base station or Node B detects an energy level transmitted on the channel wherein the energy level may be contention-free for a plurality of user equipment 104. The base station or Node B assigns time frequency resources for at least one of the plurality of user equipment wherein the time frequency resources are proportional to the detected energy level.

Method and apparatus for the dynamic and contention-free allocation of communication resources

In a code division multiple access communication system providing a plurality of communication type services between a first unit (100) and a second communicating unit (200) by time-multiplexing a plurality of data channel signals (101, 102, 103) associated with the plurality of communication type services to produce a time-multiplexed data channel signal (106) which are combined to produce a combined signal (136). Combined signal (136) is transmitted from first unit (100) to be received by second unit (200). After producing a code-demultiplexed time-multiplexed data channel signal (218), and a plurality of signal-to-interference ratios estimated based on a plurality of time-multiplexed portions of signal (218), a plurality of power control thresholds corresponding to the plurality of communication type services are compared to the plurality of signal-to-interference ratios. As a result, producing a plurality of power control data bits corresponding to the plurality of communication type services based.

Amitava Ghosh

Papers

Method and apparatus for controlling uplink transmission timing in a communication network

Method and apparatus for trellis decoding in a multiple-access system

Method and apparatus for conveying control channel information in ofdma systems

Method and apparatus for the dynamic and contention-free allocation of communication resources

Method and apparatus for communicating signals of various channel types in cdma communication systems