Shahid Mumtaz

Direct mobile-to-mobile communication: paradigm for 5G

Direct mobile-to-mobile communication, also known as device-to-device (D2D), is expected to be a part of LTE-A in 3GPP Release 12. Direct communication will improve spectrum efficiency, overall system throughput, and energy efficiency, and decrease the delay between devices. It will enable new peer-to-peer and location-based applications and services. Introducing D2D poses many challenges and risks to the longstanding cellular architecture, which is centered on the base station. Therefore, in this article we explain the architectural and technical challenges for D2D communication in the 3GPP standard, and at the end of the article we also highlight the real-life applications and use cases for D2D communication. It is clear that D2D can offer a palette of interesting colors that can paint new business opportunities for mobile stakeholders, promoting its candidacy for next generation wireless communication system.

Green HetNet CoMP: Energy Efficiency Analysis and Optimization

This paper investigates advanced energy-efficient wireless systems in orthogonal frequency-division multiple access (OFDMA) downlink networks using coordinated multipoint (CoMP) transmissions between the base stations (BSs) in a heterogeneous network (HetNet), which is adopted by Third-Generation Partnership Project (3GPP) Long-Term Evolution (LTE)-Advanced to meet International Mobile Telecommunications-Advanced targets. HetNet CoMP has received significant attention as a way of achieving spectral efficiency (SE) and energy efficiency (EE). Usually, in the literature, the total network power consumption is restricted to the sum of the power consumption of all BSs. The significance of the power consumption of the backhaul links in wireless networks is normally omitted for its trivial effect with respect to that of the radio BSs. For SE and EE analysis of HetNet CoMP, the energy and bandwidth consumption of the backhaul is considered, without which, the investigation remains incomplete. However, SE and EE are design criteria in conflict with each other, and a careful study of their tradeoff is mandatory for designing future wireless communication systems. The EE is measured as “throughput (bits) per joule,” whereas the power consumption model includes RF transmit (radiated), circuit, and backhaul power. Furthermore, a nonideal backhaul model such as a microwave link is also investigated within intra-HetNet-CoMP (inside one cell), where an implementing fiber is not feasible. An intercell interference (ICI) coordination method is also studied to mitigate ICI. At the end, a novel resource allocation algorithm is proposed-modeled as an optimization problem - which takes into account the total power consumption, including radiated, circuit, and backhaul power, and the minimum required data rate to maximize EE. Given an SE requirement, the EE optimization problem is formulated as a constrained optimization problem. The considered optimization problem is transformed into a convex optimization problem by redefining the constraint using cubic inequality, which results in an efficient iterative resource allocation algorithm. In each iteration, the transformed problem is solved by using dual decomposition with a projected gradient method. Simulations results demonstrate how backhaul has a significant impact on total power consumption and the effectiveness of the studied schemes. In addition, the results demonstrate that the proposed iterative resource allocation algorithm converges within a small number of iterations and illustrate the fundamental tradeoffs between SE and EE. Our analytical results shed light on future “green” network planning in advanced OFDMA wireless systems like those envisioned for a fifth-generation (5G) system.

Cognitive vehicular communication for 5G

Device-to-device (D2D) is increasingly becoming a prominent technology within the 5G story, portrayed as a means of offloading traffic from the core network. The ever increasing demand for vehicular traffic consumption is providing the impetus for a new architectural design that can harness the benefits of D2D for vehicular users, taking a step toward offloading vehicular traffic from the core network. We propose the notion of extending D2D for vehicular scenarios with the potential to coordinate vehicular traffic using the LTE band. Furthermore, we then extend this approach by investigating cognitive radio in synergy with a geo-location database, to exploit white spaces as a means of further offloading vehicular users. Our simulation results have shown that our approach can outperform the legacy IEEE 802.11p in terms of delay.

Smart Device to Smart Device Communication

This book presents a comprehensive analysis of D2D communication over LTE-A band. The book uses 3GPP LTE-A as a baseline and explains all fundamental requirements for deploying D2D network under cellular systems from an architectural, technical and business point of view. The contributors explain the standardization activities of Release 12 of LTE-A, which has been recently acknowledged as support of D2D communication in LTE-A. The text updates the research community on the D2D roadmap as well as new features emerging for consideration in 3GPP.

Millimeter Wave Communications for Future Mobile Networks

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.

Energy efficient interference-aware resource allocation in LTE-D2D communication

Interference management is an important subject in Device to Device (D2D) communication when underlying a LTE-A cellular band. By default, in LTE-A there is negligible intra-cell interference due to the orthogonality of the subcarriers but this orthogonality will be lost when D2D communication takes place under cellular users (CU). Therefore, one of the key aspects of D2D communication is the set of spectrum bands in which D2D communication takes place. Hence, in this paper we will propose two novel resource allocation (RA) schemes: the first RA scheme (cell level) mitigates the interference between D2D and CU and the second RA scheme (user level or scheduling) schedules the resources in an energy efficient way between D2D and CU. These RA schemes increase the throughput and reduce the overall energy cost per bit of the system. Afterwards, these schemes are compared with the conventional methods and the simulation results show that the proposed schemes obtain higher throughput and save significant amount of energy per bit.

Joint CSIT Acquisition Based on Low-Rank Matrix Completion for FDD Massive MIMO Systems

Channel state information at the transmitter (CSIT) is essential for frequency-division duplexing (FDD) massive MIMO systems, but conventional solutions involve overwhelming overhead both for downlink channel training and uplink channel feedback. In this letter, we propose a joint CSIT acquisition scheme to reduce the overhead. Particularly, unlike conventional schemes where each user individually estimates its own channel and then feed it back to the base station (BS), we propose that all scheduled users directly feed back the pilot observation to the BS, and then joint CSIT recovery can be realized at the BS. We further formulate the joint CSIT recovery problem as a low-rank matrix completion problem by utilizing the low-rank property of the massive MIMO channel matrix, which is caused by the correlation among users. Finally, we propose a hybrid low-rank matrix completion algorithm based on the singular value projection to solve this problem. Simulations demonstrate that the proposed scheme can provide accurate CSIT with lower overhead than conventional schemes.

Smart Direct-LTE communication: An energy saving perspective

Direct-LTE communication underlying a cellular infrastructure, or more commonly known as device to device (D2D), is discussed in this paper. When enabling D2D communication in the system, one can see several benefits compared to the conventional infrastructure based communication, such as improved energy efficiency, increased overall system throughput and decreased traffic load in the network. The aim of this paper is to give an energy efficiency perspective of D2D communication to assist all major mobile stakeholders to perceive the benefits when facilitating D2D communication in the network. This paper is tutorial in nature, initially elaborating on the fundamental concept surrounding D2D communication towards technical perspective, business opportunities and open challenges when considering deployment. Furthermore, a simulation study of a typical D2D use case is carried out that includes the energy efficiency perspective; we use 3GPP Long Term Evolution Advanced (LTE-A) as a baseline technology and candidate for launching D2D communications.

One Integrated Energy Efficiency Proposal for 5G IoT Communications

To further enhance the energy efficiency (EE) performance of fifth generation (5G) Internet of Things systems, an integrated structure is proposed in this paper. That is, other than prior studies that separately study the wireless and wired parts, the wireless and wired parts are holistically combined together to comprehensively optimize the EE of the whole system. The integrated system structure is introduced beforehand with the proposed unified control center components for better deployment of the select-and-sleep mechanism. In addition, in the wireless part, one cellular partition zooming (CPZ) mechanism is proposed. In contrast, in the wired part, a precaching mechanism is introduced. With these proposals, the proposed system EE performance is investigated. Comprehensive computer-based simulation results demonstrate that the proposed schemes display better EE performance. This is due to the fact that system power consumption is further reduced with these schemes as compared to the prior work.

Massive Internet of Things for Industrial Applications: Addressing Wireless IIoT Connectivity Challenges and Ecosystem Fragmentation

This article provides an overview of the development and standardizations of connectivity solutions for enabling the Industrial Internet of Things (IIoT). It also highlights key IIoT connectivity technologies and platforms that have the potential of driving the next industrial revolution. In addition, the article addresses the main challenges standing in the way of realizing the full potential of the IIoT, namely attaining secure connectivity and managing a vastly fragmented ecosystem of connectivity solutions and platforms. Finally, IIoT connectivity challenges are illustrated by the example of future building automation.