Kazi Mohammed Saidul Huq

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.

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.

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.

Energy efficiency of downlink packet scheduling in CoMP

The foreseen increase in the volume of mobile traffic and the correspondent increase in greenhouse gas emissions is now placing energy efficiency EE at the forefront of mobile network design. As a step towards incorporating more energy friendly mobile platforms in future networks, Third Generation Partnership Project Long-Term Evolution LTE-Advanced has adopted Coordinated Multi-Point CoMP transmission/reception because of its ability to mitigate and/or coordinate inter-cell interference. However, there is room for reducing energy consumption further by exploiting the inherent flexibility of dynamic resource allocation protocols. To this end packet scheduling schemes play a fundamental role in multi-user scenarios and provide a potential research playground for optimising energy consumption in future networks. However, there is no effective benchmark in place for experimenting new design approaches. This paper provides a first attempt to analyse the Energy Efficiency of different downlink packet scheduling in CoMP for LTE networks using classical packet scheduling algorithm approaches such as Maximum Carrier to Interference ratio MCI, Proportional Fairness PF and the Round Robin scheduling RR, and provides some input to future comparison considerations. Copyright

Energy-efficient interference management in LTE-D2D communication

This paper focuses on one of the key enabling technology that will compose future 5G network, the Direct-LTE communication underlying a cellular infrastructure, also commonly known as Device-to-Device (D2D). Energy efficiency algorithms are proposed for the communication between D2D users and cellular users (CUs) and, following the Lagrangian duality theory, an optimal power and rate control solution is given for D2D users, while satisfying the interference limits related to CUs. Finally, the new algorithm is used to achieve proportional fairness between D2D users and CUs and to show with numerical results that the interference to CUs can be limited to always be under a predefined threshold.

Comparison of energy-efficiency in bits per joule on different downlink CoMP techniques

Coordinated MultiPoint (CoMP) transmission / reception techniques have been adopted by the 3GPP community for LTE-Advanced (Long Term Evolution-Advanced) to increase spectral efficiency and cell-edge throughput. Energy efficiency (EE) was previously ignored by most research efforts and was not considered by 3GPP as an important performance indicator until very recently. EE concerns have spurred considerable research in recent years as they enable both energy consumption and CO2 reduction over conventional cellular systems. As the “green evolution” becomes a major trend, energy-efficient transmission becomes more and more important. In this paper we investigate energy efficiency i.e., the number of corrected bits that can be transmitted throughout the channel per joule of energy consumed of different downlink CoMP techniques in LTE-Advanced. In addition, we use system level simulation to evaluate the performance.

Coordinated paradigm for D2D communications

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, the purpose of this paper is to propose a novel scenario with the help of coordinated multipoint (CoMP) technology to remove inter and intra interference between D2D and CU. So far no works have been done on coexistence analysis of CoMP and D2D. This paper is the first effort on coexistence analysis of these two technologies. It is clear that the combination of D2D and CoMP can offer a palette of interesting colors that can paint new business opportunities for mobile stakeholders promoting its candidacy for 5G wireless communication system. To this end, we present numerical results, which prove that this novel scenario will increase the spectral and energy efficiency of whole system and offloaded the traffic from core network.

Enhanced C-RAN Using D2D Network

With the surge in smartphone sensing, wireless networking, and mobile social networking techniques, mobile crowdsensing (MCS) has become a promising paradigm for 5G networks. An MCS systems service quality heavily depends on the platform, which brings the users under a common cloud with very low delay. Therefore, MCS needs a new platform that brings the best not only from the users perspective, but also from the operators perspective. In this article, we propose a novel architecture for MCS by combining two technologies, those being C-RAN and D2D. C-RAN is a promising enabling technology that can at the same time cope with the ever increasing mobile traffic demand and reduce the surging costs experienced by service operators. In spite of the many advantages offered by C-RAN, one of the main concerns for operators is its associated fronthaul delay. To handle such delay, we come across this D2D solution in C-RAN networks. D2D is adopted as an effective candidate for very low delay between links and has already provided evidence of its potential for novel business opportunities. This article shows, together with standardization aspects, how combining C-RAN and D2D technologies can help to solve the delay issue and fulfill most of the targets specified for 5G networks in terms of delay, capacity, energy efficiency, mobility, and cost.