Direct communication between two or more devices without the intervention of a base station, known as device-to-device (D2D) communication, is a promising way to improve performance of cellular networks in terms of spectral and energy efficiency. The D2D communication paradigm has been largely exploited in non-cellular technologies such as Bluetooth or Wi-Fi but it has not yet been fully incorporated into existing cellular networks. In this regard, a new proposal focusing on the integration of D2D communication into LTE-A has been recently approved by the 3GPP standardization community as discussed in this paper. In cellular networks, D2D communication introduces several critical issues, such as interference management and decisions on whether devices should communicate directly or not. In this survey, we provide a thorough overview of the state of the art focusing on D2D communication, especially within 3GPP LTE/LTE-A. First, we provide in-depth classification of papers looking at D2D from several perspectives. Then, papers addressing all major problems and areas related to D2D are presented and approaches proposed in the papers are compared according to selected criteria. On the basis of the surveyed papers, we highlight areas not satisfactorily addressed so far and outline major challenges for future work regarding efficient integration of D2D in cellular networks.

In-Band Device-to-Device Communication in OFDMA Cellular Networks: A Survey and Challenges

This paper provides an overview of cognitive radio (CR) networks, with focus on the recent advances in resource allocation techniques and the CR networks architectural design. The contribution of this work is threefold. First, a systematic way to study the resource allocation problem is presented; various design approaches are introduced, such as signal-to-interference-and-noise ratio (SINR) or transmission power-based, and centralized or distributed methods. Second, CR optimization methods are presented, accompanied by a comprehensive study of the resource allocation problem formulations. Furthermore, quality of service criteria of the physical or/and the medium access control layers are investigated. Third, challenges in spectrum assignment are discussed, focusing on dynamic spectrum allocation, spectrum aggregation and frequency mobility. Such approaches constitute an emerging trend in efficient spectrum sharing and affect the performance of resource allocation techniques. The open issues for future research in this area are finally discussed, including adaptability-reconfigurability, dual accessibility, and energy efficiency.

Radio Resource Allocation Techniques for Efficient Spectrum Access in Cognitive Radio Networks

Spectrum handoff in cognitive radio networks

The future 5G wireless is triggered by the higher demand on wireless capacity. With Software Defined Network (SDN), the data layer can be separated from the control layer. The development of relevant studies about Network Function Virtualization (NFV) and cloud computing has the potential of offering a quicker and more reliable network access for growing data traffic. Under such circumstances, Software Defined Mobile Network (SDMN) is presented as a promising solution for meeting the wireless data demands. This paper provides a survey of SDMN and its related security problems. As SDMN integrates cloud computing, SDN, and NFV, and works on improving network functions, performance, flexibility, energy efficiency, and scalability, it is an important component of the next generation telecommunication networks. However, the SDMN concept also raises new security concerns. We explore relevant security threats and their corresponding countermeasures with respect to the data layer, control layer, application layer, and communication protocols. We also adopt the STRIDE method to classify various security threats to better reveal them in the context of SDMN. This survey is concluded with a list of open security challenges in SDMN.

Software-Defined Mobile Networks Security

Progression on spectrum sensing for cognitive radio networks: A survey, classification, challenges and future research issues

Currently, the radio spectrum is statically allocated and divided between licensed and unlicensed frequencies. Due to this inflexible policy, some frequency bands are growing in scarcity, while large portions of the entire radio spectrum remain unused independently of time and location. Cognitive Radio is a recent network paradigm that aims a more flexible and efficient usage of the radio spectrum. Basically, it allows wireless devices to opportunistically access portions of the entire radio spectrum without causing any harmful interference to licensed users. The present document surveys the literature on Cognitive Radio. It aims to provide a comprehensive and self-contained description of this research topic area, mainly focusing on communication protocols, spectrum decision issues, and future research directions. It is a tutorial in nature and consequently does not require any previous knowledge about Cognitive Radio. Readers are only required to have some general background on wireless data networks. Emphasis is put on Cognitive Radio genesis, issues that must be addressed, related technologies, standardization efforts, the state of the art, and future research directions according to the vision of the authors.

Cognitive radio: survey on communication protocols, spectrum decision issues, and future research directions

Currently, there are several ongoing efforts for the definition of new regulation policies, paradigms, and technologies aiming a more efficient usage of the radio spectrum. In this context, cognitive radio (CR) emerges as one of the most promising players by enabling the dynamic access to vacant frequency bands on a non-interference basis. However, the intrinsic characteristic of CR opens new ways for attackers, namely in the context of the effective detection of incumbent or primary users (PUs), the most fundamental and challenging requirement for the successful operation of CR networks. In this article, we provide a global and integrated vision of the main threats affecting CR environments in the context of the detection of primary users, with a particular focus on spectrum sensing data falsification and primary user emulation attacks. We also address solutions and research challenges still required to address such threats. Our discussion aims at being complete and self-contained, while also targeting readers with no specific background on this important topic of CR environments. It is, as far as our knowledge goes, the first work providing a global and clear vision of security threats and countermeasures in the context of primary user detection in CR.

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A survey on security attacks and countermeasures with primary user detection in cognitive radio networks

This paper describes WMPI, the first full implementation of the Message Passing Interface standard (MPI) for clusters of Microsoft's Windows platforms (Win32). Its internal architecture and user interface, and some performance test results (for release v1.1), that evaluates how much of the total underlying system capacity for communication is delivered to the MPI based parallel applications, are presented. WMPI is based on MPICH, a portable implementation of the MPI standard for UNIX® machines from the Argonne National Laboratory and, even when performance requisites cannot be satisfied, it is a useful tool for application developing, teaching and training. WMPI processes are also compatible with MPICH processes running on Unix workstations.

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WMPI - Message Passing Interface for Win32 Clusters

Currently, the radio spectrum is statically allocated and divided between licensed and unlicensed frequencies. This results in its inefficient usage. Cognitive Radio (CR) is a recent paradigm which aims at addressing this inefficiency. It allows unlicensed users to opportunistically access vacant licensed frequency bands, as long as any harmful interference to incumbent users is avoided. In this context, providing appropriate medium access control (MAC) protocols is a core issue. However, the existing proposals omit relevant issues, are too complex, or are based on unrealistic assumptions in practical terms. Therefore, in this paper, we propose and analyze, through simulation, what we intend to be a really practical CR MAC protocol for distributed (i.e., ad-hoc) multi-hop CR scenarios, with high variability in terms of the availability of vacant frequency bands in time and space. Evaluation results confirm that the proposed approach, designated as CoSBT MAC, can result in relevant benefits.

Cooperative sensing-before-transmit in ad-hoc multi-hop cognitive radio scenarios

Cognitive radio (CR) users (i.e., secondary users) are wireless nodes which are allowed to select and access licensed frequency bands, provided that they do not cause any harmful interference to the respective incumbent users (i.e., primary users). One of the possible approaches consists in having the secondary users locating and accessing vacant frequencies dynamically. However, in scenarios with hidden primary users (i.e., a secondary user cannot sense a primary user on its respective channel, but the two coverage areas overlap each other), it is unfeasible to address the protection of primary users with solutions which are exclusively based on local and non-cooperative sensing schemes. In this work, we propose a cooperative approach which enables an effective protection of primary users in fully distributed CR scenarios, even when the hidden node problem is a concern. Our proposal is based on a key concept we designate as “filtering based on suspect channels” and takes full advantage of any underlying learning scheme based on observation and past experience. It was also successfully integrated with an existing CR medium access control (MAC) protocol. Simulation results show the proposal is effectively capable of delivering high levels of protection concerning the primary users, while preserving the secondary users' communication performance.

José Marinho

Papers

Cognitive radio: survey on communication protocols, spectrum decision issues, and future research directions

A survey on security attacks and countermeasures with primary user detection in cognitive radio networks

WMPI - Message Passing Interface for Win32 Clusters

Cooperative sensing-before-transmit in ad-hoc multi-hop cognitive radio scenarios

Enhanced protection of hidden primary users through filtering based on suspect channels classification