Future Wireless Mobile Networks Research Articles

Enhancing heterogeneous mobile network management based on a well-founded reference ontology

The fulfillment of the Always Best Connected & Served concept in future mobile wireless networks depends on their ability to maintain a seamless association between the user’s equipment and the network. As a result, many researchers and developers have proposed several decision-support mechanisms to cope with this challenge. One of the promising mechanisms to aid mobile wireless networks in achieving ubiquitous coverage with a seamless connection is semantic reasoning. However, once it relies on ontologies, proper representation of Link and Connection – entities that bind the communication nodes – is paramount. Unfortunately, although several network-related ontologies present these concepts, they are unclear on which entities they bind, nor do they present them simultaneously. Also, the same ambiguity can be perceived in vocabulary recommendations of several telecommunication standard bodies. Our main contribution is the ontological analysis that clarifies the definition of Link and Connection in telecommunication domain. Besides, we analyze their dependencies while refining other concepts such as Medium, Server, and Neighbor. Thus, we provide the foundations for a new network-related ontology to support mobility management in wireless networks.

Toward intelligent wireless communications: Deep learning - based physical layer technologies

Advanced technologies are required in future mobile wireless networks to support services with highly diverse requirements in terms of high data rate and reliability, low latency, and massive access. Deep Learning (DL), one of the most exciting developments in machine learning and big data, has recently shown great potential in the study of wireless communications. In this article, we provide a literature review on the applications of DL in the physical layer. First, we analyze the limitations of existing signal processing techniques in terms of model accuracy, global optimality, and computational scalability. Next, we provide a brief review of classical DL frameworks. Subsequently, we discuss recent DL-based physical layer technologies, including both DL-based signal processing modules and end-to-end systems. Deep neural networks are used to replace a single or several conventional functional modules, whereas the objective of the latter is to replace the entire transceiver structure. Lastly, we discuss the open issues and research directions of the DL-based physical layer in terms of model complexity, data quality, data representation, and algorithm reliability.

Programmable 1.47 Tb/s (92 Gb/s x 16) optical wireless broadcasting system empowered by a single spatial light modulator and a modified RSS algorithm.

We have proposed and experimentally demonstrated a programmable multi-access-point optical wireless broadcasting system with ±15° field-of-view by employing a single spatial light modulator (SLM) and a modified rotated-splitting-SLM algorithm. The 16 access points are generated and arbitrarily distributed by the proposed continuous tunable broadcasting algorithm. The optical beams for each point carry 92-Gb/s PAM-4 optical signal and transmitted over 1 km standard single mode fiber and 1.2 m indoor free space distance, offering a total wireless capacity beyond 1.47 Tb/s. The measured results show that the proposed multi-access-points transmission system with ultra-high transmission capacity and reconfigurability can be used for future indoor wireless mobile networks.

Study of 5G-NR-MIMO Links in the Presence of an Interferer

Many communication systems are based on the Multiple Input, Multiple Output (MIMO) scheme, and Orthogonal Space–time Block Transmit diversity Coding (OSTBC), combined with Maximal Ratio Receive Combining (MRRC), to create an optimal diversity system. A system with optimal diversity fixes and optimizes the channel’s effects under multi-path and Rayleigh fading with maximum energy efficiency; however, the challenge does not end with dealing with the channel destruction of the multi-path impacts. Susceptibility to interference is a significant vulnerability in future wireless mobile networks. The 5th Generation New Radio (5G-NR) technologies bring hundreds of small cells and pieces of User Equipment (UE) per indoor or outdoor local area scenario under a specific Long Term Evolution (LTE)-based station (e-NodeB), or under 5G-NR base-station (g-NodeB). It is necessary to study issues that deal with many interference signals, and smart jammers from advanced communication equipment cause deterioration in the links between the UE, the small cells, and the NodeB. In this paper, we study and present the significant impact and performances of 2×2 Alamouti Phase-Shift Keying (PSK) modulation techniques in the presence of an interferer and a smart jammer. The destructive effects affecting the MIMO array and the advanced diversity technique without closed-loop MIMO are analyzed. The performance is evaluated in terms of Bit Error Rate (BER) vs. Signal to Interference Ratio (SIR). In addition, we proved the impairment of the orthogonal spectrum assumption mathematically.

Low complexity Massive MIMO detection algorithm based on improved LAS

Massive multiple-input multiple-output (M-MIMO) technology is a key technology for 5G communications and future mobile wireless networks. Although the likelihood ascent search (LAS) algorithm in the existing detection algorithms is relatively low in complexity, the algorithm is easy to fall into the local optimum, resulting in poor global performance. Therefore, based on this algorithm, this paper proposes an improved detection scheme based on the LAS algorithm in the reduced neighborhood. This algorithm combines the idea of a reduced neighborhood and iteratively improves the LAS algorithm. The algorithm is designed by reducing the size of the neighborhood and increasing the number of iterations. The algorithm compares the BER performance of different neighborhood parameters, and obtains a set of parameters to significantly reduce BER through simulation comparison.

Transfer Learning for Tilt-Dependent Radio Map Prediction

Machine learning will play a major role in handling the complexity of future mobile wireless networks by improving network management and orchestration capabilities. Due to the large number of parameters that can be monitored and configured in the network, collecting and processing high volumes of data is often unfeasible or too expensive at network runtime, which calls for taking resource management and service orchestration decisions with only a partial view of the network status. Motivated by this fact, this paper proposes a transfer learning framework for reconstructing the radio map corresponding to a target antenna tilt configuration by transferring the knowledge acquired from another tilt configuration of the same antenna, when no or very limited measurements are available from the target. The performance of the framework is validated against standard machine learning techniques on a data set collected from a 4G commercial base stations. In most of the tested scenarios, the proposed framework achieves notable prediction accuracy with respect to classical machine learning approaches, with a mean absolute percentage error below 8%.

IEEE Access Special Section Editorial: Secure Modulations for Future Wireless Communications and Mobile Networks

Security has become an extremely important research topic in wireless networks over the last decade, as it is intimately related to both individual privacy and national security. Directional modulation, as a conventional type of secure modulations, transmits confidential information along the desired directions of legitimate receivers, and artificial noise in other directions, to deliberately confuse eavesdroppers in line-of-sight channels. Recently, artificial noise is also introduced into spatial modulation, leading to a secure spatial modulation strategy. In this Special Section in IEEE A CCESS, secure modulation is defined broadly as any secure modulation method, which includes, but is not limited to, secure directional modulation, secure spatial modulation, and secure index modulation.

Complexity of coordinated beamforming and scheduling for OFDMA based heterogeneous networks

Coordination is foreseen to be an important component of future mobile radio networks. It is especially relevant in heterogeneous networks, where high power base stations produce strong interference to an underlying layer of low power base stations. This work investigates in detail the achievable performance gains for one coordination technique—coordinated beamforming. It reveals the main factors that influence the throughput of the mobile stations. These findings are combined with an analysis of the computational complexity. As a result, a heuristic algorithm is presented that achieves results close to an exhaustive search with significantly less calculations. Detailed simulation analysis is presented on a realistic network layout.

Efficient Resource Allocation in Cognitive Networks

Cognitive radio (CR) in conjunction with multiple-input multiple-output (MIMO) orthogonal frequency-division multiple access is a candidate technology for future mobile radio networks. The short communication range of underlay CR systems is commonly a major limiting factor. In this paper, we propose a computationally and spectrally efficient resource allocation scheme for multiuser MIMO orthogonal-frequency-division-multiplexing-based underlay CR networks to provide good spectral efficiency gain and, therefore, increased communication range. Since the formulated optimization problem defines a mixed-integer programming (combinatorial task) that is hard to solve, we propose a two-phase scheme to produce efficient solutions for both the downlink and the uplink. Particularly, the first procedure elaborates on an adaptive precoding that is characterized by spectral efficiency due to the degrees of freedom it can provide. The second procedure develops a fast subcarrier mapping algorithm, which can be worked out through optimal power distribution among the CR users. The proposed scheme is optimal for the downlink but, however, near-optimal for the uplink. Simulation results demonstrate the bandwidth and computational efficiencies of the proposed scheme compared with the state of the art.

Interference cancellation for non-orthogonal multiple access used in future wireless mobile networks

Non-orthogonal multiple access (NOMA) is suggested as a radio access candidate for future wireless mobile networks. It utilizes the power domain for user multiplexing on the transmitter side and adopts a successive interference cancellation (SIC) as the baseline receiver scheme, considering the expected mobile device evolution in the near future. However, recent research focuses more on the performance evaluation of NOMA in context of assuming the perfect SIC at receiver side. In order to clarify the performance gap between the perfect and the practical SIC in NOMA schemes, and to examine the possibility of applying NOMA with practical SIC, this paper investigates the performance of NOMA applying multi-input multi-output (MIMO) technology with zero-forcing (ZF) and minimum mean square error (MMSE) SIC schemes. We propose an analysis on error effects of the practical SIC schemes for NOMA and in addition propose an interference-predicted minimum mean square error (IPMMSE) IC by modifying the MMSE weight factor using interference signals. According to the IPMMSE IC and analysis of IC error effect, we further suggest the remaining interference-predicted MMSE (RIPMMSE) IC to cancel the remaining interference. The simulation results show that by considering practical IC schemes, the bit error rate (BER) is degraded compared with conventional orthogonal multiple access (OMA). This validates that the proposed IC schemes, which can predict the interference signals, provide better performance compared to NOMA with conventional ZF and MMSE IC schemes.

Dynamic Operations of Cloud Radio Access Networks (C-RAN) for Mobile Cloud Computing Systems

In this paper, we jointly consider cloud radio access networks (C-RAN) and mobile cloud computing (MCC) in a holistic framework. In particular, we study how to dynamically operate C-RAN to enhance the end-to-end performance of MCC services in next-generation wireless networks. An intrinsic challenge in such a system is that channel state information (CSI) is outdated. With delayed CSI, only suboptimal C-RAN operations can be made if deterministic optimization techniques are applied directly. We formulate the topology configuration and rate-allocation problem with delayed CSI under a stochastic optimization framework. Such a framework maximizes MCC services' sum throughput with constraints on the response latency experienced by each MCC user. We propose an optimal policy for the stochastic optimization problem, which has the advantage of low computation cost. Offline and online algorithms are developed based on the optimal policy. Using simulation results, we show that, with the emergence of MCC and C-RAN technologies, the design and operation of future mobile wireless networks can be significantly affected by cloud computing, and the proposed scheme is capable of achieving substantial performance gains over existing schemes.

Cloud computing meets mobile wireless communications in next generation cellular networks

In next generation cellular networks, cloud computing will have profound impacts on mobile wireless communications. On the one hand, the integration of cloud computing into the mobile environment enables MCC systems. On the other hand, the powerful computing platforms in the cloud for radio access networks lead to a novel concept of C-RAN. In this article we study the topology configuration and rate allocation problem in C-RAN with the objective of optimizing the end-to-end performance of MCC users in next generation cellular networks. We use a decision theoretical approach to tackle the delayed channel state information problem in C-RAN. Simulation results show that the design and operation of future mobile wireless networks can be significantly affected by cloud computing, and the proposed scheme is capable of achieving substantial performance gains over existing schemes.

Guest Editorial: Special section on self-organizing radio networks

This IEEE Transactions on Vehicular Technology special section on self-organizing radio networks (SORNs) focuses on the study of most recent achievements in SONs, the presentation of solutions to remaining challenges, and the investigation of the significant potential of SONs to be of use in the deployment of future mobile wireless networks. The high interest in and timeliness of the topics addressed in this Special Section is documented by the submission of 33 manuscripts on May 15, 2012. In the following, the Guest Editors briefly introduce the ten papers that have been accepted for inclusion in this Special Section as part of the June 2013 issue of the IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY.

Capacity Maximization through Energy-Aware Multi-Mode Relaying

In future wireless mobile networks, data rate and quality of service are expected to be comparable to those of wired deployments. To achieve this target, novel architectures must be adopted, successfully countering the disadvantages of the wireless transmission. Inspired by that, cooperative relaying was proposed because of the various gains it introduces to the network. In this work we propose a scheme consisting of multi-mode decode and forward relays facilitating the communication between a base station and a user terminal (UT). By equipping the relays with two interfaces, we can exploit the plethora of the available wireless protocols. Also, instead of performing multi-relay transmissions, we adopt an opportunistic relaying scheme due to its simplicity and outage-optimality. Additionally, we incorporate successive transmissions to improve the spectral efficiency, thus recovering the half-duplex loss in capacity due to the two-hop transmission. However, as inter-relay interference arises from successive transmissions, we propose mitigation techniques through interference cancellation and out-band transmissions using the multi-mode relays. At the same time, an energy-aware mechanism is implemented in the selected relay's transmission, opting for power reduction, as the channel state information is acquired prior to the signal's forwarding to the UT. Finally, we give numerical results by comparing the proposed energy-aware multi-mode relaying (EA-MMR) scheme, with two other schemes in terms of average end-to-end capacity, outage probability, delay distribution and power gain.

Future Wireless Mobile Networks

In this article, the authors outline some key benefits that stem from the use of mechanical relaying within or across the cells in future wireless mobile networks. The authors have argued that, when information messages that can be stored are elastic enough and subsequently carried by mobile nodes, before relayed to other terminals or the BS at a later time, interference and energy consumption levels can be dramatically decreased during network operation due to the locality of the transmissions. In addition, mechanical relaying allows for innovative resource-management techniques to be deployed in the network, such as providing load balancing or switching-off BSs with low levels of utilization. To fully understand the issues regarding mechanical relaying, it is necessary to examine in a more detailed manner the required architectural changes together with the implementation aspects of integrating the mechanical relaying paradigm with the current and emerging mobile networks such as LTE advanced. This will be part of our future line of enquiry.

이동통신 역방향 스케줄러에서의 고신뢰성 자원 할당 기법

본 연구에서는 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)와 같은 이동통신 네트워크에서 역방향 전송이 전용회선 방식이 아닌 패킷 전송으로 이루어지는 환경에서의 고신뢰성 역방향 패킷 스케줄링 기법을 제안하고, 기존 방안과 성능을 비교하여 장단점을 분석한다. 제안하는 고신뢰성 역방향 패킷 스케줄링 기법은 전송속도 혹은 처리용량의 극대화를 추구하는 기존 방식과 다르게 현재 차세대 이동통신의 핵심 연구 분야로 고려되는 Machine Type Communication (MTC) 분야에서, 단말의 위치 및 단말의 무선링크 상태에 독립적으로, 반드시 단말이 생성한 정보가 네트워크로 전송되어야 하는 요구사항을 만족하도록 제안되었으며, 성능 평가를 통하여 제안방안이 기존 방안 대비 우수한 신뢰성을 제공하는 것을 확인하였다. In this paper, we propose the reliability constrained resource allocation scheduling algorithm in cellular network for uplink transmission, where uplink transmission is supported via packet switching schemes without the dedicated uplink circuit links. We evaluate the performance of the proposed algorithm, and compared with the conventional works to identify the pros and cons. The proposed uplink scheduling algorithm is to satisfy the constraints requirements of the MTC services which is considered as the core technology for future mobile wireless networks. It is different to conventional works which target to maximize the link capacity. The proposed algorithm provides reliable uplink transmission independent to the location and the quality of the wireless link of the mobile terminal. Based on the performance evaluation results, we conclude that the proposed method provides enhanced reliability performance than conventional works.

A Hybrid Resource Allocation Strategy with Queuing in Wireless Mobile Communication Networks

The main objective of third and future wireless mobile communication networks is to provide services efficiently to the mobile users in all environments. In wireless mobile Communication the channel allocation and quality of service are the major factors and important issues to decide the system performance. Here in our work a Hybrid Channel Allocation(HCA)strategy for channel allocation and queuing technique applied to Hybrid Channel Allocation strategy for Quality of Service(QoS) provisioning are implemented. The proposed HCA strategy considers new calls in Fixed Channel Allocation (FCA) method and handoff calls in Dynamic Channel Allocation (DCA) method to reduce the call blocking and call dropping probabilities. The application of queuing technique applied to HCA strategy increases the efficiency of the cellular system performance especially in micro and pico cellular environments and effectively utilize the available allocated radio spectrum. The performance shows the decrease in call blocking and dropping and an increased number of users in the available channels.

Approaches to resource reservation for migrating real-time sessions in future mobile wireless networks

This paper presents two novel frameworks for session admission control and resource reservation in the context of next generation mobile and cellular networks. We also devised a special scheme that avoids per-user reservation signaling overhead in order to meet scalability requirements needed for next generation multi-access networks. The first proposal, Distributed Call Admission Control with Aggregate Resource Reservation (VR), uses mobility prediction based on mobile positioning system location information and takes into account the expected bandwidth to be used by calls handing off to and from neighboring cells within a configurable estimation time window. In conjunction, a novel concept called virtual reservation has been devised to prevent per-user reservation. Our second proposal, Local Call Admission Control and Time Series-based Resource Reservation, takes into account the expected bandwidth to be used by calls handed off from neighboring cells based only on local information stored into the current cell a user is seeking admission to. To this end, we suggest the use of two time series-based models for predicting handoff load: the Trigg and Leach (TL), which is an adaptive exponential smoothing technique, and Autoregressive Integrated Moving Average (ARIMA) that uses the Box and Jenkins methodology. It is worth to emphasize that the use of bandwidth prediction based on ARIMA technique still exist for wireless networks. The novelty of our approach is to build an adaptive framework based on ARIMA technique that takes into account the measured handoff dropping probability in order to tuning the prediction time window size so increasing the prediction accuracy. The proposed schemes are compared through simulations with the fixed guard channel (GC) and other optimized dynamic reservation-based proposals present in the literature. The results show that our schemes outperform many others and that the simpler local proposal based on TL can grant nearly similar levels of handoff dropping probability as compared to those from more the complex distributed approach.

Integrated Radio Resource Allocation for Multihop Cellular Networks With Fixed Relay Stations

Recently, the notion that a logical next step towards future mobile radio networks is to introduce multihop relaying into cellular networks, has gained wide acceptance. Nevertheless, due to the inherent drawbacks of multihop relaying, e.g., the requirement for extra radio resources for relaying hops, and the sensitivity to the quality of relaying routes, multihop cellular networks (MCNs) require a well-designed radio resource allocation strategy in order to secure performance gains. In this paper, the optimal radio resource allocation problem in MCNs, with the objective of throughput maximization, is formulated mathematically and proven to be NP-hard. Considering the prohibitive complexity of finding the optimal solution for such an NP-hard problem, we propose an efficient heuristic algorithm, named integrated radio resource allocation (IRRA), to find suboptimal solutions. The IRRA is featured as a low-complexity algorithm that involves not only base station (BS) resource scheduling, but also routing and relay station (RS) load balancing. Specifically, a load-based scheme is developed for routing. A mode-aware BS resource-scheduling scheme is proposed for handling links in different transmission modes, i.e., direct or multihop. Moreover, a priority-based RS load balancing approach is presented for the prevention of the overloading of RSs. Within the framework of the IRRA, the above three functions operate periodically with coordinated interactions. To prove the effectiveness of the proposed IRRA algorithm, a case study was carried out based on enhanced uplink UMTS terrestrial radio access/frequency-division duplex with fixed RSs. The IRRA is evaluated through system level simulations, and compared with two other cases: 1) nonrelaying and 2) relaying with a benchmark approach. The results show that the proposed algorithm can ensure significant gains in terms of cell throughput

Movement-based mobility management and trade off analysis for wireless mobile networks

Mobility management plays a central role in providing ubiquitous communications services in future wireless mobile networks. In mobility management, there are two key operations, location update and paging, commonly used in tracking mobile users on the move. Location update is to inform the network about a mobile user's current location, while paging is used for the network to locate a mobile user. Both operations will incur signaling traffic in the resource limited wireless networks. The more frequent the location updates, the less paging in locating a mobile user; thus, there is a trade off in terms of signaling cost. Most trade off analysis in the literature is carried out under the assumption that some time variables are exponentially distributed. However, such assumptions will not be valid, particularly for the wireless Internet. In this paper, we present some general analytical results without these assumptions, which are essential for the general trade off analysis. Specifically, we analytically derive the average number of location updates during the interservice time for a movement-based location update scheme under fairly realistic assumptions, which are crucial for all trade off analysis. Our general analytical results make thorough numerical analysis for finding the optimal mobility management under various network operation scenarios possible.