Use Of Radio Resources Research Articles

Resource-Efficient Parallelized Random Access for Reliable Connection Establishment in Cellular IoT Networks.

The role of various internet-of-things (IoT) devices responsible for data collection and reporting becomes more important in the era of Industry 4.0. Due to the various advantages (e.g., wide coverage, robust security, etc.), the cellular networks have been continuously evolved to accommodate IoT scenario. In IoT scenario, connection establishment is essential and primary for enabling IoT devices to communicate with centralized unit (e.g., base station (BS)). This connection establishment procedure in cellular networks, random access procedure, is generally operated in a contention-based manner. So, it is vulnerable to simultaneous connection requests from multiple IoT devices to the BS, which becomes worse as the contention participants increase. In this article, we newly propose a resource-efficient parallelized random access (RePRA) procedure for resource-efficiently ensuring reliable connection establishment in cellular-based massive IoT networks. Key features of our proposed technique are twofold: (1) Each IoT device simultaneously performs multiple RA procedures in parallel to improve connection establishment success probability, and (2) the BS handles excessive use of radio resources based on newly proposed two types of redundancy elimination mechanisms. Through extensive simulations, we evaluate the performance of our proposed technique in terms of connection establishment success probability and resource efficiency under various combinations of control parameters. Consequently, we verify the feasibility of our proposed technique for reliably and radio-efficiently supporting a large number of IoT devices.

Autonomous Controller-Aware Scheduling of Intra-Platoon V2V Communications

In this paper, we investigate the problem of reducing the use of radio resources for vehicle-to-vehicle communications in an autonomous platooning scenario. Achieving reliable communications, which is a key element allowing for the tight coordination of platoon vehicles' motion, might be challenging in a case of heavy road traffic. Thus, in this paper, we propose to reduce the number of intra-platoon transmissions required to facilitate the safe autonomous control of vehicle mobility, by analyzing the impact of cars' behaviors (in terms of acceleration changes) on the evolution of the inter-vehicle distance errors within the platoon. We derive formulas representing the relation between the platoon leader's acceleration changes and the evolution of the distance error, velocity difference, and the accelerations for the first pair of vehicles. Furthermore, we propose a heuristic algorithm for selection of the intra-platoon messaging period for each platoon vehicle that minimizes the use of radio resources subject to the safety constraint, represented as the fraction of the total time when emergency braking is activated. The presented simulation results indicate that the proposed approach is capable of ensuring safe platoon operation and simultaneously providing a significant reduction in the use of resources, compared with conventional fixed-period transmission.

Dynamic Spectrum Allocation Using Multi-Source Context Information in OpenRAN Networks.

Bearing in mind the stringent problem of limited and inefficiently used radio resources, a multi-source mechanism for the dynamic adjustment of occupied frequency bands is proposed. Instead of relying only on radio-related information, the system that collects data from various sources is discussed. Mainly, using the ubiquitous sources of information about the presence of users (such as city monitoring), it is possible to identify areas that have high or low expected traffic with high probabilities. Consequently, in low-traffic areas, it is not necessary to allocate all available spectrum resources while maintaining the quality of service. This leads to the improved spectral efficiency of the network. As the level of trust in certain information sources may differ among various operators, we propose to implement such functionality in the form of an application. Our contribution is a proposal for an algorithm that limits the use of radio resources through fuzzy and soft connections of multiple sources of contextual information. The simulation results presented in this paper show that it is possible to reduce the spectrum used with a slight and simultaneous reduction in user bitrate, which increases the spectral efficiency of the entire system. Hence, following the concept of an open radio access network, various policies for information merging may be specified.

Ergodic capacity of internet of things’ devices in presence of channel state information imperfection

Non-orthogonal multiple access (NOMA) is deployed to improve spectral efficiency for applications in fifth generation networks. NOMA system splits power domain to many parts to further serve massive users by relaxing the orthogonal use of radioresources. In this paper, a relay is required to help the source communicate with destinations with a fixed power allocation scheme. We derive expressions to highlight ergodic performance of two users the deployment of NOMA is suitable to different rate requirements from destinations (e.g., a cellular users have different requirements compared with internet of things devices). By conducting Monte-Carlo simulations, we find main system parameters which have crucial impacts on ergodic capacity. This paper is different other recent studies since we emphasize on imperfect channel state information (CSI) and Rician fading model for our analytical results.

A Novel Approach to Adaptive Resource Allocation for Energy Saving in Reconfigurable Heterogeneous Networks

Abstract The dense deployment of small cell networks is a key feature of next generation mobile networks aimed at providing the necessary capacity increase. Wireless heterogeneous networks are created by combining several radio access technologies, each with its own potentials, capabilities and limitations. In these networks, providing real-time services with quality assurance is essential. For effective use of radio resources, the Radio Resource Management method was introduced which its performance and efficiency is better than the control of independent radio resources in any radio access technology. In this paper, we introduced a novel approach to select the most effective radio access technologies by taking into account some performance parameters like the type of service, users’ distribution pattern and the cost of the services. It also optimizes the handover relations between macrolayer and small cells. The proposed approach is a self-optimizing model can be employed to control resources and improve performance indices associated with mobile networks without human interference by only relying on network intelligence. In order to maximize the network performance, we applied the dynamic backhauling technique to analyze the uplink signaling data which increased the validity level of the decision-making process. Based on the extracted semantic information, the network decision-making engine is able to adjust the network parameters and efficiently allocate the resources. The numerical results exhibit considerable power saving for different traffic models in addition to reduce the rate of vertical handovers. The results also show increase the network throughput by up to 30%.

New look on relay selection strategies for full-duplex multiple-relay NOMA over Nakagami-m fading channels

By removing the orthogonal use of radio-resources, non-orthogonal multiple access (NOMA) has been introduced to improve the spectral efficiency of fifth generation (5G) and beyond networks. This paper studies the system performance in a dual-hop multi-relay NOMA using decode-and-forward (DF) scheme over Nakagami-m fading channels. A group of NOMA users is considered, i.e. the near and far users which are decided by how strong these related channels are. Specifically, we obtain a closed-form expression of the outage probability of the near/far NOMA users when the several relay selection schemes are adopted for selecting the best among M intermediate relays. As main finding, this paper introduces three strategies including two-stage relay selection, max-min and power allocation based relay selection schemes. As main benefit, the NOMA users are considered to employ selection combining technique in order to improve signal transmissions for an increased reliability in the context of massive connections in 5G wireless communications. By conducting numerical simulations, we evaluate the impact of the number of intermediate relays, the NOMA power allocation factor, and the Nakagami-m fading severity parameter on the outage performance of the NOMA users. Finally, the outage probability along with throughout in delay-limited transmission mode are provided via numerical results and the necessary comparisons are provided.

How URLLC Can Benefit From NOMA-Based Retransmissions

Among the new types of connectivity unleashed by the emerging 5G wireless systems, Ultra-Reliable Low Latency Communication (URLLC) is perhaps the most innovative, yet challenging one. Ultra-reliability requires high levels of diversity, however, the reactive approach based on packet retransmission in HARQ protocols should be applied carefully to conform to the stringent latency constraints. The main premise of this paper is that the NOMA principle can be used to achieve highly efficient retransmissions by allowing concurrent use of wireless resources in the uplink. We introduce a comprehensive solution that accommodates multiple intermittently active users, each with its own HARQ process. The performance is investigated under two different assumptions about the Channel State Information (CSI) availability: statistical and instantaneous. The results show that NOMA can indeed lead to highly efficient system operation compared to the case in which all HARQ processes are run orthogonally.

Performance Comparison of Massive MIMO System with Orthogonal and Nonorthogonal Multiple Access for Uplink in 5G Systems

In the attempt to respond to market demands, new techniques for wireless communication systems have been proposed to ensure, to all active users that are sharing the same network cell, an increased quality of service, regardless of any environmental factors, such as their position within the cell, time, space, climate, and noise. One example is the nonorthogonal multiple access (NOMA) technique, proposed within the 5G standard, known for supporting a massive connectivity and a more efficient use of radio resources. This paper presents two new sets of complex codes— multiple-user shared-access (MUSA) and extended MUSA (EMUSA), and an algorithm of allocation such that the intercorrelation should be as reduced as possible that can be used in MUSA for 5G NOMA-based technique scheme. Also, it analyzes the possibility of creating complex codes starting from PN (cPN), which is a novel idea proposed in this paper, whose results are promising with respect to the overall system performances. First, a description of the basic principles of MUSA are presented; next, the description of the proposed system will be provided, whose performance will be tested using Monte Carlo MATLAB simulations based on bit error rate (BER) versus signal-to-noise ratio (SNR). The system performances are evaluated in different scenarios and compared with classical code division multiple access (CDMA) having the following system parameters in sight: the number of antennas at the receiver side and the number of active users.

Enhanced Integrated Satellite-Terrestrial NOMA with Cooperative Device-to-Device Communication

The currently deployed terrestrial wireless networks experience difficulties while coping with the massive connectivity demands of coexisting users and devices. The addition of satellite segments has been proposed as a viable way of providing improved coverage and capacity, leading to the formation of integrated satellite-terrestrial networks. In such topologies, non-orthogonal multiple access (NOMA) can further enhance the efficient use of wireless resources by simultaneously serving multiple users. In this paper, an integrated satellite-terrestrial NOMA network is studied where cooperation between ground users is allowed, following the device-to-device (D2D) paradigm. More specifically, the proposed satellite NOMA cooperative (SANOCO) D2D scheme optimally selects pairs of users, by considering the channel conditions of the satellite and the terrestrial D2D links. In SANOCO-D2D users are served through NOMA in the satellite link, and then, if the weak user fails to decode its signal, terrestrial D2D communication is activated to maintain the total sum rate of the system. Comparisons with conventional orthogonal multiple access (OMA) and an alternative NOMA optimal user pairing scheme show that significant sum rate and spectral efficiency gains can be harvested through SANOCO-D2D under varying channel conditions and terrestrial D2D bandwidth.

Analysis of Control Overhead Reduction by Semi-Persistent Scheduling

For the efficient use of radio resource, semi-persistent scheduling (SPS) has been adopted to reduce control overhead required for resource allocation. In this letter, for voice over Internet protocol traffic, a lower bound on blocking probability and a closed-form maximum achievable control overhead reduction ratio are derived through a novel Markov chain model. Also, the performance evaluation of SPS under various resource assignment algorithms is provided on the blocking probability and overhead reduction ratio. Analytical expressions are validated through simulations.

Hybrid NOMA/OMA With Buffer-Aided Relay Selection in Cooperative Networks

Non-orthogonal multiple access (NOMA) aims to increase the spectral efficiency of fifth generation networks by relaxing the orthogonal use of radio-resources. In this paper, a network with multiple half-duplex buffer-aided (BA) relays is considered, where the source transmits with a fixed rate toward two users. The users might demand the same rate by the source (e.g., two cellular users requiring the same service), or they could have different rate requirements (e.g., a cellular user coexisting with an Internet of Things device). By deploying multiple BA relays, increased reliability and additional degrees of freedom are provided. Leveraging the spectral efficiency of NOMA and the increased diversity gain of BA relaying, two relay selection algorithms with broadcasting are proposed for power-domain NOMA and hybrid NOMA/OMA, namely BA-NOMA and BA-NOMA/OMA, respectively. BA-NOMA can improve the performance in terms of the outage probability when the power allocation factor $\alpha$ is selected such that robustness against channel uncertainties due to, e.g., outdated channel state information is provided. Moreover, BA-NOMA/OMA further improves the sum-rate by switching to OMA when the relays cannot serve the users through NOMA. For both cases, a theoretical analysis for the outage probability is conducted and the asymptotic performance is studied. Finally, numerical results and comparisons with other state-of-the-art algorithms are provided for the outage probability, average throughput, and average delay.

Reconfigurable optical‐radio wireless networks: Meeting the most stringent requirements of future communication systems

AbstractIn this paper, we propose a reconfigurable optical‐radio wireless network characterized by high flexibility and performance. The hybrid network can be dynamically configured, adapting itself to the changing requirements of users or operating environments, dynamics of the transmission medium, and availability of resources. First, the basic concept, system architecture, and key operating modes are introduced. Possible operating scenarios and their relationship to the operating modes are discussed. Then, a practical implementation of the hybrid network is introduced, describing the network components, architecture, modulation scheme, and implementation technologies. Implementation was carried out using mostly off‐the‐shelf components and universal software radio peripheral blocks. Particular attention has been put in implementing a fast handover mechanism between modes, an essential requirement for seamless network reconfiguration. Network performance is evaluated and different switching approaches are compared. The paper demonstrates practically the proposed concept based on dynamic system reconfiguration. For the implementation, a mode switching algorithm was developed making decisions based on the quality of the wireless channels. The system was tested with live video packets transmitted through the network. System performance was assessed through data throughput and packet loss measured for different modulation parameters. The proposed concept, essentially a software‐defined hybrid network, is flexible and makes efficient use of radio resources. Moreover, the network has the potential to achieve high performance. All these characteristics make reconfigurable optical‐radio networks an attractive candidate for fifth generation and beyond.

Cooperative Passive Coherent Location: A Promising 5G Service to Support Road Safety

5G promises many new vertical service areas beyond simple communication and data transfer. We propose CPCL (cooperative passive coherent location), a distributed MIMO radar service, which can be offered by mobile radio network operators as a service for public user groups. CPCL comes as an inherent part of the radio network and takes advantage of the most important key features proposed for 5G. It extends the well-known idea of passive radar (also known as passive coherent location, PCL) by introducing cooperative principles. These range from cooperative, synchronous radio signaling, and MAC up to radar data fusion on sensor and scenario levels. By using software-defined radio and network paradigms, as well as real-time mobile edge computing facilities intended for 5G, CPCL promises to become a ubiquitous radar service which may be adaptive, reconfigurable, and perhaps cognitive. As CPCL makes double use of radio resources (both in terms of frequency bands and hardware), it can be considered a green technology. Although we introduce the CPCL idea from the viewpoint of vehicle-to-vehicle/infrastructure (V2X) communication, it can definitely also be applied to many other applications in industry, transport, logistics, and for safety and security applications.

A Context-Aware Edge-Based VANET Communication Scheme for ITS.

We propose a context-aware edge-based packet forwarding scheme for vehicular networks. The proposed scheme employs a fuzzy logic-based edge node selection protocol to find the best edge nodes in a decentralized manner, which can achieve an efficient use of wireless resources by conducting packet forwarding through edges. A reinforcement learning algorithm is used to optimize the last two-hop communications in order to improve the adaptiveness of the communication routes. The proposed scheme selects different edge nodes for different types of communications with different context information such as connection-dependency (connection-dependent or connection-independent), communication type (unicast or broadcast), and packet payload size. We launch extensive simulations to evaluate the proposed scheme by comparing with existing broadcast protocols and unicast protocols for various network conditions and traffic patterns.

An efficient cooperative exploration strategy for wireless sensor network

Wireless sensor networks (WSNs) are used in several applications such as healthcare devices, aerospace systems, automobile industry, security monitoring. However, WSNs have several challenges to improve the efficiency, robustness, failure tolerance and reliability of these sensors. Thus, cooperation between sensors is an important deal that increases sensor trust. Cooperative WSNs can be used to optimize the exploration of an unknown area in a distributed way. In this paper, the distributed Markovian model strategy that is used due to their past state-dependent reasoning. Moreover, the exploration strategy depends totally on the wireless communication protocol. Hence, in this paper, we propose an efficient cooperative strategy based on cognitive radio and software-defined radio which are promising technologies that increase spectral utilization and optimize the use of radio resources. We implement a distributed exploration strategy (DES) in mobile robots, and several experiments have been performed to localize targets while avoiding obstacles. Experiments were performed with several exploration robots. A comparison with another exploration strategy shows that DES improves the robots exploration.

Risk-Aware Resource Allocation for URLLC: Challenges and Strategies with Machine Learning

Supporting ultra-reliable low-latency communications (URLLC) is a major challenge of 5G wireless networks. Stringent delay and reliability requirements need to be satisfied for both scheduled and non-scheduled URLLC traffic to enable a diverse set of 5G applications. Although physical and media access control layer solutions have been investigated to satisfy scheduled URLLC traffic, there is lack of study on enabling transmission of non-scheduled URLLC traffic, especially in coexistence with the scheduled URLLC traffic. Machine learning (ML) is an important enabler to manage this coexistence scenario due to its ability to exploit spatial/ temporal correlation in user behaviors and use of radio resources. In this article, we first study the coexistence design challenges, especially the radio resource management (RRM) problem, and propose a distributed risk- aware ML solution for RRM. The proposed solution benefits from hybrid orthogonal/non-orthogonal radio resource slicing, and proactively regulates the spectrum needed for satisfying the delay/reliability requirement of each URLLC traffic type. A case study is introduced to investigate the potential of the proposed RRM in serving coexisting URLLC traffic types. The results further provide insights on the benefits of leveraging intelligent RRM. For example, a 75 percent increase in data rate with respect to the conservative design approach for the scheduled traffic is achieved, while the 99.99 percent reliability of both scheduled and non-scheduled traffic types is satisfied.

Achieving Full-Duplex Communication: Magnetless Parametric Circulators for Full-Duplex Communication Systems

In a crowded electromagnetic spectrum with ever-increasing demand for higher data rates to enable multimedia-rich applications and services, the efficient use of wireless resources becomes crucial. For this reason, full-duplex communication [1]-[4], which increases the capacity of transmission channels by operating the uplink and downlink simultaneously on the same frequency channel (see Figure 1), is returning to the spotlight after decades of being presumed impractical. This long-held assumption resulted mainly from the need for large isolation (IX) between the transmit (Tx) and receive (Rx) nodes [also known as self-interference cancellation (SIC)], which typically needs to be greater than 100 dB, a challenging task that requires several innovations at the network and physical layer levels.

An Efficient Small Data Transmission Scheme in the 3GPP NB-IoT System

This letter proposes an efficient small data transmission scheme in the narrow band (NB)-Internet of Things (IoT) system. For the efficient use of radio resources, the proposed scheme enables devices in an idle state to transmit a small data packet without the radio resource control connection setup process. This can improve the maximum number of supportable devices in the NB-IoT system which has insufficient radio resources. Numerical results have shown that the proposed scheme can increase the maximum number of supportable devices by about 60% compared with the conventional scheme.

Smart service system(SSS): A novel architecture enabling coordination of heterogeneous networking technologies and devices for Internet of Things

In Internet of Things (IoT), the devices or terminals are connected with each other, which can be very diverse over the wireless networks. Unfortunately, the current devices are not designed to communicate with the collocated devices which employ different communication technologies. Consequently, the communication between these devices will be realized only by using the gateway nodes. This will cause the inefficient use of wireless resources. Therefore, in this paper, a smart service system(SSS) architecture is proposed, which consists of smart service terminal (SST), and smart service network (SSN), to realize the IoT in a general environment with diverse communication networks, devices, and services. The proposed architecture has the following advantages: i) the devices in this architecture cover multiple types of terminals and sensor-actuator devices; ii) the communications network therein is a converged network, and will coordinate multiple kinds of existing and emerging networks. This converged network offers ubiquitous access for various sensors and terminals; iii) the architecture has services and applications covering all smart service areas. It also provides the adaptability to new services and applications. A SSS architecture-based smart campus system was developed and deployed. Evaluation experiments of the proposed smart campus system demonstrate the SSS's advantages over the existing counterparts, and verify the effectiveness of the proposed architecture.

Introduction to the Issue on Signal Processing for Exploiting Interference Toward Energy Efficient and Secure Wireless Communications

INTERFERENCE has been the central focus for meeting the ever increasing requirements on quality of service in modern and future wireless communication systems, and has long been considered as a deleterious factor that limits the system capacity. In conventional communications systems, the design objective is to allow users to share a medium with minimum or no interference. Thus, great efforts are made to avoid, mitigate, and cancel interference. For instance, to support multiple users, orthogonal access methods in time, frequency, code well as spatial domains have been used in different generations of cellular systems. In future-generation heterogeneous cellular networks, due to the increasing number of uncoordinated lowpower nodes such as femtocells to improve the coverage and pacity, interferences need to be mitigated in multiple domains, rendering their management a challenge. Interference mitigation/avoidance techniques provide convenient mechanisms allow multiple users to share the wireless medium. However, they lead to inefficient use of wireless resources.