Ultra-dense Radio Access Network Research Articles

Location Aware Beamforming in Millimeter-Wave Band Ultra-Dense Radio Access Networks. Part 2. Model of a Set of Radio Links

The second part of the study of beamforming issues, based on positioning in ultra-dense millimeter wave radio access networks, is devoted to the formalization and software implementation of a complex simulation model of the functioning of a set of directional radio links. Each directional radio link between a base station (gNodeB – gNB), equipped with an antenna array, and a user equipment (UE), operating in omnidirectional mode, is formed according to the location of the UE, known at the gNB. The set of gNB→UE directional radio links, simultaneously operating in a common frequency range, is studied as a set of traffic beams, that implement space division multiple access (SDMA). Spatial multiplexing is implemented through three-dimensional beamforming at the gNB and makes it possible to compensate for propagation losses and high levels of interference. In the first part of the study, it was shown that the problem of practical implementation of SDMA in ultra-dense radio access networks is a significant (tens of dB) spread in the signal to interference plus noise ratio (SINR), depending on the arrangement of two devices. The purpose of this study is to establish the dependence of SINR on 1) the beamwidth of the gNB sector in the direction of the user equipment in the radio link of the signal of interest (SOI); 2) uncertainty of the UE location; 3) interference from radio links of signal not of interest (SNOI): a) within its sector, b) other sectors of its cell and c) other cells in the network. The simulation model developed and implemented in software in this work for the first time made it possible to establish the interdependence of the UE positioning error factors and the required width of the traffic beam for its service. In particular, it was found, that as the positioning error decreases from 10 to 1 m, the required beam width in the horizontal and vertical planes narrows to 3 °, which makes it possible to increase the SINR to 25 dB. A simultaneous transmission multiplexing study showed that for 64 spatially multiplexed UEs, as the cell size increases from 20 to 300 m, the SINR increases by approximately 30 dB, subject to a beamwidth constraint of 3°. Unlike similar studies, in this model, the contribution from interference from simultaneously operating traffic beams within its sector, other sectors of its cell and other cells in the network is shown separately for the first time, which allows to differentiate the origin of interference and use scientifically based beamwidth control for their compensation.

Optimization of Channel Segregation-Based Fractional Frequency Reuse for Inter-Cell Interference Coordination in Cellular Ultra-Dense RAN

To cope with ever growing mobile data traffic, we recently proposed a concept of cellular ultra-dense radio access network (RAN). In the cellular ultra-dense RAN, a number of distributed antennas are deployed in the base station (BS) coverage area (cell) and user-clusters are formed to perform small-scale distributed multiuser multi-input multi-output (MU-MIMO) transmission and reception in each user-cluster in parallel using the same frequency resource. We also proposed a decentralized interference coordination (IC) framework to effectively mitigate both intra-cell and inter-cell interferences caused in the cellular ultra-dense RAN. The inter-cell IC adopted in this framework is the fractional frequency reuse (FFR), realized by applying the channel segregation (CS) algorithm, and is called CS-FFR in this paper. CS-FFR divides the available bandwidth into several sub-bands and allocates multiple sub-bands to different cells. In this paper, focusing on the optimization of the CS-FFR, we find by computer simulation the optimum bandwidth division number and the sub-band allocation ratio to maximize the link capacity. We also discuss the convergence speed of CS-FFR in a cellular ultra-dense RAN.

Estimation of Permissible Angular Separation of Devices for the Beamforming Scenario in Ultra-Dense Millimeter-Wave Radio Access Networks

This study is devoted to estimating the allowable angular separation between devices operating in ultra-dense radio access networks in the millimeter frequency range, for the subsequent formation of a three-dimensional radiation pattern with optimal characteristics by the base station antenna array. The content of this work can be divided into two parts. In the first part of this work, a mathematical formalization of the number of radio emission sources estimation and their angular coordinates is given. Based on the presented mathematical model and the developed simulation program, in the second part of the work, the study and determination of the accuracy characteristics of the angular separation of devices depending on interference in the scenario of diagram formation of ultra-dense radio access networks when devices use the combined azimuth and elevation measurement algorithm are carried out.

5G Wireless Technology

Abstract: After the up rise of 4G wireless mobile technology takes place; researchers, mobile operator industries representative, academic institutions have started to look into the advancement (technological) towards 5G communication networks due to some main demands that are meliorated data rates, better capacity, minimized latency and better QoS (Quality of Service). To established the 5G mobile communication technological foundation, various research works or projects entailing main mobile infrastructure manufacturers, academia and international mobile network operators have been introduced recently. Nevertheless, 5G mobile services to be made available for use, their architecture, and their performance have not been evidently explicated. In this paper, we represent thorough overview of 5G the next generation mobile technology. We mainly throws light on 5G network architecture, 5G radio spectrum, ultra-dense radio access networks (UDRAN), traffic offloading of mobile, cognitive radio (CR), software defined radio (SDR), software defined networking (SDN), mixed infrastructure, and 5G network impact on the society. Keywords: 5G wireless technology, evolution from 4G to 5G

A graph coloring-based interference coordination algorithm for cluster-wise ultra-dense RAN

Ultra-dense radio access network (RAN) with distributed multi-user multi-input multi-output (MU-MIMO) is considered as a promising approach to improve the coverage and link capacity. However, its prohibitively high computational complexity impacts its further extension and application. Our previous work has proved that forming users/antennas clusters can greatly alleviate the computational complexity, but the inter-cluster interference is produced, thereby reducing the spectrum efficiency. In this paper, we propose a graph coloring algorithm-based inter-cluster interference coordination for ultra-dense RAN with distributed MU-MIMO. It is confirmed by computer simulation that our proposed algorithm can improve both the sum capacity and the user capacity compared with no coloring case.

МОДЕЛИРОВАНИЕ СВЕРХПЛОТНЫХ СЕТЕЙ РАДИОДОСТУПА 5G С ДИАГРАММООБРАЗОВАНИЕМ

In this paper, we investigate the connectivity and probability of successful radio reception in the Poisson model of a 5G ultra-dense radio access network formed by devices with the possibility of location aware beamforming. The difference be-tween the proposed model and the existing prototypes is the complex account for the gains of devices, as well as the influence of radio wave propagation losses, slow and fast fading in the radio channel on the performance of the radio access network. The study is carried out for sessions of directional and omni-directional radio communication, and the beamforming mode is based on the preliminary positioning of neighboring devices. Mathematical modeling of a set of simultaneously operating radio lines in the Poisson model of an ultra-dense 5G radio access network makes it possible to estimate the gain in connectivity and the probability of successful radio reception when forming a beam based on preliminary positioning of devices in comparison with the case of omnidirectional antennas. The results of mathematical modeling of a ultra-dense radio access network with devices equipped with six-element circular antenna arrays showed a significant increase in connectivity indicators and the probability of successful radio reception in comparison with the case of omnidirectional antennas and confirmed the possibility of spatial multiplexing of simultaneous transmissions with a territorial separation of devices on 20% of the range of radio coverage based on the signal-to-noise ratio criterion. The result of the study is the establishment of the dependences of the connectivity and the probability of successful radio reception for an ultra-dense 5G radio access network, built on the basis of devices operating in the adaptive diagramming mode, as well as confirmation of the possibilities of spatial multiplexing of simultaneously operating transceiver devices with their territorial separation by 20% of the range of radio coverage based on the signal-to-interference ratio criterion. The obtained dependences of connectivity and the probability of successful radio reception allows to scientifically substantiate construction of an initial approximation of ultra-dense 5G radio access network from devices with the possibility of beamforming based on positioning, taking into account practical recommendations for their territorial diversity with an ultra-dense distribution.

Decentralized Precoding for Cache-Enabled Ultra-Dense Radio Access Networks

This letter studies the fully decentralized optimization of the precoding matrices for the downlink of multiple-input-multiple-output cache-enabled ultra-dense radio access network. To avoid signalling exchange between coordinated edge radio access nodes (RANs), we first construct a virtual downlink cache-enabled ultra-dense radio access network. Following, a new concept of signal-to-interference-leakage-plus-noise ratio is defined. Based on this concept, a virtual weighted sum rate maximization problem is formulated to optimize the precoders. We then propose a computationally efficient decentralized optimization algorithm that achieves stationary point to the problem. Numerical results show that the proposed algorithm can achieve more than 96.15% of the performance of the centralized optimization without any signalling exchange between coordinated edge RANs for multiple-input single-output cases.