We study optimal delivery strategies of one common and K independent messages from a source to multiple users in wireless environments. In particular, two-layered superposition of broadcast/multicast ...and unicast signals is considered in a downlink multiuser OFDMA system. In the literature and industry, the two-layer superposition is often considered as a pragmatic approach to make a compromise between the simple but suboptimal orthogonal multiplexing (OM) and the optimal but complex fully-layered non-orthogonal multiplexing. In this work, we show that only two-layers are necessary to achieve the maximum sum-rate when the common message has higher priority than the K individual unicast messages, and OM cannot be sum-rate optimal in general. We develop an algorithm that finds the optimal power allocation over the two-layers and across the OFDMA radio resources in static channels and a class of fading channels. Two main use-cases are considered: i) Multicast and unicast multiplexing when K users with uplink capabilities request both common and independent messages, and ii) broadcast and unicast multiplexin when the common message targets receive-only devices and K users with uplink capabilities additionally request independent messages. Finally, we develop a transceiver design for broadcast/multicast and unicast superposition transmission based on LTE-A-Pro physical layer and show with numerical evaluations in mobile environments with multipath propagation that the capacity improvements can be translated into significant practical performance gains compared to the orthogonal schemes in the 3GPP specifications. The impact of real channel estimation is also analyzed and it is shown that significant gains in terms of spectral efficiency or increased coverage area are still available even in the presence of estimation errors and imperfect interference cancellation for the two-layered superposition system.
Ensuring a reliable and stable communication throughout the mobility of User Equipment (UE) is one of the key challenges facing the practical implementation of the Fifth Generation (5G) networks and ...beyond. One of the main issues is the use of suboptimal Handover Control Parameters (HCPs) settings, which are configured manually or generated automatically by certain self-optimization functions. This issue becomes more critical with the massive deployment of small base stations and connected mobile users. This will essentially require an individual handover self-optimization technique for each user individually instead of a unified and centrally configured setting for all users in the cell. In this paper, an Individualistic Dynamic Handover Parameter Optimization algorithm based on an Automatic Weight Function (IDHPO-AWF) is proposed for 5G networks. This algorithm dynamically estimates the HCPs settings for each individual UE based on UE's experiences. The algorithm mainly depends on three bounded functions and their Automatic Weights levels. First, the bounded functions are evaluated, independently, as a function of the UE's Signal-to-Interference-plus-Noise-Ratio (SINR), cells' load and UE's speed. Next, the outputs of the three bounded functions are used as inputs in a new proposed Automatic Weight Function (AWF) to estimate the weight of each output bounded function. After that, the final output is used as an indicator for optimizing HCPs settings automatically for a specific user. The algorithm is validated throughout various mobility conditions in the 5G network. The performance of the analytical HCPs estimation method is investigated and compared with other handover algorithms from the literature. The evaluation comparisons are performed in terms of Reference Signal Received Power (RSRP), Handover Probability (HOP), Handover Ping-Pong Probability (HPPP), and Radio Link Failure (RLF). The simulation results show that the proposed algorithm provides noticeable enhancements for various mobile speed scenarios as compared to the existing Handover Parameter Self-Optimization (HPSO) algorithms.
Rapid development in mobile phone technologies increase the average mobile phone usage duration. This increase also triggers exposure to radiofrequency radiation (RF), which is a risk factor for the ...health. In this study, it was aimed to investigate the effect of mobile phone working with LTE-Advanced Pro (4.5 G) mobile network on the optic nerve, which is responsible for the transmission of visual information.
Thirty-two rats divided into two groups as control (no RF, sham exposure) and experimental (RF exposure using a mobile phone with LTE-Advanced Pro network; 2 hours/day, 6 weeks). The visual evoked potential (VEP) was recorded and determined amplitudes and latencies of VEP waves. Optic nerve malondialdehyde level, catalase and superoxide dismutase activities were determined. Furthermore, ultrastructural and morphometric changes of optic nerve were evaluated.
In VEP recordings, the mean VEP amplitudes of experimental group were significantly lower than control group. In ultrastructural evaluation, myelinated nerve fibres and glial cells were observed in normal histologic appearance both in sham and experimental group. However, by performing morphometric analysis, in the experimental group, axonal diameter and myelin thickness were shown to be lower and the G-ratio was higher than in the sham group. In the experimental group, malondialdehyde level was significantly higher and superoxide dismutase and catalase activities were significantly lower than sham group. There was a high correlation between VEP wave amplitudes and oxidative stress markers.
Findings obtained in this study support optic nerve damage. These results point out an important risk that may decrease the quality of life.
In orthogonal frequency division multiple access networks buffer aided non-transparent in-band half duplex decode and forward relay nodes aim to improve coverage and capacity under fairness ...considerations. Existing centralized radio resource management and inter cell interference coordination schemes achieve these goals at the cost of heavy signalling overhead. Especially for frequency division duplex downlink transmission this is an critical issue. Fully decentralized schemes often focus on different types of frequency reuse schemes with less amount of necessary feedback. Here, it is often overseen that in a practical deployment, the backhaul link quality is the bottleneck of the two hop transmission and needs to be taken into account. Moreover, it is often modelled way too optimistic and necessary co-scheduling with single hop UE further limits the possible data rate. In order to minimize the required overhead this work proposes a hybrid radio resource management (RRM) scheme. The RRM includes synchronous adapted two-hop proportional frequency selective resource scheduling as the decentralized part. Asynchronous subband power allocation scheme with very limited feedback is proposed to maximize the wireless backhaul link quality with no loss for single hop UE. Comprehensive system level simulation results show stable fairness and throughput when minimizing the required feedback and improvements for the backhaul links based on the centralized adapted power allocation including no losses in the overall system. In addition possible energy savings for the shared channel are presented when applying the proposed scheme.
In this paper, a dynamic-mobility robustness optimization (D-MRO) technique has been developed to dynamically estimate handover control parameters (HCPs) settings for each user individually. This ...technique is operating based on the weight function (WF), which operates as a function of user equipment's (UE's) signal to-interference-plus-noise-ratio (SINR), cells' load, and UE's mobility speed. To validate the compatibility of the proposed technique over various mobility conditions in the fifth generation (5G) network, the performance of the analytical HCPs estimation technique is compared with other mobility robustness optimization (MRO) techniques from the literature based on a simulation study. The simulation is executed by utilizing MATLAB software, and results are analyzed in terms of handover probability (HOP), handover ping-pong probability (HPPP), and radio link failure (RLF). Simulation results show that the proposed optimization technique contributes significantly in addressing the problem of the existing MRO solutions at various mobile speed scenarios and the presented method outperforms the nominated performances.
Localization based on wireless signals has been introduced using a positioning method that relies on satellite navigation positioning systems, such as the Global Positioning System (GPS). The main ...issue with a passive localization system, such as this, is that although we would only gather anonymous information, we still need the user's approval. In this paper, a fingerprint-based localization approach based on Long-Term Evolution (LTE) Advanced Pro Signal is proposed. The authors analyzed received signal strength indication (RSSI) related to the communication between the base station and the user equipment (UE). Using a machine learning approach (i.e., a generative adversarial network - GAN), the proposed system allows understanding the correlation between RSSI and the position of the user in the space. The state of art related to fingerprinting-based localization has been drawn up as a costly and time-consuming offline training phase. The GAN will generate new models (RSSI, localization), and the experimental results show improvement in accuracy when compared with the effort to perform the offline phase. The results indicate great accuracy, 0.4 meters and 10 meters, respectively indoor, and outdoor environments case and the measurement campaign was fast and time saver.
This paper provides the mobility and coverage evaluation of New Radio (NR) Physical Downlink Control Channel (PDCCH) for Point-to-Multipoint (PTM) use cases, e.g., eMBMS (evolved Multimedia Broadcast ...Multicast Services). The evaluation methodology is based on analyses and link level simulations where the channel model includes AWGN, TDL-A, TDL-C as well as a modified 0dB echo to model different PTM scenarios. The final version of this work aims to provide insightful guidelines on the delay/echo tolerance of the NR PDCCH in terms of mobility and coverage. In this paper, it is observed that under eMBMS scenario, i.e. SFN channel, due to the time domain granularity of pilots distributed inside the PDCCH region, the system can support very high user movement speed/Doppler with an relatively low requirement on the transmit Signal/Carrier-to-Noise Ratio (SNR/CNR). On the other hand however, the system falls short on its coverage due to the low frequency domain granularity of pilots that effects the channel estimation accuracy.
With the success of 4th generation of mobile communication, known as LTE, there is an increasing demand for additional spectrum to be made available to mobile network operator worldwide. However, ...spectrum is a finite resource and local regulators have only a limited - if at all - amount of frequencies available that could be auctioned off to service providers. Therefore, the industry is exploring unlicensed spectrum and sparsely occupied spectrum by geography, which demands fair sharing and coexistence with existing technologies using those frequencies. Further, new ideas like spectrum sharing models are investigated by the industry under guidance of local regulators who adopted this innovative concept.
The first release of standards for 5 th generation (5G) mobile communication has been approved in the 3 rd Generation Partnership Project (3GPP). During the 5G standardization, performance of ...Transmission Control Protocol (TCP) in the 5G mobile networks was studied. It has been observed that the TCP performance is improved when protocols in the Radio Access Network (RAN) take the TCP behavior into consideration. The authors have been studying TCP ACK filtering that can work well with the link layer protocols in RAN, where the TCP ACKs can be intentionally discarded. It has been shown that proposed methods accomplish good TCP throughput while the number of TCP ACKs is largely reduced. In this paper, the authors tackle a remaining issue: finding the suitable value of "discard ratio". It is proposed that the suitable value is obtained based on the average number of TCP ACKs transmitted in one transmission time interval. Simulation results demonstrate that the suitable value for the TCP ACK filtering can further improve the TCP performance when the number of mobile stations is small. In addition, it improves both throughput and fairness of the TCP when the number of mobile stations becomes large.
With the unceasing increase of the mobile data traffic, network operators are forced to improve the performance of their networks. The traffic explosion is intensified by the recent deployment of ...Long Term Evolution (LTE) networks. However, operators cannot opt for deploying more cells, as this will increase their financial investments. Operators are seeking for mobile technologies with higher spectral efficiency in bit/s/Hz, cloud-based intelligent architecture, etc. The operators' requirements are under investigation by 3rd Generation Partnership Project (3GPP) to develop the next mobile generation (5G), which should match the technical requirements and economic feasibility. The road to 5G is still not clear. Therefore, telecom players marked a next step towards 5G by issuing new standard version "Release 13", referred by experts as LTE-Advanced Pro or `4.5G'. In this paper, we discuss the main characteristics of this new release and the planned roadmap to reach the final target of 5G.
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