Open Radio Access Network (O-RAN) architectures are driving a shift towards modular, software-defined RANs, where virtualization is key for flexible component development. OpenAirInterface (OAI) provide software-based RAN functionalities, complemented by Near-Real-Time RAN Intelligent Controllers (Near-RT RICs) like FlexRIC. However, the performance of these virtualized environments is fundamentally limited by the underlying compute infrastructure. This study establishes a crucial performance baseline by isolating the impact of raw computational constraints within a virtualized O-RAN testbed composed of OAI simulators and the FlexRIC controller. To achieve this, our setup deliberately excludes radio virtualization middleware, ensuring all signal processing and channel emulation to be offloaded to the CPU. We assess the impact of these constraints on the end-user’s Quality of Experience (QoE) by streaming video and audio files to a client within the simulated UE’s network namespace. Our findings reveal that video quality degrades significantly, as reflected in low VMAF, while audio quality holds steady under the same constraints.

This paper presents an analytical analysis of a spread spectrum underlay channel designed to coexist with the 5G New Radio (NR) Orthogonal Frequency Division Multiplexing (OFDM) waveform. This coexistence is intended for scenarios where this underlay channel is utilized by either a 5G base station or users. This analytical investigation plays a crucial role in designing the underlay-5G OFDM waveform and facilitates decisions related to the relative average symbol energy levels of the 5G channels, i.e., Physical Downlink Shared Channel (PDSCH) and underlay, the choice of modulation schemes, and spreading factors based on the target reliability of the channels and the signal-to-noise ratio (SNR) at the receiver. We derive and present the bit error rate (BER) expressions for the PDSCH and the underlay channels. Monte Carlo simulation results show that the proposed BER expressions are highly accurate. The expression for the BER of the PDSCH is generalized for M-QAM modulation schemes, and the BER of the underlay with BPSK/QPSK is presented. Our findings provide insight into the appropriate parameterization of underlay symbol energy level and spreading factors to avoid degradation to the PDSCH channel as a function of the PDSCH modulation scheme and the received SNR.

The advent of 5G positioning techniques by 3GPP has unlocked possibilities for applications in public safety, vehicular systems, and location-based services. However, these applications demand accurate and reliable positioning performance, which has led to the proposal of newer positioning techniques. To further advance the research on these techniques, in this paper, we develop a 3GPP-compliant 5G positioning testbed, incorporating gNodeBs (gNBs) and User Equipment (UE). The testbed uses New Radio (NR) Positioning Reference Signals (PRS) transmitted by the gNB to generate Time of Arrival (TOA) estimates at the UE. We mathematically model the inter-gNB and UE-gNB time offsets affecting the TOA estimates and examine their impact on positioning performance. Additionally, we propose a calibration method for estimating these time offsets. Furthermore, we investigate the environmental impact on the TOA estimates. Our findings are based on our mathematical model and supported by experimental results.

With the emergence of autonomous vehicles and intelligent transportation systems, vehicular communications will play a significant role in innovating, optimizing and realizing the next generation transportation systems. However, with the rise in these intelligent transport systems, it will be necessary to have flexible, efficient, scalable, and cost-effective vehicular infrastructure in place to support these transportation systems. This work studies the existing 5G NR architectures and radio capabilities, and alternative evolved 5G architectures which can be expanded to V2X communications. A novel V2X architecture with unique characteristics and advanced capabilities is proposed. A Python-based simulator is designed, which models vehicular mobility and signaling and data traffic. All the candidate V2X architectures are studied and evaluated using the simulator. These candidate architectures are evaluated using a variety of relevant metrics including the backhaul bandwidth utilization, IP packet latency, Physical Resource Block (PRB) Utilization efficiency, end-to-end packet transmission ratio. The simulation results clearly demonstrate that the proposed novel V2X architecture provides superior performance compared to other candidate architectures and provides additional benefits of flexibility, scalability, ease of deployment on a massive scale, power efficiency, and low cost.

For emergency response scenarios like firefighting in urban environments, there is a need to both localize emergency responders inside the building and also support a high bandwidth communication link between the responders and a command-and-control center. The emergency networks for such scenarios can be established with the quick deployment of Unmanned Aerial Vehicles (UAVs). Further, the 3D mobility of UAVs can be leveraged to improve the quality of the wireless link by maneuvering them into advantageous locations. This has motivated recent propagation measurement campaigns to study low-altitude air-to-ground channels in both 5G-sub6 GHz and 5G-mmWave bands. In this paper, we develop a model for the link in a UAV-assisted emergency location and/or communication system. Specifically, given the importance of Line-of-Sight (LoS) links in localization as well as mmWave communication, we derive a closed-form expression for the LoS probability. This probability is parameterized by the UAV base station location, the size of the building, and the size of the window that offers the best propagation path. An expression for coverage probability is also derived. The LoS probability and coverage probabilities derived in this paper can be used to analyze the outdoor UAV-to-indoor propagation environment to determine optimal UAV positioning and the number of UAVs needed to achieve the desired performance of the emergency network.

The expected growth of wireless data subscribers has fueled the development of third generation cellular systems such as IS-2000 and UMTS. The performance of a data system cannot be quantified accurately without considering the characteristics of data traffic. This paper presents a common framework of data traffic models and evaluates the performance of an IS-2000 system for different types of services. The types of services embraced in the paper include telnet, WWW, ftp, email, and fax. A comprehensive simulator suitable for evaluation of the radio interface performance of a CDMA data system is outlined. Performance metrics for a data system are summarized. The simulation results show that the system performance varies widely as a function of the types of services because each service has different packet characteristics.

Conventional handoff algorithms are susceptible to varying propagation environments, traffic intensities, and user speeds due to the lack of parameter adaptation. This paper proposes a new class of adaptive handoff algorithms that views the handoff problem as a pattern classification problem. Adaptive direction biasing is proposed to reduce the processing load and improve the cell membership properties. The paper shows that the desired balance among the system characteristics can be achieved by making appropriate design tradeoffs in a pattern classification based handoff framework.