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Radio Access Network (RAN) virtualization stands as a pivotal concept in the realm of 5G networks and beyond. It emerges as a viable solution not only to address energy cost concerns but also to optimize material and radio resource management. Despite numerous deployment trials worldwide, a comprehensive realization of Virtual RAN (V-RAN) remains elusive. Current platforms tackle various aspects of V-RAN but encounter numerous limitations. In this paper, we conduct a survey on the progress of RAN virtualization to date and discuss the persisting barriers to its full realization in future mobile radio networks. Initially, we revisit the fundamentals of virtualization and its evolution over recent decades, elucidating the distinctions between Cloud RAN (C-RAN), V-RAN, and Open RAN concepts. Subsequently, we offer an in-depth tutorial on the implementation procedures of V-RAN as per different vendors. Lastly, we shed light on persisting issues within vendor platforms and demonstrate, via simulations, the constraints on their performance concerning supported Base Band Units (BBUs) and devices, as well as coordination among various entities.

In this paper, we present a hardware implementation and an evaluation of the effectiveness and feasibility of a smart jamming attack that targets specific uplink physical channels to destabilize 5G communication systems. Using software defined radio (SDR), we examine the susceptibility of the 5G Physical Uplink Shared Channel (PUSCH) to a smart jamming attack as well as the impact of such an attack on user equipment (UE) throughput. The smart jamming attack is designed to exploit the radio access procedure by: 1) identifying the user’s cell radio network temporary identifier (C-RNTI); 2) decoding the physical downlink control channel (PDCCH) information containing the specific UE resources; and 3) generating a quadrature phase shift keying (QPSK) modulated Orthogonal Frequency-Division Multiplexing (OFDM) waveform to effectively deny uplink access. A detailed description of the implementation of the overall testbed used to evaluate and quantify the effectiveness of the custom implementation of a smart jamming attack is presented in this paper. The evaluation results show that the smart jamming attack successfully denied uplink access by reducing the throughput of a specific UE by 100%.

The 3rd Generation Partnership Project (3GPP) is investing a notable effort to mitigate the endogenous stack and protocol delays (e.g., introducing new numerology, through preemptive scheduling or providing uplink granted free transmission) to attain to the heterogeneous Quality of Service (QoS) latency requirements for which the fifth generation technology standard for broadband cellular networks (5G) is envisioned. However, 3GPP’s goals may become futile if exogenous delays generated by the transport layer (e.g., bufferbloat) and the Radio Link Control (RLC) sublayer segmentation/reassembly procedure are not targeted. On the one hand, the bufferbloat specifically occurs at the Radio Access Network (RAN) since the data path bottleneck is located at the radio link, and contemporary RANs are deployed with large buffers to avoid squandering scarce wireless resources. On the other hand, a Resource Block (RB) scheduling that dismisses 5G’s packet-switched network nature, unnecessarily triggers the segmentation procedure at sender’s RLC sublayer, which adds extra delay as receiver’s RLC sublayer cannot forward the packets to higher sublayers until they are reassembled. Consequently, the exogenously generated queuing delays can surpass 5G’s stack and protocol endogenous delays, neutralizing 3GPP’s attempt to reduce the latency. We address RLC’s related buffer delays and present two solutions: (i) we enhance the 3GPP standard and propose a bufferbloat avoidance algorithm, and (ii) we propose a RB scheduler for circumventing the added sojourn time caused by the packet segmentation/reassembly procedure. Both solutions are implemented and extensively evaluated along with other state-of-the-art proposals in a testbed to verify their suitability and effectiveness under realistic conditions of use (i.e., by considering Modulation and Coding Scheme (MCS) variations, slices, different traffic patterns and off-the-shelf equipment). The results reveal current 3GPP deficits in its QoS model to address the bufferbloat and the contribution of the segmentation/reassembly procedure to the total delay.