Enabling the transport of fronthaul traffic in next generation cellular networks (5G) following the Cloud Radio Access Network (C-RAN) architecture requires re-designing the fronthaul network featuring high-capacity and ultra-low latency. With the aim of leveraging statistical multiplexing gains, infrastructure reuse and, ultimately, cost reduction, the research community are focusing on Ethernet-based packet-switch networks. To this end, we propose to use high queueing delay percentiles of G/G/1 queueing model as the key metric in fronthaul network dimensioning. Simulations reveal that that the Kingman's Exponential Law of Congestion provides accurate estimates on such delays for the particular case of aggregating a number of eCPRI fronthaul flows, namely functional splits IU and IID. We conclude that conventional 10G, 40G and 100G transponders can cope with multiple legacy 10-20 MHz radio channels with worstcase delay guarantees. Conversely, scaling to 40 and 100 MHz channels will require the introduction of 200G, 400G and even 1T high-speed transponders.

Packet-switched fronthaul networks are often designed following the rule that the worst-case network delay must be below a given target end-to-end network latency budget. However, the theoretical maximum delay can be too pessimistic in particular scenarios, where the latency budget needs to be a very small or there is a need to stretch the distance between the radio heads and the baseband units. In this paper, we propose to use a very high packet delay percentiles as an alternative to the maximum theoretical delay in order to stretch the range of the fronthaul links at the expense of a higher frame loss ratio (FLR), within the limits established by eCPRI and the IEEE 802.1 CM. Several methods to estimate the percentiles for the I U / II D eCPRI functional splits are analyzed. Namely, G/G/1 and N*D/D/1 queueing models are tested and compared with simulation as dimensioning tools. The results support that the N*D/D/1 queue is able to model the behavior of a packet-switch fronthaul aggregator using the eCPRI standard for 5g New Radio (NR) Fronthaul streams and can be used as a tool to dimension the length of the links. The experiments show that the fronthaul links' lengths can be increased by 60% and 10% for 50-and 100-MHz NR channels, respectively, while keeping the latency budget and frame loss ratio within the IEEE 802.1 CM limits.INDEX TERMS 5G, C-RAN, delay percentiles, eCPRI, fronthaul networks, G/G/1, IEEE 802.1CM, N*D/D/1, new radio (NR), time-sensitive networking (TSN).

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In order to meet the requirements of services and applications envisioned for post-5G and 6G networks, research efforts are heading towards the convergence of architectures aiming to support the wide variety of new compute-demanding and latency-sensitive applications in the context of Tactile Internet. In this paper, we study the resource allocation and association of users with different delay requirements in a shared-backhaul fiber-wireless (FiWi) enhanced Heterogeneous Cloud Radio Access Network (H-CRAN) with Multi-access Edge Computing (MEC) and offloading. As opposed to traditional resource and association management, we propose a decentralized algorithm based on a full dual decomposition of the optimization problem to operate the network. Results show that this approach outperforms the traditional one in terms of average delay and energy consumption, achieving up to 80% average delay improvement in high-load scenarios.

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