A Converged Evolved Ethernet Fronthaul for the 5G Era

Abstract

We assess the performance of two distinct functional splits based on latency/latency variation and mapping efficiency, both individually and in unison. By considering hardwareoffloading possibilities for a low-layer split (especially a preresource mapper split) using an option-6 software-based local thermal equilibrium split as an example, we show how data rate, Ethernet frame size and, in general, traffic generation characteristics will be very important aspects in the design of the future Ethernet mapping function. Then, an integrated Ethernet fronthaul with legacy and new/evolved split functionality operating at 100 Gb/s link rate is presented with the state-of-the art sub-100-ns latency variation for a timing-protocol flow. This is achieved through the application of a gap-filling aggregator, used for the first time in such a mobile fronthaul application.Index Terms-Mobile fronthaul, Ethernet fronthaul, cloudradio access network (C-RAN), time-sensitive networking.

D-RoF and A-RoF Interfaces in an All-Optical Fronthaul of 5G Mobile Systems

“…where S-the number of sectors per gNB-DU/RRH/AAU, A-the number of antenna modules in array per one sector, f s -speed of sampling (in CPRI for 20 MHz radio baseband channel is equal to 30.72 MS/s (3.84 · (20/5) · 2), in wider BB radio channel is proportionally higher [8,9]), b s -number of bits per sample (depending on the format of the sampled signal: is equal 15 per one I/Q subcarrier for 4G/5G-Rel-15 (cyclic prefix orthogonal frequency division multiplexing (CP-OFDM))), IQ-a factor indicating a separate sub-sampling I as in-phase and Q as quadrature (is equal 2), HF (Headers Factor)-a factor indicating the redundancy of CPRI headers (redundancy is 1/15, therefore, amounts to 16/15), LC-alphabet nB/mB line code (8B/10B-ratio of 10/8-used in CPRI Options 1-7, 64B/66B-ratio of 66/64-used in CPRI Options 7A-10).…”

“…The division presented in Figure 7 indicates the places where the separation of the network elements functions can be made, which is also an important determinant of the directions of evolution and the emergence of NG-RAN Split/Option standards at the F1 and F2 interfaces [1,32,46]. The rate consumption calculations that will occur at the Split D during the maximum load, according to the CPRI Forum [9], can be carried out on the basis of a simplified and adapted formula [2,48]…”

“…A lot of research and development have been devoted to various optimization solutions for transportation systems of streams from D-RoF interfaces. The author reviewed the available studies [6][7][8][9][10][11][12][13], which contained the results of studies showing the undoubted legitimacy of using the D-RoF technique. In these studies, particular emphasis was put on showing that a particular type of Split/Option or method of digitizing a radio signal to a bit form gives the opportunity to increase a link efficiency.…”

Comparison of digital signal processing approaches for subcarrier multiplexed 5G and beyond analog fronthaul

“…The remaining RAN protocol stack processing is split between the DU and a Radio Unit (RU). 3GPP has not reached a consensus on the split point in RAN functions between the DU and RU, but possible options within the baseband Physical (PHY) layer have been proposed [4][5][6][7][8][9][10]. The fronthaul is the transport network for this F2 interface between the functionally decomposed DU and RU.…”

Testbed Verification of New Fronthaul Technology for 5G Systems

“…The use of an IP/Ethernet-based fronthaul should much more easily enable the use of software-defined networking (SDN) techniques already being developed for transport networks [13]. Then, for orchestration and control of the virtualized RAN and fronthaul, performance monitoring is required [14]. Measurements should be sent to the orchestration/control function to ensure slice service requirements are met.…”