S link. In this case, the PHB can be decided either from the MPLS label, by a combination of the MPLS label and the EXP field or from a combination of the MPLS label and some link layer encapsulation. This is called L-LSP. 102 Open Radio Access Network (O-RAN) Systems Architecture and Design References 1. Diffserv to QCI Mapping, https://tools.ietf.org/id/draft-henry-tsvwg-diffserv-to-qci-03.html,2020. 2. Telecom Infra Project, Learnings from virtualized RAN technology trials over non-ideal fronthaul, 2019. 3. Zynq UltraScale + RFSoC, https://www.xilinx.com/products/silicon-devices/soc/rfsoc.html 4. Layerscape Access LA1200 Programmable Baseband Processor.https://www.nxp.com/products/proces sors-and-microcontrollers/arm-processors/layerscape-multicore-processors/layerscape-access-la1200-pro- grammable-baseband-processor:LA1200. 5. Crest Factor Reduction (CFR) Concept, https://rfmw.em.keysight.com//wireless/helpfiles/n7614/Content Main/Crest_Factor_Reduction_Concept.htm. 6. Crest Factor Reduction, https://zone.ni.com/reference/en-XX/help/374264L-01/rfmxspecan/crest_factor_- reduction/. eCPRI Specification v2.0, "Common Public Radio Interface: eCPRI Interface Specification," May 2 2019. 8. Ingress Protection Code, https://en.wikipedia.org/wiki/IP_Code. Hardware system dimensioning This chapter discusses dimensioning aspects. Dimensioning is tightly coupled with require- ments and often an iterative analysis between dimensioning and peak/average requirements is needed to come up with a system that is both cost and power efficient as well as high (enough) performance. Key topics that are relevant include Use-case dimensioning for throughput, user count, and latency topics including oversubscription Derive eCPRI bandwidth for dimensioning of fronthaul interfaces Mid/backhaul dimensioning Hybrid Automatic Repeat ReQuest (HARQ) context store and restore bandwidth and sizing Double Data Rate (DDR) memory size and bandwidth dimensioning Radio unit (RU) analog transmit and receive chain dimensioning System dimensioning inv