 200 MHz 320 Gbit/s (CPRI) 320 Gbit/s (CPRI) 640 Gbit/s (CPRI) 1280 Gbit/s (CPRI) 8-20 Gbit/s 16-40 Gbit/s 32-80 Gbit/s 64-160 Gbit/s 800 MHz 640 Gbit/s (CPRI) 1280 Gbit/s (CPRI) 2560 Gbit/s (CPRI) 5120 Gbit/s (CPRI) Figure 9.5 Low layer split point capacities. Even with this, the RU capacity can be very high if the air interface bandwidth is large and there are many streams. The remote antenna (RU) needs n X 10G/25G Ethernet ports to connect to the network. For a site with multiple RUs, the capacities need to be supplied for each RU. While CPRI and OBSAI use a constant bit stream continuously between the antenna and the baseband, the O-RAN specification is frame/packet based. What is common is that radio L2/L1 scheduling takes place in the baseband over the low layer split point interface, and all scheduled transmissions should be received in time by the RU, calling for quite deterministic behavior on the transport link. 9.2.6 Latency One key 5G objective is reducing the e2e latency of user communication. Transport con- tributes significantly to this, since for long distances, propagation delay alone becomes a major factor. Wireless transmission as a media has an inherent advantage here over fiber/copper, since the signal propagation delay is smaller in the air (3.3 VS. 5 us/km) In addition to the e2e latency, any transport link on a 3GPP logical interface has to also meet the system requirement: how long a delay can be tolerated with the 5G sys- tem interface still remaining operational. Both the e2e latency and the system operation aspect are relevant, and which one becomes more stringent is interface dependent. The e2e latency targets for 5G are documented, for example, in 3GPP TR38.913, "Study on Scenarios and Requirements for Next Generation Access Technologies" [5], and in "NGMN 5G Extreme Requirements: End-to-End Considerations" [6]). The performance chapter (Chapter 10) includes further analysis. 3GPP documents 8 ms (with only the radio stack considered), while 10 ms is assumed for the radio access netwo