d with LTE. The transport network has to be prepared in advance. In the absence of a traffic profile (traffic volume and mix of services), the transport capacity need for a single (first mile) access link is estimated from the air interface capac- ity and from the requirement to support the single user peak rate. The single user peak rate is important, as it is easily observable for the user. With 5G, that rate is high, and some access links easily become bottlenecks for that service even for a single user, mean- ing that the maximum bit rate is not available through these sites unless access link capacity is first expanded. At hub sites, traffic flows from multiple cell sites are collected, and statistical multi- plexing is exploited to reduce capacity on the uplinks. 9.2.2 Access Link For the single access link, a common way to establish the transport capacity based on air interface capacity is shown in Figure 9.3. The benefit of this approach is that the estimate can be done without any traffic mix assumption and that the access link then reflects the air interface capacity. The difficulty is that it is not in any direct way tied to real traffic demand and also that the air interface in practical networks is seldom in ideal conditions. In Figure 9.3, for each gNB sector, a peak bit rate and an average bit rate is given. In addition, the single user peak rate is shown. Often the transport network is at minimum Air interface bit rates Transport bit rates Single Single Peak Single Peak All Peak User Peak Average r All Average All-But-One Average Figure 9.3 Dimensioning: example gNB configuration with three sectors. 9.2 Capacity and Latency required to support the maximum single user peak rate that the system and terminals offer. The single user peak rate then depends on terminal capabilities, and those may increase significantly over time. To arrive at a transport capacity, protocol overhead (OH) is added, which is logical interface and traffic mix dependent. All-average refers to a case where all sectors of the 