nts and categorize them into four unique categories, A+, A, B, and C, as sum- marized in Table 10-16. Note that although some values are not specified to fall into a particular category, they can still have a timing requirement and are identified as "Not specified in 3GPP." Table 10-16 Timing Accuracy Categories 3GPP Defined 5G NR Feature MIMO or Tx diversity transmission Category A+ Category A+ Intra-band contiguous Carrier Aggregation BS Type 1: Category B Category A BS Type 2: Category A Intra-band noncontiguous Carrier Aggregation Category B Category C Inter-band Carrier Aggregation Category B Category C Category C Category C Dual Connectivity Category C Category C Not specified in 3GPP Not ready in 3GPP Supplementary uplink Not applicable for LTE Not ready in 3GPP In-band spectrum sharing Not ready in 3GPP Not ready in 3GPP Positioning Not specified in 3GPP Not ready in 3GPP MBSFN Not specified in 3GPP Not ready in 3GPP These requirements, as illustrated in Figure 10-31, are further presented as relative and absolute time error (TE) between the various components of the architecture. The absolute TE is defined against a commonly agreed reference time (UTC) traceable to a PRTC-the previously mentioned +1.1 us at the interface to the radio. Alternatively, relative TE is the absolute value of the maximum allowable TE between any two RU devices. Figure 10-31 is used in the following discussion to explain the timing requirements outlined in Table 10-17. EeRE/RE Case 1.1-20 ns T-TSC class B 60 ns |TE| relative at UNI Case 1.2-20 ns T-TSC class C |TE| relative 15 ns at UNI Case 2 30 ns Case 1 20 ns |TE| absolute = +1.1 us |TAE| = 260 ns (category B) or 130 ns (category A) Figure 10-31 Time Accuracy Definition The user-network interface (UNI) represents the handoff point between the transport network and the radio device (the last interface before it connects to the radio). The term TERE (from eCPRI) represents the maximum absolute TE in the radio equipment (RU)-see Figure 10-31. Finally, the TAE represents the maxi