 specifies a range for the allowed subcarriers, and communicates both the delay and the permissible range via the SIB to the NB-IoT UE. The UE can choose from 12 subcar- riers. If the UE uses a specific range within the designated subcarriers, this would signal to the base station that the UE supports multi-tone transmission format. Internet of Things 771 The NPRACH resources are separately provided for each coverage enhancement group. They consist of the assignment of time and frequency resources and occur periodically, where an NPRACH periodicity between 40 ms and 2.56 seconds may be configured. Their start time within a period is provided in the system information, whereas the number of repetitions and the preamble format determine their end. In the frequency domain, subcar- rier spacing of 3.75 kHz is utilized. The NPRACH resources occupy a contiguous set of 12, 24, 36, or 48 subcarriers and are located on a discrete set of subcarrier ranges. Depending on the cell configuration, the resources may be further partitioned into resources used by UEs supporting multi-tone transmission for msg3 and UEs that do not support it. The physical random-access preamble is based on single-subcarrier frequency-hopping symbol groups. A symbol group is illustrated in Fig. 6.18, which consists of a cyclic pre- fix of length TCP and a sequence of five identical symbols with total length TSEQ. The pre- amble consists of four symbol groups transmitted without gaps and is transmitted N INPRACH RP times. The NPRACH transmission can only start 30720 NNPRACHTS time units after the start of a radio frame whose frame number satisfies Nf mod(NNPRACH /11 period = 0. Following the transmission of 256(TCP + TSEQ) time units, a gap is inserted [2]. The NPRACH preamble formats, that is, format 0 and format 1, differ in the cyclic prefix length. The five symbols have a duration of TSEQ = 1.333ms, appended with a cyclic pre- fix of TCP = 67 us for format 0 and TCP = 267 us for format 1, making a total length of 1.4 and 1.6 ms, respectively. The