ith each symbol group comprising one cyclic prefix and five symbols, as shown in Fig. 6.17. The length of the cyclic prefix is 66.67 us (Format 0) for cell radius up to 10 km and 266.7 us (Format 1) for cell radius up to 40 km. Each symbol, with fixed symbol value 1, is modulated on a 3.75 kHz tone with symbol duration of 266.67 us. However, the tone frequency index changes from one symbol group to another. The waveform of NPRACH preamble is referred to as single-tone frequency hopping. An example of NPRACH frequency hopping is illustrated in Fig. 6.18. To support coverage Preamble format 2048T 5.8192T 8192T 5.81927, 3.75 kHz 67 us (Format 0) 1.333 267 us (Format 1) Figure 6.17 Time domain structure of NPRACH [2]. Chapter 6 Preamble symbol group = n RA SC (i) Frequency location of a random access symbol group = Hopping From 3GPP TS 36.211: The frequency location of NPRACH is determined from RRC parameter nprach- Numsubcarriers Inprach-subcarrier offset-r13 in SIB2 Repetition Repetition Repetition The preambles can be repeated up to 128 times 3.75 kHz Repetition Repetition Repetition num repetitions perpreamble attempt-r13in SIB2 The start of the frame that meets the following: nf mod NPRACH period /10)=0 = Inprach-start time Inprach-start time Inprach-start time 30720N INPRACH+ 30720N NPRACH+ 30720N INPRACH start start start NPRACH period Inprach-periodicity Figure 6.18 Illustration of NPRACH time and frequency domain resource allocation and transmission timing [2,25]. extension, a NPRACH preamble can be repeated up to 128 times. The NPUSCH has two for- mats. Format 1 is used for carrying uplink data and uses the same LTE turbo code for forward error correction. Depending on the coverage level, the cell may indicate that the NB-IoT UE must repeat the preamble 1, 2, 4, 8, 16, 32, 64, or 128 times, using the same transmission power in each repetition. Each of the four groups is made up of a cyclic prefix and four iden- tical symbols. The NPRACH hops among 12 neighboring subcarriers (see Fig. 6.18). The base station