 preamble format to be used is broadcast in the system information. The NPRACH starting subcarriers which are allocated to UE-initiated random access are divided into two sets of subcarriers, { 0, 1, ., N NPRACH NYPRACH sc_cont sc_cont NPRACH - 1}, where the second set would indicate the UE support for multi-tone msg3 transmission. The frequency location of the NPRACH transmission is constrained within NRA = subcarriers. Frequency hopping is used within the 12 subcar- riers, where the frequency location of the ith symbol group is given by mod4 = 1,3 RA 1)mod = 0 i mod4 = 1,3 and RRA 1 i mod4 = 2 and <6 mod4 = 2 and f(-1) = 0 Chapter 6 where Ninit denotes the subcarrier selected by the MAC sublayer from {0, NPRACH SC 1}, and the pseudo-random sequence c(n) is specified in [2]. Note that the pseudo-random sequence generator is initialized with Cinit = NNcell ID NPRACH can be transmitted only with a specific timing within a NPRACH period as illus- trated in Fig. 6.18, where Inprach-StartTime and Inprach-Periodicity parameters are config- ured by higher layers via SIB2-NB. The RACH procedure for NB-IoT will be described later in layer 2 aspects. 6.3.9 Narrowband Physical Uplink Shared Channel The NPUSCH transports two types of information: uplink data via NPUSCH format 1 and uplink control information (UCI) via NPUSCH format 2. The latter always uses one subcar- rier and is always BPSK modulated. It carries HARQ ACK/NACK corresponding to NPDSCH, whereas NPUSCH format 1 can use one or more subcarriers. For single-tone /2-BPSK or /4-QPSK modulation is used, while for multi-tone QPSK modulation is used. The NPUSCH can repeat data up to 128 times to improve the link budget. NPUSCH format 1 uses the same LTE turbo code (minimum code rate 1/3) for forward error correc- tion. The maximum TBS of NPUSCH format 1 is 1000 bits, which is much lower than that in LTE. NPUSCH format 2 uses a repetition code for error control (minimum code rate of 1/16). NPUSCH format 1 supports multi-tone transmission based on the same legacy LTE n