. Transmission chain The transmission chain consists of the following operations (Figure 3.2): a) Produce the PLCP preamble field, composed of: - ten repetitions of a short training sequence, used for ACG (Automatic Control Gain) convergence, diversity selection, timing acquisition and coarse frequency acquisition in the receiver; - two repetitions of a long training sequence, used for channel estimation and fine frequency acquisition in the receiver, preceded by a guard interval (GI). b) Produce the PLCP header field from the RATE, LENGTH and SERVICE fields by filling the appropriate bit fields. c) Calculate from the RATE field the number of data bits per OFDM symbol (NDBPS), the coding rate (R), the number of bits in each OFDM sub- carrier (NBPSC) and the number of coded bits per OFDM symbol (NCBPS). d) Append the PSDU data unit to the SERVICE field. Extend the resulting bit string with bits to ZERO (at least six bits) SO that the resulting length is a multiple of NDBPS. The resulting bit string constitutes the DATA part of the frame. e) Initiate the scrambler with a pseudo-random non-zero seed, generate a scrambling sequence and XOR it with the extended string of data bits. f) Replace the six scrambled bits at ZERO following the data with six non-scrambled bits at ZERO. Those bits return the convolutional encoder to the zero state and are denoted as tail bits. g) Encode the extended, scrambled data string with a convolutional encoder (R = 1/2). Omit some of the encoder output string, chosen according to puncturing pattern, to reach the desired coding rate. h) Divide the encoded bit string into groups of NCBPS bits. Within each group, perform an interleaving of the bits according to a rule corresponding to the desired RATE. i) Divide the resulting coded and interleaved data string into groups of NBPSC bits. For each of the bit groups, convert the bit group into a complex number according to the modulation encoding tables. Wi-Fi Integration to the 4G Mobile Network j) Divide the complex number string into groups