Modulator includes 16QAM modulator , QPSK modulator and BPSK modulator. 16 QAM modulator consists of deserilizer, interleaver and mapper. QPSK modulator consists of deserilizer, interleaver and mapper. BPSK modulator merely consists of interleaver and mapper. The Interleaver operates at an OFDM symbol level with a block size of (48, 96, or 192) bits. The Mapper also operates at the OFDM symbol level with a block size of (48, 96, or 192) bits. Each block is divided into sub-blocks at the OFDM sub-carrier level. Sub-blocks are of size (1, 2, or 4) bits. The Mapper first converts each sub-block into a complex number representing BPSK, QPSK, or 16-QAM constellation points. Note that the modulation type may be different for the header and data parts of the message. The resulting 48 complex pairs are then normalized by KMOD. The interleaver is defined by a two step permutation. The first permutation ensures that adjacent coded bits are mapped onto nonadjacent subcarriers. The second ensures that adjacent coded bits are mapped alternately onto less and more significant bits of the constellation.Specifically, the first permutation is defined by the rule
i = (NCBPS/16)(k mod 16) + floor(k/16) k=0,1,...,NCBPS-1
The second permutation is defined by the rule
j = s x floor(i/s) + (i+NCBPS-floor(16 x i/NCBPS)) mode s i=0,1,...,NCBPS-1
s= max(NBPSC/2,1)
k is the index of the coded bit before first permutation; i is the index after the first permutation and before second permutation; j is the index after the second permutation.
Parameters:
val bitsWidth: Int width of inputs
val dataWidth: Int width of outputs
val Ncbps: Int the number of bits in a single OFDM symbol
val Nbpsc: Int coded bits per subcarrier
IO:
Inputs:
Val mod_ctrl: UInt ` modulation scheme control signal
val in.bits.bits: UInt input
val in.bits.pktStart: Bool package start signal
val in.bits.pktEnd: Bool package end signal
val in.valid: Bool valid signal
val out.ready: Bool ready signal
Outputs:
val out.bits.iq: DspComplex modulated output
val out.bits.pktStart: Bool package start signal
val out.bits.pktEnd: Bool package end signal
val out.valid: Bool valid signal
val in.ready: Bool ready signal
Tests:
Include tests for bpsk, qpsk and qam16 modulator. Run testOnly modem.modulatorSpec