Cell Reference Signal and Mapping

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Cell Reference Signal and Mapping
PT. Fusi Global Teknologi
fusi.co.id

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Cell Reference Signal and Mapping

  1. 1. Cell Reference Signal and Mapping Yanuar T. Aditya N.
  2. 2. Cell Reference Signal are used for… • Cell search and initial acquisition • Downlink channel estimation at the UE • Downlink channel quality measurements
  3. 3. Cell Search
  4. 4. Downlink RS (Reference Signals) • Transmitted by each antenna (currently using single antenna) – Freq. domain spacing is 6 subcarrier – Time domain spacing is 4 OFDM symbols
  5. 5. Screenshot #1 CELL ID = 0 ; B/W = 10 MHz
  6. 6. Screenshot #2 CELL ID = 1 ; B/W = 10 MHz
  7. 7. Screenshot #3 CELL ID = 6 ; B/W = 10 MHz
  8. 8. Cell RS Equation • Shall be transmitted in all downlink subframes • Shall be transmitted in one or several antennas for number_of_slot=1:20 for ofdm_symbol=1:7 calculate rofdm_symbol,number_of_slot(m) m = 0,1,…,2*N_RB - 1
  9. 9. Pseudo-Random Sequence Generator • Initialized with • Then, initialize the the Gold-Sequence m_seq1 and m_seq2. Each has 31-bit length. for length=1:31 if length=1 m_seq1[length] = 1 else m_seq1[length] = 0
  10. 10. …more • m_seq2 denoted by (need cinit) for length=1:31 m_seq2[length] = c_init mod 2 c_init = c_init / 2
  11. 11. So far… for length=1:31 { if length=1 m_seq1[length] = 1 else m_seq1[length] = 0 } for number_of_slot=1:20 for ofdm_symbol=1:7 { calc_c_init() for length=1:31 { m_seq2[length] = c_init mod 2 c_init = c_init / 2 } calc_pseudo_rand() calc_cell_RS() } calc_pseudo_rand() { for n=1:M_pn+Nc { m_seq1[n+31]=m_seq1[n+3]^m_seq1[n] m_seq2[n+31]=m_seq2[n+3]^m_seq2[n+2]^m_seq2[n+1]^m_seq2[n] } for n=1:M_pn { pseudo_rand[n]=m_seq1[n+Nc]^m_seq2[n+Nc] } }
  12. 12. The cell RS value …init m_seq1 for number_of_slot=1:20 for ofdm_symbol=1:7 { …init c_init …init m_seq2 …calc_pseudo_rand() for m_index=1:N_RB*2 { out_signal[number_of_slot][ofdm_symbol][m_index].re = (1-2*pseudo_rand_seq[2*m_index])/SQRT_2; out_signal[number_of_slot][ofdm_symbol][m_index].im = ((1-2*pseudo_rand_seq[2*m_index+1])/SQRT_2); } }
  13. 13. Mapping
  14. 14. …more
  15. 15. Poured into code for num_sub=1:2*N_RB /* 1 to 100 on 10 MHz */ for ofdm_sym=1:7 { if antenna_port == 0 || antenna_port == 1 { check_v01_value() slot[6 * num_sub + (v + v_shift)][ofdm_symb] = cell_RS[l][num_sub] } else if antenna_port == 2 || antenna_port == 3 { check_v23_value() slot[6 * num_sub + (v + v_shift)][ofdm_symb] = cell_RS[l][num_sub]] } }
  16. 16. Result
  17. 17. Q & A

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