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

1. Cell Reference Signal and
Mapping
Yanuar T. Aditya N.

2. Cell Reference Signal are used for…
• Cell search and initial acquisition
• Downlink channel estimation at the UE
• Downlink channel quality measurements

3. Cell Search

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. Screenshot #1
CELL ID = 0 ; B/W = 10 MHz

6. Screenshot #2
CELL ID = 1 ; B/W = 10 MHz

7. Screenshot #3
CELL ID = 6 ; B/W = 10 MHz

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. 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. …more
• m_seq2 denoted by (need cinit)
for length=1:31
m_seq2[length] = c_init mod 2
c_init = c_init / 2

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. 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. Mapping

14. …more

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. Result

17. Q & A