Sidelink Synchronization Signal Block (S-SSB) Grid Generation

THe modules maps the sidelink primary synchronization signal (S-PSS), sidelink secondary synchronization signal (S-SSS), demodulation reference signal (DMRS) for PSBCH and PSBCH payload to S-SSB grid. The S-SSB grid in 5G spans 11 or 13 OFDM symbols and 132 subcarriers (11 RBs). This modules can return multiple SSBs carrying same S-PSS, S-SSS but DMRS and different PSBCH information which is typically the case when transmitting multiple S-SSBs in a half frame. In such cases, only the S-SSB index information changes across S-SSBs. The details about the S-SSB generation is provided in section 8.4.2 of 3GPP TS 38.211 [3GPPTS38211_SSSBGrid].

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Examples:

When \(\text{N}_{\text{SSBs}} = 1\):

flag    = np.random.randint(2)
numIDs  = 1 if flag else np.random.randint(1,10)

nid1    = 311
nid2    = 1
nSymb   = 11
psbch   = 1-2*np.random.randint(2, size=(99*(nSymb-4)))

sssbObj = SSSB_Grid(nid1, nid2, numSymbols = nSymb)
sssb    = sssbObj(psbch = psbch)

print("************ Simulation Parameters *************")
print()
print("                   nid1: "+str(nid1))
print("                   nid2: "+str(nid2))
print("Number of S-SSB Symbols: "+str(nSymb))
print("         Shape of psbch: "+str(psbch.shape))
print("          Shape of sssb: "+str(sssb.shape))
print()
print("********************************************")

******** Simulation Parameters *********

                   nid1: 311
                   nid2: 1
Number of S-SSB Symbols: 11
         Shape of psbch: (693,)
          Shape of sssb: (1, 132, 14)

****************************************

# Display the Sidelink-SSB Grid
fig, ax = sssbObj.displayGrid()

When \(\text{N}_{\text{SSBs}} > 1\) :

flag    = np.random.randint(2)
numIDs  = 1 if flag else np.random.randint(1,10)

nid1    = np.array([311, 210, 64])
nid2    = np.array([0, 1, 0])
nSymb   = 13
psbch   = 1-2*np.random.randint(2, size=(3, 99*(nSymb-4)))

sssbObj = SSSB_Grid(nid1, nid2, numSymbols = nSymb)
sssb    = sssbObj(psbch = psbch)

print("************ Simulation Parameters *************")
print()
print("                   nid1: "+str(nid1))
print("                   nid2: "+str(nid2))
print("Number of S-SSB Symbols: "+str(nSymb))
print("         Shape of psbch: "+str(psbch.shape))
print("          Shape of sssb: "+str(sssb.shape))
print()
print("********************************************")

******** Simulation Parameters *********

                   nid1: [311 210  64]
                   nid2: [0 1 0]
Number of S-SSB Symbols: 13
         Shape of psbch: (3, 891)
          Shape of sssb: (3, 132, 14)

****************************************

# Display the Sidelink-SSB Grid
fig, ax = sssbObj.displayGrid(option=0)

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More example on S-SSB Resource mapping can be found in Tutorials. The details about the input-output interface of the SSSB_Grid implementation is provided below.

class toolkit5G.ResourceMapping.SSSB_Grid(nID1, nID2, numSymbols=13)

Generates the sidelink synchronization signal block grid as per Section 7.4.3 of 3GPP TS 38.211.

Parameters:

• nID1 (int or NumPy integer array) – denotes the \(N_{ID,1}^{SL}\). All the values should be taken from the interval \(\{0, 1, 2, \dots, 335\}\).

• nID2 (int or NumPy integer array) – denotes the \(N_{ID,2}^{SL}\). All the values should be taken from the interval {0, 1}.

• numSymbols (int) – denotes the \(N_{symb}^{S-SSB}\). Values should be taken from the interval {11, 13}.

• isNormalized (bool) – Defines the normalization flag. This flag is used to normalize the power of each symbol in SSB to one.

Important

If SSB is un-normalized, the total power is different across symbols.

Input:

• spss ([127,], np.complex64) – Defines Sidelink-PSS Sequence of length 127 to be loaded in the S-SSB. Default value is None. When spss is None, it is generated based on nID2.

• ssss ([127,], np.complex64) – Defines Sidelink-SSS Sequence of length 127 to be loaded in the S-SSB. Default value is None. When spss is None, it is generated based on nID1 and nID2.

• dmrsSequence ([:, 33*``numSymbols-4``], np.complex64) – Defines DMRS Sequence of length 144 to be loaded in the S-SSB. Default value is None. When spss is None, it is generated based on nID1 and nID2.

• psbch ([:, 99*``numSymbols-4``], np.complex64) – Defines PSBCH Payload of length 432 to be loaded in the S-SSB. It shouldn’t have more than 2 dimensions. Default value is None. When spss is None, it is generated randomly based on the resources configured in 3GPP standards.

Warning

psbch and dmrsSequence shouldn’t have more than 2 dimensions. Moreover, both these variables should have same number of SSBs (pbchSymb.shape[0] should equal dmrsSeq.shape[0]).

Important

Cell-ID should be same for all the pbchSymb and dmrsSeq .

Output:

[…, 132, 14], np.complex64 – Sidelink synchronization signal block grid.

Raises:

• ValueError – [Error:SL_SSB] Size mismatch between ‘nID1’ and ‘nID2’!

• ValueError – [Error:SL_SSB] length of ‘S-PSS’ must be a 1D or 2D array!

• ValueError – [Error:SL_SSB] length of ‘S-PSS’ must be a multiple of 254!

• ValueError – [Error:SL_SSB] length of ‘S-SSS’ must be a 1D or 2D array!

• ValueError – [Error:SL_SSB] length of ‘S-SSS’ must be a multiple of 254!

• ValueError – [Error:SL_SSB] length of ‘S-SSS’ and ‘S-PSS’ is inconsistent!

• ValueError – [Error:SL_SSB] length of ‘S-DMRS’ must be a multiple of 33*``numSymbols-4``!

• ValueError – [Error:SL_SSB] length of ‘S-SSS’, ‘S-PSS’ and ‘S-DMRS’ is inconsistent!

• ValueError – [Error:SL_SSB] length of ‘S-PBCH’ must be a multiple of 99*``numSymbols-4``!

• ValueError – [Error:SL_SSB] length of ‘S-SSS’, ‘S-PSS’, ‘S-DMRS’ and ‘S-PBCH’ is inconsistent!

• ValueError – [Error S-SSB]: ‘nID1’ must be within 0 and 335!

• ValueError – [Error S-SSB]: ‘nID1’ must be within 0 and 335!

• ValueError – [Error S-SSB]: ‘nID1’ must be an integer or integer numpy array!

• ValueError – [Error S-SSS]: ‘nID2’ must be either 0 or 1!

• ValueError – [Error S-SSS]: ‘nID2’ must be either 0 or 1!

• ValueError – [Error S-SSS]: ‘nID2’ must be an integer or integer numpy array!

• ValueError – [Error S-SSS]: ‘numSymbols’ must be either 11 or 13!

• ValueError – [Error S-SSS]: ‘numSymbols’ must be an integer!

displayGrid(index=0, option=1, displayGrid=True)

Provides the method to display S-SSB grid.

Input:

• index (int) – Define the Index of S-SSB whose grid has to be displayed. It should always be less than number of s-ssb grids.

• option (int \(\in \{0,1\}\).) –

  • If option=0, then heat map of the SSB is displayed.

  • If option=1, displays the grid locations (relative t-f locations) where S-PSS, S-SSS, DMRS and PSBCH payload are loaded in the S-SSB grid.

SSSB_Grid.displayGrid(index=0, option=1, displayGrid=True)

Provides the method to display S-SSB grid.

Input:

• index (int) – Define the Index of S-SSB whose grid has to be displayed. It should always be less than number of s-ssb grids.

• option (int \(\in \{0,1\}\).) –

  • If option=0, then heat map of the SSB is displayed.

  • If option=1, displays the grid locations (relative t-f locations) where S-PSS, S-SSS, DMRS and PSBCH payload are loaded in the S-SSB grid.

References:

[3GPPTS38211_SSSBGrid]

(3GPP TS 38.211 version 17.1.0 Release 17) 5G;NR;Physical channels and modulation ‘5.2.2 Low-PAPR sequence generation type 1’