Cell-Specific Resource Mapping [10]

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KSB− (F P CT − 1) · DF P SC, i = 0, F P CT = 4, DF P SC, i > 0, F P CT = 4, DF P SC, i > 0, F P SC = 3, DF P C = 1, KSB− (F P CT − 1) · DF P SC, i = 0, F P CT = 3, DF P C 6= 1, DF P SC, i = 1, 2, F P CT = 3, DF P C 6= 1, DF P SC, i = 1, 2, F P CT = 2,

KSB, i = 0, F P CT = 1,

(2.11)

where F P CT = 2 and DF P SC = KSB/2. The number of minibands for each frequency partition is given by

KM B,F P i = (F P Si− K^{SB,F P i}· N¹)/N2, 0 ≤ i < F P CT. (2.12)

The mapping of subband PRUs and miniband PRUs to the frequency partition is given by

P RUF P i(j) =

 P RUSB(k1), 0 ≤ j < L^{SB,F P i},

P P RU_{M B}(k₂), L_{SB,F P i}≤ j < (LSB,F P i+ L_{M B,F P i}), (2.13) where

k₁ = Xi−1 m=0

L_{SB,F P m}+ j (2.14)

and

k2 = Xi−1 m=0

LSB,F P m+ j − L^{SB,F P i}. (2.15)

Fig. 2.13 depicts the frequency partitioning for BW = 10MHz, KSB = 7, F P CT = 4, F P S0 = F P S_i = 12, and DF P SC = 2.

2.3 Cell-Specific Resource Mapping [10]

P RUF P is are mapped to LRUs. All further PRU and subcarrier permutations are constrained to the PRUs of a frequency partition.

2.3.1 CRU/DRU Allocation

The partition between CRUs and DRUs is done on a sector-specific basis. Let LSB−CRU,F Pi

and LM B−CRU,F Pi denote the number of allocated subband CRUs and miniband CRUs for F Pi (i ≥ 0). The number of total allocated subband and miniband CRUs, in units of a subband (i.e., N1 PRUs), for F Pi (i ≥ 0) is given by the downlink CRU allocation size, DCASi. The numbers of subband-based and miniband-based CRUs in F P0 are given by DCAS_SB,0 and DCAS_{M B,0}, in units of a subband and a miniband, respectively. When DF P C = 0, DCASi must be equal to 0.

For F P0, the value of DCASSB,0 is explicitly signaled in the SFH as a 5, 4 or 3 bit field to indicate the number of subbands in unsigned binary format, where DCAS_SB,0 ≤ KSB,F P. A 5, 4 or 3 bit downlink miniband based CRU allocation size (DCASM B,0) is sent in the SFH only for partition F P0, depending on FFT size. The number of subband based CRUs for F P0 is given by

LSBCRU,F P0 = N1· DCAS^SB,0. (2.16)

The mapping between DCAS_{M B,0}and the number of miniband based CRUs for F P₀is shown in the Figs. 2.14 to 2.16 for FFT sizes of 2048, 1024 and 512, respectively. For those system bandwidths in range of (10, 20], the mapping between DCASM B,0 and number of miniband-based CRUs for F P0 is based on Fig. 2.14, and the maximum valid value of LM B−CRU,F P0

is less than ⌊88 · N^{P RU}⌋/96. For system bandwidths in the range of [5, 10], the mapping between DCASM B,0 and number of miniband-based CRUs for F P0 is based on Fig. 2.15, and the maximum valid value of LM B−CRU,F P⁰ is less than ⌊42 · N^{P RU}⌋/48.

For F Pi (i > 0, F P CT ≥ 2) only one value for DCASⁱ is explicitly signaled for all i > 0, in the SFH as a 3, 2 or 1 bit field to signal the same numbers of allocated CRUs for F Pi

(i > 0, F P CT ≥ 2).

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Figure 2.14: Mapping between DCASM B,0 and number of miniband based CRUs for F P0

for FFT size 2048 (from [10, Table 789]).

For F Pi (i > 0, F P CT ≥ 2), the number of subband CRUs (L^{SB−CRU,F P}i) and miniband CRUs (LM B−CRU,F Pi) are derived using the two equations.

LSB−CRU,F Pi = N1· min{DCASⁱ, KSB,F Pi}, (2.17)

LM B−CRU,F Pi =

 0, DCASi ≤ K^{SB,F Pi},

(DCAS_i− KSB,F Pi) · N1, DCAS_i > K_{SB,F Pi}, (2.18) When F P CT = 2, DCASSB,i and DCASM B,i for i = 1 and 2 are signaled using the DCAS_SB,0 and DCAS_{M B,0}fields in the SFH. Since F P₀ and F P₃ are empty, L_{SB−CRU,F P}0 = LM B−CRU,F P⁰ = L_{DRU,F P}0 = 0 and L_{SB−CRU,F P}3 = LM B−CRU,F P³ = L_{DRU,F P}3 = 0. For i = 1 and 2, LSB−CRU,F Pi = N1· DCAS^SB,0 and LM B−CRU,F Pi is obtained from DCASM B,0 using

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Figure 2.15: Mapping between DCASM B,0 and number of miniband based CRUs for F P0

for FFT size 1024 (from [10, Table 790]).





  





 









 











  



















 



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Figure 2.16: Mapping between DCASM B,0 and number of miniband based CRUs for F P0

for FFT size 512 (from [10, Table 791]).

the mappings in Figs. 2.14 through 2.16 for FFT sizes of 2048, 1024 and 512, respectively.

The number of CRUs in each frequency partition is denoted L_{CRU,F Pi}, where

LCRU,F Pi = LSB−CRU,F Pi+ LM B−CRU,F Pi. (2.19)

The number of DRUs in each frequency partition is denoted by LDRU,F Pi, where

LDRU,F Pi = F P Si− L^{CRU,F Pi}. (2.20)

and F P Si is the number of PRUs allocated to F Pi. The mapping from P RUF Pi to CRUF Pi is given by

CRUF P i[j] =

 P RUF P i[j], 0 ≤ j < L^{SB−CRU,F Pi}· N¹, 0 ≤ i < F P CT, P RU_{F P i}[k + L_{SB−CRU,F Pi} · N1], L_{SB−CRU,F Pi} ≤ j < LCRU,F P i, 0 ≤ i < F P CT.

(2.21) where k = s[j − LSB−CRU,F Pi], with s[ ] being the CRU/DRU allocation sequence defined as

s[j] = {P ermSeq(j) + DL P ermBase} mod {F P Sⁱ− L^{SB−CRU,F P}i · N¹} (2.22)

where P ermSeq() is the permutation sequence of length (F P Si− L^{SB−CRU,F Pi}) and is de-termined by SEED = IDcell · 343 mod 2¹⁰, DL P ermBase is an interger ranging from 0 to 31, which is set to preamble IDcell. The mapping of P RUF P i to DRUF P i is given by

DRUF P i[j] = P RUF P i[k + LSB−CRU,F Pi], 0 ≤ j < L^{DRU,F P i} (2.23)

where k = s[j + LCRU,F Pi − L^{SB−CRU,F P}i].

2.3.2 Subcarrier Permutation

The DL DRUs are used to form two stream distributed logical resource unit (DLRU)s by subcarrier permutation. The subcarrier permutation defined for the DL distributed resource allocations within a frequency partition spreads the subcarriers of the DRU across the whole

distributed resource allocations. The granularity of the subcarrier permutation is equal to a pair of subcarriers.

After mapping all pilots, the remainder of the used subcarriers are used to define the distributed LRUs. To allocate the LRUs, the remaining subcarriers are paired into contiguous tone-pairs. Each LRU consists of a group of tone-pairs.

Let L_SC,l denote the number of data subcarriers in lth OFDMA symbol within a PRU, i.e., LSC,l = PSC − n^l, where nl denotes the number of pilot subcarriers in the lth OFDMA symbol within a PRU. Let LSP,l denote the number of data subcarrier-pairs in the lth OFDMA symbol within a PRU and is equal to LSC,l/2. A permutation sequence PermSeq() is defined in section 2.3.3, performs the DL subcarrier permutation as follows. For each lth OFDMA symbol in the subframe:

1. Allocate the nl pilots within each DRU as described in Section 2.3.3. Denote the data subcarriers of DRUF P i[j] in the lth OFDMA symbol as

SC_DRU,j,l^{F P i} [k], 0 ≤ j < LDRU,F P i, 0 ≤ k < LSC,l. (2.24)

2. Renumber the L_{DRU,F P i} · LSC,l data subcarriers of the DRUs in order, from 0 to L_{DRU,F P i}· LSC,l − 1. Group these contiguous and logically renumbered subcarriers into LDRU,F P i· L^SP,l pairs and renumber them from 0 to LDRU,F P i· L^SP,l − 1. The renumbered subcarrier pairs in the lth OFDMA symbol are denoted as

RSPF P i,l[u] = {SCDRU j,l^{F P i} [2v], SC_{DRU j,l}^{F P i} [2v + 1]}, 0 ≤ u < L^{DRU,F P i}LSP,l, (2.25)

where j = ⌊u/L^SP,l⌋, v = {u} mod (L^SP,l).

3. Apply the subcarrier permutation formula to map RSPF P i,l into the sth distributed LRU, s = 0, 1, . . . , LDRU,F P i− 1, where the subcarrier permutation formula is given by SC_{LRU s,l}^{F P i} [m] = RSPF P i,l[k], 0 ≤ m < L^SP,l, (2.26)

where

k = LDRU,F P i· f(m, s, l) + g(P ermSeq(), s, m, l). (2.27)

In the above,

1. SC_{LRU s,l}^{F P i} [m] is the mth subcarrier pair in the lth OFDMA symbol in the sth distributed LRU of the tth AAI subframe;

2. m is the subcarrier pair index, 0 to LSP,l− 1;

3. l is the OFDMA symbol index, 0 to Nsym− 1;

4. s is the distributed LRU index, 0 to LDRU,F P i− 1;

5. P ermSeq() is the permutation sequence of length L_{DRU,F P i} and is determined by SEED = {IDcell · 1367} mod 2¹⁰; and

6. g(P ermSeq(), s, m, l) is a function with value from the set [0,L_{DRU,F P i}-1], which is defined according to

g(P ermSeq(), s, m, l) = {P ermSeq[{f(m, s) + s + l} mod {L^{DRU,F P i}}]

+DL P ermBase} mod L^{DRU,F P i} (2.28)

where DL P ermBase is an integer ranging from 0 to 31 (Section 2.3.3), which is set to preamble IDcell, and f (m, s, l) = (m + 13 · (s + l))mod L^SP,l.

2.3.3 Random Sequence Generation

The permutation sequence generation algorithm with 10-bit SEED (Sn−10, Sn−9, ..., Sn−1) shall generate a permutation sequence of size M according to the following process:

• Initialization

1. Initialize the variables of the first order polynomial equation with the 10-bit seed, SEED. Set d1 = ⌊SEED/2⁵⌋ + 619 and d² = SEED mod 2⁵.

2. Initialize the maximum iteration number, N = 4.

3. Initialize an array A with size M to contents 0, 1, . . . , M − 1(i.e.,A[i] = i, for0 ≤ i < M).

4. Initialize the counter i to M − 1.

5. Initialize x to −1.

• Repeat the following steps if i > 0

1. Increment x by i.

2. Calculate the output variable of y = {(d¹· x + d²) mod 1031} mod M.

3. If y ≤ i, set y = y mod (i + 1).

4. Swap A[i] and A[y].

5. Decrement i by 1.

• P ermSeq[i] = A[i],where 0 ≤ i < M.

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