5.2b Extended coverage common control channel downlink (EC-CCCH/D/M) , Extended coverage paging indication channel (EC-PICH) and Extended coverage packet associated control channel (EC-PACCH/M)

3GPP45.003GSM/EDGE Channel codingRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.2b.1 Block constitution

The message delivered to the encoder has a fixed size of K_d information bits {d(0),d(1),…,d(K_d -1)}, where:

– EC-CCCH/D, EC-PICH: K_d=88

– EC-PACCH/D: K_d=80

– EC-PACCH/U/M: K_d=64 for M=1,4,8,16

– EC-PACCH/U/M: K_d=56 for M=48

In addition, for EC-PACCH/D, up to M sequences of USF bits {u(m,0),u(m,1),u(m,2)}, m=0,…,M-1, are delivered to the encoder, where M=16, 8, 4 or 1 depending on the number of blind physical layer transmissions.

NOTE: USF bits need not be delivered for those blocks that are transmitted on timeslots no GPRS/EGPRS MS is monitoring for USF.

5.2b.2 Data coding

a) Parity bits:

Eighteen data parity bits p(0),p(1),…,p(17) are defined in such a way that in GF(2) the binary polynomial:

d(0)D^K_d+18-1 +…+ d(K_d-1)D18 + p(0)D17 +…+ p(17), when divided by:

D18 + D17 + D14 + D13 + D11 + D10 + D8 + D7 + D6 + D3 + D2 + 1, yields a remainder equal to:

D17 + D16 + D15 + D14 + D13 + D12 + D11 + D10 + D9 + D8 + D7 + D6 + D5 + D4 + D3 + D2 + D + 1.

The parity bits are added after the block of K_d bits, the result being a block of K_d+18 bits, {b(0),…,b(K_d+18-1)}, defined as:

b(k) = d(k) for k = 0,1,…, K_d-1

b(k) = p(k‑K_d) for k = K_d,…, K_d+18-1

b) Tail-biting convolutional encoder

The six last bits are added before the block of K_d+18 bits, the result being a block of K_d+24 bits {c(‑6),…,c(0),c(1),…,c(K_d+18-1)} with six negative indices:

c(k) = b(K_d+18+k) for k = -6,…,-1

c(k) = b(k) for k = 0,1,…, K_d+18-1

This block of K_d+24 bits is encoded with the 1/3 rate convolutional mother code defined by the polynomials:

G4 = 1 + D2 + D3 + D5 + D6

G7 = 1 + D + D2 + D3 + D6

G5 = 1 + D + D4 + D6

This results in a block of (K_d+18)*3 coded bits {C(0),…,C((K_d+18)*3-1)} defined by:

C(3k) = c(k) + c(k‑2) + c(k‑3) + c(k‑5) + c(k‑6)

C(3k+1) = c(k) + c(k‑1) + c(k‑2) + c(k‑3) + c(k‑6)

C(3k+2) = c(k) + c(k‑1) + c(k‑4) + c(k‑6) for k = 0,1,…, K_d+18-1

The code is punctured in such a way that the following coded bits are not transmitted:

EC-CCCH/D, EC-PICH	C(floor(n*318/202)) for n=0,…,201
EC-PACCH/U (M=1,4,8,16)	C(floor(n*246/130)) for n=0,…,129
EC-PACCH/D	C(floor(n*294/180)) for n=0,…,179
EC-PACCH/U (M=48)	C(floor(n*222/116)) for n=0,…,115

The result is a block of K_pc coded bits {pc(0),pc(1),…,pc(K_pc-1)}, where K_pc=114 for EC-PACCH/D and K_pc=116 for EC-CCCH/D, EC-PICH and EC-PACCH/U/1, EC-PACCH/U/4, EC-PACCH/U/8, EC-PACCH/U/16 and K_pc=106 for EC-PACCH/U/48.

5.2b.3 USF coding (only for EC-PACCH/D)

For each of the up to M delivered USF sequences, the USF bits are block coded as for Packet data block type 4 (CS-4) in subclause 5.1.4.2. The input d(0),d(1),d(2) in subclause 5.1.4.2 shall be {u(m,0),u(m,1),u(m,2)} for USF number m.

Denote the resulting twelve encoded bits of USF number m as {u’(m,0),u’(m,1),…,u’(m,11)}.

5.2b.4 Mapping on a Burst

5.2b.4.1 EC-CCCH/D/M and EC-PICH

The mapping is given by the rule:

e(B, j) = pc(j) for j = 0,1,…,115 and B=0,1

5.2b.4.2 EC-PACCH/D/M

The mapping is given by the rule:

e(B,j) = pc(j) and e(B,59+j) = pc(57+j) for j = 0,1,…,56 and B=0,1,2,3

and

e(B,57) = q(2B) and e(B,58) = q(2B+1) for B = 0,1,2,3

where

q(0),q(1),…,q(7) = 0,0,0,1,0,1,1,0.

NOTE: For a standard GPRS MS, bits q(0),…,q(7) indicates that the USF is coded as for CS-4.

5.2b.4.3 EC-PACCH/U/M

The mapping is given by the following rule for M = 1,4,8 or 16:

e(B, j) = pc(j) for j = 0,1,…,115 and B=0,1,2,3

The mapping is given by the following rule for M = 48:

e(B,j) = pc(j) and e(B,63+j) = pc(53+j) for j = 0,1,…,52 and B=0,1,2,3

and

e(B,53+i) = q(i) for i = 0,1,…,9

where

q(0),q(1),…,q(9) = 0,0,0,0,0,0,0,0,0,0

5.2b.5 Blind physical layer transmission

Each burst is transmitted M times, where M is the number of blind physical layer transmissions. For EC-PACCH/D, M=1, 4, 8 or 16. For EC-PACCH/U, M=1, 4, 8, 16 or 48. For EC-CCCH/D, M=1, 8, 16 or 32. For EC-PICH, M=1, i.e. no blind physical layer transmission is applied.

Denote the resulting bursts of transmission m as R(m,B,j) = e(B,j) for m=0,…,M-1, B=0,1 (EC-CCCH) or B=0,1,2,3 (EC-PACCH), and j=0,…,115 or m=0, B=0,1 (EC-PICH).

5.2b.6 Bit stealing for USF (only for EC-PACCH/D)

For those m for which a USF has been delivered to the encoder, replace bits in the repeated bursts with encoded USF bits as follows:

for m=0,…,M-1

R(m,0,0) = u’(m,0)

R(m,0,51) = u’(m,4)

R(m,0,102) = u’(m,8)

R(m,1,100) = u’(m,1)

R(m,1,35) = u’(m,5)

R(m,1,86) = u’(m,9)

R(m,2,84) = u’(m,2)

R(m,2,19) = u’(m,6)

R(m,2,70) = u’(m,10)

R(m,3,68) = u’(m,3)

R(m,3,3) = u’(m,7)

R(m,3,52) = u’(m,11)

5.2b.7 Mapping onto physical channels

5.2b.7.1 EC-PACCH

The mapping onto PDCHs is done as specified for downlink MCS-1/M in subclause 5.1b.2.3 for M=1,4,8,16. The mapping onto PDCHs is done as specified for uplink MCS-1’/48 in subclause 5.1b.4.3.

5.2b.7.2 EC-CCCH/D and EC-PICH

Burst R(m,B,j), B=0,1, j=0…,115, is mapped onto burst B’ of the timeslot carrying the EC-CCCH/D or EC-PICH, where

B’ = B + 2m, for m=0,…,M-1 (EC-CCCH/D) and m=0 (EC-PICH)

NOTE: The burst number B’ denotes the relative transmission order of the bursts on the timeslot. The mapping to absolute TDMA frame number is specified in 3GPP TS 45.002 [8].