3.13 Data channel for ECSD at full rate, 43.5 kbit/s radio interface rate (43.2 kbit/s services (E-TCH/F43.2))

3GPP45.003GSM/EDGE Channel codingRelease 17TS

The definition of a 43.5 kbit/s radio interface rate data flow for data services is given in 3GPP TS 44.021.

3.13.1 Interface with user unit

The user unit delivers to the encoder a bit stream organized in blocks of 870 information bits (data frames) every 20 ms.

3.13.2 Convolutional encoder

3.13.2.1 Tailing bits for a data frame

Before convolutional encoding 6 tail bits {d(k)=0, k=870,…875} are added to the end of each data block .

3.13.2.2 Convolutional encoding for a data frame

This block of 876 bits {d(0),…,d(875)} is encoded with the ½ rate convolutional code defined by the following polynomials:

G4 = 1 + D2 + D3 + D5 + D6

G7 = 1 + D + D2 + D3 + D6

resulting in 1752 coded bits {c(0), c(1),…, c(1751)} with

c(2k)= d(k)+d(k‑2)+d(k‑3)+ d(k‑5)+d(k‑6);

c(2k+1)= d(k)+d(k‑1)+ d(k‑2)+ d(k‑3)+ d(k‑6) for k = 0,1,…,875; u(k) = 0 for k<0

The code is punctured in such a way that the following 384 coded bits:

c(2+8(k-1)) for k=1:219; c(4+16(k-1)) for k=1:110; c(6+32(k-1)) for k=1:55

are not transmitted.

The result is a block of 1368 coded bits, {c(0),c(1),…, c(1367)}.

3.13.3 Interleaving

The interleaving is done as specified for E-TCH/F28.8 in subclause 3.11.4.

3.13.4 Mapping on a Burst

The mapping is done as specified for E-TCH/F28.8 in subclause 3.11.5.