4.2.6 Radio frame segmentation
25.2123GPPMultiplexing and channel coding (FDD)Release 17TS
When the transmission time interval is longer than 10 ms, the input bit sequence is segmented and mapped onto Fi segments. Following rate matching in the DL and radio frame size equalisation in the UL the input bit sequence length is guaranteed to be an integer multiple of Fi.
The input bit sequence is denoted by 
where i is the TrCH number and Xi is the number bits. The Fi output bit sequences per TTI are denoted by 
where ni is the segment number and Yi is the number of bits per radio frame for TrCH i. The output sequences are defined as follows:
= 
, ni = 1…Fi, k = 1…Yi
where
Yi = (Xi / Fi) is the number of bits per segment.
In downlink, the ni -th segment is mapped to the radio frame ni -1 of the transmission time interval.
In uplink when UL_DPCH_10ms_Mode is not configured by higher layers, the ni -th segment, 1 ni Fi is mapped to radio frame ni -1 of the transmission time interval.
In uplink when UL_DPCH_10ms_Mode is configured by higher layers, the nith segment, 1 ni Fi, is mapped to theradio frame 2ni – 2 of the transmission time interval. No bits are input to the radio frame 2ni – 1.
4.2.6.1 Relation between input and output of the radio frame segmentation block in uplink
The input bit sequence to the radio frame segmentation is denoted by 
, where i is the TrCH number and Ti the number of bits. Hence, xik = dik and Xi = Ti.
The output bit sequence corresponding to radio frame ni is denoted by 
, where i is the TrCH number and Ni is the number of bits. Hence, 
and Ni = Yi.
4.2.6.2 Relation between input and output of the radio frame segmentation block in downlink
The bits input to the radio frame segmentation are denoted by 
, where i is the TrCH number and Qi the number of bits. Hence, xik = qik and Xi = Qi.
The output bit sequence corresponding to radio frame ni is denoted by 
, where i is the TrCH number and Vi is the number of bits. Hence, 
and Vi = Yi.