TABLE OF CONTENTS The physical broadcast channel (PBCH) is transmitted over four subframes (one subframe in each frame of 10 ms) with a 40 ms timing interval. The 40 ms timing is detected blindly without requiring any explicit signaling. Also, each subframe transmission of BCH is self-decodable and UEs with good channel conditions may not need to wait for reception of all the four subframes for PBCH decoding.
The transmission chain processing for the broadcast control channel is depicted in Figure 9.6. The BCH data arrives to the coding unit in the form of a maximum of one transport block every transmission time interval (TTI) of 40 ms.
Error detection is provided on BCH transport blocks through a cyclic redundancy check (CRC). The entire transport block is used to calculate the CRC parity bits. Let us denote the bits in a transport block delivered to layer 1 by
| (9.23) |  |
where A is the size of the transport block. The parity bits are given as:
| (9.24) |  |
where L = 16 is the number of parity bits. The CRC bits are scrambled according to the eNode-B transmit antenna configuration with the sequence x ant , k as indicated in Table 9.5 to form the sequence of bits c k as below:
| (9.25) |  |
| Number of transmit antenna ports at eNode-B | PBCH CRC mask |
|---|---|
| 1 | |
