Hello,
The synchronization problem may have two jobs between Tx. and Rx. There is bit synchronization, then frame synchronization.
Bit synchronization: tries to center the positive or negative edge of the clock at the center of the bit width. This is done through PLL.
Frame synchronizatiobn: such as in E1 frame which consists of 16 bits. At Transmitter,You can send a 32-bit synchronization pattern. The pattern is inserted at the start of each frame by sending single sync bit after 15 bits of data.
At the receiver, store 32 frames in along shift register (16bit*32). Finally make a simple decode circuit that takes the bits number 0,31,63,...,511 and compares them with your sync pattern.
I hope I touched ur question because it is not so clear what u exactly need.
regards,
S. Yassin