Aseven-octet pattern of alternating 0s and 1s used by the receiver to establish bit synchronization is a

Preamble

Explanation:

 Preamble is a 7- octet pattern of alternating the 0's and 1's and it allow devices in the network to easily synchronized the receiver clock. It also provide the bit level synchronization.

It basically allow the start of frame delimiter to provide the byte synchronization and assign a new frame. The bits are transmit orderly from left to right in the frame.