7 – Unrepeatered Transmission

The worldwide subsea transmission infrastructure consists of a combination of long-distance repeatered and shorter distance unrepeatered cable systems. This chapter addresses unrepeatered systems, also known as repeaterless or single-span systems. One obvious benefit of unrepeatered systems over repeatered systems is that no active element (repeater) is required on the submarine link connecting the submarine line terminal equipment (SLTE) typically located in cable landing stations (CLSs). Another difference between unrepeatered and repeatered systems is the submarine cable, in terms of structure (presence or not of an electrical power conductor) and fiber count. The chapter covers history and recent developments, applications, technologies and future outlook.