Rain effects on SDH-based networks using protection switching

In this paper, radio relay systems for Synchronous Digital Hierarchy (SDH)-based networks with path type Synchronous transfer Module of order 0 (STM-0) without protection switching and with 1+1 switching configuration as said in Recommendation ITU-R F.750 are considered. Byte Interleaved Parity (BIP) codes are used for error monitoring. Rain causes fading and the blocks are received in errors because of this fading and the SES may occur because of these errored blocks and the system may arrive in unavailable state. In this paper, the unavailability ratios of these two systems are calculated and the results are compared with the objectives in Recommendation ITU-R P.1703 and it is assumed that the link comprises the access portion of a network and forms a part of a national portion of a constant bit rat digital path element.