5G integrated transport solutions and key technologies based on OTN evolution

As a new generation of mobile communication standards, 5G becomes a hotspot in the industry. The 5G network provides eMBB (enhanced Mobile Broadband), uRLLC (ultra Reliable & Low Latency Communication) and mMTC (massive Machine Type of Communication) services, and has new requirements of transport networks for bandwidth, capacity, latency and networking flexibility. At present, the main solutions to 5G transport are SPN over OTN, IPRAN over OTN, and packet-enhanced OTN. This paper focuses on the key requirements of 5G transport networks, 5G packet-enhanced OTN transport solution, key technologies and standard progress. Referring to the progress of the 3GPP standard, the functions of the 5G RAN are re-architected into three functional entities: CU, DU and AAU. The transport network is divided into three parts: fronthaul, midhaul and backhaul. 5G has higher requirements of transport networks for bandwidth, ultra-low latency, time synchronization and flexible connection. The typical bandwidth (64T/R antenna, 100MHz spectrum bandwidth) between the AAU and the DU of the 5G fronthaul network is 25GE, which is several times higher than the bandwidth of fronthaul CPRI3~CPRI7 in the 4G era. The Sub 6GHz low-frequency 5G single-S111 base station has an average bandwidth of 3~5GHz, which is increased by more than 10 times compared with the 4G macro station. The large bandwidth requirement of 5G poses a big challenge to the transport network. The coordination between 5G base stations and the load balancing and multi-homed backup requirements of the core network cloud-based deployment make the traffic more complex and dynamic, requiring the transport network to provide sufficient bandwidth extension and flexible service connection.