Demonstration of mobile backhaul uplink jitter reduction with optical-wireless cooperative control for multiple traffic flows

We experimentally demonstrate the performance of mobile backhaul (MBH) uplink jitter reduction techniques with optical-wireless cooperative control under multiple traffic flow conditions. Mobile systems beyond the 5th generation (5G) and 6th generation (6G) will require low jitter in addition to low latency, but current new radio (NR) mobile systems cause packet jitter in uplink traffic because of the radio transmission schemes used, such as downlink/uplink separation in time division duplexing (TDD) and medium access control (MAC) service data unit (SDU) concatenation to compose transport blocks. Our proposed uplink jitter reduction techniques perform traffic shaping at a router in the MBH network to reduce uplink jitter. The shaping rate is calculated with mobile scheduling information forwarded from a next generation node B (gNB) via an extended cooperative transport interface (eCTI). The eCTI is an interface between gNBs and network equipment for realizing optical-wireless cooperative control. We developed a shaper prototype that implements functions for receiving mobile scheduling information as eCTI frames, calculating the shaping rate, and executing shaping. eCTI frame formats are also defined by specifying where the mobile scheduling information is stored in an Ethernet frame. Using a shaper prototype, we experimentally evaluated the end-to-end (E2E) jitter performance for a single traffic flow, multiple gNB traffic flows, and multiple user equipment (UE) traffic flows. The results show that the uplink jitter reduction techniques reduce jitter from more than 1 ms to less than 300 µs, which meets the future jitter requirement of less than 1 ms.