to about 20 km. CPRI implementations require tight frequency and timing synchronization and accurate time of day (ToD) clock synchronization. A frequency precision of 16 ppb and ToD accuracy within 1.5 us are required for CPRI transport. The advantage of any functional split mainly depends on the availability of an ideal or non-ideal transport network. In a non-ideal fronthaul transport case, the functional split needs to occur at a higher level in the protocol stack, which reduces the level of centrali- zation that can be achieved through C-RAN. In this case, the synchronization and band- width requirements can be relaxed at the expense of some of these 4G/5G RAN features such as massive MIMO, CA, and multipoint joint processing. The following solutions can be used to help overcome these obstacles. White Rabbit technology44 is a combination of physical layer and PTP timing. White Rabbit introduces the technique of measuring and compensation for asymmetry to mitigate time and phase transfer errors. White Rabbit pro- vides sub-nanosecond timestamp accuracy and pico-second precision of synchronization for large distributed systems and allows for deterministic and reliable data delivery. To achieve sub-nanosecond synchronization, White Rabbit utilizes synchronous Ethernet (SyncE)45 to achieve synchronization and IEEE 1588v2. White Rabbit uses the PTP to achieve sub-nanosecond accuracy. A two-way exchange of the PTP synchronization mes- sages allows precise adjustment of clock phase and offset. The link delay is known pre- cisely via accurate hardware timestamps and the calculation of delay asymmetry. Alternatively, partial timing support compatible with ITU-T G.8275.2 standard can be used where the position of a grandmaster clock is moved closer to the PTP slaves in the RRHs. This is an excellent alternative to full on-path support White Rabbit for those operators who are not willing or cannot upgrade their networks for White Rabbit physical layer support. White Rabbit is a multidisciplinary project for development 