r some operators, higher fronthaul bandwidth requires deploying (or leasing) new fiber, thus substantially increasing capital spending. Of course, the actual bandwidth requirement for each split option varies depending on configuration and air interface features deployed; however, in order to illustrate the impact on transport network bandwidth of each split option we use one typical network configuration example. In this exercise we assume a 128 TxRx Massive MIMO system with 100 MHz system band- width, 16 + 16 I/Q samples, 256QAM, 30 KHz SCS in a sub-6 GHz spectrum. Table 4.5.1 provides a rough estimation of downlink bandwidth for each split option. This analysis shows that lower split options impose higher requirements on the fronthaul transport network bandwidth. The calculation only takes into account user data transmis- sion; however, in reality there will be also control messages and transport protocol over- head. One obvious way to reduce the transport network bandwidth demand is to select a higher split option (at a cost of reduced performance); however, other solutions are possible (some of which are elaborated upon below). Data compression is one such technique that may help alleviate the bandwidth demand to a certain extent. There are some popular compression algorithms that are suitable for I/Q data compression, which have been analyzed based on the compression ratio and the error vector magnitude (EVM). The current version of the O-RAN specification defines three compression methods: Block floating point Modulation compression u-law. Table 4.5.1 Front haul transport downlink bandwidth comparison. Split option Bandwidth (Gbps) Description The Medium Access Control (MAC) and upper layers are in the central unit PHY and RF are in the distributed unit ~ 376 Inverse/Fast Fourier Transform (FFT), cyclic prefix (CP) addition/removal and Physical Random Access Channel (PRACH) filtering are in the remote unit All other PHY functions are in the distributed unit i/FFT, CP addition/removal, PRACH filtering and p