Novel Sharing Optical Switching Architectures And Transmission Performance For Clouding Radio Access Network

With 4G deploying and 5G developing rapidly,the capacity of radio access network(RAN)is becoming larger.Clouding RAN receives great interests due to its simple resource management,low power consumption and low system costs.By partitioning baseband units(BBU)and remote radio units(RRU),the system efficiency is enhanced.CPRI is currently the common interface between BBU and RRU but its bandwidth capacity is extended with the high number of antennas,which is hard to support the RAN in future.Based on wavelength division multiplexing and subcarrier multiplexing,the requisite wavelengths and system overhead can be greatly cut off with high bandwidth efficiency.Based on the above-mentioned transmission scheme,we proposed a resource sharing C-RAN architecture,which uses wavelength selective switch(WSS)to allocate the wavelength resources flexibly for bidirection.With the flexible WSS configuration,the central office allocates different resource from different output ports to different cell site group,coping with the problem of traffic migration in RAN.Moreover,by pooling the hardware resource,the proposed system reduces the number of optical transceivers,cutting down the system overhead.When system rate is low(e.g.at late night),our system employ the parallel signal detection to achieve wavelength bandwidth sharing so that the unnecessary transceiver can be turned off,decreasing the system power consumption.We also demonstrated the proposed architecture experimentally.37 dB and 39 dB loss budget are respectively obtained for downlink and uplink with 1:128 splitting ratio over 25 km fiber transmission,which proved that the system can cater to the development of RAN in future.