A data interaction system, comprising: a Base Band Unit, BBU, pool, an Optical Multiplexer/Demultiplexer, OMD, unit and multiple sites, wherein the BBU pool comprises one or more BBUs, the OMD unit comprises two OMD modules, each of the sites comprises an Optical Add-Drop Multiplexer, OADM, module and one or more Radio Remote Units, RRUs; the BBU pool is connected to the OMD unit, the OADM module in each of the sites is connected with the two OMD modules of the OMD unit via two optical fiber links in different directions, each of the OADM modules is connected with the one or more RRUs via the two optical fiber links in different directions, and the BBU pool and the sites are concatenated into a ring topology network; the sites are divided into multiple site groups, and sites in each of the multiple site groups use a same wavelength and are uniformly distributed in the ring topology network; wherein the number of sites between two adjacent sites of a same site group is less than a maximum number of concatenated sites using different wavelengths in the ring topology network; each of the one or more BBUs is configured to: split a downlink electrical signal to be sent to each RRU into two parts, convert the two parts of the downlink electrical signal into a downlink optical signal with two parts having a same wavelength, and send the two parts of the downlink optical signal to the OMD unit; and receive an uplink optical signal from the OMD unit, and convert the uplink optical signal into an uplink electrical signal and process the uplink electrical signal; the OMD unit is configured to: multiplex downlink optical signals of different wavelengths from different BBUs of the one or more BBUs, and send the two parts of the downlink optical signal to the OADM module in each of the sites separately via the two optical fiber links in different directions via the two OMD modules respectively; and demultiplex the uplink optical signal received from the OADM module into uplink optical signals of different wavelengths, and send the demultiplexed uplink optical signals of different wavelengths to corresponding BBUs; the OADM module in each of the sites is configured to: acquire, from the two optical fiber links in different directions, downlink optical signals which have the same wavelength as a local wavelength, and send the downlink optical signals to RRUs connected with the OADM module; and receive an uplink optical signal with two parts having the local wavelength from the RRUs connected with the OADM module, multiplex the two parts of the uplink optical signal having the local wavelength with other uplink optical signals of different wavelengths, and send the two parts of the multiplexed uplink optical signals to the OADM module of a next site respectively via the two optical fiber links in different directions until the two parts of the multiplexed uplink optical signals are sent to the OMD unit via the two OMD modules respectively; and each of the one or more RRUs is configured to: convert the received downlink optical signals into downlink electrical signals, extract a corresponding signal from the downlink electrical signals and process the corresponding signal, multiplex the remaining of the downlink electrical signals with an uplink electrical signal to be sent to a BBU of the one or more BBUs, split the multiplexed electrical signals into two parts, convert the two parts of the electrical signals into two parts of uplink optical signals having the local wavelength, and send the two parts of the uplink optical signals having the local wavelength respectively via the two optical fiber links in the different directions to a next RRU of the one or more RRUs until the two parts of the uplink optical signals are sent to the OADM module.