Multi-user beamforming remote radio units using bit-interleaved sigma-delta modulated radio-over-fiber

The 5th generation of cellular networks promises unprecedented data rates. However, the technology is not there yet to keep this promise in high-density environments such as sports stadiums and shopping malls. A 750 Gbps aggregated data rate is foreseen in a medium-size stadium. To support this tremendous amount of data, a large number of antennas spread around the stadium are required. This to reduce interference allowing to serve multiple users at once using distributed beam steering and distributed Massive MIMO techniques. One of the main challenges remains how to interconnect all these antennas such that they can be jointly optimized for the environment. This project will combine efficient sigma-delta radio over fiber (SDoF) technology with efficient beam-forming systems capable of sending information to different users in different directions. SDoF converts a multi-level radio signal into a binary stream but can be recovered with simple filtering. As such, the reception is very easy. This project will extend this concept to support multiple streams simultaneously and perform beamforming on them. This can be done very efficiently due to the seemingly digital nature of the signal. Furthermore, this concept will also be extended towards the uplink path of the radio-link, which is currently missing in all SDoF demonstrations. Within this project, an integrated circuit will be developed that incorporates these techniques to validate them in a system demonstrator