Space Division Multiple Access for Optical Attocell Network Using Angle Diversity Transmitters

In this paper, an optical space division multiple access (SDMA) scheme is proposed for optical attocell networks. In the system, the conventional single-element transmitter in each optical cell is substituted by an angle diversity transmitter which can simultaneously serve multiple active users at different positions. The type of configuration can increase the available bandwidth resource and also mitigate intercell interference in optical attocell networks. The results show that an optical SDMA scheme significantly outperforms the conventional optical time division multiple access scheme. The SDMA scheme improves the average spectral efficiency of the system by a factor of 26 for a 37-element light emitting diode angle diversity transmitter. In addition, the upper and lower bound of the optical SDMA performance are derived analytically. These bounds can precisely estimate the performance of SDMA systems. Also, the study is extended to take account of user position errors, and Monte-Carlo simulations show that the system is very robust to user position errors.