  This paper proposes an uplink optical wireless communication (OWC) link
design that can be used by data centers to support communication in spine and
leaf architectures between the top of rack leaf switches and large spine
switches whose access points are mounted in the ceiling. The use of optical
wireless links reduces cabling and allows easy reconfigurability for example
when data centres expand. We consider three racks in a data center where each
rack contains an Angle Diversity Transmitter (ADT) positioned on the top of the
rack to realize the uplink function of a top-of-the-rack (ToR) or a leaf
switch. Four receivers are considered to be installed on the ceiling where each
is connected to a spine switch. Two types of optical receivers are studied
which are a Wide Field-of-View Receiver (WFOVR) and an Angle Diversity Receiver
(ADR). The performance of the proposed system is evaluated when the links run
at data rates higher than 19 Gbps. The results indicate that the proposed
approach achieves excellent performance using simple On-Off Keying (OOK)
