Clock synchronization is one of the enabling technologies for real-time networking. This paper is motivated by the need for WLAN support of real-time factory automation networks. These networks need synchronized clocks for the typical time-slotted arbitration schemes. As this type of service is not yet available wireless LANs, this work investigates possibilities for synchronizing clocks, based on higher layer synchronization approaches such as IEEE 1588 over WLAN. Different clock synchronization schemes are discussed in this study, some of those utilize the features of IEEE 802.11 and some of them not. In addition to that, this currently still ongoing work shows the difficulties of provision of highly accurate timestamps for the sake of synchronization.