OFDMA will be the predominant technology for the air interface of broadband mobile wireless systems for the next decades. In recent years, OFDMA-based networks based on IEEE 802.16, and increasingly also on 3GPP LTE are rolled out for commercial use. This article gives an overview of the main challenges for the deployment and operation of state-of-the-art OFDMA networks, along with an outlook into future developments for 4G and beyond 4G networks. Categories and Subject Descriptors C.2.1 [Network Architecture and Design]: Wireless Communications; C.2.3 [Computer Communication Networks]: Network Operations General Terms Design, Standardization, Algorithms, Management Keywords OFDMA, WiMAX, LTE, Radio Resource Management, Deployment, Network Operation, Survey