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The provision of very high data rates in a ubiquitous manner throughout the service area is a great challenge for 4G and beyond-4G wireless networks. Towards that end, the deployment of fixed relays by the operators has become an accepted radio access network concept in various standardization activities including LTE-A and 802.16j. It is envisaged that next-generation networks will comprise a plethora of wireless relay stations. Worthy of mention is the plug-and-play type of relay known as nomadic relay. We devise novel radio resource management (RRM) schemes to facilitate the operation of fixed relay stations (FRSs) and nomadic relay stations (NRSs) in OFDMA-based multicellular networks. Two schemes of different decentralization levels are devised and classified as distributed and semi-centralized. A novel user-based dynamic routing or link selection that significantly reduces the feedback overhead is employed. We develop methods by which the NRSs act autonomously to acquire radio resources without relying on a central entity. NRS operation is the same in the two schemes and can be extended to any other OFDMA-based RRM scheme. Through the asynchronous opportunistic medium access of the NRSs, smart and opportunistic intra-cell channel reuse is attained. This is different from the static intra-cell reuse patterns often adopted in literature. Furthermore, we introduce a method to enable the cooperation between an NRS and a serving FRS to assist a troubled wireless terminal (WT). We thus establish the concept of nomadic relay-augmented fixed relay networks. To the extent of our knowledge of the literature, no other work has undertaken this task so far.