Various proposed schemes pertaining to interleaving of combinations of multiple resource units (RUs) in wireless local area networks (WLANs) are described. In one example, data in a service data unit (SDU) is processed. The process data is then transmitted to a receiving entity over at least some of a plurality of resource units (RUs). The processing of the data involves either: (i) performing tone mapping by using one joint tone interleaver on one or more combinations of multiple RUs of the plurality of RUs within one frequency segment of a predefined bandwidth; or (ii) performing tone mapping by using multiple tone interleavers on the one or more combinations of multiple RUs of the plurality of RUs over multiple frequency segments of the predefined bandwidth.