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 (1010). The process data is then transmitted to a receiving entity over at least some of a plurality of resource units, RUs, (1020). 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 (1012); 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 (1014).