A method of multi-user wireless communications at an apparatus, comprising: receiving, via a channel, a first modulated symbol from a first user equipment, UE, (310, 410) the first modulated symbol being frequency-shift keying, FSK, modulated based on a first spreading code, wherein the first spreading code corresponds to a first location assignment for tones in the first modulated symbol; receiving, via the channel, a second modulated symbol from at least one second UE (320, 420), the second modulated symbol being FSK modulated based on a second spreading code different from the first spreading code, wherein the second spreading code corresponds to a second location assignment for tones in the second modulated symbol, the second location assignment being different from the first location assignment; and decoding, based on the first spreading code and the second spreading code, each of the first modulated symbol and the second modulated symbol to produce a distinguishable symbol transmitted by each of the first UE (310, 410) and the at least one second UE (320, 420), wherein the decoding comprises: determining a power for each tone associated with the first modulated symbol and the second modulated symbol, identifying the distinguishable symbol transmitted by the first UE (310, 410) based on the power of each tone and the first spreading code, and identifying the distinguishable symbol transmitted by the at least one second UE (320, 420) based on the power of each tone and the second spreading code. receiving, via a channel, a first modulated symbol from a first user equipment, UE, (310, 410) the first modulated symbol being frequency-shift keying, FSK, modulated based on a first spreading code, wherein the first spreading code corresponds to a first location assignment for tones in the first modulated symbol; receiving, via the channel, a second modulated symbol from at least one second UE (320, 420), the second modulated symbol being FSK modulated based on a second spreading code different from the first spreading code, wherein the second spreading code corresponds to a second location assignment for tones in the second modulated symbol, the second location assignment being different from the first location assignment; and decoding, based on the first spreading code and the second spreading code, each of the first modulated symbol and the second modulated symbol to produce a distinguishable symbol transmitted by each of the first UE (310, 410) and the at least one second UE (320, 420), wherein the decoding comprises: determining a power for each tone associated with the first modulated symbol and the second modulated symbol, identifying the distinguishable symbol transmitted by the first UE (310, 410) based on the power of each tone and the first spreading code, and identifying the distinguishable symbol transmitted by the at least one second UE (320, 420) based on the power of each tone and the second spreading code. determining a power for each tone associated with the first modulated symbol and the second modulated symbol, identifying the distinguishable symbol transmitted by the first UE (310, 410) based on the power of each tone and the first spreading code, and identifying the distinguishable symbol transmitted by the at least one second UE (320, 420) based on the power of each tone and the second spreading code.