A method of mapping m individual objects to source symbols for delivering data from a transmitter to a receiver in a communication system, the m individual objects ordered from object 1 to object m, wherein m>1, includes: aggregating the m individual objects into an aggregate object, including for each individual object j, calculating a number of source symbols S(j) for containing data of the individual object j; and partitioning the aggregate object into Z source blocks, including for each source block k and each individual object j, calculating a number of source symbols NSS(j, k) of individual object j in source block k, wherein the S(j) source symbols for each individual object j are arranged consecutively within consecutive source blocks, starting from a first source block for which NSS(j, k)>0 to a last source block for which NSS(j, k)>0.