A method of implementing adaptive coding and modulation of a broadcast signal, the method comprising: associating a first modulation and coding scheme with a first signal quality range; associating a second modulation and coding scheme of a higher order than the first modulation and coding scheme with a second signal quality range of better quality than the first signal quality range; receiving a first data packet destined for a first link within the first signal quality range and a second data packet destined for a second link within the second signal quality range; encapsulating the first data packet and at least a part of the second data packet in a first frame; and transmitting the first frame in the broadcast signal according to the first modulation and coding scheme, characterised in that the encapsulating step further comprises: applying a policy of encapsulating data packets associated with different modulation and coding schemes in one frame to be transmitted according to a lowest order modulation and coding scheme of the different modulation and coding schemes, the policy being applied only when there are no other remaining data packets associated with the lowest order modulation and coding scheme, wherein the policy comprises: determining a length of a prospective pad for the at least one data packet associated with a first modulation and coding scheme; determining that no data packet associated with the first modulation and coding scheme remains to fill the prospective pad; and filling the prospective pad with the data packet associated with the second modulation and coding scheme. associating a first modulation and coding scheme with a first signal quality range; associating a second modulation and coding scheme of a higher order than the first modulation and coding scheme with a second signal quality range of better quality than the first signal quality range; receiving a first data packet destined for a first link within the first signal quality range and a second data packet destined for a second link within the second signal quality range; encapsulating the first data packet and at least a part of the second data packet in a first frame; and transmitting the first frame in the broadcast signal according to the first modulation and coding scheme, characterised in that the encapsulating step further comprises: applying a policy of encapsulating data packets associated with different modulation and coding schemes in one frame to be transmitted according to a lowest order modulation and coding scheme of the different modulation and coding schemes, the policy being applied only when there are no other remaining data packets associated with the lowest order modulation and coding scheme, wherein the policy comprises: determining a length of a prospective pad for the at least one data packet associated with a first modulation and coding scheme; determining that no data packet associated with the first modulation and coding scheme remains to fill the prospective pad; and filling the prospective pad with the data packet associated with the second modulation and coding scheme. determining a length of a prospective pad for the at least one data packet associated with a first modulation and coding scheme; determining that no data packet associated with the first modulation and coding scheme remains to fill the prospective pad; and filling the prospective pad with the data packet associated with the second modulation and coding scheme.