A method comprising: transmitting a pair of timeslots of a subcarrier of a primary carrier, wherein transmitting the pair of timeslots includes transmitting demodulation reference signals in respective last and second to last resource elements of each of the pair of timeslots; said method being characterized by: transmitting first and second timeslots of a subcarrier of an extension resource carrier that is aggregated with the primary carrier, the first timeslot having a first plurality of resource elements that are ordered from a first resource element to a last resource element, wherein transmitting the first and second timeslots of the subcarrier of the extension resource carrier includes: transmitting a first symbol in a select one of the first plurality of resource elements that is not the last resource element, wherein the first symbol is a user equipment-specific demodulation reference signal; and transmitting a second symbol in the last resource element of the first plurality of resource elements, wherein the second symbol is other than a user equipment-specific demodulation reference signal. transmitting a pair of timeslots of a subcarrier of a primary carrier, wherein transmitting the pair of timeslots includes transmitting demodulation reference signals in respective last and second to last resource elements of each of the pair of timeslots; said method being characterized by: transmitting first and second timeslots of a subcarrier of an extension resource carrier that is aggregated with the primary carrier, the first timeslot having a first plurality of resource elements that are ordered from a first resource element to a last resource element, wherein transmitting the first and second timeslots of the subcarrier of the extension resource carrier includes: transmitting a first symbol in a select one of the first plurality of resource elements that is not the last resource element, wherein the first symbol is a user equipment-specific demodulation reference signal; and transmitting a second symbol in the last resource element of the first plurality of resource elements, wherein the second symbol is other than a user equipment-specific demodulation reference signal. transmitting first and second timeslots of a subcarrier of an extension resource carrier that is aggregated with the primary carrier, the first timeslot having a first plurality of resource elements that are ordered from a first resource element to a last resource element, wherein transmitting the first and second timeslots of the subcarrier of the extension resource carrier includes: transmitting a first symbol in a select one of the first plurality of resource elements that is not the last resource element, wherein the first symbol is a user equipment-specific demodulation reference signal; and transmitting a second symbol in the last resource element of the first plurality of resource elements, wherein the second symbol is other than a user equipment-specific demodulation reference signal. transmitting a first symbol in a select one of the first plurality of resource elements that is not the last resource element, wherein the first symbol is a user equipment-specific demodulation reference signal; and transmitting a second symbol in the last resource element of the first plurality of resource elements, wherein the second symbol is other than a user equipment-specific demodulation reference signal.