Patent ID: 8649448

Claim:
A demapping device for a Modified Dual Carrier Modulation (MDCM) system, comprising: a received signal processing unit to receive an MDCM signal preprocessed by an operation preparation unit, and calculate differences between squares of distances between a received signal and each of a plurality of constellation points, to perform demapping; an index search unit to search for a constellation point closest to the received signal based on the differences between squares of distances between the received signal and the plurality of constellation points; and a demapping operation unit to search for constellation points close to the closest constellation point, and send demapping result data, obtained by demapping the received signal based on differences between squares of distances between the closest constellation point and each of the constellation points close to the closest constellation point, to a decoding device, wherein the received signal processing unit calculates the difference between the squares of the distances between the received signal and each of the plurality of constellation points using the following equation: E 2 dindex1 −E 2 dindex2 =ar FDE,R [k]+br FDE,R [k+ 50 ]+c|H[k]| 2 +d|H[k+ 50]| 2 where E dindex1 is a distance between the received signal r demap [k] received via subcarrier k and a first constellation point, E dindex2 is a distance between the received signal r demap [k] and a second constellation point, r FDE,R [k] is a real number part of a channel compensation value for the signal r demap [k] received via the subcarrier k, r FDE,R [k+50] is a real number part of a channel compensation value for the received signal received via subcarrier k+50, H[k] is a channel signal corresponding to the subcarrier k, H[k+50] is a channel signal corresponding to the subcarrier k+50, k is an integer of 0 to 49, and a,b,c and d are an integers.