Grouping and Power Allocation for Adaptive Modulation in Multichannel Communications

• Main Authors: Chien-Fan Peng, 彭建帆
• Other Authors: Kuen-Tsair Lay
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/81098795632009718623

碩士 === 國立臺灣科技大學 === 電子工程系 === 97 === The technique of multichannel communication has been intensely investigated in recently years. It offers the feasibility to take into account the different characteristics of different subchannels and thus make the best use of them, typically achieved by adopting adaptive modulation/coding (AMC) schemes and also by power allocation (PA) for the subchannels. One difficulty with the afore-mentioned AMC-PA problem is that the computation complexity becomes prohibitively high as the number of subchannels grows. In this thesis, we try to reduce the computation complexity in the AMC-PA problem, through a method that we call the grouping scheme, wherein the subchannels are divided into a few groups. The same modulation scheme is adopted for all the subchannels in the same group. The grouping scheme consists of three stages. In the first stage, the subchannels are divided into a few groups, wherein each group consists of all the subchannels whose fading gains are close to each other. Then, a modulation scheme is chosen, according to a data rate maximization algorithm, for each group. In the mean time, the power allocated to each group is also computed. The second stage is regrouping, wherein the modulation of the best subchannel in a group has a chance to be upgraded. The third stage is an energy recycling mechanism, through which the bit error rates are lowered. Experimental results show that our regrouping mechanism can achieve a data rate very close to the optimum value (achieved when each subchannel is treated as a single group of its own). At the price of this slight decrease in data transmission rate, however, the computation complexity is greatly reduced.