Research on Application of Adaptive Variable-Rate MQAM in VHF/UHF Band
Yong Shan Ding · Jisuanji fangzhen · 2007
Based on the characteristics of electromagnetic wave's propagation over mobile radio channels,the effect of mobile radio fading channels on data transmission was analyzed.Then a communication system working in VHF/UHF band was designed to make high bandwidth efficiency.The core technology of the system is adaptive variable-rate MQAM.It adjusts the modulation level by means of detecting the energy of the received signal,so the problem of adjustment delay could be overcome.The problem exists in methods such as adaptive adjustment by symbol error detection.The results of wireless-channel simulation show that the bandwidth efficiency of this system is more than 3.2bit/s/Hz,which is better than the corresponding index of existing wireless data communication systems in VHF/UHF band.