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Description:
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Adaptive modulation and diversity combining represent very important adaptive
solutions for future generations of wireless communication systems . Indeed , to
improve the performance and the efficiency of these systems , these two techniques
recently have been used jointly in new schemes named joint adaptive modulation
and diversity combining (JAMDC ) schemes . Considering the problem of finding lowcomplexity ,
bandwidth -efficient , and processing -power efficient transmission schemes
for a downlink scenario and capitalizing on some of these recently proposed JAMDC
schemes , we propose and analyze three fully joint adaptive modulation , diversity
combining , and power control (FJAMDC ) schemes . More specifically , the modulation
constellation size , the number of combined diversity paths , and the needed power
level are determined jointly to achieve the highest spectral efficiency with the lowest
possible combining complexity , given the fading channel conditions and the required
bit error rate (BER ) performance . The performance of these three FJAMDC schemes
is analyzed in terms of their spectral efficiency , processing power consumption , and
error -rate performance . Selected numerical examples show that these schemes considerably
increase the spectral efficiency of the existing JAMDC schemes with a slight increase in the average number of combined paths for the low signal to noise ratio
range while maintaining compliance with the BER performance and a low radiated
power resulting in a substantial decrease in interference to co -existing systems /users . |