earticle

영어

In mobile communications systems, data transmission at high bit rates is essential for many services such as video, high quality audio and mobile integrated service digital network. When the data is transmitted at high bit rates, over mobile radio channels, the
channel impulse response can extend over many symbol periods, which leads to Inter-symbol interference (ISI). Orthogonal Frequency Division Multiplexing (OFDM) is one of the promising technology to mitigate the ISI. In an OFDM signal the bandwidth is divided into many narrow sub-channels which are transmitted in parallel. Each sub-channel is typically chosen narrow enough to eliminate the effect of delay spread. By combining OFDM with CDMA dispersive fading limitations of the cellular mobile radio environment can be overcome and the effects of co-channel interference can be reduced. In this paper, the performances of equalization techniques by considering 2 transmit 2 receive antenna case (resulting in a 2×2 MIMO channel). Assume that the channel is a flat fading Rayleigh multipath channel and the modulation is BPSK.
The ultimate goal is to provide universal personal and multimedia communication without regard to mobility or location with high data rates. To achieve such an objective we need a strong equalization techniques to compensate ISI.
ꠑ Zero Forcing (ZF) equalization
ꠑ Minimum Mean Square Error (MMSE) equalization
ꠑ Zero Forcing equalization with Successive Interference Cancellation (ZF-SIC)
ꠑ ZF_SIC with optimal ordering and
ꠑ MIMO with MMSE SIC and optimal ordering