With transmit diversity techniques, the multiple antennas at a base station can be used efficiently to improve the system performances. Among them, space-time codes, a transmit diversity technique, are the combination of space diversity and coding, and owing to their simplicity and good performance, they are a good choice for transmitting. This article will explore the advantages and disadvantages of all kinds of diversity and Space-time Block Coding (STBC) in order to prove Maximal ratio combining using minimum mean square error ratio the best combining methods, whereas the size of mobile phones will be very big if it used on mobile phones. Through the further discussion on the performance of system architecture in depth proposed by Alamouti [1], and as a result, we realize the new scheme with one receiving antenna and two receiving antennas is worse than traditional MRRC with one transmitting antenna and four receiving antennas by 3dB. In the same BER, the higher order diversity we use, the smaller SNR it will be, which indicates the importance of considering the tradeoff between the size of the hardware and the system performance.
Diversity RAKE receiver Maximal Ratio Combining Minimum Mean Square Maximal ratio receive combining MRRC Maximum likelihood Space-time block code