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Space–Time Processing Không gian-thời gian xử lý (STP) đã trở thành một trong các công nghệ điều tra nhất trong truyền thông không dây là nó cung cấp các giải pháp cho các vấn đề môi trường không dây chẳng hạn như sự can thiệp, băng thông, và phạm vi [25]. Trong chương này, chúng tôi trình bày những nguyên tắc chung của STP và chứng minh những lợi ích lớn từ các ứng dụng của nó. | 125 CHAPTER 8 Space-Time Processing Space-time processing STP has become one of the most investigated technologies in wireless communications as it provides solutions to wireless environment problems such as interference bandwidth and range 25 . In this chapter we present the general principles of STP and demonstrate the major benefits from its applications. 8.1 INTRODUCTION STP signifies the signal processing performed on a system consisting of several antenna elements whose signals are processed adaptively in order to exploit the rich structure of the radio channel in both the spatial space and temporal time dimensions. STP techniques can be applied either to the transmitter or the receiver or both. Fig. 8.1 illustrates different link structures depending on the number of antennas used in receiving or transmitting modes. These options can be associated with both uplink and downlink. Depending on the number of antennas the channel is classified as single input SI or multiple input MI for transmit and single output SO or multiple output MO . When STP is applied at only one end of the link it is usually referred to as a smart antenna technique. When STP is applied at both the transmitter and the receiver MIMO multiple input multiple output techniques are used. Smart antenna and MIMO technologies have emerged as the most promising area of research and development in wireless communications and they are capable of resolving the capacity limitations due to traffic congestions in future high-speed broadband wireless access networks 25 . It has been recently shown that under Rayleigh fading the capacity of a multiple-antenna link increases almost linearly with the number of transmitting antennas provided that there are at least as many receiving antennas as transmitting antennas and the channel gain between each transmitting receiving antenna pair is known to the receiver 195 196 . To achieve this intended increase in capacity various space-time coding schemes have been
