Multi-antenna transmission diversity method and device of orthogonal frequency division multiplexing system

Abstract

The present invention relates to a multi-antenna transmit diversity method in wireless communication and discloses a multi-antenna transmit diversity method and apparatus of the orthogonal frequency division multiplexing (OFDM) system to realize the multi-antenna transmit diversity and obtain frequency diversity grain of a coding speed of 1 and to improve the transmitting reliability. In the present invention, before the orthogonal frequency division multiplexing modulation the frequency domain signal is multiplied with different phase sequence, then the signals are performed diversity transmitting through the orthogonal frequency division multiplexing modulation to each antenna to realize the frequency diversity gain and obtain a high coding speed; wherein, the phase sequence can be determined at random and can also be designed as required, thus, the frequency punching effect can be avoided effectively and the channel transmit reliability is improved; in addition, the phase sequence can realize the self-adapting adjustment according to the transmit quality evaluation and feedback of the receiving end and the system robustness is improved; the free setting of the phase sequence improves the flexibility of the multi-antenna transmit diversity system greatly.

Description

technical field [0001] The invention relates to a multi-antenna transmit diversity method in wireless communication, in particular to a multi-antenna transmit diversity method and device for an orthogonal frequency division multiplexing system. Background technique [0002] With the development of wireless mobile communication, users put forward higher and higher requirements for the rate and service quality of wireless communication, and mobile communication technology is also developing rapidly. The development of each generation is the breakthrough of technology and the innovation of concept. The first generation originated in the 1980s, mainly using analog and frequency division multiple access (Frequency Division Multiple Access, referred to as "FDMA") technology. The second generation (2nd Generation, referred to as "2G") originated in the early 1990s, mainly using time division multiple access (Time Division Multiple Access, referred to as "TDMA") and code division m...

AI Technical Summary

Problems solved by technology

Compared with traditional single-carrier transmission systems, the main disadvantage of OFDM is that OFDM is more sensitive to carrier frequency offset and timing errors than single-carrier systems

Obviously, the appearance of the frequency punching effect will greatly reduce the channel transmission performance, especially when the interleaving code and other coding methods are used, the transmission signal itself is regularly interleaved in the transmission code stream. If the signal appears in the frequency blind spot, it will cause serious problems. as a result of

It can be seen that this diversity method has hidden dangers in reliability, which may cause deterioration of channel transmission performance

[0047] Summarizing the above schemes, it can be seen that the cyclic shift of the OFDM symbols transmitted on each antenna in the time domain is equivalent to a phase rotation in the frequency domain, and the frequency responses of different antennas are multiplied by the rotation phase and then superimposed, which strengthens the The frequency selectivity of OFDM sub-channels can obtain frequency diversity gain through channel coding to improve system performance, but the obtained frequency diversity gain is smaller than that obtained by space-time block codes.

[0048] In practical applications, the above scheme will have the following problems: frequency selectivity is completely determined by a parameter of time delay, and the selectivity cannot be flexibly controlled; inappropriate value of time delay will cause some frequency point responses at certain intervals to be Zero, resulting in punching effect, affecting the performance of the decoder and reducing the reliability of transmission

[0049] One of the main reasons for this situation is that the CSD method uses a fixed cyclic shift mechanism to achieve multi-antenna diversity, and the additional fixed phase shift for different OFDM sub-channels causes the frequency hole effect and reduces the channel reliability.

Images