【摘要】：Media-based Modulation(MBM)是近年來提出的一種空間復(fù)用技術(shù)。其基本思想是在發(fā)射機(jī)通過廉價(jià)元器件改變發(fā)射天線周圍的射頻特性,從而改變發(fā)射機(jī)與接收機(jī)之間的信道狀態(tài),使發(fā)射機(jī)與接收機(jī)之間可以產(chǎn)生多種信道狀態(tài)。發(fā)射機(jī)利用這些不同的信道狀態(tài)承載信息,發(fā)送到接收機(jī)。MBM可以與傳統(tǒng)的射頻調(diào)制技術(shù)相結(jié)合,既可以發(fā)送信道狀態(tài)信息,又可以發(fā)送射頻調(diào)制信息。因此,MBM相對(duì)于傳統(tǒng)的多天線技術(shù)在系統(tǒng)的頻譜效率和能量效率上存在巨大的潛力。首先,本文研究了 MBM的實(shí)現(xiàn)原理。MBM有兩種工作方式,即可以只發(fā)射信道狀態(tài)信息,還可以發(fā)射信道狀態(tài)信息和射頻調(diào)制信息。通過研究MBM系統(tǒng)的符號(hào)映射規(guī)則,本文提出了一個(gè)等效系統(tǒng)模型。在此系統(tǒng)模型下,針對(duì)MBM系統(tǒng)不同的工作方式,推導(dǎo)并分析了其信道容量。結(jié)果表明MBM在信道容量上存在著巨大的優(yōu)勢(shì)。同時(shí),研究了 MBM系統(tǒng)接收機(jī)的兩種檢測(cè)方式,即最大似然檢測(cè)和球形解碼,并提出了降低復(fù)雜度的球形解碼算法。仿真結(jié)果表明,降低復(fù)雜度的球形解碼算法的誤碼率性能與最大似然解碼相同,而計(jì)算復(fù)雜度相比于最大似然解碼和傳統(tǒng)的球形解碼都有很大程度的降低。然后,由于MBM系統(tǒng)的發(fā)射機(jī)能夠產(chǎn)生豐富的信道狀態(tài),為了進(jìn)一步提高系統(tǒng)的性能,本文研究了 MBM系統(tǒng)的信道狀態(tài)選擇算法。MBM系統(tǒng)可以通過采用一部分對(duì)系統(tǒng)增益較高的信道狀態(tài)來承載和傳輸信息,進(jìn)而降低系統(tǒng)的誤碼率。本文針對(duì)MBM兩種不同的工作方式,提出了兩個(gè)信道狀態(tài)選擇算法即CS-MBM和CS-MSBM。這兩個(gè)算法的原理是最大化系統(tǒng)的最小歐式距離,大大的降低了選擇過程的復(fù)雜度。仿真結(jié)果表明,當(dāng)系統(tǒng)的星座圖具有較高維度時(shí),系統(tǒng)的誤碼率性能很好,當(dāng)系統(tǒng)的星座圖維度較低時(shí),系統(tǒng)的誤碼率性能有少量損失。最后,由于MBM利用信道狀態(tài)承載信息,精確的信道估計(jì)必不可少。然而實(shí)際的信道是時(shí)變的,尤其是在高速移動(dòng)環(huán)境下。因此本文研究了 MBM系統(tǒng)在時(shí)間選擇性信道下的誤碼率性能。為了能夠提高接收機(jī)估計(jì)信道的準(zhǔn)確性,本文推導(dǎo)了 MBM系統(tǒng)中基于最小均方誤差準(zhǔn)則和遞歸最小二乘準(zhǔn)則的信道追蹤算法。理論分析表明,這兩個(gè)算法的復(fù)雜度在宏觀上是相同的,但是具體的實(shí)現(xiàn)過程中遞歸最小二乘算法要復(fù)雜得多。仿真結(jié)果表明兩個(gè)算法都能夠在很大程度上提高系統(tǒng)的誤碼率性能,而且遞歸最小二乘算法相比最小均方誤差算法性能更加優(yōu)越。同時(shí),導(dǎo)頻長(zhǎng)度也影響兩個(gè)算法的性能,導(dǎo)頻越長(zhǎng),兩個(gè)算法的性能越好。
[Abstract]:Media-based Modulation (MBM) is a spatial reuse technology proposed in recent years. The basic idea is to change the radio frequency characteristics around the transmitter antenna through cheap components, thereby changing the channel state between the transmitter and the receiver, so that there can be a variety of channel states between the transmitter and the receiver. The transmitter uses these different channel state information to transmit to the receiver. MBM can be combined with the traditional radio frequency modulation technology to send both channel state information and radio frequency modulation information. Therefore, MBM has great potential in spectrum efficiency and energy efficiency compared with traditional multi-antenna technology. Firstly, this paper studies the implementation principle of MBM. MBM can transmit only channel state information, channel state information and radio frequency modulation information. By studying the symbolic mapping rules of MBM systems, an equivalent system model is proposed in this paper. Under this system model, the channel capacity of MBM system is deduced and analyzed according to the different working modes. The results show that MBM has great advantages in channel capacity. At the same time, two detection methods of MBM receiver, maximum likelihood detection and spherical decoding, are studied, and a spherical decoding algorithm is proposed to reduce the complexity. Simulation results show that the BER performance of the spherical decoding algorithm with reduced complexity is the same as that of the maximum likelihood decoding, while the computational complexity is much lower than that of the maximum likelihood decoding and the traditional spherical decoding. Then, because the transmitter of the MBM system can produce rich channel state, in order to further improve the performance of the system, In this paper, the channel state selection algorithm for MBM system is studied. The MBM system can carry and transmit information by adopting a part of channel state with high system gain, thus reducing the bit error rate of the system. In this paper, two channel state selection algorithms, CS-MBM and CS-MSBM., are proposed for two different working modes of MBM. The principle of these two algorithms is to maximize the minimum Euclidean distance of the system, which greatly reduces the complexity of the selection process. Simulation results show that the BER performance of the system is very good when the constellation diagram of the system has a higher dimension, and the BER performance of the system has a little loss when the constellation dimension of the system is low. Finally, because MBM uses channel state to carry information, accurate channel estimation is essential. However, the actual channel is time-varying, especially in high-speed mobile environment. Therefore, the BER performance of MBM system in time selective channel is studied in this paper. In order to improve the accuracy of receiver channel estimation, a channel tracking algorithm based on minimum mean square error criterion and recursive least square criterion in MBM system is derived in this paper. Theoretical analysis shows that the complexity of the two algorithms is the same in macroscopic, but the recursive least squares algorithm is much more complex in the process of implementation. Simulation results show that both algorithms can greatly improve the BER performance of the system, and the performance of the recursive least squares algorithm is better than the least mean square error algorithm. At the same time, the pilot length also affects the performance of the two algorithms, the longer the pilot frequency, the better the performance of the two algorithms.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN929.5

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本文編號(hào)：2422904