Research On Equlization Methods For Monobit Digital Receivers In Time Domain

With the development of IR-UWB and that of modern communication technology, the advantages of IR-UWB in indoor short-distance communication start to appear. IR-UWB is a simple and effective technology. Its advantages include:low hardware complexity, low power consumption, low costs and high transmission speed. IR-UWB could cover most of the indoor communication requirements currently.Although UWB communication systems have many great advantages, they did not develop very well in the past decades. One of the main reasons is that it is still hard to realize UWB systems by integrated circuits hardware. Firstly, UWB signals occupy a large bandwidth. The width of the pulse is extremely short. The receiver has to employ ADC with high sampling rate and high resolution. Now it is considerably hard to design and make ADC with high sampling rate and high resolution due to the limited hardware techniques. Secondly, UWB signals have the strong ability to distinguish multi-paths. This ability is useful when we try to get the location of the objects inside a room. However, when applied to communication systems, it will cause severe inter-symbol-interference (ISI). ISI will limit the quality of the systems. In order to solve the first problem, researchers have proposed a solution that employs low resolution ADC to avoid the technique problem. Monobit technology is a specific example. In this paper, we will try to study how to solve the ISI problem in monobit communication systems. We will try to equalize the signal in time domain.The paper is organized as follows:The first chapter is the introduction. We will retrospect the development history of the IR-UWB technology. We will also introduce both the advantages and disadvantages. In the second chapter, we discuss several classical equalization methods in communication systems. In chapter3we propose the monobit ML detection algorithm. In chapter4, we propose another algorithm called the joint Viterbi decoding algorithm (JVDA). We will also derive the BER equation of the ML algorithm and the computational complexity of both algorithms. The simulation results show that JVDA has about1dB SNR gain compared to separate demodulation and decoding. In chapter5, we try to represent the reasons for the SNR gains. Mean while, in chapter3and4we assume that the CSI is known in advance and it is accurate. In chapter5, we propose an algorithm to estimate the CSI by training symbols. We also analyze the character of the UWB indoor channel model. To sum up, the research result in this paper can suppress the ISI in high-speed IR-UWB communication systems effectively. Hence it could increase the probability of realizing the IR-UWB communication systems.