UWB Communication System Based on Transmitted Reference
|Course||Communication and Information System|
|Keywords||UWB transmitted reference receiver performance|
Ultra-wideband (UWB) is a new short-range wireless radio technology in recent years. UWB impulse radio systems transmit data by modulation of nanosecond and sub-nanosecond pulse. UWB impulse radio systems has high spectrum utilization ratio, low transmission power and well system security, thus it is very suitable for indoor environment and short-range, high-rate wireless radio systems. It has been a hot spot in current researches.The ultimate purpose of any communication systems is effectively receiving signal and restoring its information, therefore the receiver technology is a core content of UWB system, and have become an important research field now. Most research focus on correlation receiver in UWB impulse radio systems. Correlation receiver need multiplied generated reference to receive signal. According to the produce of UWB correlation template, there are two kinds of UWB radio systems: Locally Generated Reference receiver and Transmitted Reference receiver. The LGR UWB radio system multiplied locally generated reference to receive signal, and use Rake receiver; and The TR UWB radio system multiplied transmitted reference, which is also transmitted UWB radio system and is delayed signal, and use autocorrelation receiver.Rake receiver is mostly used during to its good collecting resolvable multipath components and the improvement of receiving performance. Also the channel estimation is difficult completed for high rate sampling. Because of UWB own characteristic, the design of Rake receiver is more difficult than any other receivers, mainly because the channel eastimation is difficult. The difficult receiver is not suitable for application. Because of the use of the ns level extremely narrow pulse and the multipath UWB channel, the complexity and sensitivity of UWB receiver are increased in order to resolve the multipath signal. In addition, the serious frequency selectivity of UWB channel and the low transmitted power limits of UWB system is a great design challenge to the receiver.To reduce the complexity of the system, Based on the research of the basic transmitted reference (TR) UWB system,and analysis two improved UWB system,blocked-pulse transmitted reference and average transmitted reference UWB system. In TR system, a reference pulse before each data pulse for the purpose of determining the current multipath channel response. As half of the transmitted pulses are always used as pilots in TR-UWB system, the information rate drops by 50%,and waste time and energy resources .The structure of transmitted pulses of average transmitted reference UWB system is the same of transmitted reference UWB system. The neighboring reference pulses of each data pulse are averaged, and used as the correlator template to decode the received data pulses. The simulation indicated that the bit-error performance of average transmitted reference UWB system is more improved than that of transmitted reference UWB system. The relations of the number of averaged reference pulses and the bit-error performance of the average transmitted reference UWB system has been analyzed. Simulation results indicated that the number of averaged reference pulses is more the bit-error performance of the average transmitted reference UWB system is better. The bit-error performance of the average transmitted reference UWB system is tend to converge, when the number of averaged reference pulses reached a certain value.BTR-UWB system changes in the structure of transmitted pulses, the information rate ascend a lot. It transmitted a few reference pulses and some data pulses as a block. The received pilot pulses are averaged, and used as the correlator template to decode the received data pulses, and improving detection performance. The atheory and simulation indicated that the bit-error performance of blocked-pulse transmitted reference UWB system is similar with transmitted reference UWB system.Multi-bit data Transmitted Reference UWB system is proposed as an improved scheme. And I make principle research and the performance analysis. It transmitted a lots of data pulses after each reference pulse. Theses data pulses send different bits of data. Proved through experiments, after a reference pulse to carry different data pulse receiver performance of the system has little effect on this change. Refer to the back of each pulse can carry data signals of different bits, to improve system efficiency of data transmission.Analyze the processes of sending, transmitting and receiving. And discuss its performance of receiving. Simulate the communicate process. The simulation indicated that the bit-error performance of Multi-bit data Transmitted Reference UWB system is closed to that of average transmitted reference UWB system, and is better than those of the basic transmitted reference UWB system and blocked-pulse transmitted reference UWB system. MTR-UWB system is a data and information to enhance efficiency and improve the reception of UWB communications systems.