HARQ Technology The Performance Study

As the quick development of Information Industry, in the field of information transmission, the requirement of transmitting the data efficiently and reliably are increasing. How to decrease the code error rate without increasing the band wide and decreasing the data rate has become the hot problems in the information theory field.The thesis is concerned with hybrid automatic repeat request, which is a combination of forward error control and automatic repeat request.In the wireless communication, the error-correction anti-inference techniques researchers always use are forward error control. That is use the channel code to correct the errors induced from the transmission in the wireless channel. The characters of FEC are high reliability of the channel transmission and the high code rate of the channel code. The short coming are the reliability is low when the receiver has received the error pattern which could not be corrected.Otherwise, the character of the automatic repeat request is: the channel code is not used to correct the errors, the error-detection code is used to check whether the errors exist in the received packet. If the error is detected, the retransmission is started, the packet is retransmitted, until the packet is received correctly. So the character of automatic repeat request is: when the channel condition is bad, each packet is transmitted repeatedly, which lead to low reliability of the channel transmission. But the automatic repeat request could guarantee the correction of the packet, so it has high reliability.There are seven parts in the whole paper as follows:The first chapter, the general situation and background and research meaning of hybrid automatic repeat request are introduced.The second chapter, several error control techniques and their shortcomings are listed. The application of HARQ in the communication system is proposed.The third chapter, the basic principle and system framework are introduced, and the basic principle of type-Ⅰ,Ⅱ,ⅢHARQ and Chase HARQ are introduced and compared.The fourth chapter, the encoding and decoding principle of the convolutional code are listed. The performance and application situation are analyzed.Part five, the parameters of HARQ are researched. The performance of ARQ combined with convolutional code and turbo code are introduced and compared.The six chapter, the principle and performance of ARQ combined with convolutional code are introduced.The seven chapter, the conclusion and the foresight are given.HARQ is a link adaptation technique, it could adapt the data transmission to the channel condition, in order to improve the data transmission. HARQ has been applied in the 3G wireless communication. The 3G system support data transmission, and adopt the high efficient and reliable communication mechanism. HARQ which is combined with ARQ and FEC has high reliability and reliability at the same time...