Abstract of my proposed project
Keywords: Time-varying multipath fading channel, Channel estimation, Channel equalization, Error correcting coding
In this research project, the principle and practice of non-linear error correcting codes, jointly considering channel estimation and equalization, for slowly and fast multi-path fading channels will be developed, along with their corresponding maximum-likelihood decoding algorithms. After two years of working on this subject, we have found a common mathematical property that all good (non-linear) codes have to satisfy for fading channels. Based on this property, we can construct codes by rules, not by computer searches, which have comparable performance to the computer-searched optimal code by Skoglund. Moreover, a maximum-likelihood recursive decoding metric formula for sequential decoding algorithms for our codes has been established. Our achievement made feasible the combining-estimation-and-equalization codes over the fading channels. As a result, reaching high transmission rate in a highly mobile environment may become an achievable goal by the introduction of our codes.
Introduce to myself
I come from a normal family in Tainan, with my father serving in a bank and mother. My family education told me to always try my best in accomplishing every task and grab every opportunity given. My family provided a suitable learning environment. It cared and expectations positively affected my behavior and way of life. On the other side, it also taught me several ethical teachings, one of which stated, “Life should be embraced by being thankful.” Its valuable lessons encouraged me to become a highly self-respected individual. My outdoor activities include: jogging, Tai-Chi and swimming.
I believe that, “Put yourself in other people's shoes”. There has been increasing disappointments regarding young people my age being less self-disciplined and more self-centered. I have been involved in many community service activities such as children career and orphanages work through school. By doing volunteer work, not only have I learned to appreciate every human being, in spite of their races, religions and cultural backgrounds, I learned to be more helpful and considerate.
I am not afraid to try new things. The field in which I am interested in is mainly working on research and development of communications, mathematics and statistics. I am determined to face possible new challenges ahead and I know I can make very positive contributions to our research society.
My professional capacity
I received my B.S. degree with the second best grade among all undergraduates in the department of information and computer engineering, Chung-Yuan Christian University, in 1994, and M.S. degrees in communications engineering from National Chiao Tung University (NCTU), Taiwan, Republic of China, in 2000. I am currently studying toward my Ph.D. degree in the department of communications engineering, NCTU, Taiwan.
I performed well in my undergraduate study, and received the top-level grade in most of the major courses such as Operating System, System Programming, Computer Organization, and Digital Circuit Design. My master thesis was on the measurement and its analysis for voice over IP traffic. During July 2000 to October 2000, I worked at Telephone and Networking Communications Equipment Corporation, in which I was assigned the task of developing a CELP-based vocoder for Microsoft Windows ACM. As only a part-timer, I developed an approach that adds slight redundancy to the packets transmitted so that the codec can survive potentially bursty packet-loss in Internet. This approach was later patented in Taiwan. Later, I served in the Chinese Army, Taiwan for two years, during which I was a second lieutenant of the Communications Development Office, Ministry of National Defense. I was in charge of an E1 receiving system for satellite communications, which is used to parse the signals capturing from enemy's satellites. After fulfilling his military service, I was admitted to the Ph.D. program in the department of communications engineering, NCTU, Taiwan, and became the assistant lecturer of a network experimental course. The students who enrolled to this experimental course need to experiment on protocols including wireless LAN, CATV, SMNP, SDL and other state-of-the-art network architectures. From July 2005 to December 2005, I visited the department of mathematics and statistics, Queen's University, Canada, together with his advisor.
The graduate courses that I had taken include Digital Communications, Random Process, Digital Signal Process, Decision and Estimation, Real Analysis, Operation Research, Information Theory, and Queueing Theory. My Ph.D. research subject is mainly on how to design a code with channel estimation and equalization capability, which can be used to combat the highly time varying nature of channels without additional estimation and equalization circuitries.
My motivations to take part in this program
The motivations that I want to participate in the DAAD program are the most advance telecommunications industries and researches in Germany and my PhD research topic which is also from a German scientist’s publication. It is no doubt that German’s telecommunication companies have the up-to-day technologies of communications engineering, for example: Siemens, Becker…and so on. The research of communications in Germany is also the one of the leading countries in the world. Actually, my PhD dissertation is following a Germany scientist’s result.Channel estimation and equalization for highly time-varying channels are generally considered a difficult research subject. Up to the present, no effective techniques were shown to be able to survive very high-bit-rate transmission over a highly mobile environment. This is perhaps due to that the present wireless communication receiver separates the functional blocks of channel estimation and channel equalization, as well as channel coding, in system design. Such separate system design simplifies their development and implementation, but limits their capability against the time-varying nature of the channel. In 2002, Skoglund, Giese, a German scientist, and Parkvall showed by simulations that a proper joint design of channel estimation, equalization and coding can markedly outperform the a separate design system with genie-aided channel estimation and perfect equalization over a time-varying fading channel. Their results motivate us to research on the subject on how to design a code with channel estimation and equalization capability, which can be used to combat the highly time varying nature of channels without additional estimation and equalization functional blocks.
The non-linear code from Skoglund, Giese and Parkvall, which was used to demonstrate the potential of joint system design in performance, was obtained by computer search, and is irregular in code structure. Thus, there exists no efficient decoding scheme for their code. In addition, no systematic code construction rule was found. These make their finding of less use in practice. My dissertation therefore focuses on a systematic construction of possibly non-linear codes with channel estimation and equalization capability, following Skoglund, Giese and Parkvall's work, so that the codeword length can be adjustable according to the demand. At the same time, I shall design an efficient decoding algorithm, of maximum-likelihood (ML) whenever possible and feasible in implementation, for his codes.
After two years of hard working on the problem, my advisor and I proved analytically by re-formulating the ML metric for time-varying fading channels that on-the-fly maximum-likelihood sequential decoding even for Skoglund, Giese and Parkvall's non-linear code is attainable. We have also constructed several codes by rules, not by computer searches, which have comparable performance to Skoglund, Giese and Parkvall's code. My current work is focused on the generalization of our code construction rules so that codes with regular structures for any codeword length can be constructed. I wish I can have the opportunity to visit and discuss my research problems with the German scholars who also focus on the similar topics.
