| Author | Keattisak Sripimanwat |
| Call Number | AIT Diss. no. TC-00-02 |
| Subject(s) | Wireless communication systems
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| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. TC-00-02 |
| Abstract | This thesis deals with coding techniques based on trellis coded modulation (TCM) and pre-equalization by phase preceding for alleviating the intersymbol interference (ISI) effect in wireless communications. The high transmission rate data through this band-limited channel must be coded efficiently and the signal must be suitably equalized. The following coding and equalization techniques are proposed as new proposals for application in the wireless bandIimited channel. First, the bandwidth preserving TCM scheme in multiple form (MTCM) is investigated and classified based on a new criterion. As a result, the symbol mapping method is proposed to construct a better code. This symbol mapping concept is applied to the conventional TCM set partitioning where the signal subset is mapped onto the suitable adjacent symbol for which the symbol error event probability decreases as a result. Consequently, several new MTCM codes are constructed at throughput (Rb) 1, 1.5, 2.5, and 3 bit/s/Hz. These codes compared to the codes in the literature for AWGN channel achieve a better performance. Next, the pre-equalization method by spiral curve-phase preceding is modified eliminating the drawback of the original spiral curve on amplitude fluctuation. In addition, 0. 5 to 1 dB of preceding gain is achieved by this modification. This modified scheme with uncoded-QPSK signal gives a very significant gain of up to 30 dB compared to equalizing by the well-known sub-optimum soft output equalizer (SSE). The improved TCMIMTCM and the modified spiral curve are proposed in their concatenation form as the main contribution for application in ISI channels. An attractive gain is achieved from this system compared to the system that used SSE with the same TCM scheme. Additional several dB of gain is realized by application of soft precoded-signal detection in the proposed transmission model. For performance verification, the assumption of ISI:free channel with the precoded signal considered as an "equivalent-AWGN" channel, is used in order to explain how the new code with preceding outperforms the system with SSE. Consequently, a new analysis on pure spiral curve-phase preceding for verifying the results of simulations is proposed. A tighter bound for the precoded-QPSK signal is obtained including its extension to higher phase modulation of 8, 16, and 32 PSK. Moreover, the performance of the concatenated TCM/ MTCM with spiral curve-phase preceding is also bounded by an analysis method and it matches quite well with the simulation result. All simulations and theoretical analysis have confirmed that· the proposed transmission model can be applied successfully to the wireless communications through the band-limited (ISI) or frequency selective fading channels. |
| Year | 2000 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. TC-00-02 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Rajatheva, RM.AP.;Ahmed, Kazi M; |
| Examination Committee(s) | Erke, Tapio;Batanov, D.N.;Shwedyk, Ed; |
| Scholarship Donor(s) | The Royal Thai Government; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2000 |