正交分頻多工系統與前置迴旋碼單載波系統於非理想傳輸環境之效能分析

Performance Study of OFDM and SC-CP Systems in Nonideal Transmission Environment

李立翔(Li-Hsiang Lee)

指導教授 ： 馮世邁

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00721

摘要

無資料

關鍵字

正交分頻多工系統 ； 前置迴旋碼 ； 單載波系統

並列摘要

The OFDM system has been a widely adopted technique for both wired and wireless transmission. It is well-known that OFDM systems suffer from the noise enhancement problem due to channel spectral nulls and the PAPR problem. Recently, another new system called SC-CP (single carrier with cyclic prefix) system is receiving growing attention as another wireless transmission technique. This is because the SC-CP system can mitigate the noise enhancement problem and it does not suffer from PAPR problem.

Both of OFDM and SC-CP systems are ISI- and IBI-free if the following two conditions hold. First, the channel is quasi-static, which means the channel does not change during a data block transmission. Second, the length of cyclic prefix (CP) is larger than the channel order. When any of these two conditions is violated, the BER performance will degrade significantly.

In the first part of this thesis, we will consider a special doubly selective channel model. This type of channel is time-varying and hence no longer satisfies the quasi-static condition. We will analyze ISI effect and BER performance of the OFDM and SC-CP systems for conventional ZF FEQ and conventional MMSE FEQ respectively. Then, we derive the exact MMSE FEQ for given channel model and analyze the BER performance.

In the second part of this thesis, we will study the effect of the OFDM and SC-CP system when the CP length is smaller than the channel order. We will derive new MMSE receivers for both systems to improve the BER performance.

The simulation results will validate our performance analysis and we can find that new MMSE FEQ will outperform conventional ZF FEQ and conventional MMSE FEQ.

並列關鍵字

OFDM ； SC-CP ； doubly selective channel ； cyclic prefix

參考文獻

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