在第五代行動通訊技術(5th generation mobile networks, 5G)，正交分頻多工 (Orthogonal Frequency Division Multiplexing, OFDM)是目前主要傳輸系統，然而隨者行動網路的需求，綠能通訊(Greed Communications)和物聯網(Internet of Things, IoT)的系統也逐漸蓬勃發展，而IoT對於通信裝置主要需求為低成本(low cost)、低功耗(low power consumption)，因此索引調變(Index-modulation, IM)藉由可控制資源的開關且可傳送訊息(information)，可以降低功率消耗並減少調變的資源，因此IM是一個不錯的選擇。
在本篇論文中，提出一種新穎的IM調變方式，藉由碼域(code domain)以及頻域(frequency domain)來做為索引值稱為聯合碼以及頻率索引調變(joint code and frequency index modulation, CFIM)，藉由兩個不同域作為索引值可以提高頻譜效率(spectral efficiency, SE)以及能量效率(energy efficiency, EE)，相比傳統的索引調變有不錯的提升，且因為展頻碼(spreading code)的關係可以改善OFDM-IM因控制子載波開關導致發射分集(transmit diversity)下降的缺點，誤碼率(Bit error rate, BER)在瑞利衰落通道(Rayleigh Fading Channel)亦或者是萊斯衰落通道(Rician Fading Channel)都有相當不錯的表現，另外本篇論文最後也提出低複雜度的解調演算法，並且由模擬以及實驗分析結果在不同的演算法之間做選擇，來達到low cost的目的並在複雜度以及BER之間做取捨。

In the 5th generation mobile networks (5G), Orthogonal Frequency Division Multiplexing (OFDM) is currently the main transmission system. However, following the needs of mobile networks, the Internet of Things systems are also gradually booming, and IoT's main requirements for communication devices are low cost and low power consumption. Therefore, Index-modulation (IM) can be controlled by the switching of resources can also transmit information, which can reduce power consumption and reduce modulation resources.
In this paper, a novel IM modulation method is proposed, which uses the code domain and frequency domain as index values, called joint code and frequency index modulation. modulation, using two different domains as index values can improve spectral efficiency (SE) and energy efficiency (EE), which is a good improvement compared to traditional index modulation, and because the spread spectrum The relationship of spreading code can improve the shortcomings of OFDM-IM due to the control of subcarrier switching, which leads to the decrease of transmit diversity, and the bit error rate (BER) in the Rayleigh Fading Channel or Rician Fading Channel that has a very good performance. In addition, this paper also proposes a low-complexity demodulation algorithm at the end, and chooses between different algorithms based on simulation and experimental analysis results. To achieve the purpose of low cost and make a trade-off between complexity and BER.

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