IEEE 802.11ac為現在無線區域網路所將要使用標準，而該標準提供了更寬的RF頻寬、更多MIMO空間串流、支援高複雜的調變。因此，我們將針對其 的系統作系統之效能分析。然後應用三種預編碼(precoding)技術，分別是zero-forcing(ZF)預編碼、dirty paper coding(DPC)預編碼以及zadoff-chu matrix transform(ZCT) 預編碼，並討論各預編碼系統效能。
我們會針對系統之峰均值功率比(peak to average power ratio, PAPR) 以及位元錯誤率(bits error rate, BER)做系統效能分析。我們將系統分為未使用二位元迴旋編碼器(binary convolutional code encoder, BCC encoder)、STBC以及預編碼之系統(一);使用BCC但未使用STBC以及預編碼之系統(二);使用BCC、STBC但未使用預編碼之系統(三);使用BCC、預編碼但未使用STBC之系統(四);使用BCC、STBC以及預編碼之系統(五)。我們根據上述5種不同的系統，模擬系統架構並進行系統效能PAPR、BER之比較。最後分析、比較5種不同系統架構若遭受不可避免之載波頻率偏移(carrier frequency offset, CFO)又或者遭受到IQ不平衡(IQ imbalance)干擾時對各系統之BER影響。

IEEE 802.11ac is the latest Wireless LAN standard that used right now, and the standard provides wider RF bandwidth, more MIMO space streamings and support more complex modulation than 802.11n.We will focus on system of 802.11ac to make the analysis. We discussed 3 types of precoding technique: zero forcing precoding, dirty paper code precoding and zadoff-chu matrix transform precoding, then we compared their performance.
We aimed at the system’s peak to average power ratio (PAPR) and bits error rate (BER) to analyze their performance. Futhermore, we compared the PAPR and BER performance or multiple conditions such as basic 802.11ac system, only using BCC 802.11ac system, using BCC and STBC 802.11ac systems, using BCC and precoding 802.11ac system, using BCC, STBC and precoding 802.11ac system. According to the condition suggested by the the above mentioned, we simulated 5 types of system, and compare their performances. Finally, we analyzed whether they suffered carrier frequency offset (CFO) or the IQ imbalance interference base on their BER performance.

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