Adaptive Performance Improvement of OFDM Radio over Fiber Systems
Adaptive Performance Improvement of OFDM Radio over Fiber Systems
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DOI：
10.1109/issse.2007.4294550
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发表时间：
2007-08
期刊：
影响因子：
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通讯作者：
B. Umasankar;A. Jayalath;Xavier N Fernando
中科院分区：
文献类型：
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作者：
B. Umasankar;A. Jayalath;Xavier N Fernando
由于大的峰均功率比引起的非线性失真是OFDM系统的主要问题。在本文中，我们提出了一种有效的自适应调制技术，以减轻非线性失真的影响OFDM无线电信号在光纤上传输（无线电光纤：ROF）。首先，我们在主（高）级调制所有子载波。然后，我们确定具有高失真的子载波，并适当地将这些子载波上的调制水平降低到次级水平。这在发射机侧针对每个OFDM符号进行。重复该过程，直到非线性失真低于预定阈值。这种技术被证明可以大大提高BER性能，同时对于具有64个子载波和16 QAM作为主要调制水平和4 QAM作为次要调制水平的系统，数据速率的降低约为4%。
Nonlinear distortion due to large peak to average power ratio is a major concern with OFDM systems. In this paper, we present an efficient adaptive modulation technique to mitigate nonlinear distortion effects of OFDM radio signals transmitted over optical fiber (radio-over-fiber: ROF). First, we modulate all subcarriers at primary (high) level. Then we identify the subcarriers with high distortion and appropriately reduce the modulation level on those subcarriers to secondary levels. This is done at the transmitter side for each OFDM symbol. This procedure is repeated until the nonlinear distortion is below a predetermined threshold. This technique is shown to improve the BER performance considerably while the reduction in data rate for a system with 64 subcarriers and 16 QAM as primary and 4 QAM as secondary modulation levels is around 4%.