The joint use of the OFDM waveform for radar as well as for communications has gained high attention recently. One problem that arises from using this waveform is the high spur level that appears on the range-velocity profile where it may eclipse an existing target of relatively small radar cross-section (RCS). This spur is due to nulling some subcarriers such as the DC-subcarrier. Another problem that results from using this waveform is the small maximum range which is far less than the unambiguous range. In our paper, we propose two diverse solutions to overcome the aforementioned problems. The first is based on using the Autoregressive (AR) model to address the problem of the high spur level. The second relies on repeating the same QAM modulated symbol through some subcarriers of the same OFDM symbol to address the problem of the relatively small maximum range. Our analysis and simulations show that applying our proposed methodology contributes to efficiently reducing the spur level from one side, and extending the maximum range to the limit of the unambiguous range from the other side. Furthermore, a trade-off is offered between the data rate of the communication system and the maximum range of the radar.

OFDM波形在雷达以及通信中的联合使用最近引起了高度关注。使用此波形所引起的一个问题是，在距离-速度曲线上出现的高杂散电平可能使现有的目标相对较小的雷达横截面（RCS）黯然失色。这种杂散是由于使某些子载波（如DC子载波）为零而引起的。使用该波形导致的另一个问题是最大范围很小，远小于明确范围。在我们的论文中，我们提出了两种解决方案来克服上述问题。第一种是基于使用自回归（AR）模型来解决高杂散水平的问题。第二种方法依赖于通过相同OFDM符号的某些子载波重复相同的QAM调制符号，以解决最大范围相对较小的问题。我们的分析和仿真表明，采用我们提出的方法有助于从一侧有效降低杂散水平，并从另一侧将最大范围扩展到明确范围的极限。此外，在通信系统的数据速率和雷达的最大范围之间进行权衡。