## 1 Introduction
Although some ideas are devised, in order to be useful in real implementations, several key aspects need to be analyzed such as bandwidth, maximum data rate and physical space consumption. For this reason, in this paper, all these issues are analyzed and optimized. In addition, some guidelines for a generic Software Defined Radio (SDR) implementation of algorithms are also outlined. There are many papers where a description of implementation of a specific algorithm is shown; however, to the best knowledge of the authors, no other papers address from this perspective the real implementation of the PAPR algorithm [15]. Since, during the last several decades, the digital signal processing capabilities have been dramatically increased with the Digital Signal Processor (DSP) and the Field Programmable Gate Array (FPGA), the novel devices are able to run complex algorithms and thus many improvements can be obtained. The adoption of these circuits promises an easy adjustment of bandwidth, gain and rate, giving rise to more flexible radio systems. Thus, algorithms that were too complex for being implemented can be afforded now with the consequent improvement on the system performance. FPGAs with their intrinsically parallel structures become the preferred technology choice to overcome the processing and flexibility requirements for future generation systems. The logical outcome of these trends is, without a doubt, digital signal processing carried out by software, known as SDR [16; 17; 18]. In addition, SDR architectures allow a wide range of design techniques to achieve fully flexible transmission/reception systems for future applications. This is especially interesting in vehicular communications because the community is still researching the best transmission scheme and standard. Moreover, it will depend on the application and, since in a vehicular network there are many applications such as passive safety, active safety, entertainment, information, or optimization among others, SDR is a very promising approach. In order to pave the way to this SDR paradigm, powerful hardware is becoming popular for mobile communications devices and thus novel algorithms can be used, such as the one proposed in this paper. However, even with the new powerful advanced architectures and hardware designs, there are limitations on complexity, size, operating frequency, bandwidth and delay that need to be taken into account. Thus, the implementation should be optimized to obtain a useful system architecture. In this paper, the novel system structure and implementation of advanced algorithms for PAPR reduction proposed in [11] is described and analyzed, and some conclusions and guidelines for similar designs are drawn from the optimization process. The paper is organized as follows: Section 2 presents the ECMA-368 standard which is also advised for vehicular systems. The proposed solution is carried out in Section 3. In Section 4, an implementation of the proposed solution is described and analyzed. Then, results are presented and discussed in Section 5. Finally, some conclusions are drawn in Section 6. Notation: in this paper, the following notation is used. Lower faced and capital letters denote time-domain and frequency-domain, respectively. The sub index indicates if the signal is real part or imaginary part because NN can only operate with real-valued numbers and super index is used to specify the algorithm or model being used.