Design of QAM-OFDM Radar-Communication Integrated Signal Based on Golay Complementary sequences

The integration of radar and communication is conducive to improving the utilization rate of hardware resources and spectrum. To address the issue that the communication information in orthogonal frequency division multiplexing (OFDM) integrated signal for radar and communication affects detection performance, an OFDM integrated signal for radar and communication based on precoding was proposed. The communication information of the integrated signal was pre-coded by using the Gray Complementary Sequences (GCS) with better correlation performance to improve the performance of the ambiguity function of the integrated signal and its detection ability. Simulation results show that GCS have better correlation performance compared to M and Gold sequences, and the OFDM integrated signal pre-coded by GCS has lower Peak Sidelobes Ratio (PSLR) and comparable radar performance to LFM.

Hyperchaos-Based Spreading Codes Generator for DS-CDMA Communication Systems

In this paper, we propose a new hyperchaos-based spreading codes generator (HSCG) for multi-users direct sequence spread spectrum (DSSS) communication systems. For experimental validation, we implement the proposed generator in Xilinx FPGA Virtex-5 technology. Contrary to the traditional spreading codes, the proposed HSCG offers interesting statistical properties such as good autocorrelation, very small cross-correlation, no repetition of the generated spreading codes and high degree of security. In addition, the developed hardware architecture used for implementing the HSCG permits to generate simultaneously an infinite number of multi-length spreading codes with high hardware performances in terms of logic area consumption, throughput and latency. Real-time results are given for 32-, 64- and 128-bit chaotic spreading codes. All of these properties are validated and compared with that of classical codes (Gold sequences, Walsh–Hadamard) through bit error rate (BER) performance evaluation in a DS-CDMA system in AWGN and time-invariant multipath channels. With its interesting performances, the proposed HSCG is very useful for the next generations of mobile communication systems.