Transceiver design and implementation of a new dual-mode spread spectrum system with DQPSK-HCSOK modulation

Based on the newly proposed cyclic shift orthogonal keying (CSOK) scheme, this paper presents the top-down design and realization of a dual-mode single-carrier/multi-carrier (SC/MC) spread spectrum (SS) system, including a new DQPSK-HCSOK hybrid modulation scheme and associated differential receiver. Packet and preamble formats are also designed for packet detection, CFO compensation, and channel estimation. Compared to the ideally synchronized receiver, the overall receiver degrades by only 1 dB, showing that the proposed system is very robust against the residual CFO. Then the efficient FPGA implementation of the proposed system on Xilinx XtremeDSP platform is described. The hardware can run at 97.276 MHz, and suffers from a slight implementation loss of less than 0.1 dB at 8% PLER, in comparison to the floating-point simulation. Under multipath fading channel, the SC and MC modes perform equally well but the SC transceiver can save a lot of FPGA resources than the MC transceiver.