Design and Implementation of OCQPSK/HPSK Modem using Digital Signal Processors for Software Defined Radio Applications

It is general opinion that the future mobile multimedia networks will use different standards and a prospective solution to this problem will be software defined radio (SDR) techniques. SDR provides the flexibility to support multiple air interfaces and signal processing functions at the same time. Especially, digital signal processors and FPGAs are widely used for implementation of these adaptive and flexible functions of a baseband modem for SDR applications. Also, it is known that the modulation schemes of OCQPSK (Orthogonal Complex QPSK) and HPSK (Hybrid PSK) are used for IMT-2000 services of cdma2000 and WCDMA, respectively. Thus, in this paper, we design and implement an OCQPSK / HPSK modem using a DSP chip of Texas Instrument's TMS320C6701. One modulation scheme is operated by adaptive selection between the two schemes and 5 physical traffic channels differentiated by orthogonal codes are implemented in one DSP chip and each channel has 1Mbps data rates and 8Mcps chip rates.