We analyse throughput-delay performance of an unslotted DS-CDMA packet radio network (PRN) using Channel Load Sensing Protocol (CLSP) and packet-length adaptation. This paper shows that while error-correcting channel coding has not yet been effective in heavily-correlated flat fading environments, adapting the length of radio packets to time-varying channel conditions is a simple adaptive technique for maintaining and improving the system performance and the energy efficiency of mobile terminals. In our modeling we study the correlation between fade duration statistics and packet length in a flat Rayleigh fading channel under the effects of imperfect power control and user mobility. The results are used to derive practical and robust adaptation mechanisms and performance characteristics. Number of numerical results is presented. This paper lays groundwork for exploiting adaptive radio possibilities on media access control (MAC) layer in unslotted DS-CDMA PRNs.