Broadband Spectrum Refarming of CDMA Spectrum for OFDMA Cellular Systems

Conventional spectrum refarming (SR) techniques assemble the legacy services to partial licensed spectrum, and free up the remained spectrum for operating other systems. In this paper, we propose a new broadband SR framework in which the OFDMA system can concurrently share partial or all the CDMA spectrum that contains multiple bands. The interference temperature provided by the downlink isometric random precoded CDMA system is derived, and the in-band and cross-band interferences introduced by the OFDMA system to CDMA system are quantified. With the derived interference temperature and interference power, resource allocation problems of the OFDMA system under full-concurrent and partial-concurrent broadband SR are formulated and solved. Numerical results are provided to evaluate the SR performance, illustrate the advantage of the full-concurrent broadband SR, and show the significance of the CDMA system load planning on the SR performance.