Slow shadowing and macrodiversity in the Capture-Division Packet Access (CDPA)

Flaminio Borgonovo, Michele Zorzi, Luigi Fratta Abstract—Recently, a new method for achieving spectrum reuse in cellular systems, called Capture-Division Packet Access (CDPA), has been introduced. The method uses a single frequency in all cells, and exploits packet switching and packet retransmission as a means to overcome destructive cochannel interference. As the CDPA key factor is packet retransmission, it is also very effective in fighting lognormal shadowing attenuation as long as this attenuation can be considered independent from slot to slot. In this paper we analyze CDPA in presence of “slow shadowing”, to account for situations in which obstacles obscure the receiver for several transmission periods. The results show a severe throughput impairment with respect to the “fast shadowing” model. A variation of CDPA, Macrodiversity CDPA, that uses three corner fed antennas and three packet receivers is analyzed. The numerical results show that M-CDPA is more efficient than CDPA and that it is only slightly affected by both fast and slow shadowing. To further investigate its robustness, a non lognormal slow shadowing model, the hard shadowing model, is also analyzed.