Capacity enhancement in quad-sector cell architecture with interleaved channel and polarization assignments

The choice of the spatial frequency reuse and the channel plan in multi-cellular wireless systems plays an important role in effectively combating co-channel interference (CCI) and enhancing system capacity. In this paper, we compare the performance of four different interleaved channel and polarization assignment combinations of three spatial frequency reuse schemes in quad-sector cell architecture. The schemes are further compared with the traditional tri-sector cell cluster size N=3. For the tri-sector cell, a 90 degree sector antenna is proposed while a 60 degree one is chosen for the quad-sector cell. The relative beamwidths, from off-the-shelf antenna radiation patterns, are tradeoffs between minimizing CCI and maximizing the sector coverage at the sector boundaries. We demonstrate that (a) the quad-sector architecture has a higher capacity for 90% area coverage than the tri-sector cell. (b) the combination of interleaved channel assignment (ICA) and interleaved polarization assignment (IPA) offered the most enhanced capacity. For a reuse cluster size N=1, capacity enhancement with combined ICA and IPA measured 45% better than without using any assignment. For N=2, this measured 85% while for N=3, it measured 63%. These improvements pertain to cross-polarization discrimination (XPD) of 6 dB. (c) IPA and rotating channel assignment (RCA) in the tri-sector reuse cluster of N=3 are not effective tools for enhancing capacity