Analysis of the influence of OFDM sidelobe interference on Femto rich systems

This paper considers the existence of sidelobe emission in OFDM based rich-Femtocell systems. By modeling the interference from the arbitrary-distributed Femtocells as shot-noise process, the paper analyzes the effect of sidelobe interference on the system performance metrics such as transmission capacity (TC) and area spectral efficiency (ASE). The numerical results calculated for three different OFDM schemes show that, under the circumstance of very high Femto deployment intensity, the rigorous constraints on first-tier, namely the Macrocell outage probability and the reduction of first-tier ASE, prohibit the Femtocells from excessive subband access. Thus the out-of-band emissions contribute significantly to the system performance loss. Further analysis has shown that poor channel condition can even worsen the situation, making the existence of sidelobe interference not ignorable. Among the three schemes, OQAM-OFDM is proved to achieve the best performance. Although OQAM-OFDM has higher requirements of implementation, it is reasonable to be considered as one of the candidate transmission schemes for future Femtocell applications.