Spectral Efficiency Improvement by Base Station Antenna Pattern Control for Land Mobile Cellular Systems

Takeo OHGANE  

IEICE TRANSACTIONS on Communications   Vol.E77-B   No.5   pp.598-605
Publication Date: 1994/05/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Adaptive Signal Processing in Mobile Radio Communications)
co-channel interference,  cellular system,  adaptive array,  spectral efficiency,  

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This paper proposes using an adaptive array in a base station for signal reception and transmission in order to increase the spectral efficiency without decreasing the cell radius. The adaptive array controls the directivity pattern of the base station to reduce co-channel interference during reception; the same array pattern is applied during transmission to prevent unnecessary illumination. Computer simulation results show that the cluster size can be reduced to one with time division duplexing (TDD), indicating that we can reuse the same frequency group at all cells. Thus, the improvement in spectral efficiency is as much as 16 fold that of an omni-antenna. Moreover, load sharing, which is expected to improve the channel utilization for unbalanced load situations, is available by cell overlapping. Frequency division duplexing (FDD) requires a weight adjust function to be applied for transmission since the difference in frequency between signal reception and transmission causes null positioning error. However, simple LMS-adjusting can provide a cluster size of one as well as cell overlapping when the frequency deference is 5%.