Network-Listening Based Synchronization with Loop-Back Interference Avoidance Using Synchronization Signal

Mitsukuni KONISHI  Sho NABATAME  Daigo OGATA  Atsushi NAGATE  Teruya FUJII  

Publication
IEICE TRANSACTIONS on Communications   Vol.E101-B   No.3   pp.885-896
Publication Date: 2018/03/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2017EBP3122
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
overlaid cell structure,  HetNet,  small cell,  timing synchronization,  network listening,  radio-interface based synchronization,  

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Summary: 
Network-listening-based synchronization is recently attracting attention as an effective timing synchronization method for indoor small-cell base stations as they cannot utilize GPS-based synchronization. It uses only the macro-cell downlink signal to establish synchronization with the overlaying macro cell. However, the loop-back signal from the small-cell base station itself interferes with the reception of the macro-cell downlink signal in the deployment of co-channel heterogeneous networks. In this paper, we investigate a synchronization method that avoids loop-back interference by muting small-cell data transmission and shifting small-cell transmission timing. Our proposal enables to reduce the processing burden of the network listening and mitigate the throughput degradation of the small cell caused by the data-transmission mutation. In addition to this, the network-listening system enables the network listening in dense small cell deployments where a large number of neighboring small cells exist. We clarify the performance of our proposal by computer simulations and laboratory experiments on actual equipment.