  In this paper we propose a novel solution called dynamic spectrum refarming
(DSR) for deploying LTE small cells using the same spectrum as existing GSM
networks. The basic idea of DSR is that LTE small cells are deployed in the GSM
spectrum but suppress transmission of all signals including the reference
signals in some specific physical resource blocks corresponding to a portion of
the GSM carriers to ensure full GSM coverage. Our study shows that the proposed
solution can provide LTE mobile terminals with high speed data services when
they are in the coverage of the LTE small cells while minimally affecting the
service provided to GSM terminals located within the LTE small cell coverage
area. Thus, the proposal allows the normal operation of the existing GSM
networks even with LTE small cells deployed in that spectrum. Though the focus
of this paper is about GSM spectrum refarming, an analogous approach can be
applied to reuse code division multiple access (CDMA) spectrum for LTE small
cells.
