Two-tier femtocell networks-comprising a conventional macrocellular network plus embedded femtocell hotspotsoffer an economically viable solution to achieving high cellular user capacity and improved coverage. This paper develops an uplink capacity analysis and interference avoidance strategy in such a two-tier CDMA network with universal frequency reuse. We evaluate a network-wide area spectral efficiency metric called the Operating Contour (OC) defined as the combinations of the average macrocell users and femtocell BS per cell-site that meet a target outage constraint. A contribution of this work is an accurate characterization of the uplink outage probability taking cross-tier power control, path-loss and shadowing into account. Considering worst case interference at a corner femtocell, results reveal that interference avoidance through a time-hopped CDMA physical layer and sectorized antennas allows about a 7x higher femtocell BS density, relative to a split spectrum network with omnidirectional femtocell antennas. These results provide guidelines for the design of robust shared spectrum two-tier networks.
Chandrasekhar and Andrews REF analyzed the uplink capacity and proposed an interference avoidance strategy for the coexistence of femtocells and macrocells in a CDMA network.
Uplink Capacity and Interference Avoidance for Two-Tier Cellular Networks
IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference
IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference
Computer Science