Wireless over cable for femtocell systems

Abstract

Interference control is crucial to reach the expected spectral efficiencies in femtocell systems. Centralized and joint baseband (BB) processing of all femtocell signals can reduce inter-cell/intra-cell interference at the expense of fast signaling and strict synchronization to coordinate the multiple femtocell links. In this article, we revisit the conventional femtocell architecture by proposing the multi-cell baseband processing for interference mitigation based on a distributed antennas system. The proposed configuration resorts to the wireless over cable (WoC) paradigm and is based on the concept of replacing the in-house base station (Femtocell Access Point) with a home-device that simply transfers the analog radio frequency (RF) signals from the air-link to the existing cable connections. These home-devices act as bidirectional amplify-and-forward (AF) relays of air signals toward cable (and vice-versa) by operating a frequency conversion of the wireless spectrum to accommodate the cable specifications and coexistence with other services. Splitting RF processing (at home) from baseband processing (centralized at the nearest street cabinet or central office collecting multiple cables) guarantees that multi-cell processing exploits the same advantages as MIMO systems. The analysis of WoC for twisted pair telephone lines shows the advantages of the FemtoWoC architecture despite the coexistence with other interfering xDSL services over the cable, or the propagation over the widely deployed copper wirelines.