Wireless over cable in femtocell systems: A case study from indoor channel measurements

In this paper we consider a specific case-study where M indoor femtocells share the same radio resources for communicating to the central office. An outdoor macro-cell base station increases the level of co-channel interference (cross-tier interference). Analysis of the co-tier (arising from neighboring femtocells) and cross-tier interference levels affecting the multi-femtocell communications is based on a site-specific multi-link channel model obtained from a radio measurement campaign carried out at 2.4GHz [3]. In this context, we investigate the benefits of the Wireless over Cable (FemtoWoC) paradigm, based on the concept of deferring the PHY/MAC functionalities to a remote multicell FAP (femtocell access point), while leaving to the in-home device only the analog RF processing (amplify-and-forward -AF). Based on site-specific indoor-to-indoor and outdoor-to-indoor propagation parameters, interference mitigation for the uplink is carried out at the remote multicell FAP by taking into account realistic settings where: i) indoor radio propagation is impaired by Rician fading due to static multi-path fading components; ii) communication over the cable is affected by crosstalk produced by alien xDSL services; iii) imperfect knowledge of the radio channel limits the interference rejection performance at the multicell FAP.