Multi-cell field trial on a wireless feeder uplink for Small Cells

It is expected that the ever increasing demand for higher data rates in mobile networks will force operators to deploy denser networks using a large number of additional Small Cells (SCs). However, the identification and deployment of new sites is not an easy and therefore a costly project. A major challenge is the required broadband feeder link of new sites to the backhaul network. At locations where copper and fiber are not available, wireless technologies are the alternative which today works well for line-of-sight (LOS) connections where highly directive antennas can be used. High throughput non-line-of-sight (NLOS) wireless links, which are in the focus of this work, are much more difficult to deploy because of increased path-loss and channel fading due to moving scatterers which motivate the use of more homogeneous antennas that come along with increased interference. In this paper, we apply joint signal processing of feeding macro cells (MCs) as one potential lever to solve this interference problem. In particular, we report field trial results of a joint detection (JD) feeder uplink in an urban multi-cell testbed. One focus is on multi-cell channel parameters measured at different SC locations and heights, and another on achievable rates for a deployment using up to four antennas at each SC.