It is expected that the increasing demand for higher data rates in mobile cellular networks will force operators to deploy denser networks using a large number of additional small cells (SCs). A major challenge coming along with this project is the required broadband backhaul link to connect new sites to the core backbone network. Wireless backhaul technologies work 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 inter-cell interference. The problem of inter-cell interference is well known from the radio access of mobile stations, and one potential solution that was discussed extensively in recent publications is joint multi-antenna signal processing of macro cells (MCs). In this work, we consider joint signal processing of multiple collocated MCs. In particular, we report field trial results of a joint detection (JD) feeder uplink in an urban testbed where one macro site is equipped with six partially overlapping sectors. An evaluation of achievable data rates for different SC deployment scenarios show the great benefit of this approach.