A new multi-user receiver for PUCCH LTE format 1

In 3rd. Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, when no resources has been assigned in the uplink to a given UE (User Equipment), the ACK/NACK associated with the received packets are conveyed back to the LTE base station through the so-called Physical Uplink Control Channel (PUCCH). In PUCCH, the data streams transmitted by multiple UEs are multiplexed in the frequency-domain with the aid of spreading codes. However, in multi-cell scenarios, the presence of Inter-Cell Interference (ICI) arising from the lack of code orthogonality severely limits receiver performance. In this paper, we propose a new multi-user receiver for PUCCH LTE operating in a cell-cooperative setting. Using the fact that the received signal in PUCCH signaling follows a constrained tensor model, a multiuser receiver based on an iterative joint channel estimation and symbol detection is proposed. The uniqueness conditions of this particular tensor model allows us to derive the maximum number of terminals that can be simultaneously detected at the LTE base station. Simulation results show the remarkable performance gains of the proposed receiver compared to the conventional time-frequency decorrelator based receiver.