Abstract
In this paper, Collaborative MIMO is introduced to the Uplink of the Long Term Evolution (LTE) system. This technique uses two or more single carrier frequency division multiple access based user equipments (UEs) with single antenna each. These UEs transmit their data collaboratively over the same Resource block (RB). The Evolved Node B (eNodeB) separates the users' data by means of multiuser frequency domain equalization. This increases the whole throughput of the LTE Uplink, while moving the complexity of implementing multiple antennas to the eNodeB. In order to decode the data ZF, MMSE and successive interference cancellation (SIC) are traditionally employed although they don't exploit the full spatial diversity, whereas the standard ML is suffers from exponential complexity. In this paper, we propose a novel Initial Guess based ML (IGML) receiver whose complexity is in the same order of ML receiver of OFDM-MIMO system. Then we introduce a simplified QR-based version of the IGML receiver. We also propose two ordering techniques for the SIC receiver when used in shadowing environment. Various simulation parameters are examined to study the performance. Simulation results reveal that our IGML receiver is better by almost 4.5dB at target BER of 10(-4) compared to the traditional MMSE receiver.