xtended the 3GPP channel model to incorporate the three-dimensional component. In Oestges, Erceg, and Paulraj [11], polarization and scattering matrices are used to propose a stochastic geometry- based scattering model for the multipolarized MIMO channel. Jiang, Thiele, and Jungnickel recently proposed a simple representation of the polarized MIMO chan- nel [10]. In their work, the cross-polarized two-dimensional channel is represented as a modified copolarized two-dimensional channel according to the polarization mismatch. We follow the representation in Jiang et al. [10] later to explain intuitively the measurement results with XPD antennas. Therefore, we represent (11.1) where means element-wise multiplication, Op is the polarization rotation angle, and H2x2 is the standard 2 X 2 MIMO channel model using copolarized antennas given as H2x2 h11 h2 21 h222 h12 22 © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology TU campus 200 m Figure 11.25 A depiction of measurement track. 11.4.2 Measurement Setup A brief description of the measurement setup is as follows. For the downlink, two transmit antennas were used at the BS and two receive antennas at the UE. Two sets of measurements were performed: one with XPD antennas (+45°) at the BS and the other with copolarized antenna elements (each 45°). Both the antenna measurements were taken without precoding. At the UE, XPD antennas were used in all measurements. The two copolarized antennas at the BS were placed on top of each other with an antenna spacing of 10A. This was to ensure uncorrelated trans- mit signals. The same antennas were used in the cross-polarized measurement. The BS antennas had a down tilt of 12°. The UEs were separated by about 1 m and faced different directions. The measurement track is depicted in Figure 11.25. For brevity, we summarize the transmission parameters in Table 11.2. 11.4.3 Single-User Throughput Analysis 11.4.3.1 Channel Characteristics The measured channel characteristics for validation of 