raming, Mux REF_CLK Add-on Modules Add-on Modules DSP 1 DSP 3 V4FX* LVDS* (CPRI) (MAC) DSP 2 DSP 4 *Notes: V4FX (CPRI) is required only for NodeB Base station Gbit Eth PHY TX/RX1,2* TX/RX 1,2* LVDS is required only for UE or Mini AP If analog RF is used, both LVDS and V4FX (CPRI) slots are used for DAC resp ADC boards (not included in the figure) Master Control clock Application Terminal NodeB interface External components, not integrated in 3 HE modem rack board (front display) Figure 11.7 Functional mapping at the terminal side. Detect: Auto Pk Trig: Free RBOB NHZ Ref: -25 dBn Trace: CI/Wr UBW: 30 kHz Att: 0 d8 SWT: 100 ms SPAN: 180 MHz Center: 2.6 GHz Span: 180 MHz Figure 11.8 Uplink showing a CCD spectrum (left) and downlink (right) plain OFDM spectrum on air. © 2009 by Taylor & Francis Group, LLC Early Real-Time Experiments and Field Trial Measurements RF front ends are both digitally coupled via parallel cable using LVDS and serial 1.2 Gb/s common public radio interface (CPRI), respectively. Measurements of Multiantenna Gains Using a 3GPP-LTE Air Interface in Typical Outdoor and Indoor Scenarios Multiple antenna systems have been considered straightaway for open-loop wireless standards such as IEEE 802.11n because the gains in theoretic results by Telatar [1] are easier to realize in wireless LAN systems. However, in cellular systems, there are intricacies to realize the information theoretic gains. Fundamental issues such as cell size, delay spread, and lack of richness in spatial structure often dampen the theoretic MIMO gains. To overcome these problems, closed-loop concepts of feed- back and adaptation as well as optimal antenna placements are often needed, even in an interference-free channel. In this section, we discuss the important ingredi- ents of our cellular MIMO-OFDM system design. The main focus of this chapter is discussion of multiple antenna gains in the downlink for a single-user case/single- cell scenario. Measurement results with our MIMO configuration test bed have shown throughput excee