e information for high-performance precod- ing solutions. Even so, quantization of amplitude PMI-A, can be done with a rela- tively smaller number of bits compared to PMI- To compare the different precoding strategies, the SIR for two UEs with the same PL has been simulated for LTE release 8-conforming CBs as well as the pre- viously described codebook CA,PHI The interference is the result of "improper" precoding. Two UEs are using the full bandwidth of 96 RBs. For each RB, the optimum precoder has been selected based on per-RB PMI feedback. Figure 7.22 C 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology V = 30 kmh 4 bit for Amplitude and 6 bit phase, CDF of SIRAbsPhiUE1 40 Symbols Delay LTE based precoding Delayed feedback 4/6 bit ampl/phase precoding Left: LTE CB precoding w/o delay right: ampl/phi = 4/6 bits V = 3 kmh 2 bit for Amplitude and 3 phase, 70 ms delay A/PHI = 4/6 bit Feedback delay: 40 symbols = 2.9 ms V = 30 kmh Delayed feedback w/o delay A/PHI = 2/3 bit feedback delay: 70 ms V = 3 kmh Figure 7.22 Simulation results for different precoding strategies and for differ- ent delays. depicts several simulation results in the form of CDFs of the achievable SIR (note that the two curves are for UE1 and UE2): At the top left-hand side of the figure, LTE-based precoding is compared with CA,PHD where A and PHI are four and six, respectively. Thus, each PMI for each UE has 10 bit and the resulting SIR is, with about 25 dB at 50% CDF value, accordingly high. Compared to this LTE, release 8-based precoding achieves only for about 15% more than 10-dB SIR. On the bottom left-hand side is a simulation with a smaller CB size for A/PHI equal to 2/3. At the 50% CDF value, this results naturally in a smaller SIR compared to the 4/6 case of only 13 dB. Additionally, the effect of delayed feedback is analyzed, which, even for small mobile speeds of only 3 km/h, can be quite detrimental, if the feedback delay is large (here, 70 ms). On the top right-hand side, the same is show