Experimental Results of E-UTRA Downlink with Variable RB Allocation

This paper investigates the effect of the bandwidth allocated to the physical downlink shared channel (PDSCH) and the amount of channel quality indicator (CQI) information that is feedback by the user equipment (UE) via the physical uplink control channel (PUCCH) on the throughput performance of the PDSCH using an E-UTRA laboratory experimental system in SIMO, 2x2 MIMO, and 4x4 MIMO transmissions. Based on the experimental results, we clarify the impact of parameter M in the best-M individual method and derive the sub-optimal M value of four, which achieves nearly the best performance irrespective of the PDSCH transmission bandwidth for the target UE when the sub-band bandwidth is 720 kHz in SIMO transmission. Furthermore, we clarify that when M=4 the best performance is achieved also in the MIMO transmission, and that the gain from adaptive sub-band allocation based on the CQI of each sub-band is smaller than that in the SIMO transmission because the CQI of each sub-band is averaged between codewords and receiver antennas.