Wireless challenge

Broadband wireless technology which allows higher-than-1Gbps data transmission with extremely low transmit power may be necessary in future wireless communication systems. The wireless channel for such broadband transmissions is severely frequency-selective. Frequency-domain wireless signal processing may play an important role in achieving a good signal transmission performance. The multi-carrier (MC) multi-access technique, including OFDMA and MC-CDMA, has been gaining popularity. Meanwhile, it has been shown that the use of frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion improves the transmission performance of single-carrier (SC) multi-access, including DS-CDMA. This suggests that either SC- or MC-based multi-access technique with FDE can be used. Unfortunately, the available wireless bandwidth is limited while a higher-than-1Gbps transmission is demanded. Particular attention has been paid to multi-input/multi-output (MIMO) multiplexing (SDM) to significantly increase the throughput without expanding the signal bandwidth. Besides the broadband wireless signal processing, another practically important issue exists, which is a significant reduction of transmit power. Applying wireless multi-hop technique or distributed antenna technique is a possible solution to this issue. In this talk, we will overview the state-of-the-art broadband wireless technology.