This paper presents key techniques in Long-Term Evolution (LTE) and LTE-Advanced as well as its potential applications. LTE supports peak rates up to 300 Mbps in downlink (DL) and 75 Mbps in uplink (UL), whereas LTE-Advanced would support 1.2 Gbps in DL and 600 Mbps in UL [1]. Since both peak and average throughput are dramatically improved compared to High-Speed Packet Access (HSPA) [2], LTE and LTE-Advanced would enable new applications such as real-time high-definition (HD) video sharing services, which provide new user experiences in wireless communications.