essary to provide a flexible data rate (e.g., OFDMA/TDMA). 2.4.2 System Evolution Map When we consider the system evolution, we have to take technology, requirements of users, and other factors such as the consideration from the manufacturers into © 2009 by Taylor & Francis Group, LLC Evolution from TD-SCDMA to FuTURE IMT-Advanced 4G spectrum FuTURE 100 Mbps ~ 1Gbps FuTURE B3G TDD B3G TDD MIMO OFDM 3G and extra spectrum LTE TDD 50 ~ 100 Mbps LTE TDD MIMO-OFDM 10 ~ 20 Mbps, HSxPA/EV 1x HSxPA/EV 1x MIMO, AMC 2 Mbps Figure 2.18 Evolution map from TD-SCDMA to FuTURE TDD system. consideration. We can illustrate the evolution map from Figure 2.18. There should be three steps for evolution from TD-SCDMA to FuTURE TDD: TD-SCDMA will evolve to HSxPA/EV 1x. Nowadays, the deployment of TD-SCDMA is under way in China. People in the 2G age will experience the multimedia services provided by TD-SCDMA very soon. It can support services with data rates up to 2 Mb/s, and the chip rate is 1.28 Mc/s. This course will last for several years. Then the requirement for wireless access will be higher. In order to satisfy the requirement without completely updating the services, it is best for operators to evolve the system to HSxPA/EV 1x, which can adopt more advanced techniques such as MIMO and AMC to achieve higher transmission capability. The chip rate will be higher accordingly. 2. HSxPA/EV 1x will evolve to LTE TDD. As multimedia, Internet, etc. develop, further higher data rate services will be required (as high as 50-100 Mb/s). CDMA cannot perform better due to its technical disadvantages. Hence, MIMO-OFDM will act as the main technique, and LTE-TDD will gradually replace HSxPA/EV 1x. This step is of great importance, C 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology which can be seen as a kind of revolution for wireless access. The opera- tors have to make great changes to equipment. Due to the employment of MIMO, there will be new problems in placing the evolved BS. LTE TDD will e