LTE针对TDD特有的设计有哪些？LTE针对FDD和TDD定义了不同的子帧类型 同时根据TDD的特征

1) TDD帧结构：有special subframe;

2) preamble format 4只用于TDD中的UpPTS;

3) 同步信号位置不同

For FDD, the PSCH shall be mapped to the last OFDM symbol in slots 0 and 10;the SSCH shall be mapped to the last second OFDM symbol in slots 0 and 10.

For TDD, the PSCH shall be mapped to the third OFDM symbol in subframes 1 and 6;the SSCH shall be mapped to the last OFDM symbol in slots 1 and 11.

4) HARQ反馈定时不同：包括PUSCH与PHICH之间时延，PDSCH与PUCCH之间时延;

5) HARQ的进程数不同.