What do Unicom td-lte and Unicom fdd-lte mean?

Unicom LTE system has two standards: FDD-LTE and TDD-LTE, namely frequency division duplex LTE system and time division duplex LTE system. The main difference between them lies in the physical layer of the air interface (such as frame structure, time division design, synchronization, etc. ). FDD-LTE system uses a pair of symmetrical frequency bands to receive and send data transmitted by uplink and downlink over the air interface; The uplink and downlink of TDD-LTE system use the same frequency band to transmit in different time slots; Compared with FDD duplex mode, TDD has higher spectrum utilization. Unicom now has 56 cities covered by TD-LTE/LTE FDD hybrid networking. As follows: Shanghai, Guangzhou, Shenzhen, Chongqing, Zhengzhou, Wuhan, Chengdu, Xi 'an, Changsha, Jinan, Hangzhou, Shenyang, Harbin, Fuzhou, Nanjing, Shijiazhuang, Beijing, Tianjin, Suzhou, Qingdao, Dongguan, Dalian, Ningbo, Changchun, Haikou, Taiyuan, Nanning, Yantai, Xiamen, Kunming and Hefei. Tips: TD-LTE/LTE FDD hybrid networking will be promoted to the whole country, and other cities will be opened one after another.