FDD LTE and TDD LTE are two different standards of LTE 4G technology. LTE is a high-speed wireless technology from the 3GPP standard. 3G growth reached its end at HSPA+, and mobile operators have already started deploying 4G networks to provide much more bandwidth for mobile users. 4G speed will provide a virtual LAN reality to mobile handsets by offering very high speed access to the Internet to experience real triple play services such as data, voice and video from a mobile network.
LTE is defined to support both the paired spectrum for Frequency Division Duplex (FDD) and unpaired spectrum for Time Division Duplex (TDD). LTE FDD uses a paired spectrum that comes from a migration path of the 3G network, whereas TDD LTE uses an unpaired spectrum that evolved from TD-SCDMA.
TD-LTE does not require a paired spectrum since transmission and reception occurs in the same channel. In FD-LTE, it requires a paired spectrum with different frequencies with a guard band.
TD-LTE is cheaper than FD-LTE since in TD-LTE there is no need for a diplexer to isolate transmission and receptions.
In TD-LTE, it’s possible to change the uplink and downlink capacity ratio dynamically according to the needs. In FD-LTE, capacity is determined by frequency allocation by regulatory authorities, making it difficult to make a dynamic change.
In TD-LTE, a larger guard period is necessary to maintain the uplink and downlink separation that will affect the capacity. In FD-LTE, the same concept is referred to as a guard band for isolation of uplink and downlink, which will not affect capacity.
Cross slot interference exists in TD-LTE, which is not applicable to FD-LTE.
