Same as 4G, what is the difference between TD-LTE and LTE FDD?
First, TD-LTE saves resources and FDD is fast
LTE FDD adopts frequency division duplex, while TD-LTE is time division duplex.
In order to establish the uplink and downlink channels, FDD is divided by frequency, and on two symmetric frequencies, one manages download and one manages upload. It is like a double lane, the cars in both directions do not interfere with each other and pass through unimpeded. The performance on your cell phone is the feeling of fast speed.
TD-LTE adopts another way. It only uses one frequency, which is responsible for both uploading and downloading. The advantage is that it saves one frequency occupation than FDD, and the resource utilization is higher; the disadvantage of TDD is also obvious, because it is running two-way “traffic” on “one-way road”, TD-LTE can only control the traffic through time (time division duplex), and let the downloading traffic pass for a while, and let the uploading traffic pass for a while. traffic through, and then let the uploaded traffic through. Performance in the cell phone side, will be slower than the FDD network speed.
At present, the theoretical downlink speed of LTE FDD is 150Mbps, and the theoretical downlink speed of TD-LTE is 100Mbps.
Second, TD-LTE is suitable for hot spot area coverage, FDD is suitable for wide area coverage
The advantage of TD-LTE is that he combines upload and download channels into one, and then flexibly controls them through time, for example, the time allocated to download accounts for 70% and upload accounts for 30%, so that you will find that the traffic flow of the whole channel is always full and the resource utilization rate is higher.
Since TD-LTE is so economical, yet not all of it can be adopted.
In the hotspot area with dense users, the frequency band resources are very tight, at this time, the “double lane” of FDD is very wasteful, and TDD is more suitable. But because TDD is limited in uplink, base station coverage is smaller than FDD, therefore, in non-hotspot in wide coverage areas (suburban, township and highway), TDD needs to build more base stations than FDD, the cost is too high.
