What is the difference between TD LTE and LTE TDD?

What is the difference between TD LTE and LTE TDD, and what is the connection between TD LTE and LTE FDD? What is the principle of TD LTE and LTE FDD dual-mode chips?

-TDD is the separation of the uplink signal and the downlink signal by time, to put it bluntly, the signal in a certain millisecond is either uplink or downlink, so that there will be no interference.

FDD is that the uplink and downlink signals are separated by frequencies, and the signals in a certain millisecond have both uplink and downlink, but they are located at different frequencies, so they do not interfere.

Since the difference between FDD TDD and TDD is only to distinguish the uplink and downlink low-level signals by time or frequency, in addition to the transmitter and receiver of the lowest physical layer, the design of the upper layer can maintain 99% reuse, and the dual-mode chip is made by this principle.

- Generally speaking, the TDD control function is the function of the control plane, that is, the control function of the mobile phone to start, move, call and so on;

The same thing.

TDD is Time Division Duplex.

FDD is Frequency Division Duplex.

The difference between the two LTE modes is not really large, and dual-mode is not difficult.

The second question doesn't understand what it means.

Answer]: 1. The network architecture is different, LTE does not have a base station controller, that is, BSC in 2G and RNC in 3G;

2. TD uses TD-SCDMA, and LTE uses OFDM technology.

3. TD has CS and PS domains, LTE only has PS domains;

4. The frame structure is not the same;

<>TD-LTE is a 4G standard independently developed by China, which is developed from TD-SCDMA (3G network), and LTE-FDD is now the most widely used 4G standard in the world, and more than 90% of more than 200 LTE operators in the world use FDD standards.

Technically speaking, TD-LTE uses time division duplex, while LTE FDD uses frequency division duplex, and there is an essential difference between the two parties. TD-LTE occupies less frequency band, saves resources, has long bandwidth, and is suitable for regional hotspot coverage. FDD is faster and covers a wider area, but it takes up more resources. Suitable for wide-area coverage.

LTE is a long-term evolution of the UMTS technical standard developed by the 3GPP organization. The LTE system introduces key technologies such as OFDM orthogonal frequency division multiplexing and MIMO, which significantly increases the spectrum efficiency and data transmission rate, and supports a variety of bandwidth allocations: 3MHz, 5MHz, 10MHz, 15MHz and 20MHz, etc., and supports the world's mainstream 2G 3G frequency bands and some new frequency bands, so the spectrum allocation is more flexible, and the system capacity and coverage are also significantly improved.

The LTE system network architecture is flatter and simpler, reducing network nodes and system complexity, thereby reducing system latency and network deployment and maintenance costs. The LTE system supports interoperability with other 3GPP systems.

LTE systems are divided into FDD-LTE (Frequency Division Duplexing) and TDD-LTE (Time Division Duplexing) according to duplex mode, and the main difference between the two technologies lies in the physical layer of the air interface (such as frame structure, time division design, synchronization, etc.). The uplink and downlink of the air interface of the FDD system uses pairs of frequency bands to receive and transmit data, while the uplink and downlink of the TDD system uses the same frequency band to transmit data in different time slots, which has a higher spectrum utilization rate than the FDD duplex mode.

Generally speaking, the 4G network standards of the two operators are similar, China Unicom is currently TD-LTE plus FDD-LTE hybrid networking, the two network standards exist at the same time, as for the use of TD-LTE or FDD-LTE network, it depends on the network standard supported by the user terminal and the local network coverage. China Unicom's current TD LTE frequency is 2555-2575 MHz, 2300-2320 MHz (indoor use only) FDD frequency uplink: 1755-1765MHz; Downside:

1850-1860mhz。China Telecom holds both LTE-TDD and LTE-FDD licenses, but now it mainly uses the LTE-FDD standard. In addition, the comparison of the 4G networks of the two domestic operators is as follows:

1. There are two types of LTE system: LTE-FDD and TDD-LTE, that is, frequency division duplex LTE system and time division duplex LTE system.

2. The main difference between the two technologies is in the physical layer of the air interface.

1) The LTE-FDD system uses a pair of symmetrical frequency bands to receive and transmit data for uplink and downlink transmission at the air interface.

2) The TDD-LTE system uses the same frequency band to transmit in different time slots.

3) Compared with FDD duplex mode, TDD has a higher spectrum utilization.

fddtdd

and time-division duplex, i.e., FDD and TDD. Its specific characteristics are:

Two symmetrical frequency channels are used to transmit and receive signals respectively, and there is a certain frequency band protection interval between the transmitting and receiving channels.

The transmitting and receiving signals are carried out in different time slots of the same frequency channel, and are separated from each other by a certain guarantee time. It does not need to allocate frequencies in symmetrical bands, and can flexibly control and change the ratio of the length of the transmit and receive periods within each channel, making full use of limited radio spectrum resources for asymmetric data transmission.

They are time division and frequency division, respectively.

TDD can use asymmetric spectrum.

FDD uses a symmetrical spectrum.

Medium mobile users are mainly using TDLTE networks. China Unicom and China Telecom users then use the FDDLTE network.

Also for 4G networks, what is the difference between TD-LTE and FDD-LTE? Which is better?

What Are the Differences Between TD-LTE and FDD-LTE on 4G Networks? Which is better?

Hello, TD-LTE is actually TDD-LTE, just for publicity needs, and "abbreviated" as TD-LTE. For users, they only need to care about the terminal, tariff, signal situation and network speed, and the tariff and signal level vary from region to region, and now the three do not have commercial LTE networks, which cannot be compared. In terms of speed, if the downlink uses the same spectrum resources, there is no doubt that FDD-LTE is superior, and in terms of terminals, FDD terminals are more and more abundant.

At present, the Ministry of Industry and Information Technology has not yet had a definite result on the distribution plan, and what is known is that China Mobile will definitely use TDD-LTE, and China Unicom and Telecom are still unknown.

Hope it helps