Study log 1 (20141206) in the wireless communication network and 20141206 in the wireless communication network

Study log 1 (20141206) in the wireless communication network and 20141206 in the wireless communication network

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Start with the latest 4G technology today:

1. LTE: (Long Term Evolution, long-term Evolution );

2. Key Technologies of OFDMA (Orthogonal Frequency Division Multiplexing) and MIMO (multiple inputs and multiple outputs) are introduced;

3. Support two standard FDD-LTE (Frequency Division Multiplexing) and TDD-LTE (time division multiplexing), the main difference between the two lies in the physical layer of the air interface (such as frame structure, time division design, synchronization, etc ). FDD-LTE system air port upstream and downstream transmission adopts a pair of symmetric frequency band receive and send data, while TDD-LTE system upstream and downstream transmission uses the same frequency band in different time slots, compared with the FDD duplex mode, TDD has a high spectrum utilization rate.

4. the downstream connection uses OFDMA (Orthogonal Frequency Division Multiplexing), and the uplink connection uses SC-FDMA;

5. The LTE network is called a flat architecture. Compared with 3G networks, the RNC function is removed from the architecture, so that the ENB must have the functions of both the base station and the base station controller;

6. LTE design goals: to provide 100 Mbit/s downstream speed and 50 Mbit/s uplink speed at 20 MHz bandwidth; To improve the transmission performance of marginalized networks, allows seamless integration of Internet applications; Regional latency reduced to 10 ms,

7. LTE network architecture:

Note: An interface is a protocol. It only uses the network architecture for meta-communication. It is not a physical interface.

ENB is connected through the X2 interface;

ENB is connected to MME through the S1-MME interface;

MME and SGW are connected through the S11 interface;

The ENB and SGW are connected through the S1-U interface;

SGW and PGW are connected through the S5 interface;

Connect MME and HSS through the S6 interface;

 

To be continued