Node B

Node B:

Node B takes care of

  1. Radio-resource management functions
  2. Air-interface processing

Node B provides functions similar to functions provided by BTS in GSM networks. They are collocated with BTS so as to decrease the UMTS system cost as well as planning limitations. UMTS works at high frequencies greater than that of GSM resulting in less signal coverage range.

Image shows the Node B logical architecture:

Node B Logical Arcitecture
Node B Logical Arcitecture

Node B deals with the radio transmission and reception to/from equipment to cells.

The Responsibilities of Node B are as follows:

1. Open loop power control

2. Inner loop power control

3. RF processing

4. Frequency and time synchronization.

5. Termination of Uu interface from the user equipment. 

6. Power weighting and combining of physical channels.

7. Radio channel coding/decoding.

8. Modulation and spreading/demodulation and despreading of physical channels. 

Must Read>> Modulation/Demodulation

9. Radio channel coding/decoding.

10. Radio environment survey of parameters like signal strength, BER, etc.

11. Termination of RLC, RRC, and MAC protocols for transport channels PCH, BCH.

12. Macro diversity splitting/combining data streams.

13. Termination of MAC protocol for transport channels FACH, RACH.

14. Error detection on transport channels.

15. FEC encoding/decoding and interleaving/deinterleaving transport channels.

Must Read>> Interleaving

16. Multiplexing/demultiplexing of transport channels.

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