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WP-CDMA (Packet Wideband CDMA) là kết quả của sự hội tụ giữa W-CDMA N / A T1P1 và WIMS W-CDMA của TR46.1 ở Mỹ. Các tính năng chính của đề nghị W-CDMA WIMS được hợp nhất với các nguyên tắc của W-CDMA N / A. Đề nghị sáp nhập đã được trình lên | Radio Interface Protocols 163 UE CRNC I SRNC I 1. MBMSp-t-p control 2. MBMS data p-t-m - 3. Radio Bearer s Decision to move to point-to-point connection lur signalling for CRNC et-Up 4. Radio Bearer Set-Up Complete 5. MBMS data p-t p Figure 7.9. MBMS point-to-point and point-to-multipoint transmissions The UTRAN shall decide based on the number of UEs in a particular cell which mode of MBMS operation to use and if the situation changes the network can transfer the UEs between different states of MBMS reception as indicated in Figure 7.9. Typically there need to be more than just a few UEs to receive the same content in order to make the use of a broadcast channel without power control efficient enough. An example scenario is shown in Figure 7.10 where one cell uses point-to-multipoint while an other cell has only one joined UE which is kept in the point-to-point state. From the MBMS operation point of view CN Figure 7.10 MBMS signalling example for changing to point-to-point connection procedures are obviously simpler if the content is always provided in a point-to-multipoint manner without shifting users back and forth between different states. As the MBMS content flow may vary MBMS-specific paging can be used to save the terminal power. The bits not used in Release 99 on the Paging Indicator Channel PICH can be used for MBMS purposes to prevent UEs from continuous FACH decoding. 164 WCDMA for UMTS As such the MBMS does not cause direct changes to the physical layer and thus it is not addressed in Chapter 6. There are however a few items to note. MBMS data can be detected with selective combining. The physical layer is not impacted as this is based on selection in the RLC layer and a UE may decode the MBMS data from a new cell quickly assuming the UTRAN provides on the MCCH the MBMS neighbouring cell information to allow the UE the necessary details for decoding the data from the other cell if the same service was provided there. Otherwise UE would need to wait .
