PBCH Repetition Scheduling for Low-SINR MBMS Cell Acquisition
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Solution Overview
Problem
The SINR of physical channels received by UE in cell acquisition subframes is lower than that of PMCH signals in MBSFN subframes, leading to failures in blind detection of the PBCH under poor channel conditions, which affects the successful reception of PBCH in MBMS-dedicated cells.
Innovation Solution
The network device sends the first physical broadcast channel in multiple cell acquisition subframes with a time interval of at least 30 ms, and repeats the transmission in at least one of these subframes, adjusting the transmission based on downlink bandwidth configuration to optimize reception probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical broadcast channel is transmitted in cell acquisition subframes, then terminal device can access MBMS-dedicated cell, but SINR is lower than PMCH signals in MBSFN subframes causing blind detection failure
Solution Approach 1:
The patent applies preliminary action by transmitting the PBCH multiple times in advance across different cell acquisition subframes before the terminal device needs to decode it. This repeated preliminary transmission ensures that at least one instance can be successfully received even under poor channel conditions, thereby improving reception reliability without requiring higher instantaneous SINR.
Solution Approach 2:
The patent implements periodic action by scheduling PBCH transmissions in cell acquisition subframes that occur periodically with intervals of 40ms or more. This periodic repetition allows the terminal device to attempt decoding at multiple time instances, increasing the probability of successful reception while accounting for time-varying channel conditions.
2Reliability
If PBCH is repeatedly transmitted in cell acquisition subframes, then reception probability increases, but air interface resource utilization decreases
Solution Approach 1:
The patent applies partial action by transmitting the PBCH in only some cell acquisition subframes rather than all of them. Specifically, PBCH is transmitted in cell acquisition subframes with intervals of 40ms or more, which is less frequent than maximum repetition. This partial repetition provides sufficient reception probability improvement while minimizing resource consumption compared to continuous repetition.
Solution Approach 2:
The patent changes the transmission parameter by using different time intervals (40ms or more) between PBCH transmissions in cell acquisition subframes. This parameter adjustment optimizes the balance between reception reliability and resource utilization by spacing transmissions appropriately rather than using fixed maximum repetition.
3Ease of operation
If cell acquisition subframes are used for PBCH transmission, then terminal can perform cell acquisition, but time interval requirements reduce transmission efficiency
Solution Approach 1:
The patent applies universality by designing cell acquisition subframes to serve multiple functions: they enable both terminal device cell acquisition (through PBCH transmission) and maintain compatibility with MBMS service transmission requirements. The same subframes support both access functionality and service delivery, improving overall system efficiency without requiring separate dedicated subframes.
Data Source
AI summary
A network device determines downlink bandwidth configuration information corresponding to a terminal device; the network device sends a first physical broadcast channel to the terminal device in a plurality of cell acquisition subframes based on the downlink bandwidth configuration information, where a time interval between every two adjacent cell acquisition subframes in the plurality of cell acquisition subframes is greater than or equal to 30 ms. When a bandwidth configuration value corresponding to the downlink bandwidth configuration information is greater than or equal to a first threshold, the plurality of cell acquisition subframes in which the first physical broadcast channel is sent include at least one first cell acquisition subframe. At least five symbols of the first physical broadcast channel are transmitted in the first cell acquisition subframe.