The RADIO LINK SETUP FAIL was sent by NodeB, so we need to investigate NodeB side.
After analyzing the NodeB mainboard log, it was found that the above problem was caused by Dynamic CE allocation.
Dynamic CE is a software that schedule DSP resources periodically to drive users to achieve a total high and balanced throughput.
There are 2 UL DSPs on BBU, DSP1 and DSP4.
DSP1 controls 4 ASIC chips, and DSP4 controls 2.
When users built on DSP4 cannot grab NDC resources from DSP1, and within DSP1,users built on one chip cannot grab NDC resources from another.
This is why RL failures happen to users that setup on DSP4.
Another module, RM (Resource Manager), guarantees each user with minimun resources and Dynamic CE schedule each accessed user to make most of NodeB resources.
When a new user tries to access,Dynamic CE module may need to release some resources from other users.
When a large amount of users try to access and exhaust NDC resources, and action usch as Add or Reconfigure that need to grab NDC resources between ASIC chips may fail due to Dynamic CE way of fucntion.
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. real-time and embedded systems RACH: UE eNodeB: Random Access Preamble e Cyclic Prefix Sequence UE ID/RNTI Type RA-RNTI UE ID/RNTI Value. The terminal picks a preamble to send the random access message. The preambles in LTE are defined from a Zadoff-Chu sequence. The preamble consists of the cyclic prefix and a sequence. LTE Quick Reference Go Back To Index Home: www.sharetechnote.com. Radio Link Failure (RLF) To be honest I don't think I saw any clear/explicit definition of this term. My personal definition of Radio Link Failure is 'Physical Layer(especially low PHY) break' and in most case this failure is unintentional.
- RRC Connection Setup Failure due to RL Fail.rar (163.3 KB, 175 views)