下面是协议25.321 V7.10.0中的一段，求各位神仙帮我简单理解一下，我是通信菜鸟
时间：10-12
整理：3721RD
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11.6.2.3.2 Reordering functionality
If no timer T1 is active:
- thetimer T1 shall be started when a MAC-hs PDU with TSN > next_expected_TSN iscorrectly received.
- T1_TSNshall be set to the TSN of this MAC-hs PDU.
If a timer T1 is already active:
- noadditional timer shall be started, i.e. only one timer T1 may be active at agiven time.
The timer T1 shall be stopped if:
- theMAC-hs PDU with TSN = T1_TSN can be delivered to the disassembly entity beforethe timer expires.
When the timer T1expires and T1_TSN >next_expected_TSN:
- allcorrectly received MAC-hs PDUs with TSN > next_expected_TSN up to andincluding T1_TSN-1 shall be delivered to the disassembly entity;
- allcorrectly received MAC-hs PDUs up to the next not receivedMAC-hs PDU shall be delivered to the disassembly entity.
- next_expected_TSNshall be set to the TSN of the next not received MAC-hs PDU.
When the timer T1 is stopped or expires,and there still exist some received MAC-hs PDUs that can not be delivered tohigher layer:
- timerT1 is started
- setT1_TSN to the highest TSN among those of the MAC-hs PDUs that can not bedelivered.
If no timer T1 is active:
- thetimer T1 shall be started when a MAC-hs PDU with TSN > next_expected_TSN iscorrectly received.
- T1_TSNshall be set to the TSN of this MAC-hs PDU.
If a timer T1 is already active:
- noadditional timer shall be started, i.e. only one timer T1 may be active at agiven time.
The timer T1 shall be stopped if:
- theMAC-hs PDU with TSN = T1_TSN can be delivered to the disassembly entity beforethe timer expires.
When the timer T1expires and T1_TSN >next_expected_TSN:
- allcorrectly received MAC-hs PDUs with TSN > next_expected_TSN up to andincluding T1_TSN-1 shall be delivered to the disassembly entity;
- allcorrectly received MAC-hs PDUs up to the next not receivedMAC-hs PDU shall be delivered to the disassembly entity.
- next_expected_TSNshall be set to the TSN of the next not received MAC-hs PDU.
When the timer T1 is stopped or expires,and there still exist some received MAC-hs PDUs that can not be delivered tohigher layer:
- timerT1 is started
- setT1_TSN to the highest TSN among those of the MAC-hs PDUs that can not bedelivered.
too difficutl ot understand