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

ewinda1989

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.