WCDMA RCL层的几个状态变量,高人进

ay_come

最近在看RLC层的协议25.322，对于几个RLC state variables比较困惑。请高人指点。
1.VT(S)  VT(A)  VT(MS) 以及VR(R) VR(H) VR(MR)表示什么意思？
2.比如在AM模式下，RLC在接受和传输数据时是一组一组传输的吗？比如从SN=0到SN=10，等到穿完了，才会继续下一组数据（从SN=11开始）的传输，如果前面一组数据中某个PDU传输中没有收到ACK，就会继续重传，而不会下一组数据的传输，是吗？
3.如果是分组的话，那么是按照什么原则分组的，一组分几个PDU？
协议描述如下，没看明白，具体可以参考25.322   9.4


e RLC shall maintain the following state variables in the Sender.
a)
VT(S) - Send state variable.

This state variable contains the "Sequence Number" of the next AMD PDU to be transmitted for the first time (i.e. excluding retransmitted PDUs). It shall be updated after the aforementioned AMD PDU is transmitted or after transmission of a MRW SUFI which includes SN_MRWLENGTH >VT(S) (see subclause 11.6).
The initial value of this variable is 0.
b)
VT(A) - Acknowledge state variable.

This state variable contains the "Sequence Number" following the "Sequence Number" of the last in-sequence acknowledged AMD PDU. This forms the lower edge of the transmission window of acceptable acknowledgements. VT(A) shall be updated based on the receipt of a STATUS PDU including an ACK (see subclause 9.2.2.11.2) and/or an MRW_ACK SUFI (see subclause 11.6).

The initial value of this variable is 0. For the purpose of initialising the protocol, this value shall be assumed to be the first "Sequence Number" following the last in-sequence acknowledged AMD PDU.
he RLC shall maintain the following state variables in the Receiver:
a)
VR(R) - Receive state variable.

This state variable contains the "Sequence Number" following that of the last in-sequence AMD PDU received. It shall be updated upon the receipt of the AMD PDU with "Sequence Number" equal to VR(R).

The initial value of this variable is 0. For the purpose of initialising the protocol, this value shall be assumed to be the first "Sequence Number" following the last in-sequence received AMD PDU.
b)
VR(H) - Highest expected state variable.

This state variable contains the "Sequence Number" following the highest "Sequence Number" of any received AMD PDU. When a AMD PDU is received with "Sequence Number" x such that VR(H)&pound;x<VR(MR), this state variable shall be set equal to x+1.

The initial value of this variable is 0.
c)
VR(MR) - Maximum acceptable Receive state variable.

This state variable contains the "Sequence Number" of the first AMD PDU that shall be rejected by the Receiver, VR(MR) = VR(R) + Configured_Rx_Window_Size.