Radio resource control (RRC) message segmentation
Methods and apparatus are provided for the RRC message segmentation. In one novel aspect, the UE obtains the size Z of the RRC message and the size limit L of the underlying transmission at layer S of the UE protocol stack, wherein the layer S either the RRC layer, the PDCP layer, or a sublayer between an RRC layer and a PDCP layer. The UE triggers RRC message segmentation upon detecting Z is greater than L. In another embodiment, the layer R of the protocol stack of the UE receives, in order, a sequence of chunks of an RRC message, reassembles of the RRC message, wherein the layer R is selected from a same layer as the layer S and a layer higher than the layer S. In one novel aspect, the size limitation L is either predefined or obtained through network notification or UE inquiry.
1. A method for a user equipment (UE) with a UE protocol stack in a wireless network, comprising:
receiving a radio resource control (RRC) message with a size Z at an RRC layer;
reassembling of the RRC message by concatenating the received RRC message in sequence;
determining if the concatenated RRC message is a complete RRC message by the UE; and
sending the concatenated RRC message to an upper layer of the protocol stack when the concatenated RRC message is determined to be complete.
2. The method of claim 1 , wherein the UE determines the completeness of the RRC message based on at least one procedure selecting from checking corresponding metadata in each chunk of the RRC message, and checking concatenated octets at the RRC layer.
3. The method of claim 1 , wherein the reassembling is performed at a PDCP layer of the UE protocol stack on a PDCP packet data unit (PDU), and wherein the PDCP layer reassembles received data with a next PDCP PDU if a reserved bit of the PDCP PDU header equals 0, otherwise, the PDCP layer delivers reassembled data to an upper layer.
4. The method of claim 1 , wherein the reassembling is performed at the RRC layer by storing and concatenating chunks of the RRC message in a pending queue, and wherein the RRC layer process discarding remainder contents of the pending queue if the concatenated chunks of RRC message is a complete RRC message.
5. The method of claim 4 , further comprising: starting a reassembly timer upon detecting a corrupted RRC message and discarding received chunks of the RRC message upon timer expired and no complete RRC message is reassembled.
6. The method of claim 4 , further comprising: tracking a chunk number of segmented chunks received; comparing the chunk number with a predefined upper limit chunk number; and discarding received chunks of the RRC message in the pending queue when the chunk number is greater than the predefined upper limit chunk number.
7. A user equipment (UE), comprising:
a receiver that receives a radio resource control (RRC) message at an RRC layer;
an RRC message segmentation circuit that reassembles the RRC message by concatenating the received chunks of the RRC message at the layer R in sequence, wherein the UE determines if the concatenated RRC message is a complete RRC message by the UE; an
a protocol stack that sends the concatenated RRC message to an upper layer of the protocol stack when the concatenated RRC message is determined to be complete.
8. The UE of claim 7 , wherein the UE determines the completeness of the RRC message based on at least one procedure selecting from checking corresponding metadata in each chunk of the RRC message, and checking concatenated octets at the RRC layer.
9. The UE of claim 7 , wherein the reassembling is performed at a PDCP layer of the UE protocol stack on a PDCP packet data unit (PDU), and wherein the PDCP layer reassembles received data with a next PDCP PDU if a reserved bit of the PDCP PDU header equals 0, otherwise, the PDCP layer delivers reassembled data to an upper layer.
10. The UE of claim 7 , wherein the reassembling is performed at the RRC layer by storing and concatenating chunks of the RRC message in a pending queue, and wherein the RRC layer process discarding remainder contents of the pending queue if the concatenated chunks of RRC message is a complete RRC message.
11. The UE of claim 10 , further comprising:
a reassembly timer that is started upon detecting a corrupted RRC message and discarding received chunks of the RRC message upon timer expired and no complete RRC message is reassembled.
12. The UE of claim 10 , wherein the UE tracks a chunk number of segmented chunks received, compares the chunk number with a predefined upper limit chunk number, and discarding received chunks of the RRC message in the pending queue when the chunk number is greater than the predefined upper limit chunk number.