High reliability and early data transmission
A method of high reliability and early data transmission (EDT) is proposed. EDT allows one uplink transmission (optionally) followed by one downlink data transmission during a random-access channel (RACH) procedure, which can reduce the signaling overhead and save UE power. To improve reliability, for uplink EDT, there would be different set of RACH reattempt parameters in the UE for different types of access. For downlink EDT, there would be an indication in the paging message to trigger whether the UE would use legacy RACH or not. Further, the configuration for PRACH resource for EDT can be independent to legacy PRACH resource configuration. Under certain conditions, UE can fallback to legacy RACH procedure for high reliability.
1. A method, comprising:
receiving a paging message from a base station by a user equipment (UE) to establish a radio resource control connection in a wireless communication network, wherein the paging message comprises an indication on whether to allow network-triggered downlink early data transmission (EDT);
initiating a random-access channel (RACH) procedure by transmitting a preamble (MSG 1 ) to the base station over a physical RACH (PRACH) resource;
transmitting a radio resource control (RRC) connection or resume request (MSG 3 ) in response to the paging message to the base station upon receiving a random-access response (MSG 2 ), wherein the UE indicates a preference for downlink EDT by an indication in the RRC connection or resume request in MSG 3 ; and
receiving a contention resolution (MSG 4 ) from the base station, wherein MSG 4 is bundled with downlink data when network-triggered downlink EDT is allowed for the UE as indicated by the indication in MSG 3 .
2. The method of claim 1 , wherein a fixed Radio Link Control Acknowledged Mode (RLC-AM) is applied for the downlink data reliability.
3. The method of claim 1 , wherein the downlink data is always bundled with an RRC command message and tied to RRC reattempts.
4. The method of claim 1 , wherein the UE receives the contention resolution before receiving an RRC response message from the base station.
5. The method of claim 1 , wherein the UE receives the contention resolution together with an RRC response message from the base station.
6. The method of claim 1 , wherein the UE indicates the preference for EDT by bundling a NAS paging response and the RRC connection or resume request in MSG 3 .
7. The method of claim 1 , wherein the bundling of the downlink data with MSG 4 depends on a Quality of Service parameter signaled by the network.
8. A User Equipment (UE), comprising:
a receiver that receives a paging message from a base station to establish an RRC connection in a wireless communication network, wherein the paging message comprises an indication on whether to allow network-triggered downlink early data transmission (EDT);
a random-access channel (RACH) handling circuit that initiates a RACH procedure by transmitting a preamble (MSG 1 ) to a base station over a physical RACH (PRACH) resource;
a transmitter that transmits a radio resource control (RRCI connection or resume request (MSG 3 ) in response to the paging message to the base station upon receiving a random-access response (MSG 2 ), wherein the UE indicates a preference for downlink EDT by an indication in the RRC connection or resume request in MSG 3 ; and
a downlink EDT handling circuit that receives a contention resolution (MSG 4 ) from the base station, wherein MSG 4 is bundled with downlink data when network-triggered downlink EDT is allowed for the UE as indicated by the indication in MSG 3 .
9. The UE of claim 8 , wherein a fixed Radio Link Control Acknowledged Mode (RLC-AM) is applied for the downlink data reliability.
10. The UE of claim 8 , wherein the downlink data is always bundled with an RRC command message and tied to RRC reattempts.
11. The UE of claim 8 , wherein the UE receives the contention resolution before receiving an RRC response message from the base station.
12. The UE of claim 8 , wherein the UE receives the contention resolution together with an RRC response message from the base station.
13. The UE of claim 8 , wherein the UE indicates the preference for EDT by bundling a NAS paging response and the RRC connection or resume request in MSG 3 .
14. The UE of claim 8 , wherein the bundling of the downlink data with MSG 4 depends on a Quality of Service parameter signaled by the network.
15. A method, comprising:
transmitting a paging message by a base station to a user equipment (UE) to establish a radio resource control connection in a wireless communication network, wherein the paging message comprises an indication on whether to allow network-triggered downlink early data transmission (EDT);
receiving a preamble (MSG 1 ) from the UE over a physical random-access channel (PRACH) resource;
transmitting a random-access response (MSG 2 ) to the UE and in response receiving a radio resource control (RRC) connection or resume request (MSG 3 ) from the UE, wherein a preference for downlink EDT is indicated by an indication in the RRC connection or resume request in MSG 3 ; and
transmitting a contention resolution (MSG 4 ) to the UE, wherein MSG 4 is bundled with downlink data when network-triggered downlink EDT is allowed for the UE as indicated by the indication in MSG 3 .
16. The method of claim 15 , wherein a fixed Radio Link Control Acknowledged Mode (RLC-AM) is applied for the downlink data reliability.
17. The method of claim 15 , wherein the downlink data is always bundled with an RRC command message and tied to RRC reattempts.
18. The method of claim 15 , wherein the base station transmits the contention resolution before sending an RRC response message to the UE.
19. The method of claim 15 , wherein the base station transmits the contention resolution together with an RRC response message to the UE.
20. The method of claim 15 , wherein the base station receives the preference for EDT from the UE by receiving a NAS paging response together with the RRC connection or resume request in MSG 3 .